• • *°C*T^ 1930 Gift of | Alfred C. Redfield Estate 1983 Gat nH3 Oi ffiS SO i ° • Q irn Q BAROMETRIC PRESSURE PAUL BERT Born October 17, 1833. Died November 11. 1886. BAROMETRIC PRESSURE Researches In Experimental Physiology PAUL BERT Translated from the French by MARY ALICE HITCHCOCK, M.A. Formerly Professor of Romance Languages at the University of Akron and FRED A. HITCHCOCK, Ph.D. Associate Professor of Physiology at The Ohio State University 0 I. COLLEGE BOOK COMPANY COLUMBUS, OHIO 1943 Copyright 1943 By COLLEGE BOOK COMPANY F. C. Long, Proprietor THE F. J. HEER PRINTING COMPANY Columbus, Ohio 1943 FOREWORD It can be said of Paul Bert as it has been of Vesalius, Harvey and Boyle, that the full significance of his work could not be fully appreciated until long after his death; but it is tragic that the chaos of a far-flung war was required to bring Bert's work into its full meaning and perspective. At a time when altitude physiologists and flight surgeons are being feverishly trained by all countries at war, it becomes of first importance to English-speaking peoples that the great classic of altitude physiology should be made available in the English language. Copies of the original French edition are exceedingly rare, and one therefore cannot praise too warmly the industry of Professor and Mrs. Hitchcock in preparing the English rendering, and the patriotic foresight of the publishers in thus mak- ing the text available to the flying personnel of our Armed Forces. That such a task could be accomplished in the midst of war is of itself gratifying, for it bears evidence that our perspectives and our scholarly traditions are being maintained and will survive during these years of stress and fury. As Professor Sigerist recently re- marked in reviewing Howard Adelmann's translation of Fabricius, "Today when everyone thinks in military terms I would like to stress that the publication of such a book at such a time also repre- sents a victory equally important to the capture of a strategic hill and more endurable. One can have full confidence in the fu- ture of a nation which in the midst of a bloody war possesses the intellectual and technical resources to produce such a document of scholarship." The details of Bert's life are not widely known and it seems ap- propriate here to give a brief sketch of his meteoric career. Among his contemporaries Bert was probably better known for his pioneer studies on skin grafting — work that did much toward fostering the specialty of plastic surgery during the war of 1870 — than he was for his studies in altitude physiology. Indeed in a notice published in the Lancet on November 20, 1886, shortly after his death, there is no mention of La pression barometrique and little to suggest that Bert was a great physiologist. Born at Auxerre on October 17, 1833, Paul Bert received his early education in the Department of Yonne. He had chosen en- gineering for his profession and had entered the College de St. Barbe with a view to preparing for the polytechnic school. He was dissuaded from this in favor of the law and passed his bar exam- inations successfully. But he soon found the law boring to his inquisitive mind and, for the third time, modified his course of study on becoming acquainted with Gratiolet, the Director of the Anatomical Museum in Paris. He eventually obtained his M.D. degree in 1863 at the age of thirty. During his years at Paris he had come under the influence of Claude Bernard in whose labora- tory he served as an assistant. Bernard recognized his ingenious mind and predicted a brilliant future. His thesis, published in 1866, on the grafting of animal tissues, attracted wide notice, and it won for Bert in 1865 the prize in experimental physiology offered by the Academie des Sciences. After teaching zoology for several years at the Faculte des Sciences at Bordeaux, he was appointed in December 1869 as Bernard's successor to the Chair of Physiology at the Faculte des Sciences at Paris. Bernard at the time occupied two chairs, one at the Sorbonne, the other at the Faculte, and he resigned the latter to make place for his brilliant pupil. During the last two years of the Second Empire, Paul Bert made himself conspicuous in the political world by his uncompromising republicanism and at the fall of the Napoleonic dynasty in 1870, he was rewarded by Gambetta with the Prefecture du Nord. Elected Deputy in 1871, he became noted for his constant opposition to re- ligious congregation, which led eventually to the decrees of expul- sion against the Jesuits, Dominicans and other orders. He was in- sistent that the state schools should be taught not by nuns and friars, but by non-sectarian personnel. In 1881 he was made Min- ister of Public Instruction in Gambetta's famous Grand Ministere, but he fell with his chief after an ephemeral exercise of power. Following the death of Gambetta, Bert's political influence was on the wane and he returned to his scientific pursuits, obtaining a vacant chair in the Academie des Sciences. At the beginning of the year, the attention of the French Government was forcibly drawn to the highly unsatisfactory state of affairs in French Indo-China's Province of Tongking, and it decided to send out a Resident Gen- eral vested with special powers to effect a thorough reorganization. VI Paul Bert was chosen for the post since he had always supported the French colonial policy, and he departed for the East in Febru- ary, 1886. He was enormously active during his first five months at Hanoi and did much to effect a complete reorganization of the Tong- king government; but in November he became suddenly ill and died of dysentery on November 11th, at the early age of fifty-three. Paul Bert's activities had turned to altitude physiology about 1869 as a result of his friendship with a Dr. Jourdanet who had be- come interested in mountain sickness through personal experience while travelling in Mexico. Jourdanet was a wealthy patron of the arts and sciences, and he gave Bert the essential financial support for altitude studies, making it possible for him to develop several low-pressure chambers for man and animal. In the course of his investigations, Bert had sponsored an ascent in a balloon, Zenith, in which various determinations were to be made of the constitu- tion of the upper air (April 15, 1875) . This ill-fated expedition was undertaken by three balloon enthusiasts, MM. Sivel, Croce-Spinelli, and the only survivor of the expedition, Gaston Tissandier. The ac- count of the trip may be given in Tissandier 's words: "I now come to the fateful moments when we were overcome by the terrible action of reduced pressure. At 22,900 feet . . . torpor had seized me. I wrote nevertheless . . . though I have no clear recollection of writ- ing. We are rising. Croce is panting. Sivel shuts his eyes. Croce also shuts his eyes. ... At 24,600 feet the condition of torpor that overcomes one is extraordinary. Body and mind become feebler. . . . There is no suffering. On the contrary, one feels an inward joy. There is no thought of the dangerous position; one rises and is glad to be rising. I soon felt myself so weak that I could not even turn my head to look at my com- panions. ... I wished to call out that we were now at 26,000 feet, but my tongue was paralyzed. All at once I shut my eyes and fell down powerless and lost all further memory." The fatalities on the Zenith were due, in some measure, to com- petitive braggadocio, for the English balloonist, Glaisher, in 1862 had ascended to 24,000 feet and the Tissandier expedition wished to outdo him. They had little notion of the dangers, nor were they aware of the peril of the fixation of ideas that develops under low oxygen tension. Paul Bert began to work actively on respiratory problems early in the seventies, and in 1874 published a preliminary monograph of 167 pages entitled: Recherches expcrimentales sur Vinfluence que les modifications dans la pression barometrique exercent sur les phcno- mcnes de la vie. This is taken up in part with a description of his admirably constructed low-pressure chamber. In 1878 he published VII the book here translated which has become one of the great land- marks of physiology — a book which stands as the very cornerstone of modern altitude physiology, La pression baromctrique. Re- cherches de physiologie expcrimentale , containing 1178 pages and 89 text figures. The first 522 pages deal with the history of altitude physiology up to that date; and if Paul Bert did nothing else, we should be lastingly in his debt for this masterly historical presenta- tion— a model, be it said, for any student wishing to write in the field of medical history. The second part, occupying 518 pages, con- tains experimental protocols; the third and final part, which runs to 118 pages, contains his resume and conclusions, and is again a model of concise, orderly and logical scientific presentation. What precisely did Bert prove? There had been sharp diver- gence of opinion whether mountain sickness was due to diminution of barometric pressure per se, or to diminution of oxygen pressure. Bert performed critical experiments, keeping the absolute pressure of oxygen constant while lowering the total atmospheric pressure, repeating them time and again both in animals and man. By so doing he proved beyond all doubt that the principal symptoms of altitude sickness arise from reduced partial pressure of oxygen and not from diminution of total pressure. He thus applied for the first time to human respiration Dalton's concept of partial pressure which has become the basis of all subsequent work in the field of altitude physiology. In one of his vivid lectures on the history of physiology, Sir Michael Foster said that science travels in circles: the concept fol- lowed yesterday may be dropped today and rediscovered tomor- row. One of those who did not accept Paul Bert's conclusions was that picturesque physiologist of Italy, Angelo Mosso, who main- tained that at altitude one breathed so deeply that carbonic acid was lost with resulting alkalosis, and that oxygen-want played only a small part in mountain sickness, the major symptoms be- ing due to "acapnia"— loss of carbon dioxide. Few in this century, save Yandell Henderson, have paid due attention to Mosso and acapnia, but we are coming once again to heed what he said. More is known now about acid-base relationships in blood and tissues. The carotid sinus reflexes have also been discovered. When blood of low oxygen saturation reaches the carotid sinus, a reflex in- crease in depth and frequency of respiration occurs. The partial pressure of oxygen is a primary and determining stimulus as Bert maintained; but under conditions of low oxygen tension, hyper- ventilation of serious proportions may occur, and we have reason VIII to believe that pilots in the higher altitude ranges may in some circumstances hyperventilate to such an extent as to bring on tetany and even loss of consciousness. Thus the pendulum swings; and if we wish to gain perspective for tomorrow, we look to the past and to the work of men like Robert Boyle, Paul Bert and Angelo Mosso who give us courage and inspiration to face the future. John F. Fulton. Yale University, August 15, 1943. IX TRANSLATORS' NOTE In his preface Paul Bert comments on his use of direct quota- tions in the historical part of this book in the following words, "In my bibliographic research I have repeatedly seen the affirmations of an author changed to negations by a series of translations and analyses." Again in a footnote on Chapter II he calls attention to the fact that a passage which he quotes from the French translation of the account of the balloon flights of Glaisher and Coxwell did not occur in the English text and adds, "Can it have been added by a fanciful translator? Traduttore, traditore" (translator, traitor). This evident distrust of our author for translators has been con- stantly in our minds and our translation is, therefore, somewhat more literal than it might otherwise have been. This policy has resulted in the use of certain words and expressions that are old fashioned; for example, we have used the word hematosis to mean arterialization of blood and we have retained the expression car- bonic acid, even where our author is obviously referring to carbon dioxide. In only two respects have we departed from the plan followed in the French edition. First, the footnotes, instead of being placed at the bottom of the page on which the reference occurs, have been grouped together and put at the end of the several chapters. This method is made mandatory by the mechanics of modern type set- ting, and also greatly improves the appearance of the page. Second, we have added an index. In the French edition there was no index and the detailed table of contents together with the list of illustra- tions was placed at the end of the book. In the English edition these have been moved to the front of the book and the index put at the end. We wish to acknowledge our indebtedness and express our grati- tude to the John Crerar Library of Chicago for the uninterrupted use of a copy of the original French edition of La Pression Baro- metrique over a period of more than two years. Copies of the book XI were also loaned us for shorter periods by the Library of Congress and by the Aero-Medical Laboratory at Wright Field. Photographic copies of the illustrations in the original edition from which the plates for the present volume were prepared were furnished us by the staff of the Wright Field Aero-Medical Laboratory. We are grateful to Colonel Otis O. Benson, Jr., who arranged to have this done. Various agencies of the Ohio State University were of consider- able assistance in a number of ways. Funds to help defray the cost of clerical assistance were furnished by President Bevis, and by the Graduate School upon the recommendation of Dean Alpheus Smith. The staff of the library furnished assistance whenever called upon, and Mr. Oscar Thomas and Mr. John B. Fullen of the Alumni Office were of great assistance in a variety of ways; we are especially grateful to them both. Finally, we want to thank Professor John F. Fulton of Yale University not only for the preparation of the foreword, but also for his enthusiastic support and valuable advice throughout the entire project, and Mr. F. C. Long of the College Book Company, without whose vision and faith in Paul Bert the publication of the complete translation would have been impossible. It is with some hesitation that we turn the manuscript over to the printer. It contains errors and imperfections. Many of these could be corrected by further revision, but such revision takes time and in the present state of the world it seems desirable to make Paul Bert's classic work available to the many English speaking investigators in the field of aviation medicine with as little delay as possible. We have therefore foregone further revision and polish- ing. We know nothing would please Paul Bert more than the knowledge that his work had been of use to the Allied Nations in their struggle to free his beloved country from the shackles of its traditional enemy. Paul Bert was a liberal, a humanitarian, and a loyal patriot, as well as an outstanding scientist. During the months that we have worked on the translation of his great book our admiration and respect for him have grown. It is our sincere hope that we have made none of his affirmations negations and that we have been translators without being traitors. M. A. H. F. A. H. XII TO DOCTOR JOURDANET My dear Colleague: It is to you that I owe, not only the first idea of this work, but also the material means to execute it, which are so difficult to collect. I have been very happy to see physiological experimentation on one of the most important points of my study confirm entirely the theory which your intelligence had deduced from nu- merous pathological observations collected on the high Mexican plateaux. For all these reasons I should dedi- cate this book to you, and I do so with the greater pleasure because you are one of those persons who would make gratitude easy to even the most thankless natures. Paul Bert. XIII PREFACE No one doubts the considerable influence which changes in baro- metric pressure can exercise on living beings; we are even inclined to exaggerate its importance. If the barometric column rises or falls some millimeters, nervous or asthmatic people experience favorable or painful symptoms which they attribute to the heavi- ness or the lightness of the air. If this were really the cause, a walk from the banks of the Seine to the top of the Butte Mont- martre or the converse should produce similar results in the same people. But outside this group of data, to which I shall return in a mo- ment, many remain which present a much greater interest, and which deserve to be studied with perseverance. Are we dealing with increase in pressure? When, in the shafts of a mine or in the caissons intended to become the piers of a bridge, workmen are protected against the invasion of the water by air compressed by powerful machines to several atmospheres, they experience strange and sometimes dangerous symptoms dur- ing or after their stay in compressed air. Likewise divers who gather pearls, sponges, or coral, or attempt the salvage of sunken ships, furnished with diving apparatus and breathing an air whose pressure is proportional to the depth they reach, are frequently stricken by paralysis or death. On the other hand, medicine, mak- ing use of observations that are already old, has attempted with considerable success to make use of the influence of air at suitably low pressures, since the time of Junod, Pravaz, and Tabarie. Are we dealing with decrease in pressure? We can mention first the symptoms which threaten aeronauts when their ascent brings them to heights above 4000 meters: nausea, vertigo, hemor- rhage, syncope; then the phenomena which have been known much longer by all those who have attempted the ascent of mountains of over 3000 to 4000 meters, mountain sickness, about whose cause XV so many strange hypotheses have been suggested. Finally we find here data of a much greater importance. It is no longer a matter of a few workmen, a few invalids, or a few tourists, but of whole populations which normally and regularly live, construct cities, group themselves as peoples, in these lofty places where painful and sometimes unendurable sensations await the traveler. We feel that here our problem affects not only the hygiene of peoples, but also to a certain point, their history and politics. In the Himalayas, in the Cordillera of the Andes, populous cities are built at heights greater than that of our Mont-Blanc, where no one completely escapes mountain sickness; in Mexico, thousands of men live on the plateaux of Anahuac, at an average height of 2000 meters; the great civilizations of the Mayas and the Nahuas had their maximum of development between 2000 and 4000 meters above sea level. The reader can see by this brief survey in what important points the question affects the experimentation to which I have conscientiously devoted myself. It will consequently seem natural that such phenomena have given rise to numerous publications by doctors or travelers; but he will no doubt be surprised that so little has been attempted in laboratory experimentation to explain their cause. The simplest idea apparently would have been to construct apparatuses permitting one to reproduce changes in barometric pressure, isolating them from secondary conditions, uncontrolled variables, which inevitably accompany them in the state of nature, and to examine the immediate results of these changes on man and on animals. Now very little has been done in this direction. On the other hand, we shall find incomplete observations, pretentious dissertations, and probable or absurd explanations in great number. My purpose has been to fill this considerable gap, and to solve these important problems by a purely experimental method. In taking my position thus on solid ground, I had to set aside systematically three kinds of questions which could not be attacked in the laboratory, and for which consequently absolute conditions of proof could not be collected; that is: daily variations of the barometer, therapeutic applications and acclimatization in lofty places. I do not regret the first question, which does not seem to me even to belong to our subject of study. Slight modifications in air pressure revealed by the barometric column in a given place are accompanied by too many other meteorological phenomena (hygro- metric, electric, etc.) for anyone to determine the part, certainly very small, which they play in the condition of certain invalids. XVI \ ■ As to the other two questions, I have made great use of data given by authors who have discussed these topics, and I think that my own studies will not be without value in guiding physicians and hygienists in the midst of the innumerable difficulties which these questions involve. But I have not handled them directly, not only because of my medical incompetence, not only because labora- tory experiments on birds, dogs, or even men could hardly settle them, but also for a special and rather personal reason. Eight years ago, when Dr. Jourdanet, well known for his re- markable studies on the climatology of Mexico and for his theory of the anoxemia of altitudes, offered— with a generosity for which I hope the results of my work might be worthy recompense— to put at my disposal all the material means required by the re- searches whose importance and difficulty I had publicly indicated x in 1868, a sort of tacit agreement was established between us. I was to limit myself to studying experimentally in the laboratory by means of my instruments the modifications which changes in baro- metric pressure would produce in the vital manifestations of ani- mals or plants. Whatever the extent of my experimental equip- ment, these changes evidently could not be of long duration, so that if they were to produce convincing results, it was absolutely necessary that they should be extensive. Besides, this is the pe- culiar characteristic of laboratory experiments. M. Jourdanet properly reserved for himself the study of the effects produced by slight variations in barometric pressure, acting either for a rather brief time upon invalids — a test the exquisite delicacy of which will always terrify experimenters a little— or for years upon the same individuals, or for centuries upon successive generations, joining their effect to those of so many causes known or unknown; dangerous problems, but very likely to fascinate a wise and eager spirit, aided by an eloquent pen. We both accomplished our tasks; two years ago, M. Jourdanet published his fine book, Influence of Air Pressure on the Life of Man: Altitude Climates and Mountain Climates.2 As for me, delayed by efforts outside the field of science, too often called from my laboratory by important civic duties, it is not until today that I present the properly arranged results of my long researches. The present book which, if I am not mistaken, holds interest not only for physiologists, but also for physicians, engineers, and even travelers, is divided into three parts: history, experiments, con- clusions. XVII I have given the greatest pains to editing the history. I have tried to collect all that has been written on the subject of my study. It seemed to me that it would be very interesting for the reader to have thus before him all the pieces of evidence, with infinite variety of narration, frequent contradiction, and often instructive repetitions. I thought it best to give the actual works of the authors quoted: I distrusted even the most conscientious analyses; in my bibliographic research I have repeatedly seen the affirmations of an author changed to negation by a series of translations and anal- yses. Besides, summarizing and analytical chapters rest the mind of the reader; but each of the facts given there finds its proof in the preceding extracts. In the second part my personal experiments are recorded. The titles of the chapters show the order in which I planned their exposition. A glance at the table of contents indicates that after studying directly the influence of changes in barometric pressure, I have devoted a few chapters to new researches on the physio- logical action of carbonic acid, on asphyxia, and on blood gases. The reader will see in perusing these chapters that I have not wandered as far from my subject as this mere statement of topics might imply; the numerous references to this part of my book that I make in my conclusions give evident proof of this fact. In reporting my experiments, which number about 670, I have used the enumerative method; all those which seem to me inter- esting have been reported at length. This method has two advan- tages: first, it furnishes proof of all the conclusions, and second, it sometimes permits the reader to find in the account of the experi- ments what the author did not see there himself. Summaries added to each chapter facilitate rapid perusal of the results obtained. Finally I call attention to the fact that on each point the experi- ments are listed according to their date of performance; one can thus take account of observations which escaped attention at the beginning of the research, of improvements made by the experi- menter, and consequently of the constantly lessening number of causes of errors. Finally the third part is entitled: Recent Data, Summary and Conclusions. I first discuss the history which in the first part I carried down only to my own work. Then I draw conclusions from my whole series of researches. It will be seen that here my agree- ment with M. Jourdanet could not be carried out literally, and that I could not keep from trespassing somewhat on the domain reserved for him. The third and last chapter, whose title is General Conclusions, XVIII contains only three pages. May this temperance in the summary bring me pardon for the eleven hundred and fifty pages which I thought necessary in order to bring the reader to this point! I leave to others the delicate task of deciding whether this antithesis deserves criticism or praise. I shall merely remind the reader, pleading at last extenuating circumstances, that since the Institute did me the honor in 1875, on the recommendation of the Academy of Sciences, of bestowing upon my work the grand biennial prize,3 it seemed to me that it was my duty to spare myself neither time nor trouble to make the publication of my work more worthy of this great award. Before finishing this preface, I must thank M. Grehant and M. Dastre, my assistants in the chair of physiology of the Faculty of Sciences, Dr. Jolyet, assistant director of the laboratory, and M. Paul Regnard, assistant in the course, who aided me in my research with affectionate devotion. P:B October, 1877. 1 See my Lessons on the Comparative Physiology of Respiration; Paris, 1870, pages 121-130. 2 Paris. C>. Masson. 1875. Second edition. 1876. 3 This award of the first order is given every other year, according to the terms of the con- stitutional decree, "to the work or discovery which has made the greatest contribution to the honor or the service of the country" in the last ten years, in rotation for each of the branches of human learning represented by the five classes of the Institute. The triennial prize, by the decree of April 14, 1855, was decreed to M. Fizeau, in 18o6; it was triennial only once, and by the decree of December 22, 1860, at the request of the Institute, it became biennial, and since then the awards have been as follows: To Thiers (Academie franQaise), 1861. To Jules Oppert (Academie des inscriptions et belles-lettres), 1863. To Wurtz (Academie des sciences) , 1865. To Felicien David (Academie des beaux-arts), 1867. To Henri Martin (Academie des sciences morales et politiques) , 1869. To Guizot (Academie franQaise), 1871. To Mariette-Bey (Academie des inscriptions et belles-lettres), 1873. To Paul Bert (Academie des sciences), 1875. To Chapu (Academie des beaux-arts), 1877.— (Editor's note.) XIX TABLE OF CONTENTS First Part HISTORICAL Page Title I. Diminished pressure 3 Preliminary chapter: the lofty regions of the globe. 3 Europe " Asia 10 America *2 15 Africa Islands 15 Summary 16 Eternal snows ^ Living organisms 18 First chapter. Mountain journeys — 22 1. South America 22 The Conquerors. Acosta. De Herrera. Frezier. Bouguer. La Condamine. Don Ulloa. A. von Humboldt. Wars of Inde- pendence. S. Haigh. Miers. Caldcleugh. Schmidtmeyer. Brand. De la Touanne. Temple. Bollaert. D'Orbigny. Poep- pig. Boussingault. Meyers. Ch. Darwin. Smyth and Lowe. Arch. Smith. CI. Gay. Von Tschudi. De Castelnau. Weddell. De Saint-Cricq. Gillis. Lloyd. Grandidier. Burmeister. Markham. Martin de Moussy. Mateo Paz Soldan. Guilbert. Pellegrino Strobel. Focke and Mossbach. Pissis. Wisse. J. Remy. Steubel. 2. Central and North America 59 Wafer. Dollfus and 'de Montserrat. Burkhardt. Elliotson. Glennie. Gros. Truqui and Craveri. Laverriere. Scientific Commission of Mexico. Von Muller. Fremont. Gunnison. Hines. Williamson. Coleman. 3. Etna 69 Bembo. Filoteo. Fazello. Borelli. Riedesel. Demeunier. Houel. Delon. Dolomier. Spallanzani. Ferrara. De Gour- billon. De Forbin. De Sayve. XXI Page 4. Peak of Teneriffe 73 R. Boyle. Edens. Feuillee. Glas. Riche and Blavier. Von Humboldt. Cordier. L. de Buch. Dumont d'Urville. Le Guillou. Ch. Sainte-Claire Deville. Itier. Madame Murray. 5. Alps _' 77 Bourrit. Laborde. De Saussure. Beaufoy. Forneret and Dor- theren. De Lusy. Van Rensselaer. Hamel. Clissold. Clark and Sherwill. Hawes and Fellowes. Auldjo. Meyer. Parrot. Vincent and Zumstein. Molinatti. Hugi. H. Cloquet. Martin Barry. Atkins. Mademoiselle d'Angeville. Desor. G. Studer. Spitaler. Forbes. Lepileur. Bravais. Martins. Chomel and Crozet. Tyndall. Tyndall and Frankland. Pitschner. Piachaud. Lortet and Marcet. Durier. A. Tissandier. Hardy. Tuckett. Kennedy. C. Grove. Visconti. Gamard. Joanne. Ormsby. H. Russell. 6. Pyrenees 120 Rob. Boyle. Dralet. Ramond. Arbassiere. Cordier and Neer- gaard. Parrot. De Franqueville. Russell-Killough. Le Mula- hacen. 7. Caucasus. Armenia. Persia 123 Engelhardt and Parrot. Kupffer. Sjorgrun. Radde. Douglas Freshfield. Gardiner. Rob. Boyle. Tournefort. Parrot. Chodzko. Radde and Siev- ers. Hamilton. Taylor Thomson. R. F. Thomson. 8. Central Asia i 128 Marco-Polo. Hiouen. Tsang. Chinese Itinerary. Missionaries. S. Turner. Th. Hardwicke. Moorcroft. Fraser. Webb. Gerard Brothers. Johnson. V. Jacquemont. Wood. Burnes. Father Hue. Hoffmeister. Th. Thomson. Dalton Hooker. Robertson. Mistress Hervey. Oliver. Cheetam. Semenof. Schlagintweit Brothers. Godwin-Austin. The Pundits. The Mirza. Hayward. Faiz Buksh. Henderson. Hume. Drew. 9. Africa 161 Burton. Mann. Rebmann. De Decken. New. 10. Volcanoes of the Pacific 162 Low. Brooke. Braddel. Rutherford Alcock. Gubbins. Jef- freys. Byron. D. Douglas. Loenenstern. Wilkes. Chapter II. Balloon Ascensions 171 Charles and Robert. Leullier-Duche. Testu-Brissy. Blanchard. De Lalande. Robertson. Garnerin. Zambeccari. Biot and Gay- Lussac. Andreoli. Beaufoy and Sadler. Madame Blanchard. Eug. Robertson. Green. Comaschi. Hobard. Barral and Bixio. Welsh. Glaisher. Croce-Spinelli and Sivel. Simons. Chapter III. Theories and Experiments 195 Acosta. Fr. Bacon. Academy del Cimento. Van Musschenbroeck. Robert Boyle. Huyghens and Papin. Beale. Veratti. Cigna. Darwin. Borelli. Bouguer. Ulloa. Haller. De Luc. Bourrit. XXII Page De Saussure. Fodere. Halle and Nysten. Courtois. Legallois. Dralet. Gondret. Fraser. Govan. Gerard Brothers. Hodgson. H. Cloquet. Clissold. Roulin. J. Davy. Rostan. Cunningham. Burdach. Poeppig. Boussingault. De Humboldt. Junod. Magen- die. Favre. Barry. Martins. Rey. Tschudi. A. Smith. Hill. Maissiat. Flechner. Brachet. Castel. Vierordt. Lepileur. A. Vogt. Father Hue. Przevalski. Pravaz. Payerne. Marchal de Calvi. Speer. Mayer-Ahrens. Lombard. Valentin. Heusinger. Giraud-Teulon. F. Hoppe. Fernet. Longet. Gavarret. Duval. Lombard. Martins. Guilbert. Jourdanet. His discussions with Coindet. Cavaroz. Tardieu. Foley. Liguistin. Leroy de Meri- court. Gavarret. A. Dumas. Scoutetten. Kaufman. Coindet. Gavarret. Von Vivenot. Flemeing. Bouchard. Beclard. Hudson. Piachaud. Lortet. Marcet. Forel. Clifford-Albutt. Dufour. Javelle. Tyndall. Durier. Russell-Killough. Mistress Hervey. Henderson. Drew. Burton. Hunt. Jaccard. Armieux. Gosse. Jourdanet. The Academy of Medicine in 1875. Virlet d'Aoust. Chapter IV. Summary and Criticisms 315 1. Conditions of the appearance of mountain sickness 315 2. Symptoms of mountain sickness 328 3. Theoretical explanations 335 Pestilential exhalations. Electricity. Lack of oxygen in the air. Fatigue, cold. Theories of M. Lortet and M. Dufour. Lessening of the weight supported by the body. Escape of blood gases. Expansion of intestinal gases. Relaxing of the coxo-femoral articulation. Other mechanical actions. Excess of carbonic acid in the blood. Theory of de Saussure and Martins. Theory of M. Jourdanet. Title II. Increased Pressures 353 Chapter I. High pressures 355 1. Diving bells 355 Sturmius. Halley. Spalding. Brize-Fradin. Hamel. Colladon. 2. Apparatuses constructed in the Triger method 358 Papin. Triger. Trouessart. De la Gournerie. Blavier. Pol and Watelle. Comte. Bouhy. Brunei. Cezanne. Regnauld. Babington and Cuthbert. Francois, Bucquoy. Foley. Nail. Hermel. Limousin. Bayssellance. Gallard. Triger. Barella. Eads. Bauer. Malezieux. Unpublished information. 3. Divers with suits 390 Borelli. Halley. Leroy de Mericourt. Denayrouze. Gal. Sampadarios. Chapter II. Low pressures 411 Junod. Tabarie. Pravaz. Milliet. Sandahl. Tutschek. G. Lange. Vivenot. Freud. Elsasser. Panum. G. Liebig. Mayer. Marc. XXIII Page Chapter III. Theoretical Explanations and Experiments 440 Borelli. Musschenbroeck. Haller. Achard. Brize-Fradin. Halle and Nysten. Poiseuille. 'Maissiat. Hervier and Saint-Lager. Pravaz. Pol and Watelle. A. Guerard. Milliet. Eug. Bertin. Hoppe. Francois. Bucquoy. Hermel. Foley. Caffe. Babing- ton and Cuthbert. Sandahl. Tutschek. Vivenot. G. Lange. Elsasser. Panum. G. Liebig. Gavarret. Leroy de Mericourt. Bouchard. Gal. Chapter IV. Summary and Criticisms 489 1. Physiological action of compressed air. A. Phenomena due to compression. B. Phenomena due to decompression. 2. Theoretical explanations. A. Phenomena due to compression. Physico-mechanical explanations. Chemical explana- tions. B. Phenomena due to decompression. Second Part EXPERIMENTS Chapter I. Chemical conditions of the death of animals subjected to different barometric pressures in closed vessels 505 Subchapter 1. Pressures below one atmosphere 507 1. Experimental set-up 507 2. Experiments : 513 A. Experiments on birds 513 B. Experiments on mammals 542 C. Experiments on cold-blooded animals 550 3. Conclusions 552 Subchapter 2. Pressures above one atmosphere 552 1. Experimental set-up 552 2. Experiments 555 A. Compressions with ordinary air 555 B. Superoxygenated air; pressures between one and two atmospheres 560 C. Compressed air at very high pressures. Lethal action of oxygen 565 D. Compression with air of low oxygen content 570 E. Compression with superoxygenated air 571 F. Compression with ordinary air; elimination of carbonic acid 574 3. Conclusions 577 Subchapter 3. Summary and conclusions 578 XXIV 628 Page Chapter II. Gases contained in the blood at different barometric pressures ' 581 Subchapter 1. Operative methods and experimental discussion __. 581 Subchapter 2. Blood gases under pressures less than one atmos- phere 594 1. Experimental set-up 594 2. Experiments - 600 Subchapter 3. Blood gases under pressures greater than one atmosphere 615 1. Experimental set-up 615 2. Experiments - 618 Subchapter 4. Blood gases in asphyxia compared to decreased pressure ■-— Subchapter 5. The quantity of oxygen which the blood taken from the vessels can absorb at different barometric pressures 641 1. Pressures lower than one atmosphere 643 2. Pressures greater than one atmosphere 654 Chapter III. Phenomena presented by animals subjected to pressures less than one atmosphere 660 Subchapter 1. Symptoms of decompression 661 1. Respiration _' 666 2. Circulation 669 3. Digestion 672 4. Nervous and muscular effects 673 5. Nutrition 675 Chemical phenomena of respiration. Urinary excretion. Sugar of the liver and blood, glycosuria. Temperature. Development. 6. Lower limit of pressure 685 7. Death 687 Subchapter 2. Comparison of the phenomena of decompression with those of asphyxia in closed vessels 689 Subchapter 3. Means of warding off the symptoms caused by de- compression 694 Chapter IV. Action of compressed air on animals 709 Subchapter 1. Toxic action of oxygen at high tension 709 2. The diminution of oxidations caused by oxygen poisoning 743 3. Aquatic or invertebrate animals 751 Subchapter 2. Action of compressed air at low pressures - 754 1. Short stay in compressed air 756 A. Experiments made upon myself 756 XXV Page B. Production of urea; experiments on dogs 764 C. Chemical phenomena of respiration 765 D. Pulmonary capacity 768 E. Intra-pulmonary pressure 771 F. Arterial pressure 773 2. Prolonged stay in compressed air 775 Chapter V. Influence of changes in barometric pressure on plant life 780 Subchapter 1. Pressures less than one atmosphere 782 1. Germination ._ 782 2. Vegetation 787 Subchapter 2. Pressures above one atmosphere 788 1. Germination 788 A. High pressures with air of low oxygen content 792 B. Normal pressure; superoxygenated air 793 C. Low pressures; superoxygenated air 794 2. Vegetation 797 Subchapter 3. Summary 798 Chapter VI. Action of changes in barometric pressure on ferments, poisons, viruses, and anatomical elements 799 Subchapter 1. Fermentations by organisms 800 1. Putrefaction 800 A. Meat 800 B. Blood 817 C. Eggs 819 2. Coagulation of milk 820 3. Alteration of the urine 823 4. Brewer's yeast 826 5. Wine ferments 827 6. Molds 831 Subchapter 2. Diastatic fermentations 834 1. Saliva and diastase 835 2. Pepsin 837 3. Inversive ferment of yeast 838 4. Myrosin 838 5. Emulsin 839 Subchapter 3. Action of oxygen at high tension upon anatomical elements 839 Subchapter 4. Use of oxygen at high tension as an experimental method 842 1. Dry rot of fruit 843 2. Ripening of fruits 844 3. Venoms 845 4. Viruses 846 XXVI Page A. Vaccine 846 B. Glanders 847 C. Anthrax 847 Subchapter 5. Summary 849 Chapter VII. Effects of sudden changes in barometric pressure— . 852 Subchapter 1. Effects of sudden increases in pressure 852 Subchapter 2. Effects of sudden decreases in pressure beginning with one atmosphere 853 Subchapter 3. Effect of sudden decrease in pressure beginning with several atmospheres 859 1. Decompression without interruption 859 A. Experiments on sparrows 859 B. Experiments on rats 861 C. Experiments on rabbits 861 D. Experiments on cats 861 E. Experiments on dogs 863 2. Slow decompression in several stages 874 3. Summary and conclusions from the preceding experiments 878 Subchapter 4. Prophylaxis and treatment of the symptoms of sud- den decompression 890 Subchapter 5. Summary 895 Chapter VIII. Various questions 896 Subchapter 1. Action of carbonic acid on living beings 896 1. Lethal tension of carbonic acid in ambient air 896 2. Lethal concentration of carbonic acid in the blood 899 3. Accumulation of carbonic acid in the tissues 910 4. Symptoms and mechanism of carbonic acid poisoning 914 5. Action of carbonic acid on lower living beings 924 6. Summary and conclusions 927 Subchapter 2. Asphyxia — 928 Subchapter 3. Observations on the gases of the blood 935 Third Part RECENT DATA, SUMMARY AND CONCLUSIONS - 947 Chapter I. Decreased pressure 949 Subchapter 1. Observations, theories, and recent discussions 949 Bouchut. Chabert. Dufour. Forel. Thorpe. Tempest An- derson. Calberla. Ward. Vacher. Croce-Spinelli, Sivel and G. Tissandier. Stoliczka. Campana. Jourdanet. XXVII Page Subchapter 2. Summary and practical applications 980 1. Aeronauts 981 2. Mountain travellers 991 3. Dwellers in high places 998 4. Animal and plant life at high elevations 1005 5. Medical applications 1006 Chapter II. Increased pressure 1009 Subchapter 1. Observations, theories, and recent discussions 1009 1. High pressures 1009 Guichard. Heiberg. 2. Low pressures. Medical apparatuses 1014 J. Pravaz. G. Liebig. Leonid Simonoff. Subchapter 2. Summary and practical applications 1021 1. High pressures 1021 2. Low pressures^ _i 1024 3. Sudden decompression 1027 4. Practical applications. Therapeutics and hygiene 1027 5. Conclusion from the point of view of general natural history 1032 Chapter III. General conclusions 1036 Addenda I. Relations between heights and barometric pressures 1039 II. The new work of Dr. Mermod 1041 Index — 1045 XXVIII Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 8. LIST OF ILLUSTRATIONS Page Lortet. Respiratory tracing taken at Lyons (200 meters) 112 Lortet. Respiratory tracing taken at the summit of Mont Blanc (4810 meters), after resting an hour 112 Cupelain: Chamounix (1000 meters) - 113 Grands-Mulets (3000 meters) at midnight, half an hour before starting H3 Summit of Mont Blanc (4810 meters) 113 The construction of a bridge pier by the use of caissons 369 Diver equipped with the Denayrouze regulator, complete suit 391 Diver equipped with the Denayrouze regulator, helmet re- moved 392 Fig. 9. The aerotherapeutic establishment of Dr. Carlo Fornanini at Milan 412 bis. Respiratory modifications in compressed air 423 Circulatory modifications in compressed air - 424 Circulatory modifications in compressed air 424 Circulatory modifications in compressed air 425 Circulatory modifications in compressed air 425 Circulatory modifications in compressed air 430 Apparatus with four plates for experiments on decreased pressure 508 Mercury pump set up for the extraction of the gases of the blood 510 Composition of confined air which has become lethal at pres- sures below one atmosphere 524 Variations in the tension of the oxygen contained in com- pressed air which has become lethal at various pressures less than one atmosphere 527 Relations between the oxygen tension, duration of life, and capacity of vessels 531 Cylindrical glass apparatus for high pressures (25 atmos- pheres) set up for superoxygenated air 554 Confined air which has become lethal under pressure 568 XXIX Fig. 9. Fig. 10. Fig. 11. Fig. 12. Fig. 13. Fig. 14. Fig. 15. Fig. 16. Fig. 17. Fig. 18. Fig. 19. Fig. 20. Fig. 21. Fig. 23. Fig. 24. Fig. 25. Fig. 26. Fig. 27. Fig. 28. Fig. 29. Fig. 30. Fig. 31. Fig. 32. Fig. 33. Fig. 34. Fig. 35. Page Fig. 22. Confined air which has become lethal under pressures from 20 centimeters to 24 atmospheres 576 Graduated syringe for the extraction of blood 582 Mercury pump set up for the extraction of the gases of the blood 583 Small mercury reservoir 588 Bellows for artificial respiration 591 Large apparatus for the study of low pressures 595 Dog prepared to be placed in the cylinders of Fig. 27, and for the extraction of blood under decreased pressure 596 Different forms of cannulae for the extraction of blood under decreased pressure 598 Extraction of the blood of an animal under decreased pres- sure 599 Decrease of the quantities of Oa and C02 contained in the arterial blood, when the barometric pressure is diminished 608 Percentage decrease of the 0= and the C02 of the arterial blood when the barometric pressure is diminished,-- 611 Large compressed air apparatus, cylinder of sheet steel cap- able of withstanding a pressure of 12 atmospheres 616 Extraction of blood from an animal placed in compressed air 618 Variations of the gases of the blood at pressures above one atmosphere 623 Fig. 36. Increase of the oxygen of the arterial blood from 0 to 10 atmospheres and from 0 to 26 atmospheres 624 Dog breathing air from a rubber bag 629 Variations of the gases of the blood and the oxygen of the air in asphyxia in closed vessels, when the carbonic acid is absorbed 633 Variations in the gases of the blood in asphyxia compared to decreased pressure 635 Decrease of the gases of the arterial blood and the venous blood when the tension of oxygen breathed decreases 639 Flask arranged for saturating blood with oxygen under dif- ferent decompressions 644 Water motor shaking the flask containing the blood to be saturated with oxygen 645 Capacity of the blood for absorbing oxygen at pressures be- low one atmosphere 648 Apparatus to bring blood into contact with the air at a speci- fied decrease in pressure 650 Apparatus for saturating blood with air at high pressures 654 Oxygen capacity of the blood from a vacuum to 18 atmos- pheres of air 656 Modification of the number of respiratory movements under the influence of decompression. (Dogs, rabbits) 667 Same (Guinea pig, Experiment CCXXVII) 668 XXX Fig. 37. Fig. 38. Fig. 39, Fig. 40. Fig. 41. Fig. 42. Fig. 43. Fig. 44. Fig. 45. Fig. 46. Fig. 47. Fig. 48. Fig. 50. Fig. 51. Fig. 52. Fig. 53. Fig. 54. Fig. 55. Fig. 56. Fig. 57. Fig. 58. Fig. 59. Fig. 60. Fig. 61. Fig. 62. Page Fig. 49. Simultaneous modifications of the number of respiratory- movements R and pulse P under the influence of decom- pression; (Cat, Experiment CCXXI) 670 Same (Dog, Experiment CCXVIII) 671 Same (Dog, Experiment CCXVII) 671 Consumption of oxygen and production of carbonic acid at different pressures 677 Asphyxia without carbonic acid 691 Maxima and minima of cardiac pressure in asphyxia without carbonic acid 692 Bird in air progressively rarefied and oxygenated 695 Respiration of superoxygenated air expanded by decrease of pressure 697 Sudden modifications in the pulse rate by intermittent respi- ration of superoxygenated air 699 Modifications in the pulse rate, during decompression, result- ing from the continuous respiration of oxygen (Experi- ment CCLVI) 705 Same (Experiment CCLVII) 707 Dogs poisoned by oxygen 739 Dog during tonic convulsions of oxygen poisoning 741 Apparatus of M. Jourdanet for the therapeutic use of com- pressed or expanded air 757 Fig. 63. Gas meter for the measurement of the respiratory move- ments 758 Fig. 64. Apparatus with double valve for the study of respiration___ 759 Fig. 65. Apparatus for the chemical study of the respiration of an animal kept for any specified time in air of constant composition ^ 766 Fig. 66. Apparatus for the observation of variations in the intrapul- monary air tension 771 Variations of the intra-thoracic tension. Normal pressure___ 772 Same. Compressed air 772 Tension of the blood in the femoral artery. Normal pressure 773 Same. Compressed air 773 Tension of the blood in the carotid artery. Normal pressure 774 Same. Compressed air 774 Same. Normal pressure 774 Oxygen consumption and carbonic acid production by a piece of meat in an atmosphere of constant oxygen content 813 Death by carbonic acid; changes in the air of the bag (Experi- ment DCXV) 915 Death by carbonic acid; changes in the composition of the gases of the blood, the respiration, and the circulation (Experiment DCXV) 917 XXXI Fig. 67. Fig. 68. Fig. 69. Fig. 70. Fig. 71. Fig. 72. Fig. 73. Fig. 74. Fig. 75. Fig. 76. Page Fig. 77. Death by carbonic acid; relation of the respiration and the circulation to the carbonic acid content of the blood (Experiment DCXV) 919 Fig. 78. Death by carbonic acid; last respiratory movements (Experi- ment DCXV) 920 Fig. 79. Death by asphyxia in a closed vessel; gases of the air (Exper- iment DCXL) 932 Fig. 80. Same; gases of the blood (Experiment DCXXXIV) 932 Fig. 81. Relation between the oxygen content of the air and that of the blood 933 Fig. 82. Pulse at the Riffel Pass (2780 meters), during an attack of mountain sickness 955 Pulse at the Sattel-Tolle (4300 meters) 955 Pulse at the Riffel (2569 meters), rest on the return trip 956 Pulse at Morges (380 meters), absolute repose 956 The basket of the Zenith at a high altitude 966 Diagram of the high altitude ascension on April 15, 1875 970 Portrait of Sivel 972 Portrait of Croce-Spinelli 973 Fig. 83. Fig. 84. Fig. 85. Fig. 86. Fig. 87. Fig. 88. Fig. 89. XXXII Part I HISTORICAL Title I DIMINISHED PRESSURE Preliminary Chapter THE LOFTY REGIONS OF THE EARTH The effects produced upon the organism by a great and sudden decrease in the barometric pressure can be observed in three dif- ferent cases: mountain journeys, balloon ascensions, and experi- ments under pneumatic bells. These last two methods were absolutely unknown to the an- cients. Galileo, as everyone knows, was the first to have a clear idea of the pressure of the air; it was not until 1640 that Toricelli invented the barometer, or until 1650 that Otto de Guericke in- vented the pneumatic machine. In 1648, at the suggestion of our great Pascal, Perier made at Puy-de-D6me the memorable experi- ment in which he saw the height of the barometric column de- crease in proportion to the increase of the altitude of the place where it was observed. For balloons, the discovery is still more recent. The first hot air balloon which carried aloft Pilatre du Rozier and the Marquis d'Arlandes, ascended from Paris November 22, 1783; a few days after, December 1, Charles made an ascension with the hydrogen balloon which he had just invented. This balloon, however, was not able to carry the observers high enough for the decrease of pressure to make its effect felt upon them. In fact, the experiment proved that this effect is not clearly evident in a balloon below an altitude of 5,000 or 6,000 meters. Consequently, among the thou- sands of ascents which followed that of Charles and Robert, only a very small number can be of interest to us in our particular purpose and therefore be reported in this historical review. 4 Historical As to the third condition, the ascent of high mountains, at first glance it seems astonishing to have to state that the ancient authors have left us no precise information permitting us to believe that they noted, during the ascent of lofty mountains, any physiological symptoms worthy of attracting attention.1 In fact, in the part of the world known to the ancients, there are mountains of considerable height. At its extreme eastern limits,2 Mount Ararat and the chief peaks of the Caucasus raise their heads covered with eternal snow more than 5,000 meters above sea level; the chains of Liban and Taurus contain many peaks more than 2,500 or even 3,000 meters high; the famous Mount Argaeus reaches a height of 3,840 meters; among the hills of Hemus and Rhodope, some rise to 3,000 meters; Mount Athos is 1,975 meters high, Parnassus 2,470, Taygetus 2,400, and it is at 2,975 meters, on the towering brow of Olympus, that the poets placed the abode of the gods. Mount Etna (3,310 meters) for two thousand five hun- dred years has been threatening the Greek cities settled at its feet. The Phenicians and the Carthaginians, whose daring had established colonies as far away as the Fortunate Isles, knew the smoking peak of Teneriffe (3,715 meters). Finally, the Pyrenees and the Alps were insufficient barriers against the armies of Carthage and Rome. The reason for the silence of the authors is easily found. As von Humboldt very correctly said, the ancients feared mountains much more than they admired them. They spoke of them only with fear, with a secret horror; the magnificent spectacles they offer to the gaze did not affect them; the emotions they arouse, the noble ideas they inspire were unknown to the ancients. Love of the pic- turesque is a very modern sentiment; the ancients, and even our an- cestors up to the last century, would have regarded with an aston- ishment mingled with disdain our intrepid climbers of the Alps. Polybius first passed through the Alpine valleys; the highest moun- tains, Mont Blanc, Monte Rosa, the Jungfrau, have no names in the classical languages. The only mountain which the ancients climbed without being forced to is Etna. Seneca requests his friend Lucilius Junior to climb to the top of the volcano in his honor (Letter 79) ; these excursions were frequent in the time of Strabo,:i and according to a poem attributed today to this same Lucilius, priests burned in- cense on the edge of the crater to appease the gods; the emperor Hadrian, who was a great traveller, conceived the idea of climbing to the top of Etna to see the sunrise. None of these accounts speak of physiological symptoms; but we shall see that at the height of Lofty Regions of the Globe 5 this volcano they are slight, attack only part of the travellers, and might be confused with the ordinary effects of fatigue. The same thing is true in crossing the Pyrenees and the Alps. The passes of the Pyrenees, through which regular communications were estab- lished between Gaul and Hispania, are hardly 1,500 meters high. Whatever opinion one has about the site of the passage of Hannibal, either at the Little Saint-Bernard (2,160 meters), or the pass of Mount Viso (2,700 meters), or Mount Cenis (2,080 meters), or in the valley of Beaufort between Albert- Ville and Chamounix, the heights reached were not very great. Augustus had two roads made through the passes of the Great Saint-Bernard (2,490 meters) and the Little Saint-Bernard,4 and King Cottus, his contemporary, cut the road of Mount Cenis. In the Middle Ages, the Simplon (2,020 meters) and the Great Saint-Bernard were much frequented; chroniclers have left us descriptions of these journeys or these expeditions in which the terrible difficulties of the roads, the ex- cessive fatigue, and the cold explain sufficiently the pitiful state of the travelers, many of them, like Elfrid, archbishop of Canter- bury, perished in the snow. To attract the attention of the travellers to physiological symp- toms they would have had to make more lofty ascents, and to have suffered discomforts evidently unexplainable by ordinary causes. The lofty summits of the Alps presented the necessary conditions, as we shall see; but since their ascents offered no practical interest, they were undertaken only toward the end of the last century. But twenty years after the discovery of America, the conquest of Mexico and Peru and military expeditions across the Cordilleras brought the Spaniards into conditions where the symptoms of de- compression appeared definitely. So attention was soon attracted to them, and they were noted in ascents where they are neither great nor constant, like those of Etna and the Peak of Teneriffe. However, our Alps for a long time still remained unexplored; though the important cities and the rich valleys of Switzerland attracted many travelers, no one had the idea of climbing these dangerous peaks covered with snow, peopled with strange beings,5 and about which the most gloomy tales were told. It was not until the second half of the eighteenth century that people decided to admire them and that the idea of reaching their summits germi- nated in a few minds. It was the scientific point of view that guided the first ascents. In the account of his ascents de Saussure noted with keen alertness the symptoms brought on by a stay in rarified air. Since then, similar observations are numerous. Still 6 Historical more recently, officers, scholars, and English travelers have carried their explorations into the loftiest regions of the Himalayas. Their accounts, added to those of men who have ascended the Alps and of travellers in America, which have become more numerous, have familiarized physicians with the symptoms of mountain sickness. In the following pages I shall report most of the interesting facts collected thus by eyewitnesses, often from their own personal ob- servation. But in this preliminary chapter I should like to recall to the memory of the reader the different mountain regions in which the traveller is exposed to distress in consequence of the decrease of pressure. This simple enumeration will show him the practical importance of the question which we shall discuss here, that is, the manifestation by acute and violent symptoms of the effect of decreased pressure. Rarely does mountain sickness appear with marked intensity in our temperate regions below an altitude of 3,500 meters. In the tropics, one must mount to more than 4,000 meters to experience it definitely in ordinary conditions. We shall return to these limits and take account of the different circumstances which hasten or delay the symptoms, I mean by that, cause them to appear at a lower or higher altitude. For the moment, these approximate heights serve as a basis for the review we intend to make. Europe. Let us take Europe first; the Alps, the Pyrenees, and the Caucasus are almost the only mountain chains which offer us peaks high enough for their ascent to cause any other ill conse- quences than the weariness and the dangers customary in moun- tains. Let us first examine the Alps. This enormous mass of moun- tains which includes in a curved line two hundred leagues long innumerable peaks laden with eternal snows, descends rapidly on the south to the low plains of Lombardy, while on the north it slopes more slowly towards the high plateaux of Wurtemberg, Bavaria, and Bohemia, interrupted by secondary mountains. The heart of the system is formed by the group of Saint-Gothard, whose waters flow at the same time through the Rhine into the North Sea, through the Rhone into the Mediterranean, and through the Tessin into the Adriatic; and yet this region is one of the least elevated of the Central Alps. It is immediately dominated on the north by Galenstock (3800 meters) and Todi (3600 meters); on the east, by the group surrounding the Little Saint-Bernard, among others the Rheinwaldhorn (3400 meters) ; on the west, by the enormous mass of the glaciers of the Bernese Alps, in the midst of Lofty Regions of the Globe 7 which rise the Jungfrau (4170 meters), the Aletschhorn (4200 meters), the Schreckhorn (4080 meters), the Brietsch (3950 meters), the Monk (4100 meters), and the Finsteraarhorn (4270 meters) . Advancing toward the east, we see Mount. Bernin (4050 meters) and Mount della Disgrazia (3680 meters) separating the valley of the Valteline, in which flows the Adda, from that of the Engadine, in which the Inn conducts by the Danube to the Black Sea the waters brought to it from numerous peaks more than 3000 meters high, such as the Piz d'Err (3390 meters), the Piz Linard (3410 meters) , the Piz Languard (3270 meters) , etc. On the other bank of the Adda, the Tyrolese Alps display still loftier peaks; the Adamello (3560 meters), the Wildspitze (3770 meters), the Venediger (3675 meters), the Gros-Glockner (3890 meters), and especially the Orteler (3920 meters) . But it is towards the west and on the left bank of the Rhone that the giants of the Alps rise. First, around the Simplon (3200 meters), are Monte-Leone (3560 meters), the Fletschhorn (4020 meters) , and the Weismies (4030 meters) ; then the base of Monte Rosa, with its three surmounting peaks; the Dome du Mischabel (4550 meters) , the Matterhorn or Mount Cervin (4480 meters) , and Monte Rosa itself, the highest peak of which, the Pointe de Dufour, rises to 4640 meters. Next come the Dent-Blanche (4360 meters) , the Weisshorn (4510 meters) , the Grand Combin (4320 meters) , and farther to the west Mont Blanc (4810 meters) , which, sur- rounded by numerous almost inaccessible pinnacles, dominates all the other mountains of Europe. Beyond, the chain drops rapidly, although it still displays a few lofty summits, such as Mount Iseran (4045 meters), Mount Cenis (3620 meters), the Vanoise (3860 meters), in the Graies Alps; Mount Viso (3840 meters) . Mount Olan (4215 meters) , in the Cot- tian Alps; Mount Pelvoux (3955 meters), the Pointe des Ecrins (4100 meters) , the Grandes Rousses (3475 meters) , in the Alps of Dauphine. The Maritime Alps are still less lofty; finally come the Apennines, the highest peak of which, Monte Corvo, in the Abruzzi, is only 2910 meters high. But beside these giants, what an ap- pearance the Capitol makes with its 47 meters above sea level! At the end of the chain, a rather high mountain, Mount Alto (1080 meters), faces Sicily, the hilly soil of which, like that of Sardinia, has no peaks reaching 2000 meters. Above all these sec- ondary mountains the crater of Etna rises to 3310 meters. Among these high peaks, these abrupt pinnacles, which are climbed only by those inspired by love of science, a taste for grand 8 Historical views, or merely vanity, depressions called cols allow many travel- lers at certain points to cross the principal chain from Switzerland or France to Italy. These passes are generally very high. The best known and the highest are: in the Maritime Alps, the passes of Tende (1870 meters), of Longet (3150 meters), of the Argentiere (1905 meters), and of Maurin (2980 meters); in the Cottian Alps, the passes of Traversette (2995 meters), of the Agnello (2700 meters), of Sayse (3360 meters), of Mount Genevre (1850 meters); in the Graies Alps, the pass of Mount Cenis (2080 meters) , and of the Little Saint-Bernard (2160 meters) ; in the Pennine Alps, the pass of the Grand Saint-Bernard (2490 meters) , that of the Geant (3360 meters) , of the Seigne (2530 meters) , the pass of Balme (2200 meters) , the pass of Saint-Theodule (3320 meters) ; in the Helvetian Alps, the Simplon pass (2020 meters), the pass of Gemmi (2300 meters), the pass of Grimsel (2160 meters), that of the Fourca (2460 meters), of the Saint-Gothard (2110 meters), of Bernardin (2060 meters) , etc. The road of the Valteline, the highest carriage road in Europe, crosses the pass of Stelvio at 2810 meters, going from the basin of the Po to that of the Danube. Along the Adriatic, the Alps continue by the mountains of Croatia, Montenegro, and Serbia, with the Balkans at the north and on the south the Rhodope mountains and the chain of Pindus which gives birth to the hills of Greece. In these very hilly regions, the summits of which are however not very high, we need mention only the Dormitor (2260 meters) in Herzegovina, the Kom (2290 meters) in Montenegro, the Kriwosta (2440 meters) in Roumania; then the giant of the Rhodope mountains, the Rilo Dagh (2815 meters), and finally the mountains of Greece of which we have already spoken. The Danube, which receives the waters of the north slope of the Alps, rises in the mountain group of the Black Forest, in which there are a few peaks of moderate height; after running towards the east, it encounters the chain of the Carpathians, in which there are such peaks as the Tatra (2655 meters), the Gailuripi (2925 meters), the Ruska-Poyana (3020 meters), and which pushes it towards the south. The mountains of the interior of France have no interest for us from the standpoint of our present purpose, since the highest, Mount Dore, is only 1890 meters high; the little chain which crosses Corsica is more interesting; its highest point, Mount Cinto, rises to 2710 meters. But the Pyrenees, in a length of 150 kilometers and a maximum Lofty Regions of the Globe 9 width of 120 kilometers, have a large number of peaks which, al- though they do not have the imposing mass or the height of the Alpine groups, are nevertheless important for our purpose. In the eastern Pyrenees there are first the Canigou (2785 meters) , then the Puigmal (2910 meters) and the Corlitte (2920 meters), domi- nating on each side the pass of the Perche (1620 meters) ; finally from this pass to the valley of Aran, on a very lofty crest, a series of peaks reach a height of 2800 meters, the highest of which is the Montcalm (3090 meters). Beyond the valley, the western Pyrenees begin with the group of the Maladetta, which contains their highest point, the peak of Nethou (3405 meters). This is the center of the Pyrenees group, which in a length of some hundred kilometers contains a great number of summits rising above 3000 meters: the peak of Perdi- ghera (3220 meters) , the cylinder of Marbore (3330 meters) , Mount Perdu (3350 meters), Vignemale (3300 meters), Marmure (2950 meters) , the southern peak of Ossau (2885 meters) ; and to the north of the principal chain, the peak Campvieil (3175 meters), and the southern peak of Bigorre (2880 meters) , on which a mete- orological observatory has just been established. The passes or ports of this region also attain a considerable height: port of Viella (2455 meters) , port of Venasque (2420 meters) ; the lowest is the port of Gavarnie (2280 meters) , the highest is the Portillon (3045 meters) . Towards the west, the chain drops rapidly; then, the Pyrenees proper give way to the Cantabric Mountains, which extend to the end of Galicia. In this whole extent, only a few summits rise above 2000 meters. In the rest of Spain, the Sierra Guadarrama and the Sierra de Gredos, which dominate Madrid and pour upon it the dreaded wind of the mountains, rise at certain points to more than 3000 meters; finally along the sea, at the highest point of the Sierra Nevada, the twin summits of the peak of Veleta (3470 meters) and the Cerro de Mulhacen (3555 meters) surpass the highest of the Pyrenees. In the rest of Europe, there are no mountains which can attract our attention. Ben Nevis, the highest mountain in the British Isles, is only 1330 meters high; in Iceland, Orafa Jokul is 1950 meters; in the Scandinavian Alps, the highest mountains are Snee- hatten (2300 meters), Skagstolstinder (2450 meters), and Ymes- Feldj (2600 meters) ; in the Ural Mountains, there are no peaks reaching the height of 2000 meters; the highest, T611-pos-Is, is only 1680 meters. 10 Historical Asia. But on the borders of Europe and Asia, a considerable chain, the Caucasus, extending from the Caspian to the Black Sea, bordering on the north upon plains, and on the south upon the mountainous regions of Armenia whose ramifications we shall fol- low presently, is crowned by peaks which leave far below them the Pyrenees and the Alps themselves. Peaks of 3000 to 4000 meters are numerous there and they are dominated by Kasbek (5030 meters) , Kaschtantan (5220 meters) and Elbruz, 'to which the legend fastens Prometheus (5620 meters) . Only one carriage road crosses the chain at the foot of Kasbek, by the Caucasian gates of the ancients, at a height of more than 3000 meters. At the south of the Caucasian chain, in the hilly territory of Armenia there rise a series of peaks, some of which reach the height of 40.00 meters: Alagos (4090 meters), Kapudschich (3920 meters); above them towers the Grand Ararat (5155 meters) . From this group there extends towards the southwest the chain of the Taurus, which contains several summits more than 3000 meters high, the highest of which are Metdesis (3570 meters) and Mount Argea (3840 meters) ; in the Liban, a fork of the Taurus, the highest summit, Dor-el-Chodib, is only 3065 meters high. At the south, the mountains of Kurdistan, with Dschehil (4550 meters) ; to the southeast, the Elburs mountains, with Sawalan (4810 meters) and Demavend (5620 meters), dominate the vast plains of Iran. The center of Asia displays an orographic system much more complex and masses of mountains much more imposing. The trav- eler who goes up the Ganges sees rising on his right, from Boutan to Cashmere, over a stretch of more than 600 leagues, the formi- dable range of the Himalayas; from between the parallel lesser chains descend innumerable tributaries of the great Indian river. In this range are found the highest mountains in the world; the ridge reaches an average height of 5000 to 6000 meters; we can count by the hundred summits of more than 6000 meters; peaks less than 7000 meters high are generally marked scornfully on the English maps by mere numbers, and it seems as if mountains do not deserve to have a name unless they reach a height of 8000 meters. We shall mention: in Boutan, Dalla (7030 meters), the Oodoo Mountains (7540 meters) , Chamalari (7300 meters) ; in Sikkim, Mount Doukia (7070 meters) and Kantschin-Janja (8580 meters) ; this latter yields only to Gaurisankar or Mount Everest in Nepal, the highest mountain on earth, which raises its summit to the pro- digious height of 8840 meters; we should gain this height by heap- Lofty Regions of the Globe 11 ing the Jungfrau (4170 meters) upon Monte Rosa (4640 meters) ; it is more than seven times the height of Vesuvius (1190 meters). Also in Nepal, Jangmar (7930 meters), Djibjibia (8020 meters), Jassa (8135 meters), Marschiadi (8080 meters), Barathor (7950 meters) , and finally Dawalaghiri (8185 meters) , long considered the highest of all, but now known to be surpassed by Guarisankar. Then the Himalayan chain opens to allow the passage of the Setledj, which carries to the Indus the waters of the northern slope and those of the sacred lake of Manasarovar (4650 meters) . Beyond, it ends in the extraordinary maze of the mountains of Cashmere, in the midst of which opens the delightful valley of Srinagar, the "earthly paradise" of the Hindus. At their eastern end, the Himalayas are joined to the Langtan Mountains, the heart of chains of relatively moderate height, which form the high relief of China and Indo-China. The Himalayas thus form, on their southern slope, the gigantic talus of a high mountain plateau, as it were. This is Tibet, which over an immense extent rises above 3000 meters, and whose waters, collected in the Brahmapoutra, flow first towards the east, then, encountering the mountains of China, turn to the southwest, to join those of the Ganges. On the north, this plateau is bounded by the chain of Kuen-Loun; its western extremity is traversed by the chain of Karakorum, the summits of which rival those of the Himalayas, such as Dapsang (8620 meters), Diamer (8130 meters) , and Gusherbrum (8040 meters) . Passes, the elevation of which naturally increases as the highest ridges are approached, permit a crossing of the foothills of these principal chains, and finally of the chains themselves. Many of these passes, which are much travelled, are at a height of more than 5000 meters; the famous pass of Karakorum is 5650 meters high; the Yangi-Diwan Pass, one of the routes from Cashmere to Khotan across the Kuen-Loun chain, is 5820 meters high; the high- est ,; of all in the British Empire, the pass of Parang, has an eleva- tion of 5835 meters. The traveler who climbs the steps of this sort of gigantic stair- way descends between them much less than he has ascended; thus he reaches a vast desolate plateau; this is the Pamir (visited in the thirteenth century by Marco Polo), or the Bam-i-Dunya, that is, the roof of the world, whose average altitude is more than 4500 meters. On the east, this roof slopes down to the lofty plains of upper Tartary, and its waters, through the river Tarim, are lost in 12 Historical the desert of Gobi. Towards the west, they collect in the Oxus which carries them to the Lake of Aral. Other chains, of a considerable absolute elevation, rise above these high plateaux. On the northeast, Thian-Schan, whose cul- minating point is Bogda-Oola, borders the great desert, and joins Altai and the mountainous ridge which separates the basin of the Arctic Ocean from that of the Pacific. To the southwest, Hindou- Kouch, which prolongs Karakorum and is fully as high at-the begin- ning, joins the chain of Elburs by the mountains of Korassan. To the south, Soliman-Kouch stretches along the river Indus. America. The orographic system of America forms a striking contrast to that of Asia. Here there is no central group from which diverging chains extend, like so many gigantic arms. On the con- trary, a ridge, certain summits of which are dominated only by those of the Himalayas, stretches along the shores of the Pacific Ocean from Patagonia to Alaska. In the part farthest toward the south, the Cordillera is simple and of moderate height; but towards the north its average elevation gradually increases and reaches two maximum points, in Bolivia and at the Equator. At the same time, while its western side remains consistently abrupt, so that moun- tains 6000 meters high are sometimes less than 20 leagues from the sea, there appear on the eastern side foothills whose size constantly increases, so that in Bolivia there is a group 100 to 150 leagues wide with an average height of 4000 meters, in which there stand out particularly two parallel chains bounding the lofty valley of the lake of Titicaca (3915 meters) . These two chains, with their inter- mediate valley cut by knots, where rise the Maranon and the Ucayali, on which are built La Paz, Puno, Cuzco, Quito, and other cities, first drop, spreading out to the knot of Pasco, then rise again and reach their highest point just at the Equator. Here the eastern ridge forks in its turn and ends at the sea, by the chain of Vene- zuela and the Nevada of Santa-Marta, whose principal summit, the Horqueta (5500 meters) , rises almost on the edge of the sea of the Antilles. The western Cordillera, considerably reduced in height, next forms the isthmus of Panama, stretches along the Pacific in Central America, rises again, and spreads out in Mexico. Thence extend, as in South America, two great parallel chains, this time much farther from each other, and much less lofty. On the east, the ridge of the mountains of New Mexico, of the Rocky Mountains, of the Mountains of the Chipways, separates the waters of the Atlantic from those of the Pacific. The western chain remains near Lofty Regions of the Globe 13 the ocean, and is interrupted in its course to allow free passage for the Colorado and the Columbia. Along the immense extent of this mountainous ridge rise moun- tains, mostly volcanic, of prodigious height. Canon Bourrit seems to us extremely impertinent when he maintains that "compared to the Swiss Alps, these mountains of South America are only dwarfs mounted on great pedestals"; 7 there is, however, a basis of truth in what he says and this is interesting for our purpose. Precisely at the equator, from the terraces of the city of Quito, the astonished eye beholds eleven volcanic mountains covered with eternal snows. Some, like Cayambe (5950 meters), Iliniza (5250 meters), Chimborazo (6420 meters), are now extinct; others, like Pichincha (4860 meters), Antisana (5880 meters), and Cotopaxi (5945 meters), still send forth smoke or flames. Chimborazo has long been considered the highest peak of the Andes; that is a mis- take. Higher still are Aconcagua (6835 meters) in the Andes of Chile, and especially Illimani (7310 meters) and Sorate (7560 me- ters), which border on Lake Titicaca. A host of mountains, such as Tolima (5525 meters) and Purace (5185 meters) in Colombia; Cotocachi (4950 meters), Sangay (5044 meters), Sinchalagua (5200 meters), Tunguragua (5020 meters), Llanganati (5395 meters), Altar (5240 meters), Sara-urcu (5140 meters), in the Republic of Ecuador; Misti (6100 meters), Chipicani (6180 meters) , Jachura (5180 meters) , Tacora (5700 meters) , Pari- nacota (6330 meters), Nevado Vilcanota (5360 meters), Lirima (7470 meters), in Peru; Sahama (7015 meters), the peak of Fari- nacobo (6714 meters), Gualatieri (6690 meters), Cerro de Potosi (6620 meters), Atacama (5300 meters), Coolo (6870 meters), Soo- lolo (6795 meters), Quenuta (6870 meters), and Pomarape (6580 meters) in Bolivia; Nevada de Famatina (5820 meters) , in the Ar- gentine Republic; Cerro del Plomo (5435 meters), Cima del Merce- dario (6800 meters), Juncal (5960 meters), Tupungato (6180 me- ters), Maypu (5385 meters), San Jose (6100 meters) in Chile, are far higher than the Alps or even the Caucasus.8 The passes crossed by travelers going from the Pacific coast to the great cities of the Cordillera or directly to the basins of the Orinoco, the Amazon, or the La Plata, always reach at their highest points altitudes capable of affecting the organism. The great road which the Incas had constructed from Cuzco to Quito crosses the pass of the knot of Assuay at 4735 meters; from Potosi to La Paz, the traveler remains constantly at heights of 4000 meters and more; the post-house of Talapolco is at an altitude of 4190 meters. In ] 4 ■ Historical the Republic of Ecuador, the passes through which one can go from Quito to the sea are above 4000 meters; the road from Lima to Pasco passes at Alto de Lachagual at a height of 4710 meters; that from Lima to Tarina, at 4800 meters. In Peru, the pass of Vilcanota, between Cuzco and the sea, is at a height of 4425 meters; the road from Arequipa to Puno passes at 4750 meters; the post- house of Ancomarca, between Arica and La Paz, is 4330 meters high; the pass of Qualillas 4420 meters high, that of Tacora 4390 meters, and that of Chullunquiani 4620 meters high. Finally, of the two railroads which cross the Cordillera, the one which goes from Puerta Mejia to Lake Titicaca has its highest point at Crucero (4460 meters) ; thence it proceeds to Cuzco, remaining at a height between 3500 and 4300 meters; the one last constructed, between Callao and Oroya, passes at a height of 4760 meters, through a tunnel which had to be excavated at almost the height of Mont Blanc. But the road most frequented by travelers till now in going from one ocean to the other, was the one which crosses the Andes from Mendoza to Santiago. It runs from Buenos Aires to Val- paraiso (417 leagues), and from either of these points gives easy access by sea to other ports of the Atlantic or Pacific. There are four passes, which are, from north to south: that of "Los Patos," from Cordova to San Juan, long abandoned; that of Cumbre of Uspallata, more frequented (3920 meters) ; and that of Portillo, which requires the crossing of two passes, one of which has an altitude of not less than 4360 meters. Finally, the last, which is the lowest in the Andes in Chile, that of Planchon, which goes straight to the port of Conception, reaches the altitude of 2500 meters. Over the long extent of Central America, the Cordillera remains at an average height; among the innumerable volcanoes with which it bristles, that of Acatenango (4150 meters) in Guatemala, alone exceeds 4000 meters. The city of Mexico, like the city of Quito, is surrounded by mountains: Coluca (4580 meters), Ixtaccihualt (4790 meters), Chicle, over which Robertson junior passed in a balloon, and Popo- catepetl (5420 meters). Citlaltepetl or the peak of Orizaba (5400 meters) is about 60 leagues away. In the Rocky Mountains we should note particularly Uncom- pahgre Peak (4430 meters) ; Pike's Peak, on the summit of which (4340 meters) a meteorological observatory has just been installed; Mount Lincoln (4300 meters) ; Long's Peak (4310 meters) and Fre- mont Peak (4130 meters) , between which the great railroad from Lofty Regions of the Globe 15 New York to San Francisco passes at an altitude of 2500 meters; side by side, Mount Brown (4850 meters) and Mount Hooker (5100 meters) . The mountains along the Pacific make way for the Oregon between the Sierra Nevada in California, the highest summits of which are Mount Whitney (4500 meters), Mount Tyndall (4380 meters), and Mount Shasta (4400 meters), and the chain of the Cascades, with Mount Baker (3390 meters), Mount Hood (3420 meters) , and Mount Rainier (4400 meters) as the highest peaks. At the northern end, on the very shore of the ocean, rise the highest peaks in North America, Mount Fairweather (4620 meters) and Mount Saint-Elias (5440 meters) . Finally, in Alaska, the vol- cano Gorjaloja ends the immense American chain, which has stretched for more than 4500 leagues. Africa. Africa is far from possessing chains of mountains which can compare with the Himalayas, the Andes, or even the Alps. And yet the belt of mountains at a short distance from the sea, which surrounds the vast plateaux of the interior, rises at different points to considerable heights. The Atlas range, which in French and Tunisian possessions never reaches 3000 meters, exceeds this height sometimes in Morocco, where Mount Miltsin measures 3470 meters. In Abyssinia, the circle of mountains around Gondar and Lake Zana rises at certain points to 4425 meters (Abba-Jaret) , even to 4620 meters (Raz-Daschan) ; the pass of Buhait is 4520 meters high. On the shore of the Atlantic, the peak of Fernando-Po rises to 3260 meters, and opposite it, the Kamerun Mountains, perhaps the Bdav {6xwa) °f Hanno, reach to 4000 meters. In the colony of Natal, the chain of Drakenberg displays summits more than 3000 meters high: Cathkin Peak (3150 meters) . Finally, almost on the equator, near the shore of the Indian Ocean, the Kenia mountains are 5000 meters high, and Kilimandjaro raises its crest, clothed in perpetual snow, to 6110 meters. Let us add that in the interior a lofty mountain has been noted, the peaks of which are more than 3000 meters high; it is Alantika, which is connected to the Kamerun Mountains. Islands. The islands, which remain to be discussed, contain only a small number of mountains the height of which is great enough for their ascent to bring on physiological disturbances. The highest point of the Australian Alps, Mount Kosciusko, is only 2190 meters high. But in New Zealand, several exceed 3000 meters, and the giant of the southern island, Mount Cook, is 3770 meters high. New Guinea contains several volcanic mountains which are no less lofty- than those of New Zealand; the Owen Stanley range, the highest, 16 Historical measures 4020 meters; but I object to including among them this Mount Hercules, 10,929 meters high, the discovery of which an English captain, M. Lawson, very recently announced, and on which he claims to have ascended to 8435 meters. In the island of Hawaii, among several still active volcanoes, Mauna Loa is 4250 meters high, and Mauna Kea 4195; on the neighboring island of Maui, Mauna Haleakala reaches an altitude of 3110 meters. The innumer- able volcanoes which form the island of Java also have lofty sum- mits; Gounong-Simeron measures 3300 meters, Semeroe 3730 me- ters. In Sumatra, I will mention Indrapura (3870 meters) and Dempo (3300 meters); in Borneo, Kini Ballu (4175 meters). The mountainous ridge of Formosa has summits of 3000 to 4000 meters. In Japan, among other lofty mountains, the volcano Fujiyama, the "Unequalled Mountain," with its height of 4320 meters dominates the roadstead of Yeddo. Finally, at the South Pole, the lofty vol- canoes of Victoria Land, Erebus (3800 meters), Melbourne (4500 meters), and on the north Polar Circle, those of Kamchatka, the highest of which is Klioutchef (4805 meters), end this volcanic girdle which edges the Pacific Ocean on all its circumference, Amer- ican or Asiatic. On the island of Ceylon, the peak to which the pilgrims come to worship the Cri-Pada, the print of the foot of Buddha or Adam, rises only to 2420 meters. The mountains of Madagascar reach 3350 meters, at their highest point, Ankaratra. Piton de Neige, on Reunion, measures 3070 meters. Finally, mention of the volcanoes of Teneriffe (3715 meters) and of Etna (3310 meters) ends this long list of all the places on earth the elevation of which is great enough for an ascent of them to cause physiological disturbances the severity of which necessarily attracts the attention of travelers. Summary. All of the foregoing can be summarized rapidly in a striking form. Let us suppose that the quantity of water on the earth should increase enough so that the sea level would rise 3000 meters. What would remain, emerging above an almost limitless ocean The largest stretch of land would be formed by the high pla- teaux of Thibet, Vokan, and Pamir, from which would rise numer- ous mountains 4000 to 5000 meters high; its area would be two or three times that of France. From it would diverge series of islands which would mark the chains of Thian-Shang, Indou-kouch, and Soleiman, and the mountains of Yunam and China. At the other end of a terrestrial diameter, a long strip extending from the equator to the Tropic of Capricorn, spreading out at its Lofty Regions of the Globe 17 two ends and particularly towards the south, in the region corre- sponding to Bolivia, would be prolonged towards the south and the north by strings of lofty islands, crowded against each other; that is all that would be left of the Andes. The plateau of Armenia, separated from the emerging crests of the Caucasus, would form the last bit of land, much smaller than the other two, which would be flanked by a few summits of the Taurus and the Elburs mountains. Then the region of the Alps would have become a compli- cated archipelago, with innumerable isles and islets, Oberland, Grisons, the main range of Monte Rosa and that of Mont Blanc. Of the Pyrenees there would remain only a few peaks near the Maladetta. Mulahacen and Etna alone would be the only others still emerging in Europe. In Africa, there would be only the Abyssinian crescent and isolated points: a few islands in the Moroccan Atlas, the Peak of Teneriffe, that of Fernando-Po, the Kamerun Mountains, Kilimand- jaro and Kenia, some peaks of the Drakenberg, and Ankaratra in Madagascar. North America would still have left above the waters a certain number of summits belonging to the volcanoes of Guatemala and Mexico, to the Rocky Mountains, to the Cascades, and the Sierra Nevada; further to the north, Mount Saint Elias and the volcanoes of Alaska, facing those of Kamchatka. Finally, of Oceania which would have disappeared there would remain only the volcanoes of the southern lands, New Zealand, Haiti, New Guinea, the islands of the East Indies, Formosa and Japan. These are the regions, thus reduced in surface, the study of which .concerns us here. The survey we have made of them shows that these mountains differ from each other greatly, not only in their height, but also in their general character. Some rise rapidly, with a single rush, so to speak, to their full height; this is the type, for example, of the mountains of the islands and those of the west- ern slope of the Cordillera of the Andes. In others, the strata are heaped progressively upon each other, and summits of prodigious height do not seem, because of their high bases, to equal isolated peaks which they really surpass. In the third part of this book, we shall show that these different orographic characteristics are very important in our study. Eternal Snows. The latitude of these mountains has an equal importance. In fact, it is closely connected with the question of 18 Historical temperature. Now the line at which the eternal snows begin cor- responds very accurately with the temperature. In our Alps and Pyrenees, about 43°-47° north latitude, this line is a little above 2700 meters; on Etna (38° lat. N.) it rises to 2900 meters. In the main mountain ranges of the center of Asia, of Pamir (40° lat. N.), in the mountains of Boutan (27° lat. N.) , it varies between the enormous heights of 4000 to 6000 meters, higher, naturally, in the regions nearest the equator, and also, curiously enough, on mountain slopes facing north; on Gaurisankar, the snow begins at 5300 meters towards the north, whereas towards the south it begins at 4900 meters; the chain of Karakorum is at certain points bare of snow up to 6500 meters (Schlagintweit) . In Abyssinia (13° lat. N.) the line is about 4300 meters, and on Kili- mandjaro (3° lat. S.) it is a little more than 5000 meters. The Cor- dillera, in its long extent from south to north, does not lend itself to an average estimate. At the equator, the volcanoes around Quito have the line of eternal snow at about 4800 meters. Speak- ing generally, this snow line is lower as the distance from the equator becomes greater; at Popocatepetl (19° lat. N.), it is only 4300 meters. But in the Andes of Bolivia, and especially in the mountains which edge Lake Titicaca on the west (16° lat. S.), it rises considerably up to 6000 meters: much above the level in the mountains of the east, where it is about 4800 meters. In the Andes of the Chilean shore, on the volcano Corcobado (2290 meters) , in 43° lat. S., that is, at the same distance from the equator as Mala- detta, it is only 1800 meters. On Mount Hooker (52° lat. N.) it is 2600 meters, on Mount Elias (60° lat. N.) 1500 meters, and on Baren- Berg (2096 meters) on the island of Jan Mayen (71° lat. N.) at only 400 meters. On Tierra del Fuego, on Mount Sarmiehto. (2075 meters), in 54° lat. S., the line is at 1100 meters, much lower than on Mount Elias, which, however, is much nearer the pole. Living Organisms. The extent of vegetation varies in altitude with the snow line, which perpetually limits it. Whereas in our Alps the timber line is at about 1800 meters, in the tropical Andes the grapevine, the cinchonas, and the oaks extend up to 3000 meters. In the Himalayas, the limit is higher yet, because apricot trees are cultivated at an altitude of more than 3000 meters, and birches and poplars grow up to an elevation of 4200 meters. Animals naturally follow vegetation; birds conform to this rule, and if on the sides of Chimborazo the condors sometimes soar at the prodigious height of 7000 meters, that is because 2000 to 3000 Lofty Regions of the Globe 19 meters lower, pastures stocked with llamas, ostriches, etc., assure them abundant food. Human dwellings obey the same law. In central Europe, only a few villages are at a greater altitude than 1500 meters; the high- est in the Pyrenees, Porte, is at an altitude of 1625 meters; Saint- Veran, in the Upper Alps, and Soglio, in the Rhetian Alps, are 2050 meters high. Above that height, there are only a few chalets un- occupied in winter. The monastery of Saint Gothard is at an alti- tude of 2090 meters, that of Bernina at 2300 meters; the highest of the summer pastures to which the Alpine shepherds go is that of Fluhalpe, at 2550 meters, and we know that a sufficient number pf monks can be kept at the monastery of the Grand Saint Bernard (2470 meters) only by means of the double attraction of heavenly rewards and fat Italian prebends promised to the monks after some years of painful sojourn on the mountain. In the Rocky Mountains, Central City is at an elevation of 3460 meters on the side of Long's Peak (40° lat. N.). In the Andes, not only villages but also populous cities are built in large numbers in lofty places. Mexico City is at 2290 meters, Santa Fe de Bogota at 2560 meters, Quito with its 60,000 inhabit- ants at 2910 meters, Cuzco at 3470 meters, Micuipampa at 3620 meters, La Paz at 3720 meters, Puno at 3920 meters, Tacora at 4170 meters; Potosi, which formerly had more than 100,000 inhabitants, is at 4165 meters, Oruro at 4090 meters, Torata at 4175 meters, Portugalete at 4290 meters, Cerro de Pasco at 4350 meters; in Peru and Bolivia, the larger part of the population lives above 3000 meters.9 Villages and dairy farms are at still higher levels. The mines of Chouta are operated at 4480 meters, those of Huancavelica at 4655 meters, those of Villacota at 5042 meters (Pissiz) . The post- house of Rumihuani, on Illimani, is at 4740 meters. The railroad from Arequipa to Puno, as we have seen, crosses the Cordillera at an elevation of 4460 meters, and that from Callao to Oroya at its highest point has a tunnel at 4760 meters; now these gigantic feats required the prolonged sojourn of a great number of workmen. In the Himalayas, man has established his dwelling at heights just as astonishing. According to the Schlagintweit brothers, the capital of Little Thibet, Leh, is built at 3505 meters; in the same country, Muglab and Kibar, cities built of stone, are at 4150 and 4220 meters; the village of Chushul, highest in the Himalayas among those which are inhabited all year long, is at 4390 meters; the Buddhist monastery of Hanle, in Ladak, is at 4610 meters; about twenty lamas live there. The villages inhabited only during the 20 Historical summer are frequently situated between 4500 and 4900 meters; Norbu, for instance, is at 4860 meters. In summer, the herds feed in pastures as high as 5000 meters, like that of Larsa, at 4980 meters.10 On the high plateaux of Vokhan and Pamir, the Kirghiz bring their yaks and sheep to the elevation of 4700 meters. The Mirza sent by M. Montgomerie to Thibet even mentions a village, Thok-Djalank, at the extraordinary height of 4980 meters. The Andes and the Himalayas include the only two regions of the earth where populations numbering millions of souls live regularly above 3000 meters. On the lofty plateaux of Mexico, the regions inhabited by a great number of men are as low as about 2000 meters; in Abyssinia, they are lower yet; Gondar is at 2220 meters and the village of Endschetkab, which seems to be the highest in Abyssinia, at 2960 meters. About the same thing is true of the mountain dwellers in Armenia: Ispahan is situated at 1340 meters, Erzeroum at 1860 meters and Kars at 1900 meters. In Europe, as we have seen, the level is still lower. Men who live at these heights are certainly in conditions very different from those encountered at sea level. At 5500 meters, a liter of air weighs exactly half as much as at sea level; at 3300 meters, a third less; at 2300 meters, a quarter less. Are these special conditions helpful or harmful to the material or intellectual development of man? I shall try to discuss this question in the third part of this book. I must remind my readers, furthermore, that slow, progressive influences, which the sojourn in lofty moun- tains may exert on successive generations, will be given little atten- tion. For these important questions in hygiene and politics, I refer my readers to the noteworthy book of M. Jourdanet. In this work, and especially in the part devoted to the discussion of historical records, I shall deal only with sudden and evident symptoms caused in men and animals by an abrupt and considerable change in alti- tude and consequently in barometric pressure. And so in the fol- lowing pages I shall refer to the accounts of travellers, generally telling their own experiences. I have divided this historical part into three distinct chapters. The first contains the reports of which I have just spoken; I have classified them by orographic regions and listed them chronologi- cally. I certainly do not claim that this list is absolutely complete; but I think I have omitted nothing that is really interesting. In the second chapter the accounts of aeronauts are reported. Finally, in the third I have arranged the laboratory experiments, Lofty Regions of the Globe 21 carried out with the purpose of studying the effect of diminished pressure, the theoretical interpretations which various physiolo- gists have given a priori of the symptoms observed in mountain ascents, and finally the explanations suggested by the travelers themselves, with the popular opinions about these strange illnesses. Of course in this chapter I stop at the discussions which my own researches have aroused; my purpose is to show the state of knowledge when I began my experiments. Finally, the last chap- ter summarizes both all the data observed and all the theories suggested. 'See, however, in Chapter III, the quotation from Bacon. 2 The altitudes which I give in this general review were taken generally from the last edition of Stieler's Hand-Atlas. Those which I did not find in this atlas were taken, for Europe, from the Orographie of Brug- niere; for France, from the Geographie of M. Levasseur; for South America, from the works of Pentland and M. Pissiz. I used also the information furnished by the recent work of Berghaus (Hdhentajel von 100 Gebirgsgruppen aus alien Erdtheilen, Geogr. Jahrbuch. 1874). My intended purpose evidently does not require absolute precision; therefore I did not hesitate to use some rather old documents; for the same reason, I omitted the units in the altitude figures. 3 Strabo, Geography, Book VI, Chap. Ill, Section IX. 4 Ibid., Book IV, Chap. VI, Section IV. 6 See Schuechzer, Ovpeoupoirris Helviticus. Lugd. Bat., 1725. 0 Harcourt, On the Himalayan valleys: Kooloo, Lahoul and Spiti. Journal of the royal geogr. soc, Vol. LXI, p. 245-257; 1871. 7 Nouvelle description des glacicres et des glaciers des Alpes, second edition, Vol. II, p. 87. Geneva, 1785. "Besides the sources indicated above in a note, for these altitudes I borrowed frequently from Kloden, Handbuch der Erdkunde, Berlin, 1869, and from Stein, edition of Wappens: Handbuch der Geographie, Leipzig, 1863-70. 9 Jourdanet, Influence de la pression de Vair sur la vie de Vhomme, Vol. I, p. 108. Paris, 1875. 10 Schlagintweit, Results of a scientific mission to India and High Asia in 1854-1858. 3 vol. 1861-1863; Vol. II, p. 477. Chapter I MOUNTAIN JOURNEYS 1. South America. It is to the accounts of travellers who followed .the first Amer- ican conquerors that we owe our knowledge of the discomforts that attack man when he reaches a certain height on a mountain side. To gain this elementary information, science had to wait until Cortez attacked Mexico in 1519 and until Pizarro, twenty-five years later, took Quito and conquered Chile and Peru. And yet the conquerors themselves gave little heed to the increase of suf- fering brought them by an unknown disease; at least their his- torians do not mention it. In the account of the two expeditions which by order of Cortez ascended to the crater of Popocatepetl (5420 meters) in 1519 and 1522, the details of the second of which were told by Herrera,1 mountain sickness is not very clearly indi- cated. The companions of Francis Pizarro (62 horsemen and 102 foot- soldiers), in the daring march which took them in October, 1532, from the Pacific coast to Cuzco, the heart of the empire of the Incas, had to cross the lofty passes of the Cordillera ol the Andes through a thousand perils. The historian, Xeres,2 who is the nar- rator of this marvellous expedition, speaks only of "the great cold experienced on these heights". However, they were below the region of perpetual snow; the ground was covered with a plant like the "esparto corto" (page 65) . Ferdinand Pizarro, sent by his brother from Caxamalca to Parcama and Xauxa, on March 3, 1533, passed over "a very steep mountain of snow, into which the horses sank up to their bellies" (page 157) ; but mentioned no special com- plaint. In 1534, Pedro de Alvarado with 500 men and 225 horses under- took the conquest of Peru; disembarking at Cape San Francisco, he 22 Mountain Journeys 23 reached the road from Cuzco to Quito at a point south of Ambato; it is evident then that he crossed the Andes near Chimborazo. He must have ascended to an altitude of more than 4800 meters, since he was in the midst of snows; the sufferings of his army were terrible: There died (according to Herrera) fifteen Spaniards and six women, several negroes and two thousand Indians. When they issued from the snow, their faces were death-like. Several Indians who escaped lost their toes and even their feet; some were blind. The great expedition of Don Diego d'Almargo, in the conquest of Chile, had still more terrible results. Leaving Cuzco in 1535, he tried to cross the mountain, in spite of his captains. The Inca Gar- cilasso de la Vega3 has given a touching account of the sufferings of the army. As the land they entered was so wild, suffering soon resulted: for a few days after, they found strange obstacles in the road they took. The first was that they could not walk on account of the snow . . . the second, that food began to fail . . . and the third, that, according to the calculation of the cosmographers and the astrologers, since the moun- tains raised their summits into the middle regions of the air, the tem- perature was so low, because everything there is covered with snow, particularly in such a season as our adventurers had chosen, namely, winter when the days are the shortest and coldest of the year, that many Spaniards, Negroes, Indians, and horses were frozen and be- numbed. But the Indians, though lightly clad, had the best of it. Of the 15,000 of them, morethan 10,000 died and more than 150 of the .Spaniards , . . . It was probably in the lofty regions of Tacora, on the road be- tween La Paz and Arica, that this expedition took place, so un- fortunately undertaken in the middle of the southern winter. In 1541, i shortly after the death of Pizarro, four Spaniards, who were part of an expedition which had left Asuncion at the order of Irala, went to Lima, passing by Potosi and Cuzco. An envoy of the governor of Peru had made the same journey; "Miguel Ruedo and Ahaic were so exhausted by the hardships of the journey," says Ulrich Schmidel, who accompanied the expedition, "that they were obliged to stop at Potosi" (page 222) . These accounts, as we see, give as explanation of the sufferings and disasters only fatigue, lack of food, and cold. The Jesuit father Acosta,5 who travelled in South America about the end of the sixteenth century, was the first to note the special distress due to a special cause, the air of lofty places. Let us add that he gave a striking description of it. 24 Historical From the translation printed in Paris in 1596 by Robert Renault Cauxois, I copy the most interesting part of his account. In certain parts of the Indies, the air and the wind blowing there dizzy men, not less but more than at sea .... In Peru there is a high mountain called Pariacaca, and having heard tell of the variation it caused, I went there, prepared the best I could according to the information given by those called Vaquianos or experts; but in spite of all my preparation, when I began to mount the stairs, as they call the highest part of this mountain, I was suddenly attacked and surprised by an illness so deadly and strange, that I was almost on the point of falling from my horse to the ground, and al- though there were several in our company, each hastened his step without waiting for his companion so that he might leave this evil spot quickly. Being left alone then with an Indian, whom I asked to help me sit on my horse, I was seized by such a spasm of panting and vomiting that I thought I should give up the ghost. After vomiting food, phlegm, and bile, one yellow and the other green, I next threw up blood, so that I felt such distress in my stomach that I can say if it had lasted I am sure I would have died. That lasted only three or four hours until we had descended pretty low and had reached a tempera- ture more suited to nature, at which point our companions, about fourteen or fifteen in number, were very much exhausted, some of them asked for confession on the road, thinking they were really going to die, others dismounted and were wrecked with vomiting and diar- rhea; I was told that in the past some had lost their lives from this distress. I saw a man lying on the ground in a passion, crying out with the rage and pain caused him by this passage of the Pariacaca. But usually it does no important harm, except this annoying and dis- agreeable trouble as long as it lasts. And it is not only the pass of Mount Pariacaca that has this characteristic, but also this whole chain of mountains, which extends more than five hundred leagues; no mat- ter where one crosses it, he feels this strange distress, although it is worse in some places than in others, and worse in passes up from the seashore than in those from the plains. I myself crossed it, besides by Pariacaca, by Lucanas and Soras, and in another place by Colleguas, and in another by Cauanas, that is, by four different places in my various comings and goings, and always in this place, I felt this dizzi- ness and distress that I have mentioned, although never as much as the first time at Pariacaca, and all who have passed that way have had the same experience. . . . Not only men feel this distress, the animals do too, and sometimes stop so that no spur can make them advance. For my part, I believe that this place is one of the highest spots on earth. This whole chain of mountains is practically deserted, without any villages or habitations of men, so that one can hardly find little houses or retreats to lodge travellers at night. There are no animals either, good or bad, except maybe a few vicunas, which are the sheep of the country, which have a strange and marvellous characteristic, which I shall mention in the proper place. The grass is often burned and blackened by the wind I mentioned, and this desert lasts through the Mountain Journeys 25 twenty-five or thirty leagues of the pass, and in extent stretches more than five hundred leagues, as I said (page 87). After he had made this description, and we will admit that exactness could not have been joined to picturesqueness more skil- fully, Acosta discusses the cause of these symptoms which he says he experienced in four other crossings of the great Cordillera. We shall report in a chapter devoted to a summary of theoretical ex- planations the ideas of this reverend gentleman, ideas which are really marvellous for insight and clearness. It is hard to determine the exact point at which Acosta crossed; Pariacaca is a name that has disappeared in Peru as well as in Ecuador. It is almost certain that it was below the snow line, for his account, so exact and so detailed, does not speak of the snow; its height above sea level was therefore probably 4500 meters at the most. It is very strange to see that after describing so admirably and after explaining the painful sensations he had experienced while crossing the lofty mountains, Acosta does not consider them as accounting for the disasters undergone by the Spanish armies. Yet he knew them very well; he speaks of them; but here his clearness of mind seems to abandon him. There are other deserts or uninhabited places, which in Peru they call Punas (to speak of the second point which we promised) where the quality of the air cuts body and life from men without their feel- ing it. In the past the Spaniards travelled from Peru to the kingdom of Chile across the mountain; today they usually go by sea, and some- times along the coast; and although this route is tiresome and incon- venient, there is never as much danger there as on the mountain road, in which there are plains in passing through which several men have died and perished, and others have escaped with great luck, and some of them were maimed. In this place there blows a little wind which is not too strong or violent. But it is so penetrating that men fall dead of it almost without feeling it, or maybe their fingers and toes are left there; which may seem a fabulous tale, and yet it is a trUe thing. I knew and long frequented General Hierosme Costilla, former adminis- trator of Cusco, who had lost three or four toes, which had fallen off when he passed through the deserts of Chile, because they had been attacked and penetrated by this little wind, and when he happened to look at them, they were all dead and fell off of their own accord without giving him any pain, just as a rotten apple falls from the tree. This captain related that of a good army which he had led through this place the preceding years, since the discovery of this kingdom of Al- magro, a great part of the men remained there dead, and that he saw their bodies stretched out on the desert, without any bad odor or decay. ... No doubt this is a kind of cold so penetrating that it ex- tinguishes the vital heat by cutting off its power; and also because it 26 Historical is very cold, it does not corrupt or cause decay in dead bodies, because putrefaction proceeds from warmth and humidity (page 89). A celebrated Spanish historian, who wrote shortly after Acosta, Antonio d'Herrera, took up the ideas of the learned Jesuit, and, without quoting him, copied almost in full the passages which we have just put before our readers/' But it is evident that he could not include the whole of the explanation of Acosta; at least it would be useless to include here his chapter: Reasons why it is so dangerous' to pass through the "Puertos Nevados" which lead to Chile, and the passes of the province of Quito through which Belal- cazar and Alvarado crossed with their armies. A century and a half passed without the historians and the travellers speaking of the physiological symptoms which Acosta had noted. The "Lettres Edifiantes",7 in which there are so many details, generally childish but sometimes interesting, do not allude to them, although their writers were evidently several times in the same conditions as their predecessor. My researches in the authors of the seventeenth century have revealed nothing pertinent to our subject. But a document published at the beginning of the eighteenth century shows us that in the Andes it had been known for a long time that at certain points more or less severe symptoms attack men and animals. We even find in this document an explanation which recurs up to the present. A Frenchman, Frezier,8 visited the coasts of Chile and Peru from 1712 to 1714; he speaks at length of the rich mines in the interior of the country, and after discussing the origin of the metals, he adds: It is certain that strong exhalations issue constantly from the mines; the Spaniards who live above them are obliged to drink very frequently Mate, the grass of Paraguay, to moisten their lungs, and thus prevent a sort of suffocation. Even the mules which pass through these places, although they are much less rugged and steep than others along which the mules run, are obliged to rest almost every moment to regain breath. But these exhalations are much more evident within; they are so powerful over bodies not accustomed to them that a man who enters for a moment comes out as if crippled. . . . The Spaniards call this illness Quebrantahuessos, that is, it breaks the bones (page 150). Frezier had no opportunity to make personal observations. But a few years later, in 1736, three French Academicians, Bouguer, La Condamine, and Godin, went to Peru to measure a degree of the meridian there. It was at the time of this celebrated expedition that the symptoms of decompression were first studied and dis- Mountain Journeys 27 cussed scientifically. In one of their trips, Bouguer and La Con- damine remained three weeks on Pichincha, at an altitude of about 4860 meters. There they experienced discomforts which Bouguer '■' describes in the following terms: We were all at first considerably inconvenienced by the keenness of the air; those of us who had more sensitive lungs felt the difference more and were subject to slight hemorrhages, which no doubt came from the fact that the atmosphere, since its weight was less, did not by its compression help the vessels sufficiently to retain the blood, which, however, was still capable of the same action. Personally I did not notice that this inconvenience increased much when we hap- pened later to ascend higher; perhaps because I was already accli- mated, or perhaps also because the cold prevents the expansion of the air from being as great as it would be otherwise. Several of us, when we were ascending, fell fainting and were seized by vomiting; but these symptoms were more the result of fatigue than of the difficulty of breathing .... We sometimes felt a very severe cold, when the ther- mometer indicated only a moderate degree (page 261). Bouguer then expounds a hypothesis of which we shall speak in the third chapter; according to him, the symptoms experienced are due in part to fatigue, in part to a sort of scurvy. In the two volumes which La Condamine1" devotes to the ac- count of his journey, and which are anyway half filled by his vio- lent disputes with Bouguer, I could find only the following pas- sage referring to his stay on Pichincha: Don Antoine d'Ulloa, while ascending with us, fell in a faint, and had to be carried to a nearby cave . . . Personally I felt no difficulty in breathing. As to the affections which M. Bouguer mentions and which apparently refer to the tendency to bleed from the gums, with which I was then inconvenienced, I think it should not be attributed to the cold of Pichincha, since I felt nothing like it in other places of equal altitude, and since the same symptom attacked me again five years after at Cotchesqui, the climate of which is temperate. (Vol. I, p. 35.) But the most circumstantial and exact information is furnished us by Don Ulloa, a young naval officer whom the Spanish govern- ment had sent to protect the French mission, and who later played a great part in his nation. His accounts11 give at the same time the story of the symptoms experienced temporarily by mountain climb- ers, and those which are the consequence of a stay of several months in certain regions of the Cordillera of the Andes. Here also for the first time we find suggested the services which a sojourn in lofty altitudes can render to therapeutics: Those who are not accustomed to frequenting these places are also exposed to another discomfort, besides the cold of which we have just 28 Historical spoken; it is the Mareo of the Puna; and it is rare that they are not attacked by it. It is a disease quite like that which one feels at sea: it displays all the symptoms of it and follows the same course. The head whirls; one feels very hot; and painful nausea comes on, followed by bilious vomiting. Strength fails, the body weakens, fever appears; and the only comfort one finds is in vomiting. Some people are even so weakened that they would cause anxiety, if it were not certain that the -trouble was nothing but this Mareo. That lasts usually one or two days, after which health is restored. This inconvenience is greater or less according to the natural constitution of the person; but few escape. When anyone has felt it once, it is extraordinary that he should be attacked by it again in passing by Puna or coming from low countries or any country in which there is a high temperature (page 116). . . . There is also observed in these climates another symptom to which animals are subject. As soon as they pass from the plains to these eminences or Punas, as from countries where there are dwellings to the summits which surround them, breathing becomes so difficult for them, that in spite of the different pauses they make to get their breath, they fall and die there (page 118). Ulloa then discusses the different explanations suggested in his time to account for these phenomena, and energetically rejects the idea of toxic emanations due to minerals buried in the earth, an idea which is current even today among the common people and even in the educated classes of Bolivia and Chile. Then he adds: The men who have recently come to this climate also experience something similar to what I said about animals; while walking, they feel a suffocating and very painful fatigue, which forces them to rest a long time; that happens to them even in the flat lands; now there can be no other cause for this phenomenon than the keenness of the air; but as the lungs become accustomed to this atmosphere, the discomfort lessens. However, they still experience some difficulty in breathing when they wish to climb some slope; this is inevitable, but is not felt in other countries where the atmosphere has a regular density. This lightness of the air is favorable to those who have become asthmatic in a denser air. This asthma is known by the name of ahogos or suffocation; it is rather common there; that is why those who are attacked by it in the low countries go up into the mountains; al- though they do not entirely recover there, they live there nevertheless without pain: on the contrary, those who became so in high altitudes are well in the lowlands; so change of air is a certain alleviation in this sort of disease. The science of medicine might profit by these experi- ences, sending the patients of one country into another, although elsewhere there is not so great a difference of altitude. Difficulty of breathing is noted also to a certain degree in the high- lands of the province of Quito, but it is less painful there: no doubt that is because one of these countries is on the equator, or nearly so, whereas the other is remote from it. The conclusion is that the Punas or summits of Peru are less cold and the air less cutting than in the Mountain Journeys 29 other countries. But it is well to note that what has been said of Guancavelica is general for all the lands extending towards the south. That these details may be better understood, I shall observe here that what is called Punas in Peru, is named Paramo in the kingdom of Quito (page 120). It was in the last year of the eighteenth century that the il- lustrious Alexander von Humboldt undertook that great expedition into South America, which was the source of so many important discoveries in the history of man, the physics of the earth, and natural history.12 In 1802 he made a stay on the lofty plateau of Quito, overlooked by the gigantic peaks of Pichincha, Cotopaxi, Chimborazo, and Antisana. In March and in June 1802, he made ascents which have be- come famous of the last two volcanoes; he immediately gave a brief account of them in two letters, written the same day; I quote from them passages which are interesting from our point of view. The first is addressed to Citizen Delambre;13 it relates particu- larly the ascent of Chimborazo: It was believed till now in Quito that 2470 fathoms was the great- est height at which men could resist the rarity of the air. In the month of March 1802, we passed a few days in the great plains which sur- round the volcano of Antisana, at a height of 2107 fathoms, where cattle, when chased, often vomit blood .... On May 16, we explored a path on the snow, a gentle slope on which we climbed to 2773 fathoms. The air there contained 0.218 of oxygen . . . the Reamur thermometer stood at only +13°; it was not cold at all, but blood issued from our lips and eyes. (P. 174.) In the expedition which I made June 23, 1862, to Chimborazo, we proved that with patience one can endure a greater rarefaction of the air. We crossed 500 fathoms higher than La Condamine at the Cora- zon, and we carried instruments on Chimborazo to 3031 fathoms, seeing the mercury drop in the barometer to 13 inches, 11.2 lines; the ther- mometer stood at 1.3° above zero. Our lips bled again. Our Indians abandoned us again as usual. Citizen Bompland and M. Montufar, son of the Marquis de Selvalegre, of Quito, were the only ones who were resistant. We all felt a discomfort, a weakness, a desire to vomit, which certainly arises as much from the lack of oxygen in these regions as from the rarity of the air. I found only 0.20 of oxygen at this immense height. (P. 175.) The other letter is addressed to his brother, Wilhelm von Hum- boldt; in it, more than in the preceding letter, he speaks of the ascent of the volcano Antisana: 14 On our journey to the volcano of Antisana, the weather was so favorable that we ascended to the height of 2773 fathoms. At this alti- 30 Historical tude the barometer fell to 14 inches, 7 lines, and the rarity of the air made blood issue from our lips, our gums, and even our eyes; we felt an extreme weakness, and one of those who accompanied us on this journey fainted. . . . We succeeded in approaching to about 250 fathoms from the sum- mit of the immense column of Chimborazo. . . . We mounted to a height of 3031 fathoms, and we felt inconvenienced in the same manner as on the summit of Antisana. Even two or three days after our return to the plain, we continued to feel a discomfort which we could at- tribute only to the effect of the air in these lofty regions, an analysis of which gave us 20 per cent of oxygen. (P. 329.) Thirty-five years later,15 von Humboldt returned with details about the account of these ascents. He dwells particularly upon the physiological symptoms, and develops some very interesting theories in this regard. June 22, 1802, he was in the plain of Tapia, at an altitude of 2890 meters. The first part of the ascent had no particular inter- est for our purpose: At an elevation of 15,600 feet, all the Indians but one abandoned us. . . . They claimed that they suffered far more than we did. There were only four of us left then: M. Bonpland, . . . M. Carlos Montufar, ... a half-breed from San Juan, a nearby village, and I. (P. 413.) . . . We all began by degrees to be very uncomfortable (they were then at a height of about 5,000 meters) . The desire to vomit was ac- companied by fits of dizziness and was much more painful than the difficulty of breathing. The half-breed from San Juan, a poor and sturdy peasant, who had wished to follow us to the end out of the kindness of his heart and not from any selfish interest, suffered more than we did. Our gums and lips bled. The conjunctiva of the eyes in all of us without exception was bloodshot. These symptoms of extra- vasation in the eyes and of a discharge of blood from the gums and lips did not disturb us, because we were acquainted with them from many examples. In Europe, M. Zumstein began to bleed at a much lower elevation, on Monte Rosa.16 (P. 417.) . . . Once, on the volcano of Pichincha, I felt, without any bleeding, such a violent pain in my stomach, accompanied by vertigo, that my companions found me stretched out unconscious on the ground. The altitude was only 13,800 feet (4480 m.), and consequently not im- portant. But on Antisana, at the great height of 17,022 feet (5527 m.), Don Carlos Montufar bled profusely from the gums. All these phe- nomena vary greatly, according to the age, the constitution, the deli- cacy of the skin, and the previous muscular efforts which one has made; however, they are for each individual a sort of measure of the rarefaction of the air and the altitude he has reached. According to my observations, they appear in the Andes in white men, when the barometer stands between 14 inches and 15 inches 10 lines. (P. 418.) We shall see later what successive opinions, and considerably Mountain Journeys 31 different ones, the illustrious naturalist held about the explanation of these various phenomena. But before going on to other accounts, I should include here a fragment of one of the works of Humboldt,17 in which he gives in- formation full of interest for the subject of our study about the usual habitat of the condor and the maximum height to which it rises: The region which one may consider the habitual sojourn of the condor begins at a height equal to that of Etna, and includes layers of the air from 1,600 to 3,000 fathoms above sea level. The largest speci- mens found in the chain of the Andes of Quito have a wing-spread of 14 feet, and the smallest only 8 feet. By these dimensions and by the visual angle at which this bird appeared sometimes perpendicularly above our heads, one may judge to what prodigious height it rises when the sky is clear. Seen, for example, at a visual angle of four minutes, he would be at a perpendicular distance of 1,146 fathoms. The cavern (machay) of Antisana, situated opposite the mountain of Chuesolongo, and from which we took the measurement for the soaring bird, is 2,493 fathoms above the level of the Great Ocean. So the absolute height which the condor attained was 3,639 fathoms; there the barom- eter is hardly twelve inches high. It is a very remarkable physiological phenomenon that this same bird, which for hours soars in circles in regions where the air is so rarefied, suddenly swoops down to the sea- shore, for instance, along the western slope of the volcano of Pichincha, and thus in a few instants passes through all climates, as it were. At a height of 3,600 fathoms, the aerial and membranous sacs of the con- dor, which were filled in lower regions, . must be extraordinarily in- flated. Sixty years ago Ulloa expressed his surprise that the vulture of the Andes could soar at a height where the air pressure was only 14 inches. It was believed then, on the basis of experiments made with the pneumatic machine, that no animal could live in a medium so rare. As I have already stated, on Chimborazo I saw the barometer drop to 13 inches 11.2 lines. My friend, M. Gay-Lussac, breathed for a quarter of an hour in air the pressure of which was only 0.3288 meters. At such great heights, in general man finds himself in a very painful state of asthenia. On the contrary, in the condor the act of respiration ap- pears to take place with equal ease in media in which the pressure varies from 12 to 28 inches. Of all living beings, this is certainly the one which can at will rise furthest from the surface of the earth. I say at will, because small insects are carried still higher by ascending currents. Probably the height reached by the condor is greater than we found by the calculation given. I remember that on Gotopaxi, in the plain of Suniguaicu, covered with pumice stones, and at an eleva- tion of 2,263 fathoms above sea level, I saw this bird at such a height that it seemed only a black dot. What is the smallest angle at which objects dimly lighted can be distinguished? The weakening of the rays of light by their passage through the layers of air has a great effect upon the minimum of this angle. The transparency of mountain air is so great at the equator, that in the province of Quito, as I have shown 32 Historical elsewhere, the poncho or white cloak of a person on horseback can be seen with the naked eye at a horizontal distance of 14,022 fathoms, and consequently at an angle of 13 seconds. (P. 78.) The revolutions by which the Spanish colonies of America shook off the yoke of the mother country resulted in the crossing by troops of several thousands of men of certain passes of the Andes usually frequented by only a few travellers. The stay in rarefied air certainly brought an increase of suffering to these little armies; but the historians seem to have paid but little attention to it, pre- occupied as they are by the natural effect of the cold, the lack of food, and the excessive fatigue. Early in the year 1817, General Saint-Martin, at the head of 3000 Independents, invaded Chile by the difficult pass which leads from Mendoza to Santa Rosa, the highest point of which has an elevation of more than 4300 meters. The expedition (says M. Gustave Hubbard 1S) presented such great difficulties that the troops from Santiago and the governor of Chile re- fused to give credence to such a dangerous attempt .... A great num- ber of men perished from cold in the rarefied and frigid atmosphere through which they had to pass .... When the army left Mendoza it had 9,281 mules; only 4,300 were left on the other side of the Andes, and out of 1,600 horses only 500 survived. (Vol. I, p. 346.) The army which Bolivar led against Morillo in June 1819 from Venezuela to New Grenada, across the Andes of Colombia encoun- tered the same difficulties. The Englishmen who formed a con- siderable part of his expeditionary forces died in great numbers. The celebrated historian Gervinus says in this reference:19 The way is unmistakably marked by the bones of numerous vic- tims who die during these crossings. ... In fact, those who, overcome by weariness and cold, abandon themselves to the peculiar drowsiness to which the traveller in lofty places becomes an easy prey fall into a numbness which takes their strength from them (emparamados from paramos, a name given to the highest plateaux) and delivers them over to death without any hope of rescue (page 88). Upper and lower Peru also witnessed such expeditions. In 1821, the Spanish viceroy La Serna, forced to abandon Lima, retreated across the Cordillera, and established himself in the high valley of Jauja. Thence his troops often descended to attack the Independ- ents, until Bolivar undertook against them the campaign which ended in the battle of Ayacucho (1824), and the whole of which was carried on at a height of more than 3000 meters. It was at a still greater height, 4500 meters, that General Santa Cruz defeated the Spaniards in 1822 on the slopes on Pichincha. Mountain Journeys 33 The Spanish writer Torrente,20 in his history of the Spanish- American revolution, is correct in attributing to the altitude a considerable share in the sufferings of the armies during these marches at high altitude: When one crosses the Cordillera of the Andes of Peru, one usually suffers from two maladies: spasms and nausea. The latter is more common, especially for those who come from the low, hot land along the coast. The keenness of the air in this atmosphere hampers respi- ration and makes it very laborious, increases the pulse rate, speeds up the circulation, produces intense headaches, and causes the blood ves- sels to swell quickly, and the unfortunate victim to perish, with an issue of blood from the mouth, the eyes, and the nostrils. It is true suffocation which attacks animals also if their burdens are increased or their pace hastened ever so little. The losses of the small army of the viceroy La Serna were greater during the retreat from Lima to Jauja, because a large number of his soldiers were still convalescing. The author adds, repeating popular superstitions: It seems that the veins of precious metals and antimony which run through the territory of Peru are the cause of this atmospheric combi- nation which is so injurious to health. What would tend to prove it is the fact that its effects are much less noticeable on points of greater altitude, such as certain parts of the Cordillera of Chile, the Sierra of Pichincha, and other mountains of Quito. This nausea is known in the country by the name of Soroche, and it is experienced even in certain low lying villages, situated in metalli- ferous localities. (Vol. Ill, p. 164 and 169, note.) We have seen Saint-Martin crossing the Cordillera from Men- doza to Santiago, thus carrying out an expedition which Manuel de Almagro 21 considers "as far more difficult and worthy of ad- miration than that of Bonaparte at the Grand Saint-Bernard, which has been much exaggerated" (p. 34) . This route, as we have said, is the one usually followed by travellers who wish to cross Amer- ica. Two passes exist, one by Cumbre (3920 meters) , the other by Portillo (4360 meters). The former is more frequented. Most accounts mention the symptoms of decompression; but on this road they are usually not serious. However, Samuel Haigh,22 who ventured into the passes of Cumbre from Mendoza to Santiago during the austral winter of 1818, felt them considerably. A snow storm which assailed him compelled him to take refuge with his companions at a hill where the "casucha" of Las Vacas offered them a shelter: While climbing the hill on which it is built, (he says) I was at- tacked for the first time by the puna or soroche. This is an illness peculiar, I think, to high mountains; it is the result of the extreme 34 Historical rarefaction of the air which therefore causes difficulty in breathing. Three times I was forced to lie down on the ground before reaching the top of the hill, and I experienced shortness of breath with pain and op- pression in the chest and a sensation of nausea. The puna attacks some persons so severely that blood issues from their mouths and nostrils. However, I must say, our sufferings really began. (P. 104.) But all are not equally affected, especially when, as usually happens in the favorable season, the journey is made on mule- back. Miers,23 who crossed in May 1819, explains this very well: Those who wish to undertake this journey will be dismayed t>y the accounts of the difficulties caused by the puna, a name given to the sensation of short and difficult respiration, which often attacks us when we ascend into rarefied air. This is the terror and the subject of conversation of all who have crossed the Cordillera, who tell you that they escaped these terrifying symptoms only by eating a great many onions, and by tasting no alcoholic liquors, except wine, which is considered the antidote of the puna. These precautions, however, are not necessary, for very few persons who make the ascent on horseback experience this discomfort, except those who have a lung ailment; but many of those who have climbed Cumbre on foot, overexerting them- selves in driving the mules, have been affected. I do not think that anyone would suffer much from the puna unless he overexerted him- self. I have twice ascended and descended Cumbre on foot without being affected. Moreover neither my wife nor my child, only six months old, felt the least difficulty in breathing with the thermometer at 35°F. and the barometer at 19 and Vs inches, although we might have expected that in a child of this age with such delicate lungs one would first observe modifications in respiration, even though they were due only to excessive rarefaction of the air. (Vol. I, p. 321.) The account of the Scotchman Caldcleugh -4 is particularly inter- esting, because this traveller crossed the Andes twice in opposite directions. The first time, March 17, 1820, in very bad weather, a snowstorm, he crossed by Portillo and Piuquenes, going from Men- doza to San Jose. He does not mention any symptoms. (Vol. I, p. 285—323.) But on June 2 of the following year, while going from the Punta of San Luis to Cordova (Argentine Republic), he crossed at a much lower point, the Sierra of Cordova. He stopped at a little hut at an elevation of 3200 meters and passed the night there. The next day, ascent of the pass: The snow was frozen hard. . . . Two of the peons suffered severely from an illness called puna, which attacked them shortly after we had left the hut. This illness seemed to me to consist of heavings of the diaphragm, accompanied by great exhaustion and loss of spirits. Those attacked by it lie down, give themselves up, and often die before reaching the descent. Great quantities of garlic and onion are con- Mountain Journeys 35 sidered specific against this condition. But the surest treatment is to take the patients as quickly as possible to a less lofty place. It has been commonly noted that those of the peons who are old and addicted to bad habits suffer more from the puna than the others, and this note applied perfectly to the two whom I had to send back. One of them was extremely sick, and the other under whose care he departed was slightly affected. At present I do not know whether he managed to cross the valley. Shortly afterwards they reached the summit, at an elevation of 3840 meters. He suffered no personal distress. Schmidtmeyer,25 in the account of his crossing the Cordilleras from east to west by the volcano of Cumbre, speaks of no physiolog- ical symptom. But at the end of the book, he fills this gap: I should have spoken sooner of this exhaustion accompanied by difficulty in breathing which one experiences when crossing the range; I often heard it spoken of in Chile. But we remained on muleback up to the highest point of the pass, which we therefore reached without the slightest effort. One of our men, however, suffered from it con- siderably, but I do not know whether it was an extreme case. Usually, on the high peaks of the Andes, one experiences great difficulty in moving; that is the opposite of what happens on other mountains. (P. 349.) Proctor -° (1824), Head27 (1825), who followed the same route, in the same direction, make absolutely no mention of the puna. Lister Maw,2S who in November 1827 left Truxillo (Peru) for the basin of the Amazon, does not speak either of the effect of the pressure, except at Contumasa (2190 meters) , where he says po- etically: The rarity of the atmosphere tended greatly to raise our spirits. But Lieutenant Brand 29 is more explicit; he mentions these symptoms, and even tries to explain them, but without having experienced them himself, and yet he made his first journey from Mendoza to Santiago over Cumbre in the midst of the austral winter (August 22, 1827), He had to endure terrible cold, even down to 15° below zero. August 22, he ascended Cumbre; the thermometer stood at 34° F.: As I had often heard of the puna, or difficulty in breathing, from travellers who complained of it bitterly, I gave particular heed to it; I cannot say that I felt any more inconvenience than would have hap- pened to me if I undertook such labor, so long continued, even if I , had not been at this elevation. I suffered only from a very acute thirst, which the snow aggravated instead of satisfying. . . . But I do not intend to contradict what has been said of the puna, which has assailed many travellers severely. (P. 147.) . . , 36 Historical On my return across the Andes, in December, 1827, I saw that the mules stopped frequently to breathe, especially when climbing Cumbre, where they stopped at each zigzag, as if they suffered from pain in the lungs, and, like Acosta, I found that neither shouts nor blows could make them advance until it suited them. But that is not peculiar to Cumbre or to the other mountains of the Cordillera, for mules often stop thus, as if they felt pain in their lungs. It happened likewise to the peons, who suddenly, while walking, stopped, shouted "puna, puna" and then continued ascending. It seemed as if they knew the places where this would happen to them when on foot, for they frequently said: "Here there is much puna." I can attribute this only to the existence in these places of minerals which alter the air more or less, whence comes their effect upon the lungs. (P. 149.) The French officer De la Touanne,'0 who took part in the ex- pedition of Bougainville, and who followed the same route as Brand, was so severely attacked as to fall on the ground; he crossed the pass January 29, 1826. I estimated that the point where we were is at least 2,000 fathoms high. . . . The air is very much rarefied at this elevation; I had dis- mounted from my mule, letting him go ahead with the caravan, and I was examining some stones at the right and the left of the path. When I afterwards wished to increase my pace to overtake my travelling companions, respiration suddenly failed me; I fell down, my chest oppressed and breathing with difficulty. A peon had to bring me my mule; and from these slight symptoms I could judge what the arrieros and the travellers who have to cross this pass in bad weather must suffer. (P. 50.) After this testimony from travellers who only crossed the moun- tain, here is what is said by an English engineer, Ed. Temple,-1 who lived for a year 1826-1827, at Potosi (4165 meters), where he was employed in the exploitation of the rich mines of that country: While walking, I often experienced that difficulty in breathing which is caused by the extreme rarity of the air, and to which even the natives and the animals are subject. The royal sport of horse rac- ing cannot take place here, for the horses seem to suffer more from the zorochi than men do; I have often heard that they fall and die, if they are hurried when they are climbing a hill. (Vol. I, p. 296.) I shall also quote the passages in which the English traveller Bollaert,'12 who in the month of June, 1827, ascended the mountain Tata Jachura (5180 meters), describes the sufferings he experi- enced during the ascent. We had slight nosebleeds, buzzings in the ears, headache, dimness of vision, and our bodies were numbed by cold, all of which were caused by the puna or soroche, that is, the expansion and cold of the atmosphere. (P. 121.) Mountain Journeys 37 I now come to the important journey of d'Orbigny 33 and the in- teresting description he gives of mountain sickness. In his first journey, he is going from Arica to La Paz: May 21, 1830, I reached the point where the ravine of Palca joins another dry ravine. . . . There I left vegetation and humidity. . . . Soon I began to mount the side of Cachun, and on its summit I felt at the same time as the first effects of the rarefaction of the air a very keen cold, due to the elevation. (Vol. II, p. 377.) . . . The slope became still steeper. ... I felt more and more the severe effects of the rarefaction of the air, a very violent headache and a great difficulty in breathing; my arrieros, their mules, and even my dog, my faithful Cachirulo, were forced to stop every twenty or thirty meters, tormented like me by the soroche. . . . Whenever one feels the illness due to the rarefaction of the air, the natives say that he has the soroche. They fail to recognize the real cause, the great elevation above sea level, and attribute it to mineral emanations from antimony, called in Spanish soroche. It is this suf- fering, this difficulty in breathing in the very lofty parts of the Cordil- leras that has given them the name of puna brava. Some travellers use for the Peruvian Cordilleras the word Paramo,, not used in the coun- try, and which does not take the place of the word Puna, meaning a lofty plateau, dry and deprived of trees. After many fatigues, we reached the top of the last slope; I was at last on the crest of the Cordillera. (P. 378.) . . . Ever since my arrival at the summit of the Cordillera, I had been suffering terribly irom the rarefaction of the air. I felt frightful pains in my temples; I had nausea like that produced by seasickness, I breathed with dif- ficulty. At the least movement, I felt violent palpitations and general discomfort, added to an exhaustion which all my efforts failed to over- come. I had very strong proof of what habit can do. While I was suf- fering thus, I saw two natives, sent as couriers, nimbly and easily climbing on foot places incomparably higher than those in which I was in order to shorten their journey. . . . Yet they were at an elevation equal to that of Mont Blanc. In the evening I had a severe hemor- rhage from the nose which relieved me a little; yet I passed a night which was all the more terrible because I was without shelter, ex- posed to a keen and cutting cold which froze all the water in the neighborhood. (P. 380.) . . . May 23. I still felt the effects of the rarefaction of the air; head- ache and palpitation of the heart did not leave me a moment of repose. . . . My muleteers told me that a few months before a Spaniard who was taking the same route as they was so much affected by the rare- faction of the air that the very first day he experienced very alarming symptoms, and being unable to continue, he died the following night, without being able to get the least relief. They mentioned many other instances in which the travellers whom they accompanied had suffered atrociously from what they call the soroche. (P. 387.) . . . May 24. As I descended I breathed more easily, and I hoped that before the day ended at least a part of the discomfort I felt from the rarefaction of the air would cease. (P. 390.) 38 Historical May 29, d'Orbigny arrived at La Paz (3720 meters) : As I had felt much better when I had descended from the western plateau to the Bolivian plateau, I expected to feel no more effects from the rarefaction of the air; but in the city of La Paz it was far different. At night I felt as if I were suffocating in my room. I could not climb the steeply sloping streets without being stopped every ten paces by palpitations and lack of breath. If I talked with animation, suddenly speech failed me; when invited to several houses to take part in a general entertainment, I could not waltz twice around without stop- ping, suffocated by the same symptoms; and I almost died one day when I tried to walk to Los Obragos, a village one league away, to reach which I had to climb a very steep slope. This discomfort lasted during the whole of my first stay in La Paz. Persons born in the country feel no effects at all. All assured me that one finally gets acclimated, and I myself had the proof of this on my return three years later. However, I should advise persons with weak lungs not to subject themselves to this test, which gave me the most pain in all my travels. (P. 404.) However the acclimatization of which d'Orbigny boasts was not as complete as one might think. It is true that in the account of his second stay in 1832 at Potosi, Oruro, and La Paz he does not mention any symptoms (Vol. Ill, p. 283 et seq.) ; but he returns to the subject when he tells of certain ascents: I had to stop (July 5, 1832), while I was going from Cochabamba to the country of the Moxos, beside a frozen lake nearly 5000 meters above sea level. We felt the excessive cold all the more because we had no shelter, and the air was so rarefied that I could hardly breathe. (Vol. Ill, p. 176.) . . . The next day, on the way down, . . . with the region of the clouds, vegetation began; up to that time I had felt an oppression in my chest, so I cannot express the pleasure I felt when I began to breathe more freely a less rarefied air (P. 117.) A German traveller, Ed. Poeppig, discusses the subject at greater length; he was staying at Cerro de Pasco (4350 meters) : The new-comer to Cerro de Pasco is subject to serious inconven- iences; walking, even on level ground, tires him extraordinarily; in streets sloping upward, respiration becomes short and painful, he is seized by headaches, by afflux of blood to the lungs, certain signs that he will not be able to escape the attacks of the puna any more than other foreigners. In vain does he try to brace himself energetically against the sickness; it conquers him and triumphs over the strongest wills. Just as during a violent attack of seasickness, the spirits are de- pressed, the senses blunted, disgust and hypochondrial discourage- ment transform the most robust, the most animated, the most coura- geous in a surprising manner. The physical sufferings, when the attacks of this sickness begin, are more painful and more varied than in the usual forms of seasickness. When the puna (also called Veta, Sorocho, Mountain Journeys 39 or Mareo) is felt only moderately, the patient complains of a difficulty in breathing, which compels him to stop after about ten steps, and he tries in vain by deeper inhalations and a greater expansion of the chest to draw more of the life-giving element into his lungs. He feels as if he were shut up in a room without air, and the distressing sensation is increased by the failure of all his attempts to conquer his loss of strength'. The feet can hardly support the body, the knees bend, and every opportunity to rest, no matter how frequent, even after only a few steps, is welcome. It is a torment to climb streets sloping up- ward, and while he heaves himself painfully towards home, it is a real joy to find a doorway, a corner where he can stop and lean against something, burdened as he feels. The distress lessens only during absolute repose; but the conviction of the absolute necessity of the ill- ness, the incapacity for any intellectual effort, and the sense of loss of precious time bring on ill humor and discouragement, so that a vigorous man acts like a little child. Those who are most seriously affected by this illness are often seized with syncopes, symptoms of an afflux of blood to the head and the lungs, with an indefinable distress; and without fever, even with a feeling of inner chill, with hands and feet numb, their pulse beats at the rate of 108 to 120 times per minute. The unconquerable fatigue, the tendency to sleep are far from bringing on refreshing drowsiness, so that they cannot find repose. In fact, night brings the strongest feelings of suffocation, it is a real martyrdom; unable to endure a pros- trate position any longer, the unhappy patient seeks comfort beside the scanty fire which hardly keeps alive in the fireplace, at the risk of breathing air laden with coal fumes. The eyes are so weak that one can hardly read; in some, moreover, slight headaches appear, whereas in others there predominate discomforts and disorders of the digestive organs which resemble seasickness, from which, however, the puna is distinguished by its course as well as by its causes. When this painful stage is nearly over, often very distressing critical symptoms appear. After 6 or 7 days, the violent symptoms usually ameliorate in those who have strong lungs and a good consti- tution; otherwise, weeks may pass before the patient improves. An eruption of urticaria appears over his whole body, or is limited to the lips, on which it causes scabs, bleeding, or unendurable pain. ... In persons with thin skin and fair complexion, blood may issue from the skin without any wound, so that while the puna lasts, many dare not shave. In spite of the severity of the symptoms, there are hardly any cases in which they have caused death, and there is no danger except for those with weak lungs and especially those with heart disorders. (Vol. II, p. 84.) Poeppig then explains the reactions of different temperaments and different races, and gives therapeutic advice; he admits a cer- tain degree of acclimatization for Europeans. He next states that the residents of the country, even those born there, are not absolutely immune to the illness, especially when the nights are cold. The Indians have a sort of immunity. Beasts of 40 Historical burden have symptoms like those of men; dogs feel no effects; cats are scarce in Cerro and in lofty places, and their young are hard to raise; hens do not lay there and seldom brood. The account 35 given by M. Boussingault of the ascent of Chim- borazo, made December 16, 1831, is in strange contrast with what we have just reported. We have seen that d'Orbigny was seriously attacked by mountain sickness at about the height of 3700 meters; Poeppig has described to us the sufferings of Europeans who have come to Cerro de Pasco (4350 meters) ; now M. Boussingault and Colonel Hall, his companion, climb nearly to the summit of Chim- borazo (to 6004 meters) and report almost no serious discomfort. M. Boussingault left Rio Bamba, where he had been staying for some time, December 14, 1838. He was accompanied by Colonel Hall, with whom he had already made ascents of Antisana and Cotopaxi. December 14, they slept at the farm of Chimborazo (3800 meters), which they left on December 15 at seven o'clock in the morning, guided by an Indian from the farm. When they had reached the height of Mont Blanc, the breathing of the mules was hasty and panting: It was noon. We were walking slowly, and as we were advancing upon the snow, the difficulty of breathing while we were walking be- came more and more noticeable; we easily regained strength by stop- ping every eight or ten steps, without sitting down. At equal heights, I think I have observed that it is more difficult to breathe on the snow than on rocks; I shall attempt later to give an explanation of this. (P. 155.) This first attempt failed; the snow, which had become too deep, checked the progress of the travellers, who sank in it up to their waists; they went back down to the farm. The next day, they started at seven o'clock by another route, the one followed by Humboldt, and ascended on muleback to 4945 meters. There they had to dismount, since the mules could no longer carry their weight; it was a quarter of eleven. The two travellers continued to ascend on foot. We stopped to breathe every six or eight steps, but without sitting down. . . . But as soon as we reached a snowy surface, the heat of the sun became suffocating, our respiration was painful, and consequently our pauses for rest became more frequent, more necessary. We kept absolute silence during our advance, since experience had taught me that nothing was as exhausting as conversation at this height; and during our halts, if we exchanged a few words, it was almost in a whisper. It is largely to this precaution that I attribute Mountain Journeys 41 the health which I have consistently enjoyed during my ascents of volcanoes. This wholesome precaution I imposed despotically, so to speak, upon those who accompanied me, and on Antisana an Indian who broke the rule by calling at the top of his lungs to Colonel Hall, who had strayed from us while we were passing through a cloud, was attacked by vertigo and had a slight hemorrhage. (P. 159.) They finally reached the foot of a peak of trachyte which barred their way; it was a quarter of one, the height reached was 5680 meters, the thermometer stood at 4 degrees, and the air was very full of moisture, a condition which is constant on the glaciers of the Andes, according to M. Boussingault. Finally, after a rather long rest, after studying the terrain carefully, they once more began their climb: We were already beginning to feel more than we ever had the effect of the rarefaction of the air; we were compelled to stop every two or three steps, and often even to lie down for a few seconds. When once seated, we recovered immediately; our sufferings occurred only while we were moving. (P. 250.) Finally they arrived at a height of 6004 meters, an elevation which no one had yet reached; however this was not quite the summit of Chimborazo: After a few moments of rest, we were entirely recovered from our fatigue; none of us felt the symptoms experienced by most of those who have ascended lofty mountains. Three-quarters of an hour after our arrival, my pulse rate, and that of Colonel Hall too, was 106 per minute; we were thirsty, we were evidently in a slightly feverish con- dition, but it was not at all painful. (P. 251.) The rarefaction of the air generally produces very marked effects in persons who climb high mountains. ... As for us, we had, it is true, experienced difficulty in breathing and extreme fatigue while walking, but the symptoms ceased with the motion; when we were resting, we thought we were in a normal condition. Perhaps the mild- ness of the symptoms produced in us by the rarefaction of the air should be attributed to our prolonged stay in the lofty towns of the Andes. When one has seen the bustling in cities like Bogota, Micuipampa, Potosi, and still others, at an altitude of 2600 and 4000 meters; when at Quito, at an elevation of 3000 meters, one has witnessed the strength and prodigious activity of the toreadors; when one has seen young and delicate women dancing all night long in localities almost as high as Mont Blanc, where the famous de Saussure could hardly find enough strength to consult his instruments, and where his vigorous moun- taineers fell fainting while digging a hole in the snow; finally, when one remembers that a celebrated battle, that of Pichincha, took place at a height nearly that of Monte Rosa, one must admit that man can 42 Historical become accustomed to breathing the rarefied air of the highest moun- tains. (P. 245.) But a German traveller, Dr. Meyers,"1 who in his journey around the world from 1830 to 1832 stayed for some time in Peru and in April, 1831, made the ascent of the volcano of Arequipa (5640 meters), speaks of mountain sickness in terms which recall the description of Poeppig: At two o'clock in the afternoon we reached the summit of the mountain; my strength was exhausted, and we were suffering from the painful illness called sorocho. Little by little the symptoms of a nerv- ous or feverish state from which we had been suffering during the whole ascent had increased. Respiration took place with increasing difficulty, and gradually vertigo appeared, nausea, vomiting, then nose- bleed and fainting; in this condition we were forced to lie down on the ground, but rest restored our strength and permitted us to walk on again. The illness from which we were suffering deserves to be studied here; all travellers have heard of it, as soon as they have set foot on the coast of this country, expressing the intention of travelling in the mountains. In Peru they call it sorocho, and in Quito mareo de Puna or Puna. It appears under different forms. One of its symptoms, which is found both in the lower regions and on the summit of the Cordilleras, is a sensation of difficulty in breathing at the least effort. If one is on horseback, he feels no effect of the sort; but there appears at different degrees of intensity a sort of half-feverish condition, which is evidenced by burning heat over the whole body, headaches, dryness of the tongue, a burning thirst, and loss of appetite. The pulse rate rises to 100 or 110 at the slightest movement. The face reddens, the skin cracks in differ- ent places so that blood issues; at the same time a general fatigue appears. That is the usual condition, the first test of those who make ascents, whether in Quito, Peru, Chile, the mountains of Asia or even the highest of those in our Europe. . . . This feverish condition is made worse by exertion and also by the influence of the violent, dry and cold winds which are so common in the Cordillera; the well-informed residents of this country attribute this illness to these winds. . . . The burning effect of the sun in lofty places also helps to aggravate these symptoms ... it is a factor in the headaches and the half-feverish condition. There are some persons who attribute the illness to exhalations from the metallic veins and deposits of sulphur so common on the summit of the Cordilleras. The sorocho has been compared to seasickness, and it has even been said that those who are not subject to the latter are spared by the former. That seems to us a mistake. The half-feverish condition which we described previously is the basis of this illness, and when it becomes worse, it brings on the characteristic symptoms of diseases of the brain, the respiratory organs, and the digestive organs. One of these three organs is always particularly affected, so that different forms of the illness result. When the chest is particularly affected, difficulty in Mountain Journeys 43 breathing is added to the general fever; a sensation of weight in the chest appears, and the respiratory rate, like the pulse rate, increases; then come lacerations of the lungs, symptoms of choking, and even hemorrhages, a very rare phenomenon. . . . The death which has been observed in beasts of burden came, in our opinion, from suffocation; we ourselves, in ascending the volcano of Arequipa, experienced such respiratory difficulties that we had to stop every ten steps. Loaded animals, which are not allowed to do so, go on until they drop. In other cases, the illness attacks the digestive organs in particular, and then there appear nausea, qualms, extreme weakness, and finally vomiting, which gives a little relief. Affections of the brain are much more dangerous; they are also characterized by nausea and syncope, by a peculiar condition resembling drunkenness, and even by madness. In general it is admitted that at great heights the pulse rate is more rapid; that is because respiration itself has become much more rapid in a rarefied air. But neither respiration nor circulation is accelerated if one keeps perfectly quiet; several times, on the plateau of Tacora, after sleeping our pulse rate was no more than 70 or 72 per minute, whereas a few hours later the mere act of riding made it rise to 100 and 110. (P. 34 et seq.) They reached the summit of the mountain in a state of absolute exhaustion, and descended in a feverish condition which had not completely disappeared the next day. (P. 38.) The account of the illustrious naturalist Charles Darwin iT agrees perfectly with what we reported above in regard to the Chilean Cordillera. On May 20, 1835, he crossed the Andes, going from Santiago to Mendoza through the pass of Portillo (4360 meters) : About noon we began the tiresome ascent of Peuquenes, and then for the first time we felt some slight difficulty in breathing. The mules stopped every fifty steps, and the poor brave animals, after a few seconds, started again of one accord. Shortness of breath in rarefied air is called by the Chileans puna; and they have very ridiculous ideas about its cause. Some say: all the waters here have the puna; others: where there is snow, there is the puna; which no doubt is true. It is considered a sort of disease, and they showed me crosses on the graves of people who had died "punado." Except in regard to people who had lung or heart diseases, I think that these ideas are mistaken. No doubt at these elevations a very sick man will experience greater difficulty in breathing than others, and if he dies, this may have been the cause. The only sensation I felt was a slight oppression in the head and chest; this sensation is similar to what one feels when he leaves a warm room and exposes himself to icy air. There was much imagination in this; for, having found fossil shells on the highest peak, I forgot the puna completely in my joy. But certainly fatigue from walking is ex- treme, and breathing becomes deep and laborious. I cannot understand how Humboldt and others could have ascended to an elevation of 19,000 feet; beyond doubt a residence of some months in the lofty region of 44 Historical Quito had fortified their constitutions against such fatigue. However I was told that at Potosi (about 13,000 feet) foreigners do not become accustomed to the atmosphere until they have dwelt there a whole year. The natives all recommend onions for the puna ... as for me, I found nothing equal to fossil shells! (Vol. Ill, p. 393.) The English officers Smyth and Lowe,38 who undertook a jour- ney in 1834 to find a navigable passage to the Atlantic by way of the Pachitea, the Ucayali, and the Amazon, crossed the Cordillera much nearer the equator. They left Lima September 20, 1834. September 25, a little beyond Pucachaca, the illness attacked them: The air became very cold ... we began to feel what is commonly called the veta or marea (seasickness), which consists of an acute pain through the temples and the lower and back part of the head, and which completely prostrates those attacked by it. ... (P. 25.) They reached Cerro de Pasco September 28: Because of the altitude, and especially while we were ascending, we felt a difficulty in breathing which oppresses the lungs, especially in new-comers; but after some time, the lungs become accustomed to the condition of the atmosphere, and this illness disappears. (P. 42.) Moreover, these facts were so well known in the mountainous regions of South America, that in 1842 a Scotch physician, Archi- bald Smith,3'1 summarized in the following words the notes he had collected during a journey to Peru: Veta, Soroche, la Puna, Mareo de la Cordillera. A headache with throbbing and a painful sensation of fullness in the temples, combined with a great oppression and tension of the lungs, and frequently with stomach disorders, are the symptoms usually felt during the first days when crossing the Cordilleras or staying in Cerro de Pasco. If one walks quickly, especially if one climbs a hill, he feels extreme fullness in the chest, the temporal arteries throb violently, and headaches come on. If one tries to run, these symptoms appear immediately, and he is glad to stop and regain breath. Breathing a frosty air, July 3 at midnight, in a miserable hut in the pass of Tucto (4855 meters), gave me an excruciating sensation along the tracheal artery; until I began the descent, I constantly felt afraid that some blood vessel had opened in my lungs . . . On another occasion, on another route . . . my breath- ing was panting and difficult. Many young persons become accustomed to the effects of the rare- fied air, so that they have headaches and dyspnea only during strenu- ous exercise. Some persons, on the contrary, and especially the ple- thoric, cannot cross the Cordillera or live in Cerro de Pasco without headaches and respiratory difficulties; when they cross the Cordillera, traveling over these lofty and icy plains which the natives call Puna, they are very likely to suffer from epistaxis. (Vol. LVII, p. 356; 1842.) Mountain Journeys 45 The evidence of the French botanist Claude Gay 40 is no less con- clusive. Now the authority of this scientist is great, since for nearly fifteen years, from 1828 to 1842, he explored the Cordillera of the Andes. He expresses himself thus: I left Lima (1841). . . . After a march of four days, we crossed the first Cordillera by the pass of Tingo, 4815 meters above the level of the sea. There we felt a strange discomfort, the result of the great rare- faction of the air, known in America by the name of soroche, pouno, etc. It can very well be compared to real seasickness; there are the same symptoms, the same distress, headaches, vomiting, and such pros- tration that it almost makes life a burden, and kept me from going to consult my barometers and thermometers, which were only two paces from me. . . . This illness lasted some time; but subsequently I finally became accustomed to this rarity of the air, and I could take magnetic readings at an elevation of 4685 meters and carry out several other tasks of ter- restrial physics without being noticeably inconvenienced. (P. 28.) . . . The Indians of Cuzco . . ., although constantly at an elevation of 10,000 to 14,000 feet, are not at all inconvenienced by the great rarity of the air; they walk and talk with as much ease as we do in the low plains: and so there are found in these regions the loftiest towns and cities in the world; Ocoruco at 4232 meters, Condoroma at 4343. There are some post-houses, for example, that of Rumihuani, which are at an elevation of 4685 meters, and shepherds' houses at 4778 meters, that is, almost the height of Mont Blanc. (P. 33.) The celebrated German traveller J. J. von Tschudi41 gives an almost complete monograph on this subject. At the great altitudes to which the Cordillera rises, the effect of the rarefied air upon the organism is seriously felt; it is evidenced especially by a condition of extraordinary fatigue and great difficulty in breathing. The natives call this effect Puna or Soroche, the Spanish Creoles call it Mareo or Veta, and attribute it to metallic emanations, especially those of antimony, which plays a very important part in their physics and metallurgy. The first symptoms of the Veta usually appear at a height of 12,600 feet, and consist of vertigo, buzzing in the ears, and disturbances of vision, accompanied by violent headaches and nausea. These symptoms attack horsemen, but not so much as those on foot, it is true. The higher one ascends, the more these symptoms increase, and to them is added exhaustion of the legs so great that one can hardly move, with very painful respiration and violent palpitations. Complete rest checks these symptoms for an instant, but at the slightest movement they instantly reappear, and are often accompanied then by fainting fits and vomiting. The capillary vessels of the conjunctiva, the lips, and the nose burst, and blood issues in drops. The respiratory and diges- tive mucous membranes are the seat of similar symptoms; diarrhea and the spitting of blood are the evidence of the Veta in its worst form. 46 Historical One can compare this disease approximately to seasickness (whence its name of Mareo) ; but it alone produces respiratory distress. It is not unusual to see these symptoms become so serious that they cause the death of travellers. In 1839 at Pachachaca I met an officer who was carrying dispatches from Lima to Cuzco, but who, one year, while crossing at the Piedra parada, died in consequence of pulmonary and intestinal hemorrhages caused by the Veta. All residents on the sea- coast and the Europeans who are crossing the high Cordilleras for the first time feel this illness which is usually not persistent in healthy persons, but which attacks severely those who are weak, nervous, with diseases of the lungs or heart, and also the plethoric and the obese. A German trader from Lima, a very corpulent man, who had gone to Cerro de Pasco on business, at the end of a few hours had to leave the city rapidly, and descend into the valley to escape the Puna. By a long stay in these lofty regions, the organism becomes ac- customed to this effect of rarefied air. Vigorous Europeans can even climb the highest mountains nimbly and move about there as freely as on the coast. I had the Veta only twice, but very severely; once on a lofty plateau, and once on the mountain of Antaichahua. The first time I crossed the Cordillera, I did not feel the least inconvenience, and I was able, getting off my tired horse, to walk a long way without feeling symptoms of the Veta, so that I thought I was completely im- mune to it. . . . The Indians of the mountains, who have been living since child- hood in this rarefied air, are not subject to the Veta. . . . The physicians of Lima are accustomed to send to the mountains persons who suffer from prostration, so that the pure air may give them back their strength; but there they are attacked by the Veta most severely, and often lose their lives in the Cordillera .... The Puna seems to have a worse effect upon certain domestic animals than upon man himself. This is particularly true of cats; these animals cannot live above an altitude of 13,000 feet. They have often been brought to lofty villages, but always in vain, for after a few days they were seized by terrible convulsions like those of epilepsy to which they succumb. . . . These sick cats do not try to bite, or to run away. . . . In this country they are called azorochados and are given antimony. The delicate breeds of dogs are also affected, but not so seriously. Travellers in the Cordilleras are also subject to symptoms known by the name of Surumpe. . . . These are eye affections due to the effect of the reflection of the sun on the snow. (Vol. II, p. 66 et seq.) In his ascent of the Cordillera, Tschudi for the first time saw horses attacked by the veta, at the elevation of about 4000 meters: First they walk more slowly, stop frequently, tremble all over, and are prostrated. The higher they ascend, the harder they tremble, and the oftener they fall. If they are not unsaddled, if they are not allowed to rest completely, they lie down on the ground. The arrieros bleed an animal in this condition in four places: at the end of the tail, on the palate, on the two ears; they often cut their ears and tail half -off and split their nostrils to the width of several inches. This last method Mountain Journeys 47 seems to me to be rather useful, because the animals can then breathe a larger quantity of air. As a preventive garlic is placed in their nostrils. Mules and donkeys suffer less from the Veta, probably be- cause they know better how to rest. Horses born on the Sierra are almost immune to these symptoms. (Vol. II, p. 32.) A very striking episode in the account of Tschudi is the story of his twenty-four hour stay in the icy Puna of Peru, at an average elevation of 4300 meters: I was beginning to climb the mountain vigorously when I felt the dangerous effect of the rarefied air; while I was walking I experienced an unknown distress. In order to breathe I had to remain quiet; even then I could hardly succeed; if I tried to walk, an indescribable anguish seized me. I heard my heart beating against my ribs; my breathing was short and interrupted; there was an enormous weight upon my chest. My lips were blue, swollen, cracked; the capillaries of the conjunctiva burst and a few drops of blood issued. My senses were strangely blunted; sight, hearing, touch, were altered; before my eyes there floated a thick cloud, grayish, often reddish, and I shed bloody tears. I felt as if I were between life and death; my head whirled, my senses failed, and I stretched out trembling on the ground. In truth, if the most precious riches, if immortal glory had awaited me some hundreds of steps higher, it would have been physically and mentally impossible for me merely to stretch out my hand towards them. For some time I x'emained lying on the ground in this half-fainting condition, then I recovered a little, hoisted myself painfully on my mule, and I succeeded in going on. (Vol. II, p. 152.) The accounts given by de Castelnau 42 are no less explicit, and contain many interesting details: Our stay in September, 1845, at Chuquisaca, a city of some 11,000 to 12,000 souls (Bolivian Republic), was rather gloomy. . . . Most of my companions were also affected by the soroche, an illness caused by the rarefaction of the air at high altitudes (according to the observations of M. Pentland, Chuquisaca is 9343 English feet (2847 meters) above sea level) : it is especially while climbing the uneven streets that one feels this painful sensation of suffocation; dogs, horses, and beasts of burden are equally subject to it there, and I have seen some beasts of burden from whose nostrils blood was dripping. In this case, muleteers usually make them swallow cloves of garlic. Animals have often died from such symptoms; this is especially true of horses. No matter how little they are urged on, they try to overcome the distress they feel, and some- times fall dead in the streets; mules, on the contrary, stop of them- selves and start only when they are rested, in spite of the ill treat- ment to which an unwise master may subject them. (Vol. Ill, p. 317.) At La Paz (3717 meters) , de Castelnau attended a bull fight: Unfortunately (he says) the bulls of La Paz, raised on the frozen plains of the Puna, and which besides probably had the soroche, which, 48 Historical by the way, is terrible in this city; these bulls, I say, showed energy only in fleeing before base toreadors on foot who tried to hold them back by pulling their tails. The angry people rushed into the arena, 'and by dint of tormenting these unhappy animals, finally obtained the desired result, that is, the death of two or three Indians. (P. 376.) One of the travelling companions of Castelnau, Weddell, climbed the volcano of Arequipa in October, 1847. He expresses thus the sufferings which he felt on this ascent: The difficulty in breathing which our animals experienced com- pelled us to renounce their assistance. ... In advancing we had to tack, and even so we could not advance ten steps without stopping, so as to let the oppression which had seized upon our lungs pass. As we mounted higher, not only did this oppression increase, forcing us to make longer pauses, but weariness of the limbs was also added: a symptom more distressing than the soroche, because a halt was not enough to check it ... . The last strength of my companion was exhausted and he had to leave me. Alone I continued my journey, panting; ... I could hardly advance more than two or three meters without stopping to get my breath. (P. 449.) In May, 1846, de Castelnau left Lima for Cuzco. He therefore had to cross high mountains. At the pass of Vinda (4720 meters) , the soroche attacked him very severely: Vegetation, even the stunted thistles, disappeared. M. d'Osery complained bitterly of the soroche, and he was forced to pause con- stantly, as was Florentino. Here this disease is called veta, and people believe that it is due to the presence of veins of antimony. . . . Hardly had we reached the little settlement of Casacancha when as I dismounted I was attacked by the soroche, the effects of which I had not felt until then; I vomited bile abundantly, and felt all of the symptoms of seasickness to which I am very subject. When in the morning, after a very bad night, I wished to mount, I felt the absolute impossibility of it. M. d'Osery could hardly drag himself along; Florentino, a former sailor, was stretched out on the ground; little Catana alone was playing as usual, and seemed to feel no effects of the soroche. At last, understanding how indispensable it was to reach less inhospitable regions, we succeeded in mounting in the afternoon; but after going less than one league, we literally fell at the door of a farmhouse, where we were well treated. (Vol. IV, p. 194) . . . The altitude of Cerro de Pasco is estimated at 13,673 English feet (4166 meters) . . In spite of the burning rays of the sun, one is chilled as soon as he is in the shade, and he is constantly under the painful effect of the soroche. . . . The climate is so fatal that priests try to keep their pastorate for only three or four years, in spite of its enor- mous benefices. . . . The population, in 1845, was 18,000 souls ... It is only to the silver mines that this population is due. . . . Barley will not go to seed there. (P. 196.) Mountain Journeys 49 De Castelnau, after a few days, made an excursion to a nearby- cavern, situated at a height of 4400 meters, in which he found the bones of prehistoric animals, among others a sort of armadillo (probably a glyptodon) : We were suffering frightfully (he says) from the soroche, the stifling from which forced us to rest constantly; even the -Indians seemed affected by it. A French tourist with a picturesque account, M. de Saint-Cricq, who published his travels under the pseudonym of Paul Marcoy,4* felt similar symptoms while he was going from Arequipa to Puno. He had passed the night at the post-house of Apo (no date) : After an hour's walking, which had raised us some hundreds of meters, I began to feel a general discomfort which I attributed to the insufficiency of the atmospheric pressure. This phenomenon, which the mountain Quechuas call soroche, and to which they are immune, gifted as they are by nature with lungs a third more capacious than those of Europeans, is attributed by them to poisonous gases produced by antimony, (in Quechua soroche), even in places where this metal does not exist. A contraction of the diaphragm, dull pains in the dorsal region, twinges in the head, nausea and vertigo are forerunners of this strange disease, which are sometimes followed by syncope. But I did not go that far. My guide, warned of what I was feeling by my livid pallor and by my efforts to remain in the saddle, gave me a clove of garlic, urging me to crunch it. ... I obeyed . . . but the antidote . . . having produced no effect, my Esculapius advised me to give myself several blows with my fist on my nose, and since this would cause a hemorrhage, it should bring prompt relief; but this method seemed to me much too heroic, and I preferred to nibble a second clove.of garlic. . . About twenty minutes passed, and whether the remedy began to work or whether my lungs by degrees became accustomed to this thin air, I felt my discomfort passing away. (Vol. I, p. 76.) Lieutenant Gillis,44 of the English Navy, gives similar informa- tion, collected, it is true, second hand, but summarized in a very intelligent fashion. In the first part of his work, devoted to the geographical de- scription of Chile, the author speaks of the routes from Santiago to Mendoza, and especially of the Piuquenes route: Very few travellers reach its summit (13,189 feet above sea level) without feeling respiratory troubles; and the poor mules suffer almost as much as their masters. In Chile, this illness is called puna, in Peru, veta, soroche, or mareo, indifferently by the natives and the Creoles. The latter, in their ignorance of its real cause, attribute it to exhala- tions of metallic veins, so common in the Andes. With variations in different cases, the disease produces extraordinary fatigue, prostra- tion, vertigo, temporary blindness, and nausea, quite frequently ac- 50 Historical companied by hemorrhages from the nostrils and the eyes. Not all persons are subject to this effect, and it is clear that certain constitu- tions are more sensitive to it. The muleteers recommend garlic and onions as specifics. (Vol. I, p. 6.) The Englishman Lloyd4"' who crossed the great Sierra of Illimani, expresses himself as follows: Except for the disease called soroche, which is an affection of the lungs that is painful and often dangerous, caused by the extreme rare- faction of the air at this great altitude, almost no illness is known, except colds and dropsy. (P. 260.) The French botanist Weddell,4'5 whose sufferings when he was accompanying de Castelnau we have already reported, returned to Eolivia later. Coming from Arica, he had crossed the chain of the Cordillera without noteworthy symptoms, and after he had been in La Paz nearly two months, he had had no trouble; but on June 22, 1851, while he was botanizing, he wished to climb a steep slope rapidly; he was suddenly attacked: I can hardly express my sufferings from the soroche (he says), in this ascent which demanded of me gymnastic efforts which I was far from expecting. The fact remains that when I had reached the top of the precipice with my flowers, and was stretched out exhausted and panting on the ground, I swore, but a little late, that I would not be caught that way again. During the first few moments following my climb, I thought only of getting my breath which seemed on the point of leaving me, and a few minutes afterwards, when I thought of ex- amining my pulse, its rate was still 160 per minute. I do not think I have ever felt greater oppression than during this unexpected botan- izing expedition. From that day I felt a physical discomfort which I could not account for, and I foresaw that I was going to be ill. (P. 187.) He was, in fact, and very seriously. Except on this occasion, Weddell pays very little attention to the soroche, although in many passages of his account we recog- nize suggestions of it, sometimes in men, sometimes in domestic animals. I find nothing to quote but this interesting remark about the Indian postillions, who always proceed at a run, on the road from La Paz to Puno: They never seem out of breath (he says), whereas in this same country, a European can hardly run ten steps without being obliged to stop. (P. 547.) As you will perceive, there is a very great difference between this statement and those made by travellers on the Himalaya; the Indian coolies, they tell us, are often sicker than the Europeans Mountain Journeys 51 themselves. Weddell is not the only one to note this; the Grandi- dier brothers were also struck by it.47 August 1, 1858, these travellers left Arequipa for Cuzco: Here one experiences (says E. Grandidier in his account) a dis- tress unknown to tourists in the old world, that is, the soroche; the traveller who crosses the Cordillera feels pains all through his body; he has pain in his kidneys, in his head, his limbs feel as if they were broken, blood even gushes sometimes from his nose, eyes or ears. This general distress is due, not to the presence of antimony, as has been said without reason, but to the rarefaction of the air and the failure of ' breath. The soroche has even caused the death of some more suscep- tible persons. Mules are also subject to the effects of the soroche, and I have heard many examples of these animals dying in consequence of the rarefaction of the air. (P. 56.) And further on, while going from Paucartambo to Puno, their attention was directed to the natives on foot: The Indian follows the horseman on foot, always running without ever losing breath, however speedy the horse, and however high the mountains. The swiftness with which the Indian runs long distances surprises the European all the more because he cannot, like the native, overcome the oppression caused by the rarefaction of the air and run at this altitude without falling immediately. (P. 194.) In December, the two brothers arrived at La Paz: The road down to La Paz is wide and well kept; but the slope is so steep that one can only walk his horse down. This descent is about a league long, and it takes at least an hour to get to the city. A very much longer time is needed to climb it, because of the difficulty in breathing which the mules experience while ascending; nevertheless I was assured that the Indians mount it running and playing the flute: they are not subject to the soroche, and in this way they are like the llama, whose breathing apparatus is adapted to the Cordillera on which it lives. (P. 225.) The European who has recently arrived in La Paz feels the effects of a violent soroche; while he is walking through the town, he is forced to stop often to get his breath, so great is the difficulty of breathing and the oppression in the chest. The rarefaction of the air comes from the great elevation of La Paz above sea level; this eleva- tion is 3730 meters. (P. 227.) We have similar accounts from the German traveller Bur- meister,48 who in the first part of March, 1860, was in the Cordillera, about latitude 28° S., and longitude 72° W. However, he speaks of these symptoms only by hearsay; moreover, the maximum altitude to which he ascended was 14,000 feet: During my journey (he says) I never suffered from what is called 52 Historical the Puna, that is, the sickness which usually occurs on high moun- tains and which consists of difficulties in breathing, nausea, prostration, vertigo, and other symptoms. Only at first, when I entered the gorges near Estanzuela, I felt a heaviness in my head, as if I were going to have vertigo; but I had no other symptoms. . . . Probably I have been protected by the weakness of my constitution; for strong and portly people are more easily attacked by the Puna than those who are thin, spare, or weak. The symptoms of the same disease appear in animals, and particu- larly in horses, on the lofty paths of the mountains; they are charac- terized particularly by trembling of the limbs and violent hemorrhages, which, however, do not become fatal. Many horses, and especially the best, fall down on the ground on journeys in the mountains. The natives call this disease the Trembladera; they claim that in the moun- tains there are places where it is particularly likely to attack passing animals; they pointed out one in the Aconquija Sierra, the position of which, however, I could not determine. The Englishman Markham, 49 who in 1860 made a journey to Peru for the purpose of studying cinchona trees and finding a way of introducing them into the Indies, gives information of the same sort: On the heights of the Cordillera, men and animals are subject to a very painful disease, caused by the rarefaction of the air, and which the Peruvians call sorochi. I had been ill at Arequipa, so that I was probably predisposed to the attack of the sorochi, which affected me violently. Before reaching Apo (May, 1860), an excruciating headache, accompanied by acute suffering and pains in the lower part of the neck, made me very ill, and these symptoms grew worse during the night passed in the post house of Apo, so that at three o'clock in the morning, when we set out again, I was unable to mount my mule without as- sistance. (P. 89.) In the official description of the Argentine Confederation, Dr. Martin de Moussy/" who had dwelt for ten years in the basin of the Plata, gives a detailed description of the American form of mountain sickness: The name of puna is given to this painful sensation, this distress in breathing which some persons experience when they are at great heights. This sensation is certainly due to the rarefaction of the air, for, at 4200 meters, the general altitude of the plateau, the barometric column falls on the average to 0.46 meters . . . and it is impossible that such an enormous difference in the atmospheric pressure should not produce a profound impression upon the animal constitution. Further- more, this impression varies in different persons; some have difficulty in breathing, others suffer from cephalagia, a sort of headache, and a complete loss of appetite. Many feel no ill effects; but when they try to walk, almost everyone feels unusual fatigue. Mountain Journeys 53 As to the puna properly so-called, the difficulty in breathing, it is not peculiar to the great heights of the Cordillera; there are certain places of no great altitude where it is felt much more than in others. We ourselves experienced it at the town of Molinos, which is at an altitude of only 1970 meters, and in a valley surrounded by granitic mountains about which there is nothing peculiar. We cannot discover a cause for this peculiarity, which also exists at different points of the Andes in Bolivia. Animals also experience this difficulty in breathing in their first crossings of the Cordilleras; but they become acclimated rather quickly and their vigor is so great that mules in good condition and reasonably loaded never weaken on ordinary journeys. (Vol. I, p. 217.) Mateo Paz Soldan also gives a description of the soroche in his Geography of Peru: 51 Cerro de Pasco is situated on a slope 4352 meters above sea level. . . . The climate of this city is very cold, the temperature averages 44° F. by day and 34° by night, during the months from July to October, a season during which a great quantity of hail and snow falls. Some- times the thermometer falls to 30° and 28° in August and September; water boils at 180°. Storms, hail, and snow make this country un- inhabitable from the month of October on. Strangers there are sub- ject to the Soroche, an oppression in the chest, which in this country is called veta, and which is the result of the rarefaction of the atmos- phere, in so lofty a region .... Former miners are subject to a great many diseases and infirmities. ... If this country did not possess mines of inexhaustible richness, it would be absolutely impossible to live here. (P. 172.) About this period there appeared in the form of a thesis main- tained before the Faculty of Medicine of Paris a remarkable work by a young doctor, Ch. Guilbert,52 who, attacked by consumption, went to La Paz and there found the cure or at least a considerable amelioration of his dangerous disease. I shall quote the whole of his very concise description of the soroche: The soroche or the disease of the puna begins in two different ways: some immediately have difficulty in breathing, and that has attracted greatest attention of the observers; in others, and in my opin- ion this is the largest number, nervous symptoms appear first. There are even some travellers who have no difficulty at all in breathing. The same difference is found in the duration of these two classes of symptoms. Whereas the nervous phenomena last only 12 to 48 hours, difficulty in breathing and circulation sometimes persists for several months. The nervous system is therefore often the first affected, and re- acts upon the digestive and the locomotive systems. One first feels nausea, accompanied by very significant spitting. ... At the same time there comes a very violent headache, compared to a ring of iron which binds the temples tightly. . . . After the nausea, vomiting appears, often 54 Historical very painful, which increases the pain in the head. One also expe- riences vertigo, buzzing in the ears, sometimes drowsiness .... Another phenomenon is muscular fatigue. . . . This difficulty in muscular contraction is experienced even on horseback, and to such an extent that persons who are unable to move have to be taken down from their horses. But after the first few days, this great fatigue dis- appears completely after a very short rest. In the cities, new-comers are easily recognized; they stop for a few seconds every 40 or 50 steps. Respiration and circulation are speeded up in proportion to the elevation. The dyspnea is extreme, the inspirations very frequent. The heart-beats are stronger, more numerous; at the least effort one is attacked by violent palpitations which continue when he is riding as well as when he is walking. Even at night, one is often awakened with a start by strong palpitations in the midst of the calmest sleep. . . . The beating of the arteries is stronger, that of the intra-cranial arteries very painful, the pulse is vibrating, almost as in aortic insuf- ficiency. A rather frequent symptom is a nasal, buccal, or pulmonary hemorrhage; hemorrhages from the gastro-intestinal mucous membrane are rare. . . . But when one becomes used to the rarefied air, when equi- librium is established, and when the different systems are in harmony with the surrounding medium, hemorrhages are no more frequent than anywhere else ... An important symptom is the tendency to syncope, and so one must be very careful about bleeding the patient .... The nervous symptoms are the first to disappear; the headache lasts hardly 12 to 24 hours; the nausea and vomiting no longer . . . The third or fourth day, appetite revives a little; as soon as the patient can take a little nourishment, the heaviness in the head disappears in its turn, and there remain only the difficulty of respiration and the rapidity of the heart-beats, palpitations occurring at the least effort, and making the lack of breath still worse. Later, when equilibrium has been estab- lished, little by little all these symptoms disappear, generally at the end of a few weeks, and one becomes perfectly acclimated to these lofty regions. So Guilbert thinks that one can become perfectly acclimated to lofty regions. He recalls the words of M. Boussingault, which we quoted above, and adds: Pichincha is 4996 meters high; the Bolivian general Santa Cruz defeated the Spaniards there in 1822. Two years after, at Ayacucho, a village situated at about the same height, the Colombian general Sucre defeated the viceroy La Serna. . . . At Corocoro (4430 meters) I saw very bloody bull-fights. These bulls, nimble and wild, might have given pleasure to the travellers mentioned by Lombard,53 who saw at La Paz bulls which were gentle and unable to make the least effort without vomiting; these were bulls which had recently been brought to the mountains and which were affected by the soroche, which attacks animals as well as men. ... It is very rare to cross the Cordilleras without witnessing the sickness of some beast of burden, attacked by the soroche; it is hastily unloaded, rubbed, and after a moment of rest, allowed to follow at liberty. Mountain Journeys 55 In the special chapter I shall give the very eclectic mixture of theoretical explanations which Guilbert accepts. The Italian professor Pellegrino Strobel, ,4 who crossed the dif- ferent passes between Santiago and Mendoza, was lucky enough not to be affected by the soroche; it is true that he seems not to have mounted very high: After what M. de Moussy wrote and what my friends had told me, I expected to experience on Planchon one of the sensations described under the name of puna. But — I do not know whether I should say happily or unhappily — neither here at 3000 meters above the Pacific, nor on Cumbre of Uspallata at about 4000 meters nor in any other part of the secondary chains of the Andes, was it granted me to feel the slightest difference in respiration or appetite, still less any headaches and other pathological symptoms or physiological phenomena; and yet on account of the weakness of my constitution and the narrowness of my chest, it seems as if I should have suffered from it more than any- one else. I must therefore admit that the puna does not depend solely upon the rarefaction of the air, but also upon other concomitant causes, which appear to be wholly unknown. (P. 25.) However two German travellers, Focke and Mossbach, ■"'•"• who speak from their own experience, declare that often men and beasts become ill at still lower altitudes: Starting at an altitude of 10,000 feet, one feels the beginning of mountain sickness, that is, a stunning headache; it is the Sorocho, which attacks also beasts of burden. They refuse to go on, and to cure them, they are bled under the tongue. (P. 391.) Finally, I have the statement of a high official of the Peruvian government, an intelligent man, that having gone to Perina-Cota (4800 meters) near Guayaquiri, he saw his mules become ill at an altitude of 3000 meters; out of 40 mules, 16 had to be unloaded. Some of his companions had nosebleed. During a stay of two weeks at this great height, he experienced regularly, about three o'clock in the morning, a feeling of suffocation which awakened him; the least movement then increased it considerably; these symptoms lessened during the day. The Indians who accompanied him suf- fered from the same illness. Even today, the generally accepted explanation is poisoning by metallic emanations; they try to check its effects by garlic sachets. I also learned from this gentleman that while the railroad tunnel from Lima was being bored, at an altitude of about 4800 meters, all the workmen had been affected, even the most robust. I am sorry not to have been able to get written details of the phenomena observed during the execution of this extraordinary 56 Historical work. It is finished now, and already the locomotive conveys the travellers up to regions which formerly they could not reach with- out the most strenuous efforts. Strangely enough, nevertheless a certain number of them became ill. In a letter addressed this very year to one of my friends, there is this very characteristic passage: A special train came for us at Callao, took us up Reinar to Lima, then from there into the Andes, climbing by successive planes to an altitude of 3450 meters. . . . We thus journeyed 130 kilometers. . . . The temperature had fallen, the rarefaction of the air was such that many persons could not accompany us to the end. They felt extreme oppres- sion and their eyes were bloodshot. It would be very desirable to have careful observations made on this railroad and on the Titicaca railroad too; it would be very easy for the professors of the Faculty of Medicine of Lima to do so. I shall finish these quotations from the principal general de- scriptions of mountain sickness in the Cordillera of the Andes by copying a very interesting letter written by M. Pissis to Dr. Coignard, who asked him at my request for information which his great experience in the mountains made very valuable to me. The learned geographer in this letter describes very vividly the symp- toms which he felt, but he does not venture upon any explanation: Paris, March 17, 1874. Dear Doctor: Here are the observations which you requested of me upon the physiological effects of the rarefaction of the air on lofty mountains. The general effects are headaches, nausea, great difficulty in breathing and a contraction in the region of the false ribs, as if one were tightly squeezed by a belt. These symptoms vary greatly, however, according to the age and the constitution of the patients; when I crossed the pass of Tacora (bar. 463 mm.) a negress eighteen to twenty years old, very sturdy, was extremely ill, she had a profuse nasal hemorrhage, whereas her mistress, a woman of about fifty years, of weak constitution, was hardly affected; the same difference is observed in animals; the strong- est horses are the most likely to die. Nasal hemorrhages are frequent in them also. After one has lived a certain time in lofty regions, these effects are no longer felt; the residents of Oruro in Bolivia, at 3,796 meters (average barometric pressure 492 mm.) live as if they were on the seashore; the Indians run leagues without getting tired, and after a year's residence, I easily climbed fairly high mountains, which would have been impossible at my arrival. The highest point where I saw permanent dwellings are the mines of Villacote in the province of Chayauta; their altitude is 5,042 meters and the atmospheric pressure 421 mm. The Indians work there as they do elsewhere, but they get tired more easily when it snows, for it never rains in these regions; the workmen, even those in the depths of the mines, are ill, and yet the decrease in pressure when it storms is Mountain Journeys 57 hardly 4 or 5 millimeters. The alpacas and the vicunas live in herds at these heights, the condors fly far above, and I have found a few turtle- doves there. Although accustomed to the pressure of Oruro, when I went to these mines, I was always ill, with nausea, headache and dif- ficulty in breathing, and I could not walk eight or ten steps without having to stop to get my breath. The manager, who has lived there for two years, could walk a little further, but always had difficulty in breathing. At a height of 4,000 meters, the rarefaction of the air has only a passing effect upon the health, the residents of Oruro and Potosi become very old, and lung diseases are unknown there; the residents are generally thin, very active, but have little strength, which perhaps is partly due to their almost exclusively vegetable diet. In Chile, the highest point I reached was on the side of Aconcagua at an altitude of 5,832 meters; the summit has an elevation of 6,834 meters. At the point where I stopped, the barometer reading was 382 mm.; I was very sick and it was impossible for me to climb higher; my eyes were badly bloodshot; all objects, even the snow, seemed red to me, and even with my glasses of very dark blue glass, I had great difficulty in reading my barometer. On the way down, at about 5,000 meters, all these symptoms disappeared. In my numerous stops in the region of the Andes, I often saw condors wheeling about the sides of the highest mountains, but never soaring above their summits; but one should not be hasty in drawing a conclusion from that fact; for the heights they reach are so great that they appear only as little black dots; if there were any at the height of the summit of Aconcagua, they would certainly be invisible, even if one were at an elevation of 5,000 meters, that is, higher than Mont Blanc. At 4,000 meters one finds in the Andes of Chile guanacos, swans, ducks, turtledoves, and even humming birds. A. Pissis. If travellers who limited themselves to crossing the passes of the Cordillera or stopping on the lofty inhabited plateaux of Bolivia and Peru have experienced such symptoms, one may suppose that those who purposely attempted the ascent of the mountains which tower above the average level of the chain have experienced even more. However this is not always true. We have seen that Hum- boldt and Boussingault suffered much less on Chimborazo than other travellers at Cerro de Pasco or even La Paz. Other examples are no less strange. For instance, on January 14, 1845, Wisse 5G descended into the crater of Rucu-Pichincha to the depth of "four times the highest pyramid of Egypt", and climbed back; he does not mention any physiological symptom. We shall discuss these differences later. They are so great that certain travellers go so far as to deny that mountain sickness exists, because they never experienced it, and there reappear the explana- 58 Historical tions about poisonous air, which both the Indians of the Andes and those of the Himalaya have accepted. The most remarkable account I know, in this respect, is that of the French traveller Jules Remy,'7 who made the ascent of Pichin- cha (4860 meters) on October 2, 1856. The weather was magnifi- cent, it was warm on the summit of the mountain, where numerous humming birds were buzzing about. Remy felt no distress. My breathing is free, easy, excellent, and I feel no symptoms of distress, a fact worth noting, for it confirms my preceding observations, although contradicting those of other travellers who had stated that at these altitudes the decrease of the atmospheric column causes serious symptoms in different organs. Only on Cerro de Pasco, a mountain in Peru, celebrated for the silver mines operated there, are the morbid symptoms manifested in the . animal organism constant and universal, so far as we know. There one is infallibly attacked by a strange disease, the soroche. . . . But if it is noted that Cerro de Pasco is only about 10,000 feet above the ocean, and that after one has walked seven or eight leagues, normal health is suddenly restored, although one is then at a much greater altitude, one is compelled to admit that atmospheric pressure is not the cause of the soroche, which perhaps should be attributed to ema- nations from the ground. However, if one reads carefully this very account of J. Remy, he finds in it indications of the harmful effect of the altitude; but their slight importance had escaped our traveller. He displayed the same immunity in the ascent which, on No- vember 3, 1856, took him to the summit of Chimborazo; 58 naturally his negative conclusions were greatly reenforced here. The camp of the night before was made at an altitude of 4700 meters, a little below perpetual snow: The climb continued to be so steep that soon, under the weight of fatigue, we were obliged to stop frequently to get our breath; then thirst became extreme. . . . But we felt no symptom of discomfort or of any morbid affection, mentioned by most of the travellers who have ascended high mountains. As soon as we had stopped walking for a few seconds, even with- out sitting down, we went on with new ardor, with a sort of fury inspired in us by the sight of the summit so near us. It seemed evi- dent to us, from this new experience which confirmed so many pre- ceding ones, that at these altitudes the atmospheric column is still sufficient not to hamper respiration, and that the short breath and organic symptoms of which complaint is generally made by those who reach considerable altitudes must be attributed to some other cause. Having continued their journey in the midst of clouds, the two travellers thought, after observing the boiling point of water, that Mountain Journeys 59 they had reached the summit of Chimborazo, which they estimated to be an altitude of 6543 meters. But not everyone is so lucky. In a recent journey, Stuebel,59 while warning the reader against certain exaggerations, confesses that he suffered considerably in the ascent of Cotopaxi. On February 8, 1873, at seven o'clock in the morning, the trav- ellers started from an altitude of 3615 meters; at two o'clock, they were at a height of 4498 meters. Without great difficulties, they reached the summit of the volcano of Tunguragua (4927 meters), without being tired and "without suffering headache." (P. 273.) March 8, ascent of Cotopaxi (5943 meters, temperature 3.5°) starting from the Saint-Elie farm: Some of my people had gone on in advance, others had stayed behind. They were tired, had become a little timid, and complained of headache. . . . The arena! has a slope of 35°; it wears down the strength, so that one must summon all his moral energy not to fall just as one is reaching his goal. ... It took us twenty-eight minutes for each hundred meters. (P. 282.) . . . We began to descend. ... I found little by little all my men; one had remained 50 meters from the edge of the crater, unable to reach the goal so near at hand; the others 400 meters away, and most of the muleteers much lower. Like me, all were suffering from a very violent headache. Only one felt no effects and was not fatigued; he was carry- ing my barometer, which, however, is pretty heavy. One muleteer did not get above a height of 5,600 meters. I could testify that the vomiting is the effect of the air of these great heights, but not of a passing weakness of the stomach. But neither in this ascent nor in the preceding ones, did I see blood issuing from the noses, mouths, and ears of my people. These are circumstances upon which other travellers like to dwell. Certainly it must seem strange that M. Reiss and I mentioned no case of the sort. Now we reached a height of 6,000 meters three times, and 5,000 meters several other times, an altitude to which few travellers have ascended. We have always taken with us a certain number of men of different races. . . . The scientific result of these ascents, in which man reaches the summits only by using all his strength, will always be of slight importance. (P. 285.) 2. Central and North America. Central America. The republics of Central America contain no peaks the elevation of which is comparable to those of the grand Cordillera. So it was with great surprise that I found in the tales of an English navigator of the seventeenth century, Wafer,60 a very definite mention of mountain sickness. Wafer took part in the expedition of Dampier, and was one of the troop who tried to cross the Isthmus of Darien, in 1681. He was 60 Historical severely wounded, and with four other Englishmen fell into the hands of Indians, who, after various adventures, restored him to liberty. They then left the vicinity of the southern sea for the ocean to the north: We crossed (he says) several very high mountains, but the last one was the highest of all; it took us four days to ascend it, although there were some low spots here and there. As soon as we had reached the summit, I felt that my head was whirling strangely; I told this to my companions and the Indians, who answered that they were all in the same condition. Apparently the illness came from the great height of this mountain and the thinness of the air. . . . Our vertigo left us as we descended. (P. 174.) It should be noted that Wafer and his companions, even the In- dians themselves, his guides, were in a state of fatigue which was near complete exhaustion. But in spite of this added circum- stance, the importance of which we shall see later, I cannot account for the condition in which Wafer must have been when he says that he veered enough towards the northwest to reach Chiriqui (3430 meters) , or further yet, Pico Blanco (3600 meters) , which is nearer the sea to the north. The only explorers who, in modern times, ascended the highest volcanoes" of Central America, MM. A. Dollfus and deMontserrat,61 never mention in their detailed and interesting accounts the special illness of great heights; yet they knew it, having experienced it, as we shall see later, in their journey to Popocatepetl. The high inhabited plateaux of Mexico have caused similar ob- servations, and we shall see, in the chapter devoted to the an- alysis of theoretical explanations given by authors, that it was in regard to these plateaux that the discussion which was most fruit- ful for the topic of this book arose. I shall copy here two interest- ing quotations relating to symptoms observed in animals: Horses and mules in Mexico (says Burkhardt)62 are subject to a disease which is little or not at all known in Europe. If while the sun is hot they are driven to great efforts or to rapid and continuous move- ment, they are often seized by palpitations and an acceleration of the pulse and circulation so great that they have strong convulsions over their whole bodies. Profuse bleeding is the only remedy against this disease, which the Mexicans call asoleado. ... So before buying a horse or mule, the purchaser takes care to make the animal gallop a little, and then to notice whether palpitations in the withers give evidence of the disease. Animals often fall, as a result of this affection, if they are compelled to work uninterruptedly. (Vol. I, p. 63.) Mountain Journeys 61 I borrow the other quotation from Heusinger," ; who took it from Elliotson: M. Lyell says that the Englishmen who own mines on the plateau of Mexico, at an elevation of 9,000 feet above the sea, took greyhounds there to hunt hares; but they could not endure hunting in the rarefied air, they were out of breath before reaching the game. On the contrary, their young born in this place are not affected by the rarefied air; they hunt and overtake the game as well as the best greyhounds in England. (Vol. I, p. 260.) But I must not forget that my chief interest here is not the somewhat chronic and vague symptoms which follow the prolonged residence on rather moderate heights, but those which suddenly attack travellers who are ascending very lofty mountains. From this standpoint, among the mountains whose height is above the limit at which appear physiological symptoms due to the altitude, Popocatepetl (5420 meters) should be particularly men- tioned. Since the time (1519) when the brave Ordaz ascended it at the command of Hernando Cortez, and as reward for his courage re- ceived the authorization to bear a volcano on his coat of arms, and when a second Spanish expedition was sent by the same con- queror to get sulphur there (1522) ,04 no mountain climber had trod the summit of the giant of Mexican mountains. The first European to ascend it is the English lieutenant, W. Glennie, April 20, 1827. The sensations experienced by M. Glennie (says the secretary of the Geological Society in the extract he gives of a letter from this traveller)65 are those already described by travellers to great heights, that is, prostration, respiratory difficulties and headache, this last symp- tom appearing first at the elevation of 16,895 feet (5147 meters). It was found that tobacco and alcoholic liquors produced an extraordi- narily rapid effect upon the sensorium. A few years later, April 27, 1834, Baron Gros,66 attached to the French Legation in Mexico, made the ascent in his turn. When he had reached the limit of vegetation, he cried: We began to feel that we are no longer in the sphere where it is possible to live. Respiration is hampered; a sort of melancholy which is not without charm seizes us. (P. 50.) He passed the night at this height. Before lying down, the travellers mounted a little higher "to accustom our lungs some- what by degrees to breathing an air so unfitted for them." (P. 51.) 62 Historical The next morning, Gros and his six companions set out again: We walked one behind the other, our alpenstocks in our hands. . . . We proceeded very slowly, and were forced to stop every fifteen paces to get our breath. The flask of sweetened water was very useful to me; for being obliged to breathe with my mouth open, my throat became so dry that it was painful. (P. 53.) At 9 o'clock, we had reached the Pico del Fraile. . . . Our guides through superstitious fear refused to go on ... . The oppression which I felt was less severe than I had feared, and my pulse rate was only 120 per minute. (P. 54.) The travellers continued their journey alone, finding the in- struments which they had to carry "terribly heavy." To get a rest, they ate lunch: But only a little; it would be unwise at this height to eat a little too much or to drink any alcoholic liquor, for the nervous system is excited thereby inconceivably. (P. 55.) . . . At noon, we had reached the summit of perpendicular rocks; but our strength began to fail, and every 10 paces we were forced to make a long pause to breathe and to permit the circulation of the blood to grow somewhat slower. We had to shout to be heard at a distance of twenty paces. The air is so thin at this height, that I tried in vain to whistle, and M. Eger- ton had great difficulty in drawing a few notes from a cornet which he had brought with him. At half past two, M. de Geroult was on the highest point of the volcano. He leaped with joy. (P. 57.) We were exhausted. I had a violent headache and a strong pres- sure on the temples; my pulse rate was 145 per minute, and 108 after I had rested a little; but I felt hardly more distress than on Pico del Fraile. All four of us were frightfully pale; our lips were a livid blue, and our eyes were sunken in their orbits; and so, when we were rest- ing on the rocks, our arms above our heads, or when we were lying on the sand, with our eyes closed and our mouths open, and under our crape masks so that we could breathe more easily, we looked like corpses .... We saw three crows fly 200 feet above us. (P. 67.) .... A great many attempts have been made to ascend to the summit of the volcano; almost all have failed for different reasons. Some travellers, when they had reached a certain height, vomited blood, which compelled them to give up their undertaking. However, in 1825 and 1830, some Englishmen reached the crater. M. W. Glennie is the first, I think, to have seen it. (P. 68.) The travellers went down again and passed the night in the same place as the night before: We were too tired and especially too excited to sleep well. When I was awake, I could talk of nothing but the crater, and if I succeeded in getting to sleep, I was climbing up there all over again, the oppres- sion came on again, and I was awakened with a start. (P. 64.) Mountain Journeys 63 MM. Truqui and Craveri, in their ascent in September, 1855, were more fortunate: I ought to say (remarks one of them)'" that we experienced almost no difficulty in breathing during the ascent; at least, we thought that if we did feel any oppression, it should be attributed only to the fatigue of a long and difficult climb, (P. 316.) In January, 1857, under the guidance of M. Laverriere, Director of the School of Agriculture of Mexico, a scientific ascent of Popo- catapetl was made, and this expedition was part of a series of researches on the natural history of Mexico undertaken with the most praiseworthy ardor by the government of General Comonfort. M. Laverriere in his notes and memoranda collected the data which were of physiological interest in this ascent which was so fruitful from the standpoint of physics and geography. I am quoting in full his communication, for which I thank him sincerely: Among the tasks which had devolved upon us was the ascent of Popocatepetl, situated southeast of the city of Mexico. I expected to begin our operations by this ascent, because the season at that time seemed to me particularly favorable. In fact, all who before us had attempted the ascent of Popocatepetl had failed or had only partially succeeded. Forgetting the latitude and the peculiarities of the climate of Mexico, they had made their attempts at times when such explorations are made in Europe, that is, spring or summer. I thought, on the contrary, that our expedition should be made in winter, a period when the atmosphere in Mexico is perfectly trans- parent and suitable for observations, and when, because of a relatively lower temperature, the snows which cover the upper part of the cone occupy a greater surface on its slopes, which lessens the distance to be traversed in the deep and unstable sands which cover them, while fur- nishing by their hardness a firmer footing for the traveller. Consequently our little caravan, composed of Dr. Sonntag, astro- nomical engineer, a major-domo, two students from the School of Agriculture, and three servants, left Mexico (2278 meters) on Saturday, January 17, 1857, in very hot weather; on January 18 passed through Chalco situated on the lake of the same name; on January 19 through Amecameca (2493 meters), and entered the vast pine forests which cover the first foothills of the volcano, reaching the ranch of Tlamacas (3899 meters) on the evening of January 20. The ranch of Tlamacas, situated at the foot of the north slope of the volcano, is composed of a few cabins in which the sulphur occa- sionally brought from the interior of the crater is refined. It occupies a clearing near the timberline, and near it are found several varieties of pines, noteworthy for their hardiness, the excellence of their timber, and the abundance of their resin, and capable of being acclimatized in Europe. We passed the night in this spot. At six o'clock in the evening the 64 Historical thermometer stood at — 0.3° C, and — 2° C. an hour later. In spite of a good fire and our blankets, our sleep was uneasy and rested us but little; the Indians, on the contrary, slept like logs, and the next day they were up early, in good health and spirits, while we were stret- ching our limbs and looking surly. Wednesday, January 21, at five o'clock in the morning, everyone mounted and set out in silence; the Indians followed on foot. The cold was so penetrating that in spite of our thick garments we vied with each other in shivering. A quarter of an hour afterwards, we left the wood and approached the sandy stretch, going straight towards the steep slope of the volcano. The horses sank up to their hocks, going on slowly and painfully. Soon we had to stop frequently to let them breathe, for the air was so stinging and the path so steep that they could hardly get their breath. At half past eight we reached La Cruz (4290 meters). The horses were worn out, covered with sweat, panting. We dismounted and sent them back to Tlacamas. Numbed by the cold, we rested a little while on the sand warmed by the sun whose heat began to be scorch- ing. At nine o'clock, each one started out, his alpenstock in his hand, following our Indian guide, Angel, who with his feet wrapped in some rags, led the way with a step remarkably easy compared with ours. We followed him with difficulty, in spite of the care we had taken to lighten our garments and footgear as much as possible. Soon we reached a strip of ice which precedes the snow. It was crossed without too many difficulties, thanks to the notches cut with an axe by an In- dian sent on ahead with orders to blaze a trail up to the summit of the volcano. At the line of perpetual snow (4400 meters on the slope at this season of the year) I began to feel acute fatigue. I was wet with sweat, my breath was short and hurried, and it seemed to me as if enormous weights were fastened to my feet. Near me, a Mexican from Amecam- eca, named Saturnino Perez, who wanted to accompany us, was climb- ing with a stronger step; but his pale face, his bluish lips, his wild eyes, the contraction of his mouth, and the dilation of his nostrils showed plainly enough the effects of the altitude upon his constitution, hardy and robust though it was. The slope was steep, it is true; but as the snow was packed, we experienced less difficulty in advancing than if we had been on sand or ice. Only the air was so thin, so dry, so cold, that this advantage was more than compensated. Soon, since our strength failed, we had to halt, a very short halt, for the cold seized us straightway. Every forty or fifty steps we were forced to stop for a minute or two. Our lungs seemed to refuse to act; they hardly had the strength to raise the chest, which collapsed heav- ily after each inspiration. At 300 or 400 meters from the summit, there was a moment of hesi- tation, of prostration. Although so near, our goal seemed still enor- mously far away. The extremely steep grade, the metallic glare of the snow, the rarity of the air caused me inexpressible weakness. So I had to collect all my energy, appeal to all my reasoning power, and think of my responsibility in particular to find strength to go on. Mountain Journeys 65 Finally, thanks to a supreme effort, we reached the edge of the crater (5280 meters; temperature — 2° C.) through an opening to which I gave the name of Silicco Breach, in honor of the judicious minister who had sent us. It was half past one in the afternoon, and the part of our ascent which had been made on foot had required no less than four hours and a half. Within the crater, as soon as we had passed its edge, there was an inner slope towards the south, composed of sand and rock fragments. We dropped down upon it like inert masses, hardly conscious. My first sensation was that of inexpressible comfort. But this comfort lasted only a short time. The sand which at first I had found warm soon seemed unendurably cold to me. Moreover as the sun was beginning to de- scend, a cold little thin wind rose. I was soon shivering. To cheer myself, I wanted to eat, to drink a few gulps of an excellent sherry wine which our good Indians had brought. But since my throat was tight, I could not swallow the food, and the sight of it was distasteful. Instead of the strengthening effect expected, the wine produced a very different effect; no doubt because of a perversion of taste, I thought I had swallowed a stiff brandy, a regular fiery draught which literally burned my entrails. At the same time, and in spite of my weariness, a strange agitation seized me; it was a feeling of uneasiness, of distress, which would not allow me to rest. And yet, when I wanted to move, my strength betrayed me and almost refused me service. However, I found strength to climb back to the edge of the crater where I eagerly seized some snow to quench a little the burning thirst which tormented me. This agitation nevertheless passed away a little and my strength returned for a few hours. But in the evening, and especially during the night which we passed huddled against each other under a shelf of rock, a feverish condition seized me; my head on fire, piercing cold in my limbs, a pulse of 120 to 130, unendurable uneasiness, increased even more by the dull mutterings in the abyss beside us. It was a night I shall never forget. And therefore the dawn was greeted with joy, and after making observations according to our instructions, the signal for return was given; we left the volcano at ten o'clock and three hours afterwards, we were back at the ranch of Tlacamas, which we had left thirty hours before. The Scientific Committee GS which accompanied our unfortunate Mexican expedition also made this ascent April 23, 1865; the suffer- ings were quite endurable: The line of perpetual snow begins at a height of about 4300 meters above sea level. Here everyone dismounts, and climbs over the snow, zigzagging a little. . . . When one has ascended about 100 meters, he begins to feel great difficulty in breathing, his lungs are oppressed, and every step, every movement of his body makes him pant; he has to stop every twenty steps to get his breath, and there are certain constitutions which cannot endure the discomfort, although it is not very serious. The reflection of the sun on the snow is blinding; it is wise to pro- 66 Historical vide oneself with colored glasses and veils so as not to add to fatigue and breathlessness the vertigo which would no doubt be caused by this immense winding-sheet of snow which surrounds one. We could note, moreover, that the physical sufferings attendant upon such an ascent have been much exaggerated; none of us had hemorrhages of any sort. . . . The Indians, used to this ascent, can carry an arroba (11 kilos) and they ascend very rapidly. . . . We reached the summit of the volcano (the summit reached by the travellers is the Espinazo del Diablo (5247 meters), and not the true summit, the Pico Mayor (5450 meters). . . . The last steps are rather difficult; the rarefaction of the air, becoming greater and g'reater, adds still more to the difficulty of the ascent .... Hardly had we reached the summit than the difficulty in breathing which afflicted us ceased to be felt, and our lungs were not oppressed as long as we were resting. However, all of us could observe a certain excitement, which increased in some of us to the point of a violent headache; this excitement can be compared almost to a slight state of intoxication; the blood circulates rapidly, and the pulse rate rises to nearly one hundred per minute. (P. 194.) Besides Popocatepetl, in Mexico there is only the peak of Ori- zaba (5400 meters) the ascent of which can bring on discomforts and even symptoms. This happened to Von Muller1'"' and his companions, September 2, 1856. The travellers passed the night at 3000 Spanish feet from the summit: The consequence of a stay in such rarefied air were soon strongly felt by all of us. Our respiration had become much deeper and more rapid, a natural result of the diminished quantity of oxygen reaching our lungs at each inspiration of this thin air. We all had violent head- aches with feverish tendency. These symptoms could not surprise us, because we were at an elevation greater than that of Mont Blanc. . . . Although we were lying close together, with furs and rugs over us, we were all shivering with cold and fever. The temperature was below freezing. (P. 278.) The next day they wished to complete the ascent: The climb was extremely steep, so that in 25 steps, we mounted no more than 8 to 10 feet: besides we had to stop after these 25 steps .... None of us had nosebleed or such symptoms during the ascent; but we had severe congestion of blood in the head so that the whites of our eyes were deep red. . . . All had violent headaches, and shook terribly with fever. (P. 282.) A large company of American, English, and Mexican travellers, including artists, engineers, and mere tourists, tried to reach the summit of this peak in 1866. They did not succeed either. They were much distressed by symptoms of which one of the company in Mountain Journeys 67 the New Orleans Picayune gave a very picturesque and very strangely worded account. Although I am quoting it, I do not hesi- tate to say that it seems to me greatly exaggerated; I shall add, along with the editor of the Alpine Journal, that I am not sure that I have always understood what the author meant,70 in his obscure and bombastic style: At first they sang and whistled while they climbed; but these noisy demonstrations soon ceased. Respiration became difficult. . . . Up to about 2000 feet from the summit, the members of the company were strung out at a great distance from each other. At that time, some became weak and fell. Blood began to issue from their ears and noses; their faces were so swollen that old friends knew each other only by their garments. A few continued to climb some thousand feet, lay down, went to sleep on the snow or the black dust, and awoke panting. The artists, laden with their instruments, felt greatly the painful effects of the atmosphere; with one accord they turned around and went back down to the place where our companions who had no ambition and poor endowment of lungs had stopped. . . . The engineers and the others lay down; they were stumbling as they walked, incapable of will or action, and calling to those who were ahead. Had it not been for the continual struggle to cling to life, the distress in breathing, and the con- stant loss of blood, one would have thought he was asleep and dream- ing in a hollow in the snow or a gorge filled with ashes. We were then at an elevation of about 16,000 feet. . . . General S. went on to- wards the summit. In spite of the claims of the natives, it is doubtful that anyone ever went as far as we did. During the war with Mexico, 20 years ago at the most, an officer tried to reach the summit; but he fell paralyzed, at the height of 15,000 feet. His comrades went no further, and at this point planted a standard the staff of which is still there. Two-thirds of our company were out of sight; only three, besides the terrified guides, went on. Blood issued from our ears, nostrils, and mouths, and the veins stood out on our foreheads like dark lines; our progress was more and more uncertain, the slope steeper and more dangerous . . Colonel C. . . completely exhausted, talked incoherently like an intoxicated man. A stone which broke the shoulder of General S. . . . compelled them to retreat, at about 500 feet from the summit. North America. As we have seen, North America in many places has peaks lofty enough for travellers to experience on them the symptoms of mountain sickness. But the hardy explorers of the banks of the Colorado, the Oregon (Columbia) , and the upper Missouri, gave little heed to scientific and picturesque ascents. On the other hand, the engineers and the officers whom the government of the United States sent repeatedly to the Far West generally were satisfied with making trigonometric abstracts, and journeyed 68 Historical only over the passes, the elevation of which rarely reaches 3000 meters. However, Colonel Fremont, in his account of his expedition to the Rocky Mountains of Oregon, gives us an interesting observa- tion.71 August 13, 1842, in latitude 42° N., the travellers made the ascent of a lofty peak, and were suddenly extremely weary. The barome- ter stood at 20.522 inches, the altitude was reckoned at about 10,000 feet (3050 meters) ; the temperature was only 50° F.; they stopped to camp: I was seized shortly after (says Fremont) by violent headache and vomiting which lasted almost all night. These symptoms were probably caused by excessive fatigue, the lack of food, and also, to a certain degree, by the rarefaction of the air. . . . The next day two of our men were sick and lay down upon the rock; at that time I was seized by headache and vomiting, as on the day before, so that I was unable to go any further; M. Preuss had reached his limit, too; the thermometer stood at 50°, the barometer at 19.401 inches. (P. 67.) August 15. . . . The barometer dropped to 18.293 and the thermo- meter to 44°; we were at an elevation of 13,570 feet (4130 meters); at this great height we saw a solitary bee flying . . . This is probably the highest peak of the Rocky Mountains. Our careful method of advancing slowly had spared my strength; and with the exception of a slight tendency to headache, I felt no signs of the discomfort of the day before. (P. 70.) The mountain discussed here is marked on the maps by the name of Fremont's Peak (4130 meters) , in the State of Wyoming. In the following journey, made in 1943-44, the American ex- pedition crossed the Sierra Nevada in California at a height of 9300 feet, February 20 (ibid. p. 235) ; June 18, 1844, it reached the sources of the Arkansas, at a height of 11,200 feet (3413 meters) (P. 285) ; in neither case does the account indicate physiological symptoms. I found a similar account in the immense scientific publication of the expedition organized for determining the route of the trans- continental railroad. September 12, 1853, Captain Gunnison,72 topographical engineer, ascended Mount Creek, near Fork Lake in Colorado: The agreeable and inspiring effect of the pure air of the mountains at this elevation, a favorite theme for the eloquence of trappers and scouts, manifested itself in our men by shouts of noisy joy. But the violent physical exercise soon made them breathless; and while climb- ing the hills, our animals were soon completely exhausted, if they did not stop often to get their breath; but a few moments of rest gave them back their strength and vigor. (P. 53.) Mountain Journeys 69 And yet they were only at a height of 8559 feet (2610 meters) ; barometer 564 mm., temperature 17.5°. September 2, they had passed the highest point of their journey, 10,032 feet (3056 meters), at the pass of Coochetopa, in Colorado; they complained of no symptoms. (P. 47.) The Reverend Hines 7:' made the ascent of Mount Hood in Oregon with three companions, July 24, 1866. It was not without trouble, as he says energetically: We had only about 700 feet to go, but it taxed our sinews for two hours to climb them. The sun was shining again, and the sweat was dripping from our brows; but as we approached the summit, fatigue seemed to disappear, and it was with a feeling of triumph that we trod the summit of the highest mountain in North America. (P. 83.) Hines was wrong on this last point; Williamson,74 who climbed Mount Hood again in 1867, found its height to be only 3420 meters; it is then not the highest of the Cascades, much less of North America. More recently, a very well-known English mountaineer, M. Coleman, ascended mountains as high as or even higher than Mount Hood. In August, 1868, he climbed Mount Baker (3390 meters).75 In his account he speaks only of sulphurous exhalations from which he and his companions suffered; one of them was seized by vomit- ing (P. 365). In August, 1870, ascent of Mount Rainier (4400 meters),70 on the summit of which he passed the night, warming himself at the crevasses of the volcano, but much inconvenienced by their exhalations: here too, no physiological trouble. But that proves nothing, for we shall see, when we speak of the Alps, that professional mountaineers today seem to make it a point of honor never to speak of the sufferings of mountain sickness. 3. Etna. In the preliminary chapter, I reminded the reader that the ancients had frequently made the ascent of Etna (3313 meters); but they have left us no record that might make us think that they felt any extraordinary symptoms. The authors of the Middle Ages, who followed their steps, and told of their own journeys, are no more explicit than the ancients. Pietro Bembo,77 who in 1494 made the ascent with his friend Angelo Chabriele, does not even speak of his fatigue in his cele- brated dialogue with his son. In 1540 and 1545, Filoteo climbed Etna with several of his friends: he says nothing definite.78 Thomas 70 Historical Fazello 7:' gives a few more details in the account of his ascent of the 6th "of the Kalends of August", 1541; however he mentions nothing but an extreme fatigue: We had to climb on foot the crest of the mountain; the ascent was very arduous; here, the roughness of the soil, there, deep sand delayed us, our feet sliding backwards; in fact, the difficulties were so great that although the climb was not more than 50 steps, it took us a good two hours, and reaching the summit at last, panting and dripping with sweat, we lay down on the ground. (Decas I, liber II, caput IV; vol. I, P. 116.) But a century later, in 1671, the illustrious doctor-mathematician Borelli,8" whose attention had been aroused by the accounts of travellers in South America, notes symptoms which he indicates clearly: Among the noteworthy observations which I made at the summit of Etna in the year 1671, there is an unexpected effect due to the rare- faction of the air. There, in fact, moderate movements . . . brought on such lassitude, that young and robust men had to rest, to sit down, and to regain their strength by breathing frequently. (P. 242.) Then he tries to explain these symptoms; we shall see that he gave successively two different theories for them. But the sensa- tions which he had noted have not been experienced by all travel- lers, and we see beginning here a series of apparent contradictions, of which we shall mention numerous examples, even from our own times. In fact, Riedesel,81 in the account of his journey to Sicily, relates his ascent of May 1, 1767, and he adds: I did not find, as various travellers say, that the air was so rare- fied and thin as to check or at least to hamper the breathing greatly; which may depend, besides, upon the conformation and constitution of the chest and the lungs of each subject who tries it. (P. 132.) Demeunier,8- Houel,83 who made the same ascent at about the same time, do not mention observing any symptom. Delon,84 when he reached the summit of Etna, cried out enthusiastically: An ethereal air which crushes him, startles his being, and makes him realize an existence which warns man that he is out of the region to which his organs chain him. He is impressed by his rashness. . . . I leave to the reader the task of deciding whether this ranting expresses any physiological phenomenon, and omitting other testi- mony quite as unimportant, I come to the account of Dolomieu,83 who on June 22, 1781, made the ascent of Etna; the celebrated Mountain Journeys 71 mineralogist was very severely affected, and his guide still more than he: The cold was cutting . . . often breath failed me, and I was forced to stop short to get my breath, and to prevent strong palpitations which I felt in the pulmonary arteries. . . . My guide constantly called to me to walk more slowly, and when I reached the plain, near the Tower of the Philosopher,*0 he told me that he could go no further, that he felt very ill, and in fact, a moment afterwards, he fell unconscious, the pallor of death on his face, and in a most pitiful state. ... A few drops of wine made him revive a little; but he was very weak and like a man about to die. (P. 98.) Dolomieu continued his journey alone and reached the crater without mentioning any real sufferings in his account; he speaks only of his fatigue. The report left us by Spallanzani of his ascent on September 3, 1788, is interesting particularly because of the record he gives of the remarks of travellers who preceded him: The rarefaction of the air on the summit of Etna did not produce upon me the same effects as those experienced by some of the travel- lers who had preceded me. Chevalier Hamilton (September 26, 1769) felt his respiration hampered by the great thinness of the air; Count Borch (October 16, 1776) was still more distressed; "the rarefaction of the air on this mountain (he says) is very great, so great that the air is hardly suited for breathing." Riedesel (1767), on the contrary, felt no effects, or hardly any, as we see by this sentence: "I did not per- ceive that the air was so rarefied as several travellers state, nor so thin as to prevent breathing, or even to hamper respiration very much." Brydone (May 27, 1770) does not mention it, and I concluded from his silence that the thinness of the air did not tire him much. As for me, my servant, and my two guides, the air gave us no trouble. The difficulty of climbing . . . made our respiration painful and hurried, it is true; but after we had reached the summit, after resting a little, we soon regained our strength, and even while walking, we had no further difficulty in breathing. (P. 272.) 37 The illustrious physiologist did not show his usual acuteness there; he could not distinguish, as Borelli had done one hundred years before, between the effects of walking and those in a resting condition, and whatever he says, we can easily see that the air gave him real, though slight, disturbances. Ferrara,88 in his description of Etna, goes farther. According to him, not only did the ascent cause no distress, but he breathed with greater ease in this pure air: The lessened density of the air, no less than its extreme purity," produced a full and free respiration. . . . We felt none of those symp- 72 Historical toms which certain travellers say they experienced on the summit of Etna; those symptoms must have been an effect of their poor physical condition. We all felt very well. In his balloon, at the height of 21,482 feet, Gay-Lussac was in good shape. (P. 21.) The French traveller De Gourbillon,89 who made the ascent October 10, 1819, felt no effects himself; but that was not true of his travelling companions: M. Wilson experienced strange symptoms; his face, naturally ruddy, was wan and pale, almost entirely livid. Though younger and more nimble, and though he had not suffered as much from the volcanic exhalations, which had produced upon the latter and even upon the guide an effect like that of seasickness, my other travelling companion seemed neither fresher nor less distressed. . . . Lazarus, when he left the tomb, was no paler. (P. 436.) Likewise, Count de Forbin,90 who mounted to the crater the following year, was in very bad condition: I was hardly halfway from the Tower of the Philosopher to the summit, and already I was thoroughly disheartened. The rarefaction of the air made breathing difficult; later, the oppression became very great, it acted so much upon one of our travelling companions that he fainted. He was revived, and summoning all our strength, we reached the high- est crest of the crater after an hour and a half. Never in my life had I felt such fatigue; . . . my first impression was that I was like an invalid, prostrated, distressed by the terrors of a feverish brain .... Weariness of the senses and excitement of the imagination reduced us to a state nearly like delirium. (P. 173.) About the same time, A. de Sayve made this ascent. The results of it were told in a very interesting manner by H. Cloquet, who made use of it to prove the effect of great heights upon the organ- ism. He reported it to the Societe Philomathique in the following words:91 In the month of January, 1820, M. H. Cloquet published some details about the medical topography of Mont St. Bernard, and ideas about the effect which a stay on the towering crests of lofty mountains has upon man . . . In spite of these data, a celebrated author of our time, M. Ferrara, thought that only persons in poor health were inconvenienced while ascending to the summit of Etna, in Sicily. A careful observer, M. Auguste de Sayve, visited this famous place in the month of May, 1821, and disagrees with the learned M. Ferrara in this point. Here are the principal results of the observations which he made, and M. Cloquet considers that these results support what he has said .... At the snow limit is the little plain called Piano del jrumento, at the beginning of which are the ruins . . . known by the name of the Tower oj the Philosopher . . . Even before reaching this point, M. de Mountain Journeys 73 Sayve felt that he was breathing with difficulty; in spite of the cold, he felt very acute thirst; however, a little rest restored his strength. But the scene was to be changed .... The route passes by a hut of refuge, which is at the foot of the cone, and which is the highest building in all Europe (9,200 feet) .... From there up to the summit there is only an absolutely bare cone, 1,300 feet high. As our traveller climbed this cone of the crater, he felt his distress increase, and was obliged to stop at nearly every step. He felt extraordinary weakness in all his limbs; he was nauseated, and thinking that he had left the element suited to his physical nature, he tried, he says, to inhale a little air, but could not succeed at this critical moment; and yet he was perfectly healthy when he began his ascent; his passage through the region of snow had tired him very little; the symptoms he felt can therefore be attributed only to the rarefaction of the air. M. Aubert-du-Petit-Thouars . . . told the author that he had felt similar symptoms, especially a weakness in the stomach, when he climbed the mountain in the He de Bourbon, known as the Benard. M. Cloquet, moreover, himself experienced symptoms of this sort, when he reached a certain height in the Alps .... M. de Sayve had with him a companion who was much more severely affected; and we know that the unfortunate Dolomieu, in the same ascent, was also attacked by symptoms like those which we have just mentioned .... These different symptoms are quite varied and appear sooner in some persons than in others; but they cannot be attributed to fatigue, which never has such consequences in mountains of an elevation less than 1,000 fathoms. Moreover, they appear alike in animals and men. I shall not give more quotations. More recent authors show the same differences in power of observation, and most of them say nothing about physiological disturbances. What I have reported is enough to show that Etna is, if I may use this term, a limited mountain, in the ascent of which many persons experience no painful symptom, whereas others are more or less ill. Since the first symptoms of distress are exactly those of excessive fatigue, the difficulties of the ascent of the cone are consequently enough to explain everything, in the opinion of most of the travellers; some think the cause of the oppression is the poisonous exhalations coming from the volcano through the innumerable fissures in the ground. It is not surprising, then, that before verification of the disease peculiar to mountains, in the main range of the Andes, nothing unusual was noted in ascents of Etna. 4. Peak of Teneriffe. Discovered again in the fourteenth century by French navi- gators, the Canary Islands were conquered in the fifteenth century 74 Historical by the Spaniards. But for a long time no one dared attempt the ascent of the volcano, the summit of which seemed all the higher because its foot is at sea level. The strangest and most exaggerated estimates were made of its height. According to Th. Nicols,92 it was not less than 15 leagues; Riccioli and Kircher estimated it at ten Italian miles; in reality, it is 3716 meters. The first account of its ascent 93 that we have found is that of a journey made in 1652 by some "notable merchants and men of great esteem"; they were considerably affected by the rarefied air: At six o'clock in the morning we began to ascend the Peak . . . Some of our company became very weak and sick, and were attacked by diarrhea, vomiting, and feverish trembling . . . One of us was so ill that he could go no further. (P. 201.) The celebrated Robert Boyle °4 reported a similar account, in which the effect of the expanded air is confused with that of emana- tions from the earth, as often happens in ascents of volcanoes: One day I asked an intelligent man who had lived for several years in Teneriffe whether he had climbed to the summit of the Peak, and what sensations he had had. He replied that he had tried, that several of his companions had completed the ascent, but that the thin air and the sulphurous exhalations had made himself and a few others so sick that they halted far below the summit. The effect of these vapors was such that his skin became pale yellow, and his hair was bleached. (P. 2039.) Not all travellers experienced the same effects, and, as usual, those who were free from distress were led to deny what their less fortunate predecessors reported. Edens,95 who ascended the Peak in 1715, expresses himself as follows: What has been said about the difficulty of breathing on the summit of the Peak seems wrong; we breathed as easily up there as we did below; we had our lunch there. (P. 186.) Father Feuillee u0 made the ascent of the Peak on July 31, 1724; he says nothing of interest to us. G. Glas 97 was less fortunate: We reached the foot of the cone (he says in fact) . . . Although the distance is hardly a half mile, we were forced to stop forty times, I think, to get our breath, and when we had reached the summit, it was a quarter of an hour before we had recovered. (P. 255.) The same thing was true of the scientists whom Labillardiere ,J8 had taken with him on his journey in search of La Perouse: Mountain Journeys 75 Citizens Riche and Blavier (he says) had undertaken the ascent of the Peak one day after us (Labillardiere, who made the ascent October 17, 1791, speaks of no painful sensation) ; but these two naturalists did not succeed in climbing to the summit; they were still far from it when they spat blood, since their lungs could not become accustomed to the rarefied air, and they were forced to give up their undertaking. (Vol. I, p. 27.) It is true that, according to Bory Saint-Vincent," Riche was in very poor health and had very weak lungs .... He died as a result of his journey, soon after his return to France. (P. 182.) Von Humboldt100 (ascent of June 21, 1799) says absolutely nothing of physiological disturbances. The celebrated geologist Cordier,101 who ascended the Peak April 16, 1803, discusses these disturbances, but only to deny them, or practically so: What has been said of the keenness of the cold, . . . and the difficulty of breathing on the Peak is not correct. Moreover, I have already proved several times that the opinion generally held in this respect is more than exaggerated; I assure you that the cold was quite endurable . . . that the rarity of the air did not inconvenience us at all, although it forced us to halt quite frequently as we approached the summit. (P. 61.) The illustrious Leopold de Buch, in the accounts of his ascents of May 18 and 27, 1815, 102 does not give them a more important place: The ascent becomes more difficult after the Estancia de los Ingleses ... In spite of that, the difficulties are not comparable to those of an ascent to the summit of one of the snow covered peaks, of the Alps .... When we reached the crater, we suddenly saw appearing opposite us Mme. Hammond, a Scotch lady, with her trav- elling companions. She was the first woman ever to ascend to the summit. (P. 4.) May 27 we again ascended the Peak. (P. 5.) The account of Dumont d'Urville 10a is very interesting in its brevity. He passed the night, in June, 1826, at the Estancia de los Ingleses: The air was very pure (he says) and I felt none of these violent disturbances and these suffocating sensations experienced by different travellers. M. Quoy alone had pains in the stomach, and M. Gaimard slept all night without any trouble .... The next day, as we approached the Pain-de-Sucre, we were obliged to stop frequently to get our breath .... We lunched gayly on the crest of the Piton. (P. 37.) 76 Historical At the time of his second journey, in October, 1837, the officers of the Astrolabe and the Zelee made the ascent of the Peak. Dumont d'Urville 104 reports their sensations in these words: In agreement with my observations in 1826, MM. Dumoulin and Coupvent noted .... the numbness of the extremities of the body. During the night, the thermometer dropped to — 0.5°. MM. Dubouzet, Dumoulin, and Coupvent, especially the latter, felt severe headaches. (P. 32.) The surgeon, Le Guillou,105 reporting the same ascent, says: Several of our comrades were afflicted by a strange symptom; they had copious nosebleeds, and we were forced to stop a few moments. (P. 29.) On September 18, 1842, ascent of M. Charles Sainte-Claire De- ville; 10G he does not say a word about physiological disturbances. Itier,107 who climbed the Peak December 28, 1843, gives more importance than his predecessors to the sufferings he felt: We left the Estancia d'Ariba (3104 meters), and mounted on foot the sort of path which winds between two flows of obsidian; walking is painful among these fragments of pumice stone mingled with ashes which give under the foot; besides, the sun began to affect us, and the effect of the rarefaction of the air soon added to the fatigue of our effort. My heart throbbed violently, and the arteries of my brain shared in this distress; the headache it caused forced me to stop frequently; my companion, less accustomed to mountains than I, felt these effects much more than I did; he stopped every ten steps, suffocating, exhausted. (Vol. I, p. 28.) I shall quote finally the account reported from the notes of a traveller by Madame Elizabeth Murray, an English artist,108 of an ascent of the Peak, made in August, by four Englishmen and an American: To pass the night, we made our bivouac at the Estancia de los Ingleses, at a height of 9933 feet. (Vol. II, p. 20.) .... One of us was seized by extreme weakness, shivering, and violent headache; we covered him with rugs, lighted a good fire, and the heat, added to the effects of a little liquor, partially revived him. (P. 121.) It was late, and we stretched ourselves on the ground, wrapped in our rugs. Shortly after, my companion on the right rose and complained bitterly of extreme cold, pains, and distress in his stomach. We placed him near the fire, and gave him warm water and brandy. He began to be well enough to permit us to sleep when my neighbor on the left was attacked, then treated in the same way. Both suffered severely from the symptoms well known to ocean voyagers; these symptoms are not rare on the Peak; they are some- times attributed to sulphurous exhalations, but I think that they are Mountain Journeys 77 caused instead by the rarity of the air. At any rate, we smelled no odor of sulphur. Of the four of us, my American friend and I were the only ones who felt no discomfort. (P. 123.) Before arriving at the Rambleta (11,680 feet), many of us suffered more or less from difficulty in breathing. One of my companions, in particular, could not take more than eight to ten steps without stopping, thus forcing us to wait for him. (P. 126.) After a great many halts to regain our breath, we reached the summit. (P. 128.) We went back by the "Mai Pais", the descent of which was as disagreeable as the ascent, except that our respiration was much freer. (P. 136.) In summary, the Peak of Teneriffe is, like Etna, a limited moun- tain, in the ascent of which many travellers feel no great effects, those who are ill being only slightly affected. 5. Alps. It is not until the end of the last century that ascents were made in the Alps to heights sufficient to bring on physiological disturb- ances. Until the time of Canon Bourrit and the illustrious De Saus- sure, only a few chamois hunters had ventured above the line of perpetual snow. The main peak of Mont Blanc, today traversed in all directions every year by hundreds of tourists, bore the sig- nificant name of the Accursed Mountains; in the seventeenth cen- tury, the Bishop of Annecy, Jean d'Aranthon,100 came to exorcise its glaciers, which withdrew submissively after his benediction. Of the rival summits of Monte Rosa and the Jungfrau, there was no question. The principal passes had been frequented since the days of the Romans; many armies had crossed them; the hospice of the Grand Saint-Bernard was founded at the end of the tenth century, but no one had thought of risking his life in the ascent of one of the innumerable summits which tower above the beautiful Alpine valleys: in 1740, the first Englishmen arrived at Montanvert! However, it was well known that travellers suffered sometimes, in crossing the Alps, from pulmonary disturbances. Haller con- siders them, as we shall see in the chapter devoted to the discussion of theoretical explanations; he even speaks of hemoptyses observed by Scheuchzer: "ut in primis in J. Sch. triste exemplum exstat".110 I could not secure the work of this German geographer; m but according to Meyer-Ahrens,112 he must have experienced only the oppression and threats (Vorboten) of hemorrhage. The first traveller who has given us an account of personal dis- agreeable sensations, the second to make the ascent, today so com- 78 Historical mon, of Buet (3110 meters) is the Canon Bourrit.1 i;i At this moderate height, he experienced strange symptoms'. In 1776, I left Geneva with the purpose of ascending Buet; it was the second time that I had climbed this mountain; .... I was in good physical condition .... All three of us reached the summit feeling very well .... After ten minutes of peaceful halt, I felt a numbness in my arms and legs, and soon I had not the strength to force myself out of this condition; I was already unconscious when my companions removed me; they carried me down to the first rocks of the glacier .... The next year, .... I went there in very fine weather; .... I began to sketch, and told my guide to hold my parasol over me. After 15 minutes, I noticed that he was not holding it well; . . . , and you can imagine my surprise when I saw this man as white as snow .... and his eyes almost motionless; I made the utmost haste to get him away from this baneful summit .... Finally, in 1777, .... M. Saint-Ours .... witnessed a similar attack on the summit of Buet .... (Vol. II, p. 94.) Bourrit, however, seems to have been quite subject to syncopes; he reports two others, one on the glacier of Buet, while he was walking (Vol. Ill, P. 198), the other during his attempt to ascend Mont Blanc, September 11, 1784 (Vol. Ill, P. 300 and 304). At a still lower elevation, at the monastery of the Grand Saint- Bernard (2430 meters) , a traveller of the same period, Laborde, felt similar symptoms, although considerably less severe: The sky was clear when we reached the monastery of the Grand Saint-Bernard (July 30, 1777). It would be difficult to express the different sensations which one feels at the same time; the first that is noticeable is an attack caused by difficulty in breathing; it seemed as if the lungs did not have their usual elasticity and lacked the capacity to hold the air inspired; the difference between the air one breathes at such a height must be very evident to those who are used only to air of the plains; it is more rarified and purer because it is less filled with vapors (Lecture on the natural history of Switzerland, P. VIII). These few quotations bring us to the celebrated accounts of De Saussure; the sufferings experienced at elevations which are very low compared with Mont Blanc, the ascent of which he dared to attempt and carry out, bring out still more the bravery which he displayed in this intrepid undertaking. Canon Bourrit, when he said, as we shall see in Chapter III, that it would be difficult, if noi impossible to live long on the summit of Mont Blanc, only trans- lated, in a somewhat modified form, an opinion universally held by mountaineers. De Saussure, when he ascended Mont Blanc, had prepared for it Mountain Journeys 79 by numerous expeditions made every year on lofty mountains. Now at fairly moderate heights he had already felt symptoms, which had attracted his attention. In the account of his ascent of Buet, made July 13, 1778, in the company of Pictet, he gives l15 a very clear indication of it: The rarity of the air, as soon as one passes the elevation of 1300 to 1400 fathoms above sea level, produces very strange effects upon the body. One of these effects is that muscular strength is exhausted very quickly. (Vol. I, p. 482.) .... Another effect of this thin air is the drowsiness it produces. As soon as one has rested for a few moments at these great heights, he feels his strength entirely restored, as I have said; even the impression of the former fatigue seems wholly effaced; and yet in a few moments one sees all who are not busy, falling asleep, in spite of the wind, the cold, and the sun, and often in very uncomfort- able positions. Of course fatigue, even on the plains, produces sleep; but not so suddenly, especially when it seems to have entirely disappeared, as it does on the mountains, as soon as one has rested a few moments. These effects of the thinness of the air seemed to me quite universal; some persons are less subject to it; the dwellers on the Alps, for example, who are accustomed to living and working in this thin air, seem less affected by it; but they do not entirely escape its effect. The guides, who on the lower slopes of the mountains can climb for hours at a time without stopping, have to pause to get their breath every 100 or 200 steps, as soon as they are at an elevation of 1400 or 1500 fathoms, and as soon as they have halted for a few moments, they too fall asleep with surprising promptness. One of our guides, whom we had standing on the top of Buet with a parasol in his hand so that the magnetometer might be in the shade while M. Trembley observed it, kept falling asleep constantly in spite of the efforts which we made and which he made himself to struggle against this drowsiness. And on my first trip to Buet, Pierre Simon, who had crept into a snow crevasse to shelter himself from a cold north wind which distressed us greatly, went sound asleep there. But there are constitutions which this rarity of the air affects still more severely. One sees men, very sturdy elsewhere, consistently attacked at a certain elevation by nausea, vomiting, and even fainting, followed by an almost lethargic sleep. And all these symptoms cease although fatigue continues as soon as they have reached a denser air in the descent. Fortunately for the progress of physics, M. Pictet is not so seriously affected by the thinness of the air; however, he is more affected than the average man, for although he is very strong, very nimble, and well trained in climbing mountains, he is always attacked by a sort of distress, a. slight nausea, and an absolute loathing of food, as soon as he reaches the elevation of 1400 fathoms above sea level. As for me, I feel no effect other than being obliged to rest very 80 Historical frequently, when I ascend steep slopes at these great heights. I tested this again in my last trip to Buet. While we were climbing the slope covered with soft snow which crowns the mountain, I absolutely had to stop every fifty steps, and M. Pictet, more sensitive than I to this effect of the rarity of the air, counted his steps without telling me, and found that he could not take more than forty without getting his breath. (P. 483-85.) But that was nothing compared to what he was to observe in his trip to Mont Blanc. Already several attempts had been made to reach the summit of this colossal mountain. De Saussure recorded for us the account of these vain attempts, and it is clear that the physiological symptoms experienced by those who made these at- tempts had much to do with their failure: §1103. In 1775, four guides from Chamounix tried to reach the summit by the mountain of La Cote .... Everything seemed to promise them perfect success; .... but the reflection of the sun upon the snow and the stagnation of the air in a great valley of snow which seemed to lead them directly to the crest of the mountain gave them a feeling of suffocating heat, as they said, and at the same time gave them such distaste for the provisions with which they were supplied, that, worn out with lack of food and weariness, they retraced their steps. (Vol. II, p. 550.) §1104. In 1783, three other guides made the same attempt by the same route. They passed the night at the top of the mountain La Cote, crossed the glacier, and followed the same valley of snow. They were already fairly high and were advancing courageously, when one of them, the most daring and sturdy of the three, was seized almost suddenly by an absolutely unconquerable desire to sleep; he wanted the other two to leave him and go on without him; but they could not consent to abandon him and leave him sleeping on the snow, convinced that he would die of sunstroke; they gave up their attempt and returned to Chamounix. For this need of sleep, produced by the rarity of the air, ceased, as soon as he was in a denser atmosphere in the descent .... The heat gave them all great distress; they had no appetite; the wine and the food which they took with them had no attraction for them. September 13, 1785, De Saussure himself attempted the ascent with M. Bourrit and his son. He slept at the hut (1422 fathoms) : §1112. M. Bourrit and his son even more than he were a little affected by the rarity of the air; they did not digest their dinner well, and could eat no supper. As for me, since the thin air inconveniences me only when I am exercising violently in it, I passed an excellent night there. The next day, he mounted to an elevation of 1900 fathoms; the snow stopped him. But the ascent of Mont Blanc had become a dominating idea in Mountain Journeys 81 him. The next year, he commissioned Pierre Balmat to construct a hut at the foot of one of the crests of the needle of Goute, so that he might rest there before trying next to mount to the summit of Mont Blanc: §1963. In executing this project, Pierre Balmat, Marie Coutet, and another guide, June 9, 1786, .... reached the summit of the needle of Goute, after having all of them been extremely ill from fatigue and the rarity of the air. (Vol. IV, p. 138.) It was in consequence of this trip that Jacques Balmat, who had rejoined his compatriots and who passed the night on the mountain, found the route to Mont Blanc by the Corridor: §1965. This route had already been tried but had been discarded because of a strange prejudice. As it follows a sort of valley between eminences, it was imagined that it was too warm and had too little air ... . Fatigue and the rarity of the air caused in those who made the first attempts this prostration of which I have often spoken; they attributed this distress to the heat and the stagnation of the air, and tried to reach the crest only by uncovered and isolated ridges. The people of Chamounix also believed that sleep at these great heights would be fatal; but the test which Jacques Balmat made by passing the night there dissipated this fear. (Vol. IV. p. 140.) It seems as if the account given by De Saussure of the discovery of Jacques Balmat is not exactly correct. The illustrious physicist of Geneva seems to have been led astray by his favorite guides, who, jealous of Balmat, attributed to chance what was the fruit of long and persistent research. The interesting works of M. Ch. Durier have cast some light on this point. At any rate, June 10, 1786, Jacques Balmat, having found the true route, after several nights passed on the mountain, descended to Chamounix almost dying of fatigue and cold. Being attended by Dr. Paccard, he in- formed him of his discovery and proposed to share the glory of it with him by making the ascent with him. Paccard accepted, and on August 9, 1786, a human foot for the first time trod the summit of the highest mountain of Europe. Dr. Paccard had been ex- hausted by fatigue and no doubt also by the rarefaction of the air so that he stopped on the way and lay down; Balmat ascended alone, then returned to seek his companion, half carried him to the crest, and took him back down blinded by the snow. Unfortunately I have not been able to get an authentic account of this memorable ascent. That of Alexandre Dumas (Impressions de voyage en Suisse, Chap. X) , much less inexact than one would expect, cannot, however, be trusted in physiological matters. But what has been said and written about this journey shows that the 82 Historical two companions, especially Dr. Paccard, suffered keenly from the rarefaction of the air. At the news of the success, De Saussure, who had promised a prize to the person who should find the true way, though hoping to use it first himself, made haste to organize a new expedition. But judging that the season was too advanced, he had to put off until the following year the realization of a desire which had interested him deeply for so many years. August 1, 1787, he left Chamounix, accompanied by a servant and eighteen guides. He slept under the tent on the summit of the mountain La Cote. The evening of the second day of the ascent, he reached the little' plateau; the barometer registered 17 inches 10 lines. They made preparations to pass the night (1995 fathoms) :116 §1962. There (says De Saussure) my guides first began to exam- ine the place in which we were to pass the night; but they very quickly felt the effect of the rarity of the air. These sturdy men, for whom the seven or eight hours of walking which we had just done were absolutely nothing, had hardly lifted five or six shovelfuls of snow when they found it absolutely impossible to continue; they had to relieve each other constantly .... I myself, who am so accustomed to the air of the mountains, who feel better in this air than in that of the plain, was completely exhausted while examining my meteorological instruments. (Vol. IV, p. 144.) The next day they continued to ascend, and reached "the cliff which forms the left shoulder of the crest of Mont Blanc": §1985. When I began this ascent, I was already quite out of breath from the rarity of the air ... . The kind of fatigue which results from the rarity of the air is absolutely unconquerable; when it is at its height, the most terrible danger would not make you take a single step further. (P. 165.) Soon they were no more than 150 fathoms in elevation from the summit of Mont Blano: . §1988. I therefore hoped to reach the crest in less than three quarters of an hour; but the rarity of the air gave me more trouble than I could have believed. At last I was obliged to stop for breath every fifteen or sixteen steps; I usually did so standing, leaning on my alpenstock, but about once out of every three times I had to sit down. This need of rest was absolutely unconquerable; if I tried to overcome it, my legs refused to move, I felt the beginning of a faint, and was seized by dizziness quite independent of the effect of light, because the double crape which covered my face protected my eyes perfectly. Since it was with keen regret that I saw thus passing the time which I hoped to devote to my experiments on the summit, Mountain Journeys 83 I made different tests to shorten this rest; I tried, for example, not to continue to the end of my strength, and to stop an instant every four or five steps, but I gained nothing; I was obliged, after fifteen or sixteen steps, to take a rest as long as if I had made them consec- utively; and this was very noteworthy, that the greatest distress is not felt until eight or ten seconds after one has stopped walking. The only thing that did me any good and increased my strength was the cold air of the wind from the north; when as I climbed I had my face turned in that direction, and swallowed great mouthfuls of the air coming from it, I could take twenty-five or twenty-six steps without stopping. (P. 171.) At last the highest crest was reached: §1991. I now had to make the observations and experiments, which alone gave some value to this journey; and I was terribly afraid that I should be able to do only a small part of what I had planned. For I had already found, even on the plateau where we had slept, that every observation made carefully tires one in this thin air, and that is because, without realizing it, one holds his breath; and since there one must compensate for the rarity of the air by the frequency of his breathing, this suspension caused definite distress; I was obliged to rest and to pant after observing any instrument as after making a steep ascent. (P. 175.) What De Saussure had foreseen happened: §1965. When I had to get to work to set out the instruments and observe them, I was constantly forced to interrupt my work and devote myself entirely to breathing .... When I remained perfectly quiet, I felt only slight distress, a little tendency to nausea. But when I took pains, or when I fixed my attention for a few moments consecutively, and especially when I compressed my chest by stooping, I had to rest and pant for two or three minutes. My guides experienced similar sensations. They had no appetite. (P. 147.) §2021. Some could not endure all these kinds of sufferings, and descended first to reach a milder air. (P. 208.) Farther on, De Saussure makes a very accurate statement, which explains many exaggerations and many doubts: §2021. I observed a rather curious fact, that for some individuals there are perfectly - marked limits, where for them the rarity of the air becomes absolutely unendurable. I have often taken with me peasants, elsewhere very robust, who at a certain height were sud- denly so affected that they absolutely could not ascend higher; and neither rest, nor cordials, nor the keenest desire to reach the crest of the mountain could make them pass this limit. They were attacked, some by palpitations, others by vomiting, others by faints, others by a violent fever, and all these symptoms, disappeared as soon as they breathed a denser air. I have seen persons, but only a few, whom these symptoms forced to stop at eight hundred fathoms above sea 84 Historical level; others at twelve hundred, several at fifteen and sixteen hun- dred; as for me, like most of the dwellers on the Alps, I do not begin to be noticeably affected until at nineteen hundred fathoms; but above this limit, the best trained men begin to suffer when they hurry a little. (P. 209.) Finally they had to descend; from eleven o'clock to half -past three, De Saussure remained on the summit, and he was sorry to leave, because, he says, and I call the attention of the reader to this extremely important remark: §2021. Although I had not wasted a single moment, in these four hours and a half I could not make all the experiments which I had frequently finished in less than three hours at sea level . . . But I kept the well founded hope of finishing, on the col du Geant, what I had not done, and what probably no one will ever do, on Mont Blanc. (P. 210.) The descent was accomplished successfully and without great fatigue: As the movement one makes while descending does not compress the diaphragm, it does not hamper respiration, and one does not suffer from the rarity of the air. The example of the illustrious physicist was soon followed. Seven days after his famous ascent, the English colonel Beaufoy 117 in his turn reached the summit of the giant of the Alps. It was not without keen sufferings, as the following extracts from his account prove. Leaving Chamounix August 8, 1787, he slept with his ten guides at the hut built in 1786 by the orders and at the expense of M. de Saussure. The first physiological phenomenon which the colonel mentions is thirst: Our thirst, since we had reached the upper regions of the air, had become unendurable. Hardly had I drunk when my mouth was dry. Although I was drinking constantly, the quantity of my urine was very small; its color was very dark. The guides were similarly affected; they did not wish to taste wine .... The rarity of the air soon began to give me a violent headache; to my great surprise, I also felt a keen sensation of pain just above my knees .... When we were within .150 fathoms (270 meters) of the summit, the harmful effects of the rarity of the air was evident in all of us; an almost irresistible desire to sleep possessed us. My energy had left me; indifferent to everything, I thought only of lying down on the ground; at other times, I regretted this expedition, and when I was almost at the summit, I thought of descending, without doing it how- ever. Many of my guides were in the most pitiful condition; exhausted Mountain Journeys 85 by excessive vomiting, they seemed to have lost both strength of body and strength of mind. But shame came to our assistance. I drank the last pint of water and felt refreshed. Yet the pain of my knees had so increased, that every 20 or 30 steps I had to stop until its acuteness had diminished. My lungs did their duty with difficulty, and my heart throbbed with violent palpitations. Finally, however, but with a sort of apathy which barred joy, we reached the summit. Six of my guides and my servants immediately threw themselves down with their faces against the ground and went to sleep. I envied their repose. The colonel suffered greatly from the reflection of the sun upon the snow; he had neither veil nor glasses. Some weeks later, De Saussure, in his ascent of Mont Cenis, September 28, 1787, again made very interesting remarks from the physiological point of view: §1280. At our departure from the summit, where we had stayed for two hours, I counted by my watch with a second-hand the pulse rate of all those who composed our little caravan, and counted it again on our arrival at the post-house of Mont Cenis: J. B. Borot, guide, above 112, below 100 B. Boch, guide above 112, below 96 J. Tour, guide above 80, below 88 Tetu, my servant, above 104, below 100 My son above 108, below 108 Myself above 112, below 100 Average above 104% below 98% It will be noted that Joseph Tour was the only one whose pulse rate was higher at the foot of the mountain than at the top; that for my son, the number was the same, and that the other four had a more rapid rate on the summit, so that the average gives six beats per minute more above than below, with a difference of about 4 inches 2 lines in the height of the barometer. There is this also to be noted that after I counted the pulse rate on the mountain after a stay amounting to a rest of at least two hours for the guides; whereas on the plain, as they wished to leave, I had to count it a few minutes after our arrival. What is still more remarkable is that when I separate those who were nauseated (three of the four guides, whose names De Saussure does not give, were nearly sick on the summit) from those who remained well, I find that the average difference was 9V3 for the first, and only 2% for the second. This observation confirms what I have always believed, namely, that this discomfort partly resembles a sort of fever, produced by the frequency of the breathing, which quickens the circulation of the blood. And as for me, if my pulse was a dozen beats more above than below, even though I felt no discomfort, that is because I did not rest a single moment; I was at work continually during these two hours; if I had rested like those 86 Historical who were ill, I am sure that my pulse rate would have dropped several beats. (Vol. Ill, p. 85.) The following year, he went with his son to stay on the col du Geant (3360 meters) from July 3 to July 19, 1788; this trip, which filled the guides with terror, was undertaken with the purpose of attempting experiments which, on Mont Blanc, "the shortness of the time and the discomfort caused by the rarity of the air pre- vented me from carrying out." (Vol. IV, p. 217.) One whole very interesting chapter is devoted to Observations Relating to Physiology: §2105. It was interesting to note what effect upon our bodies would be caused by a prolonged stay in an air as rarified as that which we were breathing on the Col du Geant. It must be recalled that the average height of the barometer was, during our stay, about 19 inches, that is, 9 inches lower than at sea level, and that therefore the density of the air there was nearly one third less. M. Odier, a doctor in medicine, very eager for the progress of his profession, had given me some questions which were to serve as text for my observations. §2106. To determine precisely the degree of animal heat. During the morning of July 17, at a moment when I was very calm, and without having made any violent movement, I placed under my tongue a small mercury thermometer keeping my mouth closed, and at the same time I observed this thermometer with a magnifying glass. It was at 29 Vz, and registered the same degree under the same circumstances on the plain. To count the number of inspirations and expirations which a man in repose and not forewarned makes in a minute, and also the rela- tion of this number to that of the pulse rate. Under the same circum- stances as those of the preceding paragraph, at first I found 75 heart beats for each inspiration and as many for each expiration. But another time, taking a larger number, which for that very reason deserves greater confidence, I found that I made 10 inspirations and expirations in 35 seconds, which amounts to 17 per minute, and that my pulse rate was also 79 per minute. §2107. To try to inspire deeply enough to stop the pulse in the left wrist, supposing that the same individual can do so on the plain. July 19, when I arose, seated on my pallet, I succeeded in stop- ping the pulse of the left wrist, prolonging the inspiration for ten seconds; immediately I repeated the test, and the pulse stopped at the fifteenth second; the third time, at the thirty-fifth second the pulse was still resisting when I was forced to catch my breath. When I made the same test standing, I could not stop my pulse; but it is true that I could prolong the inspiration only for 32 seconds. Therefore this test appears, at least for me, not susceptible of regular com- parison. §2108. To count the pulse in a perfectly vertical position; if the Mountain Journeys 87 difference is greater than on the plain, it is a proof that the air of lofty mountains increases the irritability of the heart. July 18, in the afternoon, having taken a short nap on my pallet on the ground, in a horizontal position, my pulse rate in this same position was 83 per minute. I then arose, and while standing, my rate was 88; but suspecting that the effort which I had made in rising might have contributed to this acceleration, I rested a few instants, and then my pulse rate was only 82. §2109. To determine by comparison whether the inspiration can be held as long on the mountain as on the plain. In section 2104 I reported the attempts I had made on the moun- tain. I then forgot to repeat them on the plain on my return, and since then, my constitution has been so much affected by fatigues and illnesses, that the comparative tests I might make would give no result on which one could reason. To determine* if it is possible comparatively, the proportion of the urine to the amount drunk. We lacked the necessary facilities to make comparisons. §2110. To verify particularly whether the effects of the rarified air appear suddenly or gradually. It appeared to us that the general effects were almost the same during our whole stay. When we arrived, we were all more out of breath than we should have been after making an ascent equal to that on a less lofty mountain on the last day. On the following days, the discomfort was far from increasing; our companions, my son, and I thought that we were becoming accustomed to this air: how- ever, when we gave attention to it, and especially when we made efforts for this purpose, we found that if one ran, if he remamed in an uncomfortable attitude, and particularly in a position in which the chest was compressed, one was much more out of breath than on the plain, and in an increasing progression; so that, from moment to moment, it became more difficult, and at last even impossible to keep up these efforts. §2111. As our observations forced us to remain in the open air almost all day, I had advised my son and my servant always to keep a piece of crape over the face, as I did myself. My servant thought that he could do without it, but his whole face, and particularly his lips, swelled, which made him hideous, and which was accompanied by very painful cracking of the skin. That made my son think that perhaps the action of the sun produced a liberation of air which caused this swelling. To see whether this air would appear outside, he had this same young man hold his hands in water in the sun; they were immediately covered with little bubbles; he wiped them, then when he put them back in the water, more bubbles appeared; he wiped them a second time, and dipped them for the third time; but then there were no more bubbles to be seen. We concluded from that, that the bubbles which we had seen at first were only air adhering to the surface of the skin. 2212. It seemed to us that in general our nerves were more irritable, that we were more subject to impatience, and even to 88 Historical impulses of anger; our tempers were noticeably worse; hunger appeared more disturbing and more imperious; but on the other hand our appetites were more easily satisfied and digestion seemed to take place more rapidly than on the plain. Moreover, it seemed to my son and me that in our work and our observations relating to physics, our minds were noticeably freer, more active and less easily tired, I will even say more inventive, than on the plain, and I hope our readers will find the proof of it in the report of our occupations during these seventeen days. (Vol. IV; p. 315-318.) In his trip around Monte Rosa he also describes the distress felt by animals. On August 14, 1789, he was on the glacier of Mont Cervin (glacier Saint-Theodule) : 2220. The mules, which were sinking in the snow up to their girths, were unloaded; yet it was very hard for them to go on, they were panting, obliged to stop for breath, as soon as they had made a few steps. However the grade was not very steep, and the three or four hours of walking which they had had could not have tired them .... but it was the rarity of the air which affected them; they experienced all that we had experienced when we ascended Mont Blanc .... The breathing of these poor animals was extremely painful, and at the very moments when they were stopping for breath, they panted with such distress that they uttered a kind of plaintive cry which I had never heard, even when they were very weary. It is true that I had never travelled with mules at so great an elevation .... we were then 1,736 fathoms above sea level. (Vol. IV, p. 380.) Canon Bourrit, whose vain attempts had preceded the expedition of De Saussure, made the ascent of Mont Blanc in 1788, accom- panied by Woodley and Camper. I have not found any complete description of this trip. But we owe to him a few details of a somewhat later expedition, made August 11, 1802, by Forneret and Dortheren: The rarity of the air (he says)113 added to the difficulty of walking; their chests felt lacerated, and they told me that nothing on earth would induce them to undertake such an attempt again. (P. 431.) On July 14, 1809, the first ascent of Mont Blanc by a woman, Marie Paradis, a maid-servant at Chamounix. She was so ex- hausted at about the elevation of 4600 meters, that the guides who accompanied her were forced to hold her up and carry her to the crest. From 1809 to 1816, only one ascent (Rodaz, 1812) about which we have no information. A German officer, Count de Lusy, left Chamounix September 14, 1816, to ascend Mont Blanc; he had eight guides with him. From Mountain Journeys 89 the German pamphlet of Hamel, from which I shall quote presently, since I was unable to secure the account of Lusy,119 I borrow the references to the serious symptoms which attacked them: Near the summit, some of the travellers felt nausea and a strong desire to sleep; three bled from the nose and one from the mouth; that did not stop Count Lusy. (P. 36.) August 4, 1818, Count Malazesky, a Pole,120 then van Rensselaer of New York on July 11, 1819, also undertook this difficult enter- prise. The report of the latter, although quite detailed,121 contains no suggestion of any interesting physiological fact; his companions and he experienced only a great acceleration of respiration and pulse accompanied by loss of appetite. Then, in 1820, Dr. Hamel,122 court counselor of His Majesty the Emperor of all the Russias, made the ascent in the company of Colonel Anderson. His trip was interrupted near the summit by a terrible catastrophe, which took the lives of three guides, dragged down in an avalanche. He first made on August 3 an unsuccessful attempt: We started from Saint-Gervais and passed the night at Pierre- Ronde, sheltered by a few rocks. The next day at 11:30 we reached the summit of the Dome du Goute .... It was on this two hour march that for the first time I expe- rienced the effect of the rarified air upon my strength. It was abso- lutely impossible for me to take more than forty steps without stopping about two minutes to get my breath; and when I reached the summit of the Dome (2,200 fathoms), I felt so exhausted that I should have needed at least a half-hour's rest if I were to be able to go on to the crest of Mont Blanc. After I had made my calculations, I found that it would be absolutely impossible to go to the summit and come back down the needles of the Goute before night; I therefore decided to retrace my steps. (P. 306.) August 16, he once more began the ascent, this time starting from Chamounix. The travellers, accompanied by twelve guides, passed the night at the Grands-Mulets. In spite of his guides, who were alarmed by the poor condition of the newly' fallen snow, Hamel wished to go on the next day; at half -past eight in the morning, they were on the last large plateau: No one was ill. And yet for some time we had been feeling the effect of the rarity of the air; my pulse rate was 128 per minute, and I was thirsty all the time. Our guides suggested that we should lunch .here, for higher up, they said, no one has any appetite .... Each of us ate his half-chicken with pleasure.123 .... We had reached the elevation of 2,300 fathoms .... No one was 90 Historical talking, for at this height even talking fatigues one, and the air transmits the sound feebly. I was still the last, and I was taking about twelve consecutive steps; then, leaning on my alpenstock, I stopped to take fifteen inspirations. I found that in this way I could advance without becoming exhausted. Wearing green glasses and with a crape veil over my face, my eyes were fixed on my steps, which I was counting, when suddenly I felt the snow give way under my feet .... The whole sheet of snow slid from under the travellers, and three of the guides disappeared forever in an immense crevasse. After this fatal experience, no one had ventured upon this undertaking "dangerous as well as useless", when F. Clissold tried again successfully, on August 18, 1822. In his first rather brief account,124 he limits himself to saying that all the guides, except one, were "more or less affected by the rarity of the air". The detailed account which he published later 125 is much more explicit; it even contains very unusual theoretical ideas which we shall report in the proper place. It is strange to have to state that this stranger who was making his first trip to the Alps endured the decreased pressure better than the guides, almost all of whom had already ascended to the summit of Mont Blanc: We were not far from the Grands Mulets (he says) when the man who was fastened to my rope untied himself, being absolutely exhausted. I then had myself tied between two others; shortly after- wards, a second one stayed behind, and finally all, except Favret (one of the six guides) and myself, had to stop from weariness and a difficulty in breathing which they attributed to the rarity of the air; a little rest soon revived them. At two o'clock, we reached the Grand Plateau. Marie Coutet, who could hardly breathe (he had already ascended Mont Blanc five times) was surprised at my fine condition. (P. 146.) They slept in a little excavation of the Rocher Rouge (4490 meters) and suffered greatly from the cold. The next day, at dawn, they set out for the summit: Favret and I were the only ones who were comfortable, especially in breathing. As for the others, some were stretched out flat on the snow, others paused standing up, bent forward with their heads hanging, finding it easier to breathe in this position. For my part, I have felt much more fatigue in other trips and on much less lofty mountains than I felt in ascending Mont Blanc; it is true that I was walking more quickly then. My pulse rate did rise from 100 to 150 per minute, but my circulation always quickens to this degree when I climb a steep grade, so that all in all I experienced nothing particular or new to me. (P. 149.) Mountain Journeys 91 The account of the trip of Dr. Clark and Captain Sherwill 1J" contains very interesting details. They ascended Mont Blanc August 25, 1825; leaving Chamounix at seven o'clock in the morn- ing, they reached the summit the next day at five minutes past three: When they reached the Grand-Plateau, M. Clark was exhausted, Captain Sherwill was greatly nauseated and oppressed .... Simon, one of the guides, complained of headache .... On the summit of Mont Blanc, M. Clark found breathing difficult, even when he refrained entirely from moving. He felt in his chest a sensation like that which precedes hemoptysia, a disease to which he was quite subject in his youth. However he did not spit blood on the summit of Mont Blanc. One of the guides who had accidentally received a blow on the nose lost a little blood, which seemed darker in color than usual. Both M. Clark and Captain Sherwill suffered from violent headache; their faces were pale and drawn. The captain spoke of a singular sensation which he had felt near the summit: it seemed to him as if his body had an extraordinary elasticity and lightness, as if his feet hardly touched the ground. The guides were, in general, very tired and complained of headache. In 1827, July 24, another ascent by Hawes and Fellowes,1-7 accompanied by ten guides. The night was passed at the Grands- Mulets (—5°). During the ascent of the Dome du Goute, they began to feel the effects of the great elevation, the headache increased as they advanced; the veins swelled, the pulse was strong and rapid .... At a thousand feet from the summit, the travellers had nose-bleed, and nearly every one spat blood; these symptoms were extraordinarily severe in M. Felowes, who was very delicate; but M. Hawes, short, sturdy, and robust, resisted better. Their breathing was strangely affected; they could not take more than six or eight steps without stopping. Two guides, completely worn out, were sick and vomited much blood. Moreover, every one had the skin of his face cracked and lost blood within. The cold was intense .... By resting, though for only a short time, the travellers reached the crest of Mont Blanc at 2:20. (P. 267.) The same year, a Scotch traveller, Auldjo, made the same ascent on August 9. Not having been able to get the original account which he published, I am borrowing a summary of it from the work of M. Lepileur, whom I shall mention again soon: M. Auldjo says that he did not begin to feel the effects of the rarefaction of the air until he had reached an elevation of about 4,200 meters; he was then attacked by oppression and difficulty in breathing. His pulse became frequent; he felt thirst and a fullness of the veins of his head, but no headache when he was quiet. Most of his guides suffered in the same way and to the same degree. As 92 Historical he mounted, he was more exhausted, the oppression increased, a violent headache appeared, as did strong 'palpitations, general lassi- tude, and a pain in the knee and the muscles of the thigh, which made movement of the legs difficult. About the elevation of 4,570 meters, he had a strong desire to sleep, and was completely exhausted, down-hearted, and discouraged; his guides had to force him to leave the rocks of the Petits-Mulets. The rest of the ascent was extremely painful for him; they had to hoist him by a rope along the last grade. As soon as he had begun to feel ill effects, neither he nor his guides, took more than fifteen or twenty consecutive steps. While climbing the last hundred meters, the most robust and daring guide, he says, was exhausted after three or four steps, and forced to stop to get his breath. He suffered much from the cold on the side where the sun did not strike. Finally, after climbing the last twenty meters with a little less discomfort, he reached the crest, where he fell deeply asleep immediately. He was awakened after a quarter of an hour; he was better, the headache and the pain in the legs had stopped, but he was shivering and thirsty;., his pulse was frequent, his breathing difficult, although the oppression had lessened. He could not eat; the sight and the smell of food nauseated him .... (P. 20.) Mountain excursions became numerous; it was not only Mont Blanc that the travellers, who had become "tourists", aimed at. A German Swiss, Meyer,128 who published the account of his excursions in 1812, gave his attention to physiological symptoms; he found that they had been greatly exaggerated: All that De Saussure reports on the effects of the atmosphere in lofty elevations upon the animal organism has no general foundation; there are still a great many things which are hypothetical. For instance, at an absolute elevation of 10,000 to 12,000 feet and more above sea level, not one of us was drowsy or in a feverish state, or vomited or fainted, symptoms about which some travellers who reached very lofty summits have said a great deal .... Who could deny that when one is climbing, the pulse rate becomes almost immediately twice as frequent as it was before? If one walks then at a slow pace long enough to recover, the pulse will quickly return to the same rate as on the plain or in the valleys .... I had the opportunity to note that the fainting of one of our guides near the summit of the Jungfrau had been brought on largely by the great efforts he made in ascending, and partly also by the fear inspired in him by the danger he was running. None of us felt anything of the sort when we were descending. (P. 30.) Let us note the fainting of the guide, whatever the expla- nation given may be. Let us add that at lower elevations than those reached by Meyer, Dr. Parrot, a celebrated mountaineer, expe- rienced a strange symptom which he attributes, it is true, to the heat, but in which the decrease of pressure seems to me to play Mountain Journeys 93 an important part. He reports in the following words this symp- tom which happened to him September 18: r2Q I had been for two hours on the western edge of the glacier of Lesa, at the height of 3436 meters; the heat was such that my eyes began to grow red, and I felt a frontal headache with such drowsiness and fatigue that I had great trouble in observing my barometer suit- ably; I found no relief for this condition except in lying down on the ground. (P. 386.) The first ascent of Monte Rosa took place August 5, 1819; it was made by two men who lived in the neighborhood, Vincent, superintendent of the mines of Indren, and Delapierre, inspector of forests, better known by the German translation of his name, Zumstein. In the first journey, no physiological disturbance was men- tioned. But the second, which is reported with details in the Memoires de l'Academie de Turin (vol. XXV, p. 230-252; 1820), furnishes some interesting references. At first, in the night which the mountaineers passed at the foot of the last ridges in the hut of the Mineurs, which was occupied two months, "the highest in Europe" (1681 fathoms), Zumstein "felt a certain oppression in his chest which prevented him from closing his eyes all night. "Perhaps," he added prudently, "this excitement was caused only by the keen impatience for the morrow" (P. 237). When they were near the summit, as the daring travellers were crossing a dangerous ridge on steps cut in the ice, "the man who was second in line grew pale and tottering leaned towards the slope at the left (P. 241)"; rubbing him with snow restored him. On the sum- mit, after a certain time for rest, the pulse rate of Vincent was 80, that of Zumstein 101, that of one of the guides 104, and that of the sportsman who was sick 77, which naturally surprised Zumstein. At last they reached the top of the Vincent pyramid (4210 meters) : They had little appetite, but a burning thirst. Vincent had already felt discomfort while he was ascending, and Zumstein, as he stooped to pick up some silvery butterflies which were lying half dead on the snow, had an attack of dizziness, which fortunately soon disappeared. (Anal, de Briquet, p. 16.) On July 31, 1820, they repeated their ascent, in the company of the engineer Molinatti, and passed the night almost at the very summit of the mountain, at an elevation of 13,128 feet: In the middle of the night, Zumstein was awakened by palpi- tations which choked him; he got up to seek recovery and was soon better. 94 Historical The next morning, they continued to climb: M. Molinatti, exhausted by the rarity of the air, was forced to stop constantly, whereas MM. Vincent seemed to have wings, eager as they were to reach the summit first; Zumstein, about fifty steps behind, followed them panting, but soon overtook them. Thus they reached the summit of Zumstein's Point (4560 meters) , and descended without trouble. The other ascents of Zumstein, in 1821 and 1822, had no inci- dents which would interest us.130 We note, therefore, in this ascent, evident physiological disturb- ances, although less than those which the travellers to Mont Blanc had reported. Much less still are those observed by Hugi,131 who goes so far as to deny even the acceleration of the pulse rate on lofty places, which seems rather strange. The greatest elevation reached by this traveller and his com- panions was the Finsteraarhorn (4275 meters) : At these elevations I never failed (he says) to observe the pulse rate, the respiratory rate, and the temperature of the body. The results were constant; that is, in these respects heights and planes show the same results, when neither effort, nor fatigue, nor fear are involved. I am omitting the table of observations. Wahren alone, who is noted for his vigor all through the Oberland, felt a little nausea on the point of the Finsteraarhorn. While he was working at the Pyramid, he twice lost power of vision, so that he was forced to sit down. (P. 218.) On the opposite side, Hipp. Cloquet KJ- states that the symptoms of decompression are often felt, even at the low elevation of the Grand Saint-Bernard: The rarefaction of the air .... causes in the organs of respiration an alteration strange enough to be mentioned. Persons with a strong constitution and with lungs in perfect condition experience a certain pleasure in breathing an air as cool as it is pure and light; on the contrary, those who lack these advantages, and especially those who are asthmatic, experience a marked distress and an extreme difficulty in breathing, when they visit the monastery and its surroundings. At the Saint-Bernard travellers have been seen to be asphyxiated, so to speak, for want of air, and to fall in a faint, without any other known cause, and this happens often to weak and delicate persons. At the beginning of the syncope, the pulse rate is very high; but the greater the strength of the lungs, the less is this acceleration in the pulse rate. It is also to the rarity of the air that we should perhaps attribute a strange phenomenon presented by the observation of wounds in this place. Their cicatrization requires double or even triple the time it Mountain Journeys 95 would take on the plain for its entire completion .... The same thing has been observed on all high mountains. (P. 33.) The accounts of travellers on Mont Blanc are always most characteristic in reference to mountain sickness. After Auldjo, an interval of seven years had elapsed, during which only one ascent (Wilbraham, August 3, 1830) had taken place. But Sep- tember 17, 1834, Dr. Martin Barry133 made a scientific ascent the account of which is very interesting. He mentioned physiological disturbances only above the Grand Plateau: We had then reached an elevation at which I was to verify the statements of previous travellers about the exhaustion brought on by the slightest effort in a much rarefied atmosphere. I did not expe- rence such discomforts before reaching this point, and I did not see any in my guides. I could take only a small number of steps at a time, and those were short and slow. Two or three deep inspirations were enough at each step to revive me; but when I started again, the exhaustion returned as before. I felt an indifference which was not overcome by the sight of the summit so close at hand. I even had a slight fainting fit, and was forced to sit down for a few minutes; but a little wine revived me .... After a few minutes rest at the summit, the weakness, exhaustion and indifference disappeared .... (P. 112.) The account of the ascent of Count de Tilly, which took place a fortnight after that of Barry, contains so many mistakes and con- fusions that we cannot give our time to it. But the following year, an Englishman, Atkins,134 reached the summit with two com- panions, Hedringen and Pedwel, without counting the guides, and observed interesting data. His ascent took place August 23, 1837. He begins by making excuses as if for a foolish action. The first symptoms are not re- ported by him until on the Grand-Plateau: I was forced (he says) to stop every ten steps to get my breath and rest my legs. I suffered from thirst and from deathly languor. From time to time I swallowed a mouthful of vinegar, to moderate the thirst which devoured my entrails, and I often had nosebleed. Coutet was not free from distress and Jolliquet could not hold his head straight. Some of those who were ahead dragged themselves this way and that, others raised themselves, then fell down again. At the foot of the wall of La Cote lay a man stretched out at full length and motionless. I cannot say whether this was one of the guides, but he finally rejoined us ... . At last, after a terrible ascent, after having been forced to stop every two minutes to breathe, we reached the summit .... It was 7° below zero (P. 36.) .... 96 Historical The little dog which accompanied us had to struggle against sleep as soon as we had passed the Grand-Plateau, and every time we stopped, it tried to lie down at our feet, finding the snow cold. It showed more than one sign of surprise, often casting wild eyes around it. Sometimes it made an effort to run very fast, and sometimes fell down exhausted. As for its appetite, the chicken bones we gave it disappeared with astonishing speed, but it did not appear to suffer from thirst .... Hedringer, wishing to have the glory of being the first to set foot on the crest, began to run, but he had hardly taken a few steps, when from exhaustion he stretched himself out stiffly on the snow for two or three minutes, enduring cruel pains. He felt the consequences of his mistaken ardor as long as we remained on the summit (P. 56) ... Our breathing became more and more free as we descended, and we felt so light that we hardly seemed to touch the ground (P. 59). After that time, the ascents of Mont Blanc became more numer- ous. From that of Atkins to the celebrated expedition of Bravais, Lepileur and Martins, in 1844, there were 17; but I can hardly call any of them interesting except that of Mile. d'Angeville (Septem- ber 4, 1838), who had to be almost carried to the summit. Dr. Rey 1&~ in the following words reports the symptoms felt by this daring woman: I learned from Mile. Dangeville that in her usual condition her pulse beats 58 to 60 times per minute, very soft and very regular. When she left Chamounix for the ascent, it was already 64 and increasing, emotion was beginning: at the Grands-Mulets, it was 70 and irregular, although she felt better, mentally and physically. On the grade which is above the Grand-Plateau, where she began to feel a little tired and sleepy, she counted 136 beats at unequal intervals, that is, much more than double the number in her ordinary condition. When she had reached a place called the Mur de la Cote, near the last crest, she felt a sort of agony, caused by an excessive need for sleep, and she cannot tell how high this extraordinary acceleration rose during her severe attack, but five minutes after she reached the summit, the pulse of the noble and intrepid French woman had already dropped to 108 (p. 341). Now let us consider the other mountains. The celebrated naturalist Desor,130 in the report of numerous excursions with a prolonged stay in lofty places which he made in the company of the illustrious Agassiz, is surprised at feeling and observing no physiological disturbance; he is especially struck by it at the time of his ascent of the Jungfrau (4170 meters) in 1841: I must confess that while we were on the summit, and also during the ascent, we experienced none of those symptoms, such as nausea, nosebleed, buzzing in the ears, acceleration of the pulse, and many Mountain Journeys 97 other discomforts, to which most of those who have made the ascent of Mont Blanc say that they were prey. Should we attribute it to the difference of 500 meters between the height of Mont Blanc and that of the Jungfrau? Or should we seek the cause of it in the habit we had formed during several weeks of living at an elevation of more than 2,590 meters? But we should note that M. Duchatelier, who had been in the mountains only a few days, was not ill either. Without claiming to decide this question, which belongs more particularly to the realm of physiology, I am, however, inclined to think that there is a little exaggeration in all that has been told us on this subject. Per- haps also a few travellers have been deceived by their imaginations, like the students of medicine who every day think themselves attacked by the disease the symptoms of which the professor has just set forth to them. Some German physiologists, if I am not mistaken, even claim to have observed the most extraordinary symptoms on mountains only ' a few thousand feet high. (P. 409). He refers again 137 to this immunity in reference to his ascent of the Schreckhorn, or rather the Lauteraarhorn (4030 meters), August 8, 1842: I should note that no one of us experienced the least discomfort either on the summit, or on the ascent, or on the descent, so that in this respect I can fully confirm what I said elsewhere about the so- called ill effects of lofty regions. And yet to this absolute conclusion we can oppose the follow- ing fact from Desor's 138 own accounts: We had been travelling thus for a quarter of an hour when suddenly our friend Nicolet shouted to us that he could do no more. He experienced that complete fatigue by which one is attacked some- times in the lofty Alps, but which passes very quickly if one rests a moment .... "I feel sure," he said, "that I shall never reach Zermatt alive" .... (P. 342.) The travellers were only at the foot of Mont Cervin. Gottlieb Studer139 ascended the Jungfrau August 13, 1842; he felt no discomfort either and gives a strange reason for it: We perceived none of the symptoms which at such great heights travellers have often attributed to the rarefaction of the air; yet we must note that in such a long ascent, for three long hours, the chest can rest .... (P. 313). On the opposite extreme, another tourist, Spitaler,140 who with several companions made unimportant ascents, certainly exag- gerated the sufferings experienced. So, in regard to the "Venetian" on Pinzgau, a mountain of 3675 meters, he makes the following lamentable picture: 98 Historical We needed to breathe more frequently and all our muscles acted painfully; the heart beats and the pulse doubled or even tripled; the pulse was soft and weak, difficulty in breathing amounted to anguish, and stopped one of us a few hundred steps from the summit; another, returning, had a slight pulmonary hemorrhage; the secretion Of the kidneys was strangely lessened .... no one was troubled by perspi- ration, but thirst was very great. The temperature was -f- 2° to +6° R . . . — On the plain we should not have been cold, but at an elevation of 9,000 feet a painful sensation of cold seized us; our skin was flabby, our faces aged; the strength of the muscles was greatly lessened, and out of forty, only twenty-six reached the summit. The evidence of the celebrated English physicist, Principal Forbes, is much more valuable and much more exact. Forbes 141 speaks of the symptoms of mountain sickness in reference to his expedition to the col du Geant (3360 meters), April 23, 1842, on which he noted that one of his guides was slightly affected: We were about a thousand feet from the summit, when Couttet felt his respiration a little affected, but not severely. That is a very common symptom, which depends greatly on the state of the health. I hardly felt it from here to the summit. But in 1841, I was definitely affected at a lower level, when ascending the Jungfrau. The guides say that these variations depend upon the state of the air; and David Couttet assured me that on different days, he and his father had at the same time felt difficulty in breathing at a very moderate height. (P. 224). After all these travellers, naturalists or mere tourists, who spoke only incidentally of physiological symptoms, we come to a scientific expedition which has justly remained famous, the first on Mont Blanc since De Saussure, one of the members of which, Dr. Lepileur, was especially charged to observe himself and his companions from the physiological point of view. And so the report 1 4- which he makes of this ascent deserves to be analyzed here at considerable length. But before beginning the report itself, M. Lepileur, who was a frequenter of mountains, says that in his excursions previous to the ascent of Mont Blanc, he experienced or observed a certain number of interesting phenomena, particularly because of the moderate heights at. which they appeared: While I was going from Martigny to the Grand Saint-Bernard, in September 1832, I saw my brother and two of my friends display most of the symptoms of mountain sickness; one of them, a young man twenty-six years old, was seized by general discomfort, fatigue, breathlessness, and palpitations, one hour before reaching the monas- tery, and soon he could not walk without being supported and without making frequent halts at equal intervals. When he reached the Mountain Journeys 99 monastery, he went to bed, without being able to take anything but a little tea; he suffered all night from a discomfort which he compared to that of fever; the next morning he still felt oppression, and has- tened to descend to Martigny. Of the two others, one was thirty years old, and my brother seventeen: they had very little discomfort during the last half -hour of the ascent; but although they were not very tired when they arrived, they had not the slightest appetite, and even the sight and the smell of food disgusted them. During the night they recovered completely; on the next day, they were able to ascend to one of the crests to the south of the monastery, and to go back down to Martigny on foot. The fatigue of this day's efforts also took away their appetite that evening, as it did that of another of our companions, who had felt no effects at the Saint-Bernard; but then it was only fatigue, there was no trace of the discomfort which they had felt the night before. In the month of June, 1835, while I was climbing the slope of snow which extends below Chateau Pictet on Buet, at a height of about 3,000 meters, I felt my strength fail, it was very hard for me to go on. One of my friends who accompanied me had already been suffering for nearly a half-hour from fatigue in the legs and knees. He made frequent halts. As for me, I could not take more than 160 consecutive steps. A little chocolate which I ate restored me almost completely; however I was still obliged to stop from time to time, although I was much less exhausted. From Chateau Pictet to the crest of Buet the slope is very gentle, and I felt no lassitude while mounting it. In the month of July of the same year, I was climbing with a guide on the point of rock which towers above the Saint-Theodule pass on the north; about sixty meters below the crest, I perceived that the guide stopped frequently; soon it was impossible for him' to take more than eight to ten steps without stopping for breath. He was a robust man and in the prime of life, so that I could not believe that the weight of my sack which he was carrying was enough to weary him to this extent; seeing him pant, turn pale, and nearly fall in a faint, I told him to take a little rest; he would not admit his distress at first, but finally was compelled to sit down, a cold sweat ran down his face, he was exhausted. I had him eat a little bread and chocolate, which, with a ten minute rest, quite restored him. The elevation at which we were was hardly one hundred and fifty meters above the Saint-Theodule pass, that is, 3,560 meters, but I had noted when we left Zermatt about midnight that the guide was drunk,^ and that is what had made him so susceptible to the rarefaction of the air. Two days after, while climbing the Breithorn, at the east-south- east of the Saint-Theodule pass, one of my guides found it impos- sible to climb higher than the last plateau (about 3,900 meters) ; this man was sixty years old and was afflicted by a double inguinal hernia. Another guide of the same age panted greatly while climbing the terminal cone of the Breithorn (4,100 meters), the grade of which is very steep. The other two guides, men of thirty to thirty-five years, felt no more distress than I. The next year, making the same excur- 100 Historical sion with one of my friends, I was suddenly seized by unconquerable sleepiness as I was crossing the vast plateau south of the Breithorn, where a guide had had to stop the year before. I was sleeping as I walked, no matter what efforts I made to stay awake; one of the two guides had the same experience, the other and my travelling com- panion felt nothing of the sort. As we returned to the Saint-Theodule pass (3,410 meters), after a light meal taken with good appetite, we all slept in the sunshine for about an hour. When he awoke, my travelling companion was nauseated and vomited what he had eaten an hour before. I must note that the second night before, we had slept little and badly, and that after a walk of eight hours, we had had only three quarters of an hour of sleep on the night before our excursion. Several times, in Paris, I have found myself thus over- powered by sleep so that I slept and even dreamed while I was walking. Moreover, none of us felt any other discomfort during this excursion. In July, 1844, while climbing the slope of the Couvercle, at an elevation of about 2,500 meters, I felt a distress and a difficulty in climbing like that I had experienced in 1835 on Buet. This condition lasted about twenty minutes. I was not forced to stop, but I suffered, and my strength seemed much lessened; at last, without any percep- tible cause, for I continued to ascend, the discomfort suddenly ceased, I could climb without trouble the height of about 150 meters, which separated the point where I was from the Jardin. When I reached the Jardin, I ate with considerable satisfaction; but I was soon satisfied. Dr. Noel de Mussy, one of my companions on this walk, who was in the mountains for the first time, was only a little out of breath; at the Jardin, he ate with a good appetite. And yet, in the evening, while we were returning, he was much more tired than I. Another traveller who accompanied us felt no distress. Finally, in the month of September, M. Camille Bravais, who ascended with me to the rock of the Echelle, when we had reached an elevation of about 2,300 meters, had to stop every twenty steps to get his breath. It is true that M. C. Bravais, affected no doubt by a slight hypertrophy of the heart, was never able to climb a steep grade without experiencing severe palpitations. (P. 33 et seq. of the separate printing.) Now let us turn to the ascents of Mont Blanc. In the first attempt with MM. Bravais and Martins, July 30, 1844, they exper- ienced some effects on the Grand-Plateau (3911 meters), where they set up their tents for the night, and beyond which they could not go: distaste for food, diarrhea, prostration. M. Lepileur was seized by violent shivering, recurring eight or ten times an hour; M. Martins had a similar attack. They had helped their guides in setting up their tent, and had become much fatigued. August 7, all three set out again, and camped at the Grand- Plateau: the shivering attacked M. Lepileur there again; M. Martins was quite ill, Bravais felt nothing but an irresistible desire Mountain Journeys 101 to sleep at the Grandes-Montt-es (3800 meters). The face of one of the guides was cyanosed, which M. Lepileur attributes to the cold. On the descent, M. Martins had a slight hematuria. August 28, third journey; departure from Chamounix at mid- night: The ascent went very well up to about 3,100 meters. There, Tournier felt ill, lost courage entirely and was forced to descend. He was pale, his face was bathed with sweat, and he could hardly climb even a few steps, although his burden had been taken from him and although we were on a rather gentle slope. He attributed this failure of his strength to the fact that the day before, not expecting to make the ascent, he had worn himself out at a painful task. His distress ceased as soon as he was two or three hundred meters lower. At 3,600 meters, I felt no ill effects as long as I walked slowly; but when I wanted to ascend quickly, as for example, to rejoin my travelling companions, after having paused a moment, I felt discom- fort. M. Bravais suffered much from cold feet for several hours. Several times he had been obliged to stop, and we had reestablished circulation in him by slapping the dorsal side of his toes with our hands .... At the Petit-Plateau, I ate, at first with repugnance, then with pleasure, when a little food had stimulated the stomach. We all took a little wine; that was always what helped us most .... M. Bravais again, this time like the two others, became very sleepy about the elevation of the Petit-Plateau (3,800 meters). When we reached the Grand-Plateau, he was a little tired and so was I. M. Martins was not. Cachat and Ambroise Couttet were exhausted. As soon as they had halted, they lay down on the snow in the sunshine, and remained there for three or four hours, without being able to help us at all. Ambroise Couttet felt nausea besides all afternoon. As soon as he tried to stand up, he was threatened with syncope. The others helped us set up the observation instruments and clear our tent which the snow had three quarters buried on the north-east side. This labor did not tire us at all, and we were no more out of breath than the first time at Chamounix, when we had set up the tent ourselves for practice and to show the guides how it ought to be done. None of us had as much appetite as in the valley. M. Bravais had very little; M. Martins and I had none at all. However, I felt no distaste for the fresh food which we had brought. Three hours after our arrival, when I took off my crape mask which hindered me in making my observations, I felt , the beginning of a headache which stopped as soon as I put my mask back on. When I gave careful attention to the observation of some instrument, when, for example, I read a thermometer placed on the snow, and in general whenever I was in a position in which respiration was hampered, I felt a slight sensation of nausea which lasted hardly one or two seconds; the instant before and the instant after, I had no discomfort at all. MM. Martins and Bravais noticed the same effect in themselves. With that 102 Historical exception, we were very well, gay, and full of confidence. We noted this slight discomfort only to be rigorously exact. A. Simon almost fainted while I was feeling his pulse. He was standing, and just had time to lie down on the snow to avoid a complete loss of consciousness. After our arrival, he had been busy clearing the tent and setting out our camping equipment without feeling any discomfort; however, this time he was not quite as well as the others. After some time he recovered and even ate with appetite. In the evening, everyone was well; our two invalids had recovered from their fatigue; I slept at night, although very uncom- fortable because I could not stretch out my legs. I also felt some rheumatic pains in my right knee, toward the inner edge of the knee- cap, and a little neuralgia on the outer side of the left thigh. M. Bravais made observations until midnight. August 29, at four o'clock in the morning, I made the first observation. I was rested and felt quite strong, but I had no appetite; the only food I cared to eat was a few raisins; the provisions, which had been thoroughly frozen for a month, and especially the meat, filled me with disgust. About six o'clock, M. Bravais and I took a little bread and wine. The first hours of the morning were passed in making observations and a few experi- ments, during which we were standing, coming and going on the soft snow. At ten minutes past ten, we started for the summit. The crossing of the Grand-Plateau was painful because of the snow into which we sank up to the calf. I did not feel as strong as in the morning, but I felt no distress. I perspired abundantly while crossing the Grand-Plateau and during the first half-hour of the ascent. Our hands and feet were very cold, those of M. Bravais particularly. M. Martins lost his breath a little more and a little more quickly than we did. Up to the foot of the upper Rochers Rouges, about 4,400 meters, I had no discomfort of any sort; we took 350 or 400 steps consecutively without stopping for breath; but when we reached this number, we felt the need of resting for a few moments. The grade which we were climbing, measured with a geologist's compass, was, at the elevation of 4,300 meters, 42°, and the slope of our course was 16°. About 4,400 meters, I began to feel after ten or twelve steps a little fatigue with pain like that of lumbago in the legs and knees. I counted my steps again, we were still taking one hundred between halts; but the last twenty were very painful to me. This pain in the legs stopped as soon as I halted, and the first steps I took after that were very easy. I began to be very anxious that the grade should become easier. A quarter of an hour before we reached the top of the upper Rochers Rouges it did become less steep. About this height (4,500 meters) I perspired a little, but it lasted only a few moments. After a short pause, we continued the ascent; a little before the top of the upper Rochers Rouges, I had begun to feel an undefinable discomfort when I was walking; I had neither headache nor palpi- tations, once or twice I felt a few throbs in the carotids, no doubt because I had made a few steps more quickly than the others. I was not nauseated either, but I felt a general discomfort, a sort of exhaus- tion. I was weak and it seemed to me that I had just enough strength Mountain Journeys 103 to carry out the motions of locomotion for a certain time and then it would be all over; in a word, I was like a man who, at the end of a long day of walking, perfectly exhausted, feels that he can reach a point not very far away, but that he must give up going any further. I could walk only with my head lowered and my chin nearly touching the sternum. This was the attitude of us all, and when we were getting our breath, it was also with the neck stretched out and the body leaning forward during the first seconds. Clissold had observed the same thing. I felt a slight desire to sleep several times and yawned occasionally. What added greatly to the discomfort was a rather keen thirst or rather a dryness and a sticky condition of the mouth; a little snow melted on the tongue while I chewed a raisin quenched the thirst for a few moments. This uncomfortable condition developed gradually, and it was quite endurable when at about 4,560 meters a violent wind from the northwest struck us. At once we felt as if our hands, our faces, and the part of our heads which the head covering did not protect were freezing. The side of the body which the wind blew upon was also very cold, especially in MM. Bravais and Martins, whose clothing was rather thin. As we were climbing in a zigzag, when we had the wind in our faces during a squall, I experienced then in the highest degree the sensation which I described in connec- tion with our first ascent to the Grand-Plateau. It was in vain that I covered my nose and my mouth with my hand, stooped, turned aside my head; I could not breathe any more than if I had been under water. I felt the distress of asphyxia, my head whirled, and I felt slightly nauseated. When I turned my back to the squall, it seemed as if the wind made a vacuum around me, and I had difficulty in breathing. I was the only one to feel this effect of the wind, both on the first and on the third trip. This increase of discomfort lasted without stopping for a quarter of an hour or twenty minutes, I asked myself whether I could reach the summit, I felt sure that I should succeed; but I had to use all the mental strength I possessed to actuate my physical powers. Sometimes too I advanced mechanically, without thinking, so to speak. No one talked, everyone, like me, had but one thought, that of advancing a few steps more. So the distance one tra- verses between the Rochers Rouges and the summit, although it took us nearly two hours to cover it, did not leave many details in my memory, and returns to me as a vague recollection, rather painful and very short, no doubt because of its uniformity. The same thing was true for MM. Bravais and Martins, for we were all three surprised when we had to admit from our notes that it took us nearly two hours to go from the Rochers Rouges to the summit. We remembered only two or three incidents of this ascent, which, although painful, was however made without interruption and without the excessive fatigue and exhaustion experienced by some travellers. It is, I think, to the blank left in the memory by this part of the ascent to Mont Blanc that we should attribute the mistakes and the confusions so frequent in the accounts of travellers when they speak of this passage. When we halted, after two or three seconds I was in perfect condition; I felt no discomfort except a slight thirst and cold feet and hands. We did not find, as De Saussure observed in himself, that 104 Historical the distress caused by walking reached its highest point after the first eight or ten seconds of the halt. During the last quarter hour of the ascent, the slope was gentler and the wind blew less violently. These two causes, added to the joy I felt when I saw the summit only a short distance away, lessened my distress greatly. M. Bravais suffered only from the cold. We had already realized that of the three of us it was he who felt the effects of the rarified air least. M. Martins was the one who suffered most from it. He was very much out of breath, had palpitations, throbbing in the carotids, and a little headache; he felt a general fatigue, and took fewer steps than we did. When he reached the summit, he thought he was still a half hour away from it, and felt keen joy when he found he was there. None of us felt pain or fatigue or anything extraordinary in the coxofemoral articulation while we were walking; in general, we felt no fatigue in the muscles of the thigh. MM. Bravais and Martins had a little in the right anterior muscle only. Between the Rochei's Rouges (4,500 meters) and the Petits- Mulets (4,660 meters), we first took eighty steps without stopping for breath, then this number was lessened to seventy, and finally to thirty-five or forty steps between the PetTts-Mulets and the summit. However, as we came near the highest point, since the grade was very moderate, we made one or two stretches longer than the others. At about forty meters from the summit, M. Bravais wanted to see how many steps he could take climbing as quickly as possible and in the direction of the great slope. He had to stop after thirty-two steps; he felt, he said, that when he stopped, he could have taken two or three more, perhaps four, but that it would have been quite impos- sible for him to go beyond that. During the ascent, none of the guides or porters seemed affected; two of them were a little more fatigued than the others; they were Frasserand, who the day before had been rather fatigued when we reached the Grand-Plateau, and A. Couttet, who had been ill there all afternoon. Our two guides and the porter Simon seemed able to take more steps than we were. Several times they stopped only because they were asked to. M. Bravais and I reached the summit at the same time; M. Martins joined us there a few minutes afterwards . . For eight or ten minutes I had keen pain in my feet, caused by the change from intense cold to warmth. I was also rather drowsy shortly after we arrived and when the pain in my feet had stopped. I lay down on the snow where I remained five minutes, but without being able to sleep. Then I got up, the desire for sleep disappeared, and during the whole time we spent on the summit I felt absolutely no painful sensation, except a little cold the last hour. I had no appetite, although the idea of eating caused me no disgust. M. Bravais was also very well; only from time to time he felt the slight nausea which M. Martins and I had observed in ourselves the day before on the Grand-Plateau. He had an appetite and ate some biscuits and a few prunes. Shortly after our arrival at the summit, he and I each drank about a third of a glass of brandy. This liquor seemed to us delicious and very mild, to our great surprise; it did us much good, and gave us strength without causing the excitation Mountain Journeys 105 usually produced by alcohol. We also drank a little wine, during the first two hours of our stay on the summit. A moment after he reached the crest, M. Martins was attacked by nausea, and vomited some seeds of raisins which he had eaten an hour before. Vomiting relieved him. He compared his illness to seasickness. When he lay down, he had no trouble, but moving about and standing brought back the nausea. An hour afterwards, he was better; after two hours, the sickness was completely gone. He drank a little wine, but did not wish to eat. The six men we had with us ate hardly anything, but they drank about two bottles of wine and half a bottle of brandy. All were in perfect health; only two were evidently fatigued, although they would not admit it ... . We could walk without any difficulty on an almost horizontal plane; but as soon as we had to climb, we were affected by panting and general lassitude .... There was a white coating on the tongues of all of us, but less in the guides than in us, and their appetites were not, like ou^s, completely or almost completely wanting. (P. 44-54.) After a few hours of observations, they descended to the Grand- Plateau; M. Martins was attacked by panting, palpitations, and throbbing in the carotids, so that he had to sit down. During the night, M. Lepileur felt violent sciatic neuralgia on the left side. His appetite did not return until the next day when he reached the altitude of 3000 meters while returning to Chamounix; during the whole day, he had eaten only a small piece of bread dipped in a little wine. He sent fresh provisions to Martins and Bravais, who had remained on the Grand-Plateau; they received them with great pleasure and made a good meal; however, what five of them ate would hardly have equalled the ration of one man in the valley. The urine of all of them was scanty and dark. The work of M. Lepileur is finished by a series of tables indi- cating the pulse rate of himself, Martins, and three guides from Servoz or Chamounix to the summit of Mont Blanc. He summar- izes it as follows: The increase of the pulse rate is a constant result, when one is ascending, beginning with a certain elevation, .... which may vary with the individual .... My pulse was less frequent at Chamounix (60) than at Paris (67.25) ; . . . . the contrary was true of M. Martins .... The ratio of frequency between Chamounix and the summit is: for M. Martins 0.82; for me 0.68; for Muguier 0.67; for Couttet 0.60; for Simond 0.61. (P. 77-80.) M. Martins143 much later narrated the same journey; his recol- lections agree with those of M. Lepileur: On the Grand-Plateau the guides began to clear snow off the tent. 106 Historical This work was painful; each of them had hardly removed a few shovelfuls when he stopped to breathe; a hidden distress was revealed on every face; appetites were gone. Auguste Simon, the tallest, the strongest, the most daring of the guides, collapsed upon the snow, and almost fainted while Dr. Lepileur was feeling his pulse; it was the effect of the rarefaction of the air added to fatigue and insomnia, from which all of us suffered more or less. We were then about 4000 meters above sea level, and there are few men who are not inconven- ienced at 3000 meters. I am not surprised that in this ascent we felt the effects of the rarefaction of the air, which we had hardly noticed in the two previous ascents. Never had we mounted so quickly from Chamounix to the Grand-Plateau; starting from 1040 meters above sea level, after ten and a half hours of walking we were at an elevation of 3930 meters; that is a difference in level of 2890 meters, traversed in less than a half day. All discomfort disappeared when we ceased moving. (P. 25 of the separate printing.) The next day, they finished the ascent: The rarefaction of the air ... . compelled us to walk slowly; every twenty steps we stopped breathless .... We were reaching the goal, but we were walking slowly, our heads lowered, our chests heaving, like a procession of invalids. The effect of the rarefaction of the air was felt painfully: the column paused constantly. Bravais wishes to find out how long he could continue climbing as quickly as possible; he stopped at the thirty- second step without being able to take one more. At last at a quarter of two we reached the long desired summit. (P. 27.) The account of the ascent of July 19, 1859, made by MM. Chomel144 and Crozet, has also given us interesting observations; they followed a route different from the usual one, from the beaten path, we may say, so frequent have journeys to Mont Blanc become: There comes at last the cap of Mont Blanc, which, in spite of its slight elevation above the Mer de Glace, nevertheless requires two more tedious hours of ascent. During this last stretch, the lack of air makes every movement of the body painful, and one must make superhuman efforts to resist palpitations, sleep, and fainting .... Only a few feet now separate us from this long-desired summit. Our self-respect spurs us on, and rising from the snow on which we were stretched, we cover the rest of the way at a run .... And here we are on the summit of the giant of the Alps. The first impression .... was, alas! a dizziness and contractions of the stomach which made us reel. The celebrated English physicist Tyndall145 is one of the most ardent mountaineers in the Alps. Every year sees him planting his alpenstock on some new summit. And it is not only with a scientific purpose that he runs thus the greatest dangers; it is not Mountain Journeys 107 only the great spectacles of nature which attract him and thrill him; he too seems gripped by this passion for climbing for the sake of climbing, which, though it had its origin in England, is making progress today in our own country. But his evidence has all the more value for these different reasons. August 12, 1857, Tyndall made his first ascent of Mont Blanc, in the company of MM. Hirst and Huxley. The latter had to stop at the Grands-Mulets. When he reached the Derniers Rochers, Tyndall felt exhausted. The guide Simond cried at every halt: "Oh, how my knees hurt!" I lay down upon a bed composed of granite and snow, and went to sleep immediately. But my companion soon awakened me: "You frightened me," he said, "I have been listening for several minutes, and I have not heard you breathe once." We got up then, it was half past two .... To the feeling of fatigue we had felt till then was added a new phenomenon, palpitations. We were constantly subject to them, and sometimes they became so severe as to cause some apprehension. I counted the number of steps that I could take without stopping and found it to be fifteen or twenty. At each halt my heart beat hard enough to be heard as I was leaning on my alpenstock, and its subsiding was the signal for a new advance. My breath was short, but easy and unhampered. I tried to find out whether the articulation of the thigh was relaxed because of the decreased pressure, but I could not be sure .... After we had passed the Derniers Rochers, we struggled on with the stoical indifference of men who are carrying out a duty without bothering about the results. At last a ray of hope began to brighten our spirits; the summit was visible, Simond showed more energy .... at half past three I clasped hands over the summit. (P. 80.) The account of the second ascent, made September 12, 1858, merely alludes briefly to the fatigues of the mountains, (p. 189.) In 1859, an ascent still more important and very profitable for science. Tyndall, Frankland, and nine guides passed a night on the summit of Mont Blanc; they stayed there about twenty hours:14"' We did not suffer from the cold, although we had no fire and the snow was at a temperature of — 15°C. But we were all ill. I was sick when I left Chamounix .... I had frequently conquered my discom- fort on previous occasions, and I hoped for the same thing this time. But I was absolutely disappointed; my illness was more deeply rooted than usual, and it grew worse during the whole ascent. But the next morning I was stronger, whereas the opposite was true for several of my companions. (P. 54.) The same year, a German, Dr. Pitschner,147 made a remarkable ascent of this same mountain; he was very seriously affected: 108 Historical At six o'clock in the morning, we were in the Corridor (3,990 meters) ; the thermometer marked — 8°C. We had hardly been there five minutes when a strong desire to sleep seized us, and conquered me completely. My respiration was very painful; my eyes blinked, I had buzzings in my ears, headache, nausea; soon I vomited repeat- edly; Balmat was as much affected as I, and his desire to sleep was so great that he lay down on the snow, and I immediately let myself fall beside him. "I cannot go any further without sleeping a half-hour", I said to Balmat .... I fell into a lethargic sleep, interrupted by smothering spells, which finally seemed dangerous to Balmat; and so he began to stir me and shake me, without being able to awaken me. Fifteen minutes passed. His shouts awoke me, and he said to me: "You cannot stay here any longer, you must go on". Perspiration covered my face; I rubbed my face with snow, and after a score of deep breaths, I felt better .... From my sensations on the glacier, it is evident that the effect of mountain air was evidenced in me very definitely; it produces dang- erous congestions .... On our return, at three o'clock in the afternoon, the same symptoms appeared in the same place, but with much less intensity: headache, nausea, vomiting. The expedition of Dr. Piachaud,14S July 26, 1864, gave results just as interesting. The author gave heed to the physiological phenomena experienced by his companions and himself, and "attri- buted to the rarity of the air": The chief symptom (he says) is the oppression, which hardly exists when one is resting, but which appears as soon as one starts walking, then stops again when one halts. From it there results the necessity of increasing the number of inspirations, and thence such a fatigue that one is forced to halt every twenty or twenty-five steps. This fatigue, moreover, is not like that one feels as the result of a long walk; it is not the legs which are chiefly affected; it takes possession of the whole system; there is a sort of general depression both mental and physical. I should add that this peculiar condition is observed only during the ascent, for once I had reached the summit and during the descent, I felt nothing of the sort. Another noteworthy effect of the rarity of the air is sleepiness, which I could hardly resist; I felt that if I had stretched out on the snow, or if I had been alone, I should have gone to sleep immediately. I do not think that this drowsiness can be attributed to the cold, for on the summit, where the cold was very keen, I was wide awake. I also experienced very slight vertigo, but I mention it only to omit nothing. As for nausea, vomiting, fainting, hemorrhages, none of us was affected by any of them; our guides, of whom I asked infor- mation on these different points, told me that they had never observed hemorrhages. As to oppression, which is the symptom most frequently observed, I should say that it is far from being absolute, for of the six of us, I am the only one who felt it very definitely; the guides 104 ___. 104 108 ___. 104 108 ___. 104 96 ___. 96 92 80 Mountain Journeys 109 did not complain of it and M. Loppe could run when he got near the summit. (P. 86.) Examination of the pulse rate gave the following results: Chamounix Grands-Mulets Mont Blanc 1000 meters 3000 meters 4800 meters Carrier, guide 116 Couttet, guide 96 Tournier, guide 96 Payot, guide 92 Loppe, traveller 88 I now come to the two ascents of Mont Blanc which were note- worthy from the standpoint that interests us because for the first time the whole combination of physiological phenomena was studied with the precision instruments used in laboratories. Dis- turbances of circulation and respiration were thus determined in the conditions which the present exactness of physiological re- search demands. Besides, these observations serve as a basis for an entirely new theory of mountain sickness, which will be discussed in its proper place. M. Lortet149 begins with a rapid historical survey of the symp- toms felt by the most celebrated travellers. Then, before beginning the account of his journey, he lets escape the precious confession of an incredulity of which I have often heard Alpine travellers boast, even those who had made the most difficult ascents: However, in spite of so many data and proofs reported by these distinguished men worthy of credence, I had been a little incredulous and I could not help believing that imagination played a great part in the production of these phenomena. On the main range of Monte Rosa I had often ascended heights of more than 4300 meters without any difficulty and without the least discomfort, and I could not believe that 500 meters more were enough to affect an organism which had stood the test very well up to this altitude. Now I am forced to admit it, I have been convinced de visu, and even a little at my expense, of the very real existence of symptoms which, above this altitude, attack anyone who breathes and particularly anyone who moves in this rarified air. (P. 11.) He then comes to the account of his first ascent with Dr. Marcet, August 16, 1869. I copy the important points of his descrip- tion, which is remarkable for its exactness and moderation: Up to the Grands-Mulets (3050 meters), where we arrived at 3 o'clock to pass the night, we were well; no one felt the least discom- fort; we all had excellent appetites; but already our instruments announced serious disturbance of circulation, respiration, and espe- cially calorification, (heat production) 110 Historical The night at the Grands-Mulets was horrible .... At half-past two we set out. At daybreak they reached the Grand-Plateau (3932 meters) : We stopped a moment to breathe .... The guides took a little nourishment; but it was completely impossible for me to swallow a single mouthful, although I still felt quite well. We climbed very slowly; we all felt an inclination to sleep which was very difficult to struggle against and an intense occipital head- ache, thirst and dryness of the throat, only a few palpitations, but a wretched pulse which varied between 160 to 172 per minute. When we reached the ridge, we were all tired, and it seemed to me that it would be completely impossible for me to go further. None of us vomited, but almost all of us were nauseated. Like those who are attacked by seasickness, I was completely indifferent about myself and the others, and I wanted only one thing, to remain motionless. The Englishmen who were following us seemed even more affected than we were; one of them was obliged to stop and soon retraced his steps. At last they reached the summit of Mont Blanc: I no longer felt any kind of illness, but the breathlessness was extreme as soon as I wished to take a few steps rapidly. The least movement caused me disagreeable palpitations. One of my com- panions, who had felt no ill effect until then, was attacked suddenly, as soon as he had reached the summit, by dizziness and almost con- stant vomiting which did not cease until he reached the Grand-Plateau on the way down. His stomach was empty, so that he vomited only glairy and bilious matter with very painful efforts. Nothing succeeded in stopping this stomach trouble; only one thing seemed to relieve his condition at all, that was small fragments of pure ice which he managed to swallow from time to time. His pulse was very uneven, very wretched, and the thermometer placed under his tongue hardly went above +32°! The sun was warm, the atmosphere fairly calm, so it was with surprise that I observed that the temperature of the air was — 9°. We remained at the summit nearly two hours to make the experi- ments of which I shall speak later. While I was resting, I felt quite well, although it was impossible for me to take the least nourishment. (P. 16.) The second ascent went much better. The night at the Grands- Mulets was good; magnificent weather made the walking easy: We felt almost no discomfort except a leaden sleepiness while we were climbing the slope which leads to the Dome. I have never felt any- thing like it, and I am sure that I slept while I was walking. But when I reached the ridge, the cold air and rubbing my forehead with snow removed this congestion. I felt much better than on the first ascent. I even had an appetite and could eat some morsels with pleasure. However, breathlessness Mountain Journeys 111 at the slightest movement was still intense. One of our companions experienced great nausea, complete lack of appetite, but did not vomit. (P. 18.) After this general description, M. Lortet passes to the analysis of the disturbances in the various functions. And at the beginning he is careful to say: Hardly noticeable while going from Lyons to Chamounix, that is, passing from a height of 200 meters to an altitude of 1000 meters, their disturbance is, on the contrary, very appreciable from Cham- ounix to the Grands-Mulets (from 1050 to 3050 meters), still plainer from the Grands-Mulets (3050 meters) to the Grand-Plateau (3932 meters) ; finally this change becomes very great from the Grand- Plateau to the Bosses-du-Dromadaire (4556 meters), and at the summit of the Calotte of Mont Blanc (4810 meters). We shall therefore review the variations undergone by the respi- ration, the circulation, and the inner temperature of the body, taken under the tongue at different altitudes, either while walking, or after a suitable period of rest. (P. 20.) Respiration: From Chamounix to the Grand-Plateau (from 1050 to 3952 meters) disturbances of respiration are slight in those who know how to walk in the mountains, who keep their heads lowered to lessen the laryngial orifice, who breathe with their mouths closed, being careful to suck an inert object, such as a hazelnut or a little piece of quartz, which considerably increases salivation and prevents the drying out of the air passages. From Chamounix to the Grand- Plateau, the number of respiratory movements is hardly changed; while at rest, we find twenty-four per minute, as in Lyons and in Chamounix; but from the Grand-Plateau to the Bosses-du-Dromadaire and to the summit, we find thirty-six movements per minute. The breathing is very short and very difficult, even when one remains quiet; it seems as if the muscles are stiffened and the ribs are held in a vise. At the summit, the slightest movement brings on panting; but after two hours of rest these discomforts disappear little by little. Respiration drops to twenty-five per minute, but it still remains painful. (P. 20.) M. Lortet studied the changes in the amplitude of his respi- ration with the anapnograph of Bergeon and Kastus; the two tracings below give a very complete idea of them; in both, the area GFED represents the inspiration, the area DCBA, the expiration. Comparing the tracing of Figure 1, taken at Lyons, with the following, taken at the summit of Mont Blanc, after a rest of an hour and a half, we see that the quantity of air inspired and expired at the summit of Mont Blanc is much less than at Lyons. Circulation: During the ascent, although progress is excessively slow, the circulation is accelerated extraordinarily. At Lyons', when I am resting and fasting, my average pulse rate is sixty-four per 112 Historical minute. While I was climbing from Chamounix to Mont Blanc, it increased progressively, following the altitudes, to 80, 108, 116, 128, 136; and finally, while I was climbing the last ridge which leads from Fig. 1— Lortet. Respiratory tracing taken at Lyons (200 m.) Fig. 2 — Lortet. Respiratory tracing taken at the top of Mont Blanc (4810 m.) after an hour's rest. the Bosses-du-Dromadaire to the summit, to 160 and sometimes more. These ridges, it is true, are very steep, they have a grade of forty-five to fifty degrees; but slowness of the walking is very great. One generally takes thirty-two steps per minute and often much less when steps have to be cut constantly. The pulse is feverish, hasty, and weak. It is plain that the artery is almost empty. The slightest pressure stops the current in the blood-vessel. The blood must pass very rapidly in the lungs, and this rapidity increases still more the insuffi- cient oxygenation which has already resulted from the rarefaction of the air. It does not have time to receive the oxygen adequately, and neither does it have time to give off its carbonic acid entirely. Above Mountain Journeys 113 the elevation of 4500 meters, the veins of the hands, the forearms, and the temples are distended. The face is pale with slight cyanosis, and everyone, even the guides acclimated to these lofty regions feel a heaviness in the head and a drowsiness which are often very painful, due probably to a venous stasis in the brain or to a failure of oxygenation of the blood. Even after two hours of complete rest at the summit and fasting, the pulse always remains between 90 and 108 beats per minute. (P. 23.) We reproduce as very interesting examples the following sphygmographic tracings (Figs. 3, 4, 5) which, made by M. Chauveau of Lyons at the time of his ascent in 1866, give all neces- Fig. 3 — Cupelain; at Chamounix (1000 m.) Fig. 4— Cupelain; at the Grands Mulets (3000 m.) at midnight, one half- hour before starting. Fig. 5— Cupelain; top of Mont Blanc (4810 m.) sary proofs of accuracy. The guide Cupelain, who was the subject, is a very vigorous young man, who seems not to suffer from moun- tain sickness at all. For M. Lortet, who does suffer from it, the changes were still more considerable. Temperature. We now come to the subject to which M. Lortet gave most attention, and which serves as a basis for his theory of mountain sickness. I continue to quote verbatim: The thermometer was placed under the tongue, the buccal orifice being always closed hermetically, and respiration going on only 114 Historical through the nose .... The instrument was always left in place for at least fifteen minutes. (P. 31.) Fasting, while walking continues, the decrease of the tempera- ture is, according to M. Lortet, almost proportional to the altitude at which one is. This is shown by the following table. Lortet: Temperature First Second Temperature Ascent Ascent of the air 'x First Second in .fj < '3 OS '3 Ascent Ascent 3 « Chamounix 1050 36.5 36.3 37.0 35.3 + 10.1 + 12.4 64 Cascade du Dard 1500 36.4 35.7 36.3 34.3 + 11.2 +13.4 70 Chalet de la Para 1605 36.6 34.8 36.3 34.2 + 11.8 + 13.6 80 Pierre-Pointue 2049 36.5 33.3 36.4 33.4 + 13.2 + 14.1 108 Grands-Mulets 3050 36.5 33.1 36.3 33.3 — 0.3 — 1.5 116 Grand-Plateau 3932 35.3 32.8 36.7 32.5 — 8.2 — 6.4 128 Bosse du Dromadaire 4556 36.4 32.2 36.7 32.3 —10.3 — 4.2 136 Summit of Mont Blanc 4810 36.3 32.0 36.6 31.0 — 9.1 — 3.4 172 So during the muscular efforts of the ascent, the temperature of the body may drop four or five degrees, when one mounts from 1050 to 4810 meters. As soon as one stops for a few minutes, the tempera- ture rises quickly to nearly its normal figure .... Since my return to Lyons, I have observed that when one ascends rapidly one of the numerous stairways that lead to Fourvieres or the Croix Rouge, there is regularly a drop in temperature which varies almost always from three to seven tenths of a- degree. (P. 32.) It is to this drop in temperature of the body that M. Lortet attributes all the symptoms of mountain sickness. In Chapter III we shall give this theory and the objections it has aroused. The same day when MM. Lortet and Marcet suffered so severely during the ascent, M. Ch. Durier150 followed them, walking, so to speak, in their footsteps. Strangely enough, neither he nor his companions felt any symptoms: There were three of us, three companions of very different temperament; one was a lad fifteen years old, the youngest traveller — at least that I know of — ever to ascend Mont Blanc. Well! None of us felt the slightest discomfort, not even breathlessness. (P. 66.) Why this difference in impression? M. Durier asks himself. And to this question he gives an answer full of acuteness, of which we shall make use later. Mountain Journeys 115 I shall end the review of the principal ascents of Mont Blanc with that of M. Albert Tissandier;1M it is particularly interesting because its author, being an aeronaut, could compare his sensa- tions with those he felt in a balloon; he had no uncomfortable sensations: At the height of 4400 meters, respiration began to be somewhat painful and panting, but I endured the effect of the rarefaction of the air without very much trouble. My two guides looked at me at that time, and told me that often, at that altitude, travellers have a peculiar color; sometimes their vision grows dim and their strength fails; then they have to be hoisted up with great difficulty or else descend, depending upon the energy the traveller possesses. I should have been very sorry to be obliged to descend. In a balloon I have reached altitudes almost equal to that of Mont Blanc without being inconvenienced; but a mountain ascent, slow and painful, is not at all like the ascent one makes so quickly and easily in the basket of a balloon. The ascent of Mont Blanc, so much feared before the daring attempt of Jacques Balmat, and which the sufferings of De Saussure and then the accident of Dr. Hamel had invested with a terrifying renown, has in our time become frequent, almost common. In 1873, sixty travellers ascended to the summit of the giant of the Alps, among them seven women and a lad of fourteen, the youngest who has ever made the ascent, named Horace de Saussure. Since the time of the illustrious ancestor of this brave lad, I have counted on the list still incomplete given by M. Besangon,1"'2 which goes to the end of 1873, 828 ascents, 27 of which were made by women. The last, made by an Englishwoman, Mrs. Straton, shows remarkable courage; it took place January 31, 1876; on the summit the lady found a temperature of —24 degrees. But the large majority of these expeditions offer no scientific interest; they are mere tourist excursions, often managed very imprudently. Mont Blanc, of which the professional "mountaineers" speak with a certain disdain, seems to avenge itself; there have been more serious acci- dents upon it than in all the rest of the Alps. One of these disasters, the most terrible of all, perhaps has some relation to our subject. September 6, 1870, nine guides and three travellers reached the summit of Mont Blanc; they could not get down, and died the next day in the snow. In the pocket of one of them, M. Beau,1"3 was found a paper giving an account of their sufferings: We passed the night in a cavern dug in the snow, a very uncom- fortable shelter; I was sick all night. 116 Historical Most of those who have made recent ascents of Mont Blanc, the accounts of which have been preserved for us by the Alpine clubs, say nothing of mountain sickness. They go on at length about the preparations for the departure, the petty incidents of the journey, the joys of the return, but maintain complete silence about the physiological phenomena. And what I say of Mont Blanc is true of all the other ascents, even of mountains rivaling it in height. I have gone over, page by page, the journals of the English, Swiss, Italian, Austrian, and French Alpine clubs; I have patiently read hundreds of monotonous accounts, and have found very few data relating to our study; I shall mention them chronologically. August 13, 1857, M. Hardy ir'4 made the ascent of the Finster- aarhorn (4275 meters) : Wellig (inn-keeper of Eggischhorn), considering himself insulted by our jokes, went on ahead to reach the summit first. But hardly had he taken a hundred steps, when he fell as if some one had shot him. Ellis, who was walking behind him, thought that he was resting, and walked quietly up to him; but when I came, I perceived that it was more serious. His eyes were turned up, his mouth open, and he looked strangely like a fish. I did not know what to do; but Cruz adopted a queer mode of treatment .... He raised him to a seated posture and shook him so vigorously backward and forward, that after a few vibrations he revived from his faint, got up, and went to join Fortunatus. (P. 299.) Perhaps we may hesitate to attribute this sudden syncope to mountain sickness; but in the narrative of Tuckett,15"' the doubt is not possible. The matter in question is an ascent on Grivola (3960 meters), made in June 1859; an avalanche threatened to carry away the travellers: Chabot, one of the guides, complained of painful sensations in the chest and stomach, loss of appetite, vertigo, nausea, headache, resulting partly from fear and fatigue, and partly also, perhaps, due to the rarity of the air, for we had reached the height of 12,028 feet (3665 meters). (P. 297.) In my opinion, in spite of the complication of a somewhat exaggerated consumption of alcoholic beverages, the influence of rarified air is incontestable again in the following observation158: A young Englishman about twenty-four years old, a regular picture of health and strength, passed the Weissthor by Macugnagna. He was not much accustomed to difficult ascents .... and to give himself strength drank brandy and water frequently. The result was soon seen. The guides had to pull him along with ropes, in a state of Mountain Journeys 117 complete exhaustion .... In fact, as he told me, he has no notion of the way in which he overcame the difficulties and reached the summit; he was in an inert stupor the whole time. (P. 349.) M. Kennedy,157 one of the most daring and one of the first men to make ascents in the Alps, was himself attacked in one of his expeditions, not the first, far from it, nor the most difficult, nor the highest; he was climbing the Dent-Blanche (4365 meters) and was still far. from the summit: An extraordinary weight seemed to be loaded on me, hampering my movements. My legs, although I did not feel fatigued, refused to act with their usual vigor, and I was left far behind; but the pure and rarified air which blew over us and the sight of the peak of the Dent- Blanche began to revive me. (P. 36.) In certain accounts, it is only incidentally, as if buried in a sentence, that we see the symptoms of mountain sickness appearing: Guides and travellers were exhausted, stopping often for breath 15S .... (P. 107.) In other cases they are more clearly indicated, even described. The snow was hard, it was necessary to cut steps, and more159 than once the travellers had to stop to get their breath. (P. 166.) In 1864, Craufurd Grove160 ascended to Studer-joch (3260 meters) ; too great speed in walking made travellers and guides ill: Perru, who was afraid of avalanches, made us walk at a pace unusual in the Alps, which quickly produced signs of distress in the whole group; .... but the robust son of Zermatt gave no heed, and slackened his pace only when the outraged laws of respiration claimed their rights and compelled him to stop completely to get his breath . . . We reached the summit; but our joy was greatly lessened by the fact that we were almost all ill. Some of us who had relaxed beside Italian lakes from the hard work of the mountaineer had eaten figs and grapes in excess. The result of this diet, while we were walking on the ice, was too painful to be described. The guides were in a hardly less pitiful condition; they had drunk Grimsel brandy the night before. (P. 368.) The account of the ascent of Monte Rosa by Visconti,"'1 in August, 1864, is still clearer and more interesting: The rarefaction of the air inconvenienced us greatly, either because of the difficulty in breathing or because of the decrease of atmosphere pressure on the blood-vessels. For these reasons and because of the steepness of the grades, our legs and lungs tired quickly; but a few moments of rest restored their strength rapidly . . . 118 Historical Just before we reached the summit (4640 meters), we met the English travellers coming down. One of them was pale and disturbed; he • told me that the rarefaction of the air had caused frequent vomiting which had weakened him; in addition, he was dizzy. I merely felt a weakness of the stomach with frequent nausea. (P. 160.) Last I shall report an observation made by M. Gamard,1"-' dur- ing his ascent of the Jungfrau (4170 meters), August 24, 1874, which we shall discuss later: We were buried in the very side of the mountain; air failed us, and as we noticed on Monte Rosa and Mont Blanc, it is not at the summit that we suffer from this rarefaction, but in spots which the wind does not reach. At half past nine, we rested again; we were at an altitude of about 3750 meters. (P. 216.) But, I repeat, observations of this sort are extremely rare. Ball does not say a word about mountain sickness in his useful work entitled Suggestions for Alpine Travellers,1™ in which he enu- merates the dangers of ascents and the principal observations of physics and natural history which can be made there. Does this mean that everything has changed since the time of De Saussure, and that today one can safely make ascents which then were painful and difficult? In this hypothesis, however strange it may appear at first thought, there is a portion of truth, the amount of which we shall discuss later. But to make sure that the immunity is anything but general and complete, we need only question carefully those who make ascents, even those who in their accounts do not mention physiological disturbances, even those who deny the existence of such disturbances. Moreover, M. Joanne, who has read and seen and heard so much, summarizes perfectly in his excellent guidebook to Switzerland 104 all common knowledge on this point: The lightness and the great rarity of the air in the Alps, and the energy with which it speeds up evaporation cause at certain altitudes very noticeable physiological phenomena, such as considerable decrease or loss of appetite, distaste for food, nausea, drowsiness, panting, headache, fainting, etc.; some of these symptoms even compel certain individuals to turn back at once, as soon as they have reached an altitude of 3000 meters; at about 3400 meters, mules are so out of breath that they utter a sort of plaintive cry. However strength returns, in such a case, as quickly and apparently as completely as it was exhausted. Mere cessation of movement seems, in the short space of three or four minutes, to restore it so perfectly that when one starts walking again, one no longer feels any fatigue. (P. 93.) Mountain Journeys 119 But if these symptoms are so frequent, why not speak of them, or at least why not mention them in accounts which are often so prolix and loaded with uninteresting details? In the first place, we must confess, their importance and sever- ity have been so exaggerated that travellers affected only by panting and palpitations are willing to deny even the reality of an illness which they dreaded so much in advance. In this connection, I found an interesting indication in the account of ascents made in August, 1859, of Grivola (3960 meters) by M. Ormsby.165 He was climbing the "chimney" in a very dangerous position when he had a very strange dizzy feeling, and he adds: I had read so many terrible stories of the strange effects of the rarified air on man at great altitudes that I began to be very nervous .... It was the moment to be attacked by apoplexy, catalepsy, bleeding from the eyes or some other of the terrible symptoms. (P. 333.) In the second place, most of the tourists whose narrations fill the Alpine journals have hardly any scientific interests in their ascents; they climb for the sake of climbing, or seeing, or often of telling that they have climbed and seen. It is generally this last feeling which dictates their accounts, and that is why one sees them every year seeking some horn, spitze, or joch, hitherto inac- cessible or merely forgotten: a virginity often hard to conquer, the sterile conquest of which they will dispute. Finally, a point of honor has intervened; they are almost as afraid of being ridiculed for mountain sickness as they are for seasick- ness. Formerly, they sought its symptoms in themselves, they liked to boast of having experienced them, as they would have boasted of a mysterious danger they had risked; today they refuse to observe them, especially to admit them; sometimes they deny them. One of the travellers of our period who are most experienced in mountain climbing, Count Henry Russell,1'0 expresses himself on this point with the greatest clearness and authority: I regret to state that some of the most important authorities of the Alpine Club have gone so far as to deny completely a thing like the painful phenomenon known in all countries by the name of "mountain sickness", or they declare it an exception, an effect of fatigue, of exhaustion. It is true that very favored lungs can go to very high altitudes and continue to breathe comfortably. Likewise, there are travellers who are immune to seasickness, and we can therefore deny this sickness as well as the other. Mountain sickness is an ailment which has been felt all over the earth (even in the tropics), in the 120 Historical Andes, on the Altai, on the Himalayas .... everywhere. No animal is immune to it, at a certain height; and as for me, I confess humbly that I can hardly breathe on the summit of Mont Blanc; in fact, we were all sick, more or less, including the guides. On the Calotte, where the slope is very gentle, not one of us could take more than thirty-four steps without pausing a long time. And that was not fatigue, because in two hours we were descending to the Grands- Mulets, in very good health and full of vigor. (P. 243.) How few "mountaineers" and "Alpinists" will have courage to make a similar confession! 6. The Pyrenees. Since the highest mountains of the Pyrenees do not attain 3500 meters, the symptoms due to decreased pressure can be felt there only under exceptional conditions. So travellers generally do not mention this subject, and when they speak of it, it is usually to declare that they have had no such experiences. The first author to mention physiological phenomena observed in the Pyrenees is Robert Boyle,107 but he gives only second-hand information: A gentleman of learning had made the ascent of the peak of Midi in the month of September. I asked him whether he had found the air on the summit as plentiful for breathing as that belew. He said no, that he was forced to breathe more frequently and less deeply than usual. And as I thought that perhaps that came from the move- ment, I asked him whether this difficulty had ceased after his arrival at the summit; he answered: "Yes, evidently, for we could not have remained several hours on this summit with such difficulty in breath- ing." (P. 2039). During the eighteenth century, a fairly large number of ascents were made, for scientific reasons, on different mountains of the Pyrenees, and those not the least lofty. The book of Dralet 1<1S gives an interesting summary of the data formerly observed: The artists who were employed in 1700 in constructing on Canigou a pyramid for determining the meridian felt no symptom. MM. Vidal and Reboul passed three days and three nights on the summit of the peak of Midi of Bigorre without any inconvenience; I have always been immune, and so have my travelling companions, not only on this same peak, but also on the loftiest ridges which separate France from Spain .... However some travellers have been affected in the Pyrenees, even at moderate heights. In 1741, M. Plantade, celebrated astronomer of Languedoc, died at the age of 70 beside his quadrant, on the Hourquette des Cinq-Ours (1244) fathoms. Count Dolomieu, in August, 1782, almost met the same fate; he was attacked by a violent fever which kept him from reaching the summit of the peak10'; Mountain Journeys 121 M. de Puymaurin and M. Lapeyrouse, his travelling companions, were for an instant almost without pulse. M. Dusaulx, before reaching the plateau of the peak of Midi, felt dizziness and a sort of weakness, without his companions experiencing any such symptoms. These facts seem to prove, according to the opinion of M. de Saussure, that nature has fixed for the constitution of each person the altitude to which he can ascend without discomfort and without danger. But it should be noted that certain travellers have been affected at a moderate height, although accustomed to climbing very high mountains without any trouble. (Vol. I, p. 38.) After that time, the traveller and naturalist Ramond made the first ascent of Mont Perdu (3350 meters). His very interesting account 17° gives proof of very uncommon sagacity; at least he does not deny what he was fortunate enough not to feel: We were breathing without difficulty this light air which was no longer sufficient for the respiration of many others. I have seen vigorous men forced to stop at much lower elevations . . . Here we felt nothing of the sort; only the condition of the pulse indicated a change independent of the excitement of the trip: rest did not quiet it. As long as we remained on the summit, it was small, dry, difficult, and quickened in the ratio of 5 to 4; this fever, which is nervous, announced plainly the illness which we should have felt at a greater elevation; but at the point where we were affected by it, it produced an effect just the opposite of that which a degree more would have produced. Far from causing exhaustion, it seemed as if it aided my physical powers and raised my spirits. I am convinced that we often owe to it this nimbleness of limb, this acuteness of the senses, this activity of thought which suddenly dispel the prostration of fatigue and the apprehension of danger; perhaps we need not seek elsewhere the secret of the enthusiasm which permeates the accounts of all who have mounted above ordinary heights. (P. 84.) Likewise Arbanere 1T1 declares that on the summit of Mont Perdu in 1821 he: Experienced no effect of the rarefaction of the air, that distress, that anxiety, that nausea which often cause prostration at such a height. (Vol. II, p. 85.) On Vendemiaire 11, in the year XI, Cordier and Neergaard made the ascent of the Maladetta. One of them was seriously affected; here is the account the celebrated geologist gives of this complication:172 Shortly afterwards, the ridge became wholly impassable and we had to go out upon the glacier. We were then at a height of about 3000 meters. M. Neergaard was so distressed by nausea and dizziness, caused by the rarity of the air, that it was absolutely impossible for him to go any further. I will note, by the way, that mountain sickness 122 Historical almost always attacks the small number of persons whom a natural or accidental tendency makes subject to it, at the height of 2600 to 3000 meters, immediately above the timber line. (P. 266.) Cordier and his guide continued on the way and reached the summit without seeming to have experienced any unpleasant symptoms; at least the account gives no signs of any. A traveller of whom we have already spoken, who made numerous ascents, particularly in the Pyrenees, Parrot,173 gave special attention to the variations in his pulse at different heights. I reproduce his important observations: My pulse rate on the summit of Mont Perdu was 110, and a few days before, in my first attempt to climb this mountain, it was 100. Upon the Maladetta, it was 103, and some days before, at Bagneres de Luchon (628 meters), it was only 70. These variations are in a regular ratio with those of the height; they agree with the observations which I have already made on my pulse on different mountains. So my pulse rate, which is 70 at sea level, rises to 75 at a height of 1000 meters, 82 at 1500 meters, 90 at 2000 meters, 95 at 2500 meters, 100 at 3000 meters, 105 at 3500 meters, 110 at 4000 meters. (P. 216.) After him, I have hardly anything else to quote but the account of M. de Franqueville,174 who was the first to ascend the highest peak of the Pyrenees, the peak of Nethou (3400 meters) . The ascent took place July 18 and 19, 1842. The travellers reached the glacier of Nethou, very near the goal of their ascent: We were all expecting to feel some of the symptoms due to the rarefaction of the air, which generally add still more to the difficulties of great ascents. However this did not occur. But after making a few steps on the glacier, M. de Tchihatcheff was attacked by nausea so violent that he was forced to stop from time to time and lie down on the snow. A few moments of rest revived him completely, and per- mitted him to go on. As for the rest of us, neither the guides nor I felt anything special. We did not even have to struggle against this lassitude, this distress which are so painful and which so often accompany, they say, the presence of man in these lofty regions which were not made for him. Here ends all related to our subject that we have been able to find in the narratives of mountaineers in the Pyrenees. A strange document shows us that nothing important ever attracted their attention. Count Russell-Killough, who knows the Pyrenees so marvellously, has published a collection of ascents of the peak of Nethou, from the one which we have just mentioned up to 1868. In this interval, there were about two hundred, including nearly a thousand persons, twenty-two of whom were ladies. Mountain Journeys 123 The book, which contains the personal notes of each tourist, shows absolutely nothing, except the general vanity of motives which impelled so many persons to this painful ascent. Physio- logical symptoms are not even mentioned. Count Russell alone (August 24, 1863) says: "no spitting of blood". (P. 50.) Finally, I will quote in this section a few observations 17,! made in an ascent of Mulahacen, the highest peak of the Sierra Nevada of Spain; they contain the outline of a strange theory: The effects produced by the rarity of the air upon the lungs and the body were not felt as long as we remained on the mules. But now that we had to make muscular efforts, a greater shift of energy is necessary than in a dense atmosphere. The equilibrium of the air, which supports the bones as the water does for fishes, fails, and the muscles are forced to lift a greater weight; hence exhaustion. (P. 157). 7. The Caucasus, Armenia, Persia. Caucasus. The ascents of the lofty summits of the Caucasus are quite recent. Klaproth,177 in the account of his journey to Mount Caucasus and Georgia, made in 1807-1808, said: No one has ascended Elbrouz; and the Caucasians think that no one can reach its summit without special permission from God. (Vol. I, p. 131). A very serious attempt to ascend to the summit of Kasbek or Mquinvari (5030 meters) was made September 17, 1812, by Engelhard and Parrot.178 The two travellers camped at the line of perpetual snow; Parrot alone undertook the ascent to the summit. He had to surmount the usual mountain difficulties; but, he adds: The most annoying thing to me was a strange lassitude which forced me to rest every fifty steps; it arose less from oppression of the chest than from a complete weakness of the muscles which seized me suddenly, and which soon passed when I stopped for only a half-minute. It was generally followed by a strange and agreeable sensation, as if I were in a new element, to which my body, made for the stronger pressure of the lower regions, was superior in strength. An inevitable consequence of the extremely rarified air which sur- rounded us was the acceleration of the pulse and the respiration; but distress and vertigo troubled neither me nor my companions. In return, I observed in them and myself a weakening of several sense organs; we were obliged to talk very loud to make each other hear; we had difficulty in talking, not because respiration failed us, but because our tongues had lost their flexibility; even the eye seemed less active, and one would have said that an inner cause prevented it from seeing distinctly and at a great distance. (P. 302.) 124 Historical Parrot was forced to stop at an elevation of 2168 fathoms; he passed the night with his companions, but had to descend the next day without having reached the summit, which he estimates has a height of 2400 fathoms. In 1829, a military and scientific expedition approached Mount Elbrouz (5620 meters) ; Kupffer 17;' and the other scientists who were in the party resolved to attempt the ascent of the giant of the Caucasus. July 22, 1829, they reached the line of perpetual snow upon its sides: We were forced to stop at nearly every step. The air is so rarified that respiration is no longer able to restore the strength that one has lost; the blood is in violent movement and causes inflammation in the weakest parts .... All my senses were blunted, my head whirled, I felt from time to time an indefinable dejection which I could not control .... We were then at a height of 14,000 feet above sea level. (P. 33.) However they had not reached the altitude of Monte Rosa; they could go no higher, but one of their guides ascended to the summit. Sjogrun,180 who, May 26, 1836, made the ascent of "the highest mountain of the Caucasus" (his account is not clear, but I think he means Kasbek) , says absolutely nothing of physiological disturb- ances. But Radde,181 although his ascent of Elbrouz August 10, 1865, was not completed because of bad weather, shows clearly in his account the effect of rarefied air: Before us rose, all white, the summit of the mountain. A strong west wind had risen. We stopped a certain time; weariness and dizziness painfully affected my two companions and myself; we like- wise experienced a strange weakness of the knees, which soon checked all our movements .... We stopped more and more often; dizziness and weakness of the knees increased; horrible fatigue (entsetzlich) weighed me down. We had reached a height of 14,925 feet (4557 meters). (P. 102.) In their journey, in 1868, Douglas W. Freshfield, Moore and Tucker,182 accompanied by a guide from Chamounix, Fr. Devouas- soud, with whom they had made ascents in the Alps, made the two difficult ascents of Kasbek and Elbrouz. July 1, ascent of Kasbek; night passed at a height of 3300 meters; except for the excessive fatigue which forced one of them to lie down and nearly prevented another from reaching the summit, our travellers notice nothing to interest us. Mountain Journeys 125 July 31, ascent of Elbrouz; they complain only of the cold. Gardiner, Grove, Walker and Knubel 183 ascended to the summit of Elbrouz July 28, 1874. July 27, they camped at a height of 11,300 feet, and the next day reached the summit: Everyone suffered from the rarity of the air. In 1868, not one felt its effects; the peak ascended then was probably that of the east; but the difference in height, if there is any, is too slight to explain the immunity of the former expedition. It is probably the journey of Douglas Freshfield and others that is referred to here. In the same publication is a second account, by Gardiner,184 of the same ascent: After we left the col, no serious difficulty appeared. However Grove, Knubel and I suffered more or less in breathing, which forced us to stop often; we also had what I have heard a Swiss guide call "a blow in the knees". Walker had the nosebleed, but no other symptom. (P. 119.) Armenia. The plateau of Armenia, which over a vast expanse has an average altitude of over 3000 meters, is dominated by the double summit of Ararat, which was well known by the ancients and of which the books of the Bible speak, as everyone knows. But if Noah, according to the legend, could easily descend from the summit to which' the waters had carried him— which, if they had covered the lofty Ararat, would have left above them only its neighbors Elbrouz and Demavend with the highest peaks of the Andes and the Himalayas,— the ascent of the holy mountain offers quite serious difficulties. However, Pierre Bergeron, a Parisian, in his treatise on the Tartars,185 gives us the following curious infor- mation: Elmacin, an Arabian historian, relates that when the emperor Heraclius was making war in Persia, and passed by the city of Themanin, built, they say, by Noah on leaving the Ark, curiosity urged him to ascend this mountain (Ararat, which is the Taur, as the Scriptures call it, and the Greeks call it Periarde; today, it is Chielder), to see whether he could find any remains of this vessel. Haiton says also that in his time there were a few pieces left. (P. 66.) It is also to Robert Boyle186 that we owe the first account of an ascent of Ararat, with mention of the discomforts produced by a stay in so lofty a place: Having met an ecclesiastic who had ascended the lofty mountains of Armenia (on one of which, because of its great height, the people of the country say that the Ark came to rest), I asked him whether 126 Historical he had had any difficulty in breathing on the summits .... He ans- wered that he had not been able to reach the tops of these mountains because of the snow; that, however, he had noticed that he was obliged to breathe more frequently. I asked him whether this difficulty seemed to him accidental or peculiar to him; but he assured me that it was general on lofty places and was commonly observed. This same ecclesiastic felt similar respiratory symptoms when he made the ascent of a mountain in the Cevennes. (P. 2038.) The celebrated botanist Tournefort, who attempted the ascent on August 11, 1701, could not go even to the snow line: One (he says) complained that he could not breathe; as for me, I had never been so afraid that some lymph vessel would burst in my body. (Vol. II, P. 316.) The first complete ascent of which we have a record is the one made in 1829 by Parrot, the learned traveller whom we have quoted so often already; he had to make three attempts. September 12,1SS he ascended only to 3850 meters (p. 130) ; September 18, he reached 5000 meters (p. 146) . Finally, September 26, he passed the night at 4300 meters; he complains only of a feeling of fatigue and a tendency to sleep (P. 156.) The next day, departure for the summit: We had to leave one of our peasants sick at camp. Two others, over-tired by the ascent of the glaciers, lay down on the ground, then went back down. Without letting ourselves be discouraged, we continued on our way. (P. 157). The rest of their account shows that their fatigue was extreme; but no other symptom is noted. At a quarter past three, they reached the summit: "My first desire and my first pleasure was rest", says Parrot. (P. 159.) The difficulties with which popular opinion surrounded an ascent which seemed a trifle sacrilegious caused this circumstan- tial and credible account of Parrot to be called in question. But a few years later other explorers, Avtonomoff,189 August 5, 1834, Behrens,190 July 20 and August 9, 1835, Abich,1"1 July 29, 1845, proved its exactness. I could not get the complete account of these ascents, and the reports of them given by the journals of geo- graphy do not mention any physiological disturbance. But that proves nothing, for they are equally silent when they discuss19-' the celebrated ascent of the Russian Colonel Chodzko, and yet it appears from a communication the learned geodesist sent me that these disturbances were anything but negligible. Mountain. Journeys 127 Here is the account as it was given me in a letter written in French by General Chodzko: I quote it in full, thanking my emi- nent correspondent sincerely for his kindness. The expedition included five officers and sixty soldiers: The ascent began July 31 (August 11), 1850. From August 4 (16) to August 6 (18), we remained in our tents at the foot of the summit of Mount Ararat. August 5 (17), during the night, sheltered under perpendicular cliffs, we remained from eight to eleven o'clock in the evening in the midst of electrically charged clouds. The lightning flashes which one sees from below crossing the clouds like mere thin ribbons had enormous dimensions; the thunder roared at the very instant when the flash appeared; it was like the fire of a volley of cannons. After a storm of three hours, a very loud clap of thunder detached a part of the cliff, which fell with a crash. After the thunder storm was over, hurricanes of snow came on. It was a very difficult task for us to unroll and stretch a little higher two little canvas tents, under which we remained from the 16th to the 19th of August. August 18, after reaching the summit, we set up there a cross painted black. Two tents were pitched in holes dug in the snow. August 19, the observations of the zenithal distances were begun (Ararat was observed from 122 trigonometric points); they were finished after a fashion on the morning of August 24. We set out at noon, and descended rapidly. As for physiological symptoms, my head was very heavy; it seemed to me as if an iron ring pressed my skull above the ears. We had to walk very slowly in order to breathe easily. At night, when we were sleeping wrapped up in pelisses, if the cold penetrating through them awakened us, the movements we made to pull them around us cut off our breathing. The third day my head became lighter; but it was still impossible to walk quickly. In their journey to Armenia, Radde and Sievers made some fairly lofty ascents, among them one of a mountain near the lake of Chara-Gol, July 28, 1871: At an altitude of about 12,300 feet (says Radde) 1Da I had to stop. My respiration was difficult, my knees were absolutely broken. I began to be feverish .... Sievers climbed bravely on. I remained lying down completely apathetic, for two hours, awaiting his return. At the end of about two hours, he returned, as sick as I, completely exhausted and broken. (P. 177.) Among the numerous travellers who have traversed Asia Minor in all directions, I find only one, Hamilton,194 who made the ascent of Argaeus (3840 meters), July 30, 1837. He says absolutely nothing of physiological disturbances. Persia. But I have found two accounts of ascents of the extinct volcano of Demavend (5620 meters), near Teheran. 128 Historical September 8, 1837, Taylor Thomson 195 camped on the mountain side at an elevation of 2000 meters. The next morning, he set out: I had not been climbing more than an hour, when two of my men refused to go any further .... I kept on with the other two, but one of them complained so bitterly of headache and palpitations that I had to let him go back. By entreaties and threats I kept the other as far as the crater: the cold was extreme .... The temperature was 56 °F., the barometer stood at 15.05 inches .... which corresponds to 14,700 feet (4480 meters). The other ascent was made July 24 and 25, 1858, by members of the different European missions to Teheran. The English attache, R. F. Thomson, has given a detailed account of it.196 On July 24, camp was made for the night at the village of Rina (3920 meters); the thermometer registered 0° centigrade. On the morning of July 25, they set out early: The ascent of this part of the mountain brought on great fatigue especially on account of the rarefaction of the air which began to affect our lungs .... The last part of the ascent of Bamshi Bend was extremely painful because of the rarefaction of the air. We felt nausea and violent headache and a great difficulty in breathing, even while resting. M. de Saint-Questin, of the French mission, and M. Castelli, a Sardinian, who accompanied us, were affected like us. When we had rested a little and were less tired, we began our observations. They indicated the enormous height of 21,520 feet (6560 meters).587 We remained at the summit about an hour and a half. (P. 15.) 8. Central Asia. In the last half of the thirteenth century, a famous traveller, Marco Polo,198 was the first European to penetrate into the lofty regions of the plateaux of Central Asia. The celebrated Venetian, no doubt, as has been proved by the testimony of those who fol- lowed his steps five hundred and fifty years afterwards, must have felt the phenomena of which we shall soon give many descriptions, and must have observed their effects upon his com- panions and his beasts of burden; but his account gives no suggestion of it: Always one rides through mountains, and mounts so high that it is said that this is the highest spot in all the world. (P. 130.) . . . . No flying fowl is there, because of height and cold. And I tell you that fire, through this great cold, is not so bright nor so warm as in other places, nor can it cook viands so well. (P. 133.) This place, the highest in the world, is, as the English traveller Mountain Journeys 129 Wood showed later, the plateau of Pamir, at an altitude of 4700 meters. Chinese travellers, still earlier, had visited these lofty places. For instance, the pilgrim Fa-Hian189 in the year 399 crossed the pass of Karakorum (5690 meters). Also the celebrated Hiouen- Thsang200 coming from China found "a series of mountains and valleys and peaks of prodigious height. He crossed black moun- tains." (P. 55.) M. Stanislas Julien declares that this means the passes of Hindou-Kouch and the plateau of Pamir. But in the very brief reports left us there is no mention of physiological obser- vations. The description "of the provinces Wei and Zzang" of Western China, which, published in Chinese in the year 1792, has been translated into French by Klaproth -01, contains some indications which, as we shall see later, evidently refer to the symptoms of decompression. In mentioning disturbances which affect travellers in these lands of lofty mountains, the Chinese author speaks of: Heat of the body, headaches, and other diseases peculiar to the climate. (P. 23.) Later, in an itinerary remarkable for the accuracy in distances and the abundance of details, he mentions the influence of poison- ous plants, which we shall soon see playing a great part in the narratives of travellers; here, it is rhubarb which is blamed: Leaving Djedo, one travels from mountains to mountains; they extend a long way, but they are not very high. Rhubarb is abundant there; it exhales a very strong odor which annoys the traveller very much. (P. 188.) Finally, after plants, come exhalations from the ground: Further to the west of Djaya, one crosses a great snowy mountain; the road is very steep. The accumulated snow looks like silvery vapor. The mist which the mountain exhales penetrates the body and makes the Chinese sick. (P. 210.) .... From Lang Thang Keou, one follows the valley, ascending . . . The frozen snow makes the road slippery and very dangerous. There are also pestilential exhalations there. (P. 217.) During the seventeenth and eighteenth centuries, some Euro- pean travellers, missionaries, merchants, soldiers, or adventurers, visited the lofty regions of Central Asia, either in the Chinese Empire, or in that of the Grand Mogul. Only in one account, that of the Portuguese Jesuit Antonio 130 Historical d'Andrada,202 have I found clear indication of symptoms which one can attribute to the effect of the air of lofty places. This mis- sionary had the courage to cross the Himalayas almost alone on his way from Cashmere to Tibet: There begins a region of lofty mountains which one cannot cross in less than 20 days. There is nothing there but rocks almost always covered with snow .... Partly from disease and partly from a certain pestilential exhalation from the ground, suddenly one feels a violent inward revulsion which kills in a quarter of an hour. I attribute these sudden deaths to the cessation of natural warmth which is checked by the great cold, and especially to poor food. (P. 13.) But as for him and his two companions, he complains only of the extreme cold, partial freezing, numbness of hands and feet, and "loss of appetite" (P. 16), the only symptom which one can attribute to decreased pressure. However they had passed through very lofty regions, since they "reached the summits of all those mountains where lies the lake whence issue the river Ganges and another which waters the lands of Tibet" (P. 16). It is evidently Lake Manasarowar that d'Andrada means. Dr. Bernier,2"3 who in March, 1663, followed the Grand Mogul Aureng-Zeb from Lahore to Cashmere, had to cross a lofty moun- tain, still covered with snow; but he speaks only of the cold, and alludes only to the difficulties of the trip in speaking of the journeys of the merchants who go to Kashgar and Tibet across the lofty ranges. The accounts of Father Verbiest,204 who in 1683 accompanied the Emperor of China into Eastern Tartary, and those of Father Gerbillon,205 from 1688 to 1698, mention no sufferings. In October, 1714, Father H. Desideri left Lahore for Cashmere, "across the Caucasus", as the Himalayas were called for a long time. May 17, 1715, he undertook the terrible journey through Tibet, and reached Ladak June 25. Among his discomforts he mentions only fatigue, cold, wild winds, and the reflection of the sun upon the snow.200 In the second half of the eighteenth century the political rela- tions of the English with Boutan and Tibet begin. In 1774, Bogle was sent to the Grand Lama by the governor of India; J. Stewart,207 who has narrated his journey, makes no allusion to the effect of the mountains. In 1783, Samuel Turner 20S was entrusted with the same mission. He crossed the high passes of Boutan, and stayed several months Mountain Journeys 131 in Tibet. He frequently lays stress upon the extraordinary height of these regions and upon the cold and parching winds prevalent there. The only observation that can be referred to the harmful effect of altitude is the following; Turner was then at the foot of Chumalari: When we had dismounted at Terma, I felt a violent headache, which urged me to throw myself upon a rug; .... I was in pain and did not wish to talk. (Vol. I, p. 312.) .... I attributed this headache, which gave me great pain, to the change of climate. (P. 314.) Captain Thomas Hardwicke -«"' in 1796 made a journey to Srinagar in Little Tibet, during which he seems to have mounted to fairly great heights; but he mentions no symptoms that one can attribute to mountain sickness. But with the celebrated journey of Moorcroft -1" who in 1312 crossed the Himalayas to reach Lake Manasarowar, begins a new era, so to speak. After that, all the narratives of travellers will contain clearly and often with details evidence of the sufferings which altitude added to fatigue and cold. He left May 26, but it was not until June 4 that one finds in his journal the indication of a special distress: Toward the end of this day (he says) I found that my respiration quickened proportionately to the difficulties of the ascent, and I was often compelled to stop and wait until the beating of my heart grew calm. My companion had been suffering from this oppression for three days, but I had not felt it at all until then. (P. 397.) Moorcroft does not specify the height which he had then reached; he only speaks of a village named Niti where he made his camp then. After a few days, he wished from there to make the ascent of the neighboring mountains: On the morning of June 26, I set out. The ascent was very painful because of the great difficulty in breathing; of five persons, only one was capable of accompanying me .... I could not take more than five or six steps without stopping to breathe .... Having suddenly turned my back to the wind, I felt a sensation of fullness in my head, with vertigo and threats of apoplexy; and so I quickly lay down on the ground. Shortly afterwards, my panting slackened, the beating of my heart became less violent, and I could rise. But in spite of pre- cautions in walking, I was twice attacked by the same symptoms, so that it seemed wise to me to give up ascending higher. The imperious necessity of stopping to breathe every four or five steps was felt only while I was climbing. When the violent action of the heart was lessened by rest, the difficulty in breathing disappeared. It did not appear during the descent, even when I ran; but several 132 Historical times at our camp, just as I was going to sleep, I was aroused by this sensation .... Although I experienced neither excessive cold nor heat, my hands, my neck, and my face were red, the skin was sensi- tive, and blood oozed from my lips, which had never before happened to me. (P. 408.) He refers repeatedly to the oppression which precedes sleep: June 30, at sun-rise, the thermometer registered 46 °F I awoke very early, and at once was seized with difficulty in breathing and great oppression in the heart, symptoms which disappeared after a few deep inspirations. As I was going to sleep again, the smothering reappeared, and respiration became very uneasy; however, as soon as the air had grown warm, this distress lessened. (P. 412.) .... In the evening, although overcome by need of sleep, it was impos- sible for me to fall asleep because of the smothering which came on immediately, and which nothing but a few deep breaths could quiet. (P. 415.) July 3, Moorcroft reached Daba. The rest of his journey did not expose him to mountain sickness, on the cause and nature of which he did not venture any hypothesis. In 1819, Moorcroft, in the company of Trebeck, began a long expedition which was to end in 1825 with the death of the two travellers. In the publication by Wilson -11 of the results of this journey, I have found nothing relating to mountain sickness. In telling of his crossing of the pass of Chang-La, the highest he had yet crossed, Moorcroft complained only of terrible cold (Vol. I, P. 428). At the pass of Parang-La, the altitude of which he estimates as about 19,000 feet, he says only: My horse was so unable to walk, before reaching the summit, that I had to dismount and leave him to his fate. (Vol. II, p. 54.) Three years after the first journey of Moorcroft, Fraser,'-'- who accompanied the political agent sent to the army of General Martindale, went up the banks of the Jumna in 1815. He crossed the mountains from Jumnotree to Gangotree by very lofty passes, the height of which he does not give. On July 16 for the first time there appear in his narrative symptoms which one may attribute to mountain sickness: We were much annoyed by the coolies (he says) .... It was very difficult to start them moving, and they sat down after a few steps, although their burdens had been greatly lightened in prepara- tion for the difficulties of the march. They told us that they were attacked by the Seran, or poisonous air coming from the flowers which covered the ground (primroses, polyanthus, heather) ; and although their condition was perhaps partly due to drink and excesses, Mountain Journeys 133 and although something must also be attributed to laziness, their general appearance indicated something more. When they stopped, they threw their burdens on the ground, and lay down sick; generally they went to sleep immediately, and very few thought of eating first; they told us that the next day's stage would be still harder. (P. 440.) In fact, the next day, the sufferings increased: It was exceedingly cold .... Many of the Mewatees and Goorkhas were almost unable to go on, each one complaining of the bis, or poisoned wind. I thought then that this supposed poison was nothing but the effect of the rarefaction of the air due to our great altitude, which makes it insufficient for our breathing; it cannot distend our lungs; I have been brought to this belief by my own sensations. I was obliged to make tremendous efforts to continue, and could hardly find strength enough to walk. I experienced great respiratory oppres- sion, as if I lacked air. We certainly could not have endured that very long .... At last we reached the summit of Bumsooroo-ke-Ghat, where there was nothing but moss and lichens .... As soon as one of those who complained of oppression lay down, he went to sleep, but it did not seem wise to let him do so. Eating a few mouthfuls helped a little, but nothing did much good, and no one was free from this general weakness. This was the highest point of our journey. (P. 442.) From there we had to execute a series of ascents and descents . . . along a path which was very difficult and painful on account of the snow and rolling stones; we were cruelly tormented by difficulty in breathing, until we reached Chaiah-ke-Kanta. (P. 444.) They were not at the end of their sufferings. The next day, they had to make new ascents: We were troubled by the difficulty of the terrain, the poor condition of the road, and above all, by the artificial fatigue due to the oppression which we all felt most severely. (P. 449.) When we reached the high gorge of Bamsooroo, no one escaped the baneful influence. It was strange to see those who had laughed at their companions give themselves up, some to fatigue, others to sickness, in spite of their efforts to hide it from the others. I think that I escaped longer than anyone else; and yet, after passing this gorge, a few steps upward seemed to me an impossible labor, and even while I was passing over level places, my knees trembled under me, and I experienced stomachic nausea. The symptoms produced are quite varied; some persons suffer from violent headaches; others have pain in the chest, with oppression; others have nausea and vomiting; many are overwhelmed with drowsiness and fall asleep even while they are walking. But what proved that all of this was the effect of our great altitude is that when we descended and reached the region of vegetation, all these violent symptoms, all these sufferings diminished and disap- peared. (P. 459.) 134 Historical In 1816, 1817, and 1818, Captain Webb made vain attempts to cross the Himalayas, and see again the sacred lake of Manasarowar; the Tartars stopped him on the way. His observations were pub- lished in an interesting article in the Quarterly Review; 213 some of them interest us particularly: Without raising the least doubt (says the editor who reviews Webb's letters) in regard to the difficulty in breathing experienced by M. Moorcroft in his ascent of Ghaut, we shall call attention to the fact that higher ascents have often been made without any such effect, which seems to indicate that these effects depend greatly upon the state of the health. Captain Webb, however, confirms these claims, not only by the evidence of his own sensations, but by that of the moun- taineers themselves, who experience them as much as strangers do, and he assures us that neither horses nor yaks are immune to them. The natives call this illness Bis-kae-huwa, that is, poisoned air, and attribute it to the emanations from certain flowers; it appears when one is walking or when one is tired. "Everyone", says our traveller, "complained of loss of appetite for several days after our arrival at Nitee. As for me, I felt exactly the sensations which precede an attack of fever, with great oppression and exaggerated action of the heart and viscera. But one of those who accompanied me suffered one of those attacks to which the resi- dents of Boutan are subject, at the beginning of the season, and which they consider as directly produced by the Bis-kee-huwa. He had gone down to the river's edge at the close of day, and when he wished to climb back up, he lost the use of his legs and even lost consciousness; however, he still retained some feeling, but to me he looked like a man struck by apoplexy. His extremities were cold, and after vainly trying to revive him by friction and by the application of warm stones on his hands and on the soles of his feet for several hours, I decided to give him an emetic; a great quantity of foam was thrown up, and in two or three days he recovered completely. I think that this secre- tion of foam is an effect peculiar to the inhalation of toxic vapors. (P. 420.)" At about this same time the brothers Gerard began the cele- brated series of journeys across the Himalayas. In 1817 (August 27 to October 14) first journey of Captain Alexandre Gerard, from Soobathoo to Rarung and return. He was accompanied part of the way by Dr. Govan, of whom we shall speak later. His account was published for the first time from his travelling notes by Lloyd in 1841 214 (P. 191-267) . There is no mention of mountain sickness in it. The next year he set out again, this time accompanied by Dr. J. G. Gerard, his brother. They went from Soobathoo to Shipke, and returned to Soobathoo (September 22-November 22, 1818). Mountain Journeys 135 From the simple notes which they published 2i5 I extract that which concerns our subject: October 2. Our tent is pitched at an altitude of 15,095 feet; on the pass which separates Choara from Koonawur, there is only scanty grass and a little moss .... During the night which we pass there we all feel violent headaches, probably due to the rarefaction of the air, but which the natives attribute to a toxic plant which grows abun- dantly at great heights. (P. 366.) October 7, crossing of the pass of Toongrung (13,729 feet), no effect noted; October 12, the same, at 13,518 feet, at the pass which separates Koonawur from Chinese land. October 16, camp at 14,900 feet, and October 18, ascent of a peak rising to 19,411 feet (5915 meters) : Violent headaches, hardly permitting us to make any efforts .... The natives refused to go on .... To tell the truth, we ourselves could no longer walk, so severe were our headaches, with general weakness, and keen pains in the ears and chest .... The thermometer did not fall below 22°F .... and yet because of the wind, my hands were so numb that I had to rub them for a quarter of an hour before being able to use them .... The travellers who cross the pass of Gangtung consider it extremely difficult: they are covered with garments to defend them against the excessive cold, and they complain of terrible pains in the head and ears; goats, sheep, and men often die there. (P. 377.) October 24, the pass of Hungrung (14,837 feet); October 25, the pass of Rooming (14,508 feet) ; no indication. November 22, return to Soobathoo. Alexandre Gerard soon set out on a new journey. This time, he intended, if possible, to go up to the sources of the Setlej, one of the tributaries of the Indus, which comes from Lake Manasaro- war. The narrative of this journey forms the second volume of a work published in London in 1840.216 It had already been pub- lished in a shorter form in a scientific journal of Edinburgh, in 1826 and 1827.217 Both accounts are extremely chary of descrip- tions and particularly of the physiological type. I quote from the volume published in London. The journey began June 6, 1821; Al. Gerard set out from the land of Rol, at an altitude of 9000 to 10,000 feet. At the summit of the pass of Shatool, at 15,555 feet (4738 meters) , where we shall see that his brother was to suffer so greatly, he merely says: June 9. We slept very little, because of headaches and difficulty in breathing. (P. 15.) 136 Historical At the pass of Boorendo: June 16. As usually happens at these altitudes, we hardly slept at all, worn out by headaches and an extreme difficulty in breathing. (P. 37.) At the pass of Keoobrung, 18,313 feet, he is a little more explicit: June 24. I felt great difficulty in breathing, and great weakness, but no headache, although my followers suffered from the accelera- tion of circulation noted by M. Moorcroft: the temperature was 46°. August 30, he made the ascent of the pass of Manerung at the enormous height of 18,612 feet (5671 meters) . We were ascending the mountain very slowly; respiration was difficult and we were almost exhausted at every step. The crest of the pass was not visible, and we did not know when our troubles would end: the road ascended at an angle of 30° Our situation was different from anything we had experienced before; it cannot be described. Long before we reached the summit, our respiration became panting and oppressed, and we were forced to sit down after a few steps; even then we could hardly inhale a sufficient quantity of air. The slightest movement was accompanied by weakness and mental prostration. We suffered thus for two miles; the last half-mile was in perpetual snow. At the summit, the barom- eter registered 15.300 inches, the thermometer 36 °F Several of my followers could not cross the pass on account of headaches. The length and the difficulty of the ascent, the rarity of the atmosphere, the rigor of the climate, although it was summer, make this pass dangerous to the sturdiest persons. (P. 240.) September 29, he had reached Kotgurh, the end of the journey. In the first volume of the work published by Lloyd, there is a letter from Dr. Gerard, narrating his journey to the passes of Shatool and Boorendo, with the purpose of determining the line of perpetual snow. It is dated from Lake Charamace, at 13,800 feet, August 18, 1822. At the height of 15,000 feet, the same symptoms attacked him and his travelling companions: I cannot describe the extreme fatigue which the last 500 feet caused us. Distressed, sick, we could not use our arms to break off a piece of stone with a blow of the hammer. Respiration was free, but insufficient, our legs could hardly support us, and our faces were drawn as if we were going to have the fever .... All my people were in a wretched condition, I suffered from headache, and everyone was complaining. (P. 308.) It was August 9, they reached the summit of the pass of Boo- rendo, at more than 15,500 feet, the thermometer standing at 37°: Mountain Journeys 137 During the descent, I felt again the symptoms of headache, and they did not leave me until after noon; I went out to get flowers, but I was obliged to return to camp (12,800 feet). I awoke at daybreak, unrefreshed by sleep. I had the same feeling of weakness and languor as on the ascent, but not so bad. (P. 315) .... My visit had removed my doubts on the phenomena of new snow in the passes in July and August, and I had hardly any reason to doubt the strange tales of the dwellers at the foot of the mountain about the symptoms which sometimes attack travellers crossing it. They say that the phenomena of drowsiness and weakness are much more to be feared in the rainy season .... The people who live at the foot of the mountain and who breathe in a very much rarified air, or who are accustomed to climbing their steep slopes suffer much less than those who inhabit a lower zone in a denser atmosphere; but they know these effects very well, and describe their sensations with ingenious and very interesting sim- plicity .... Between Koonawur (where the people seem born to live and die in inaccessible regions) and the Indian slope of the mountains, we travelled for a long time on the crests of mountains, at a positive elevation of 16,000 feet: I met every day a crowd of people laden with grain; they were walking slowly, stopping often to get their breath, and they seemed to suffer from a uniform oppression. I have not ascertained whether they are subject to an illness like the one I experienced, and yet it must be so, and it is undeniable that above a certain height, the effects of the rarified air upon the functions of animal life are permanent and that neither habit nor constitution can conquer them. (P. 320.) .... Sandy and I, in our excursion to the peak 19,500 feet high, although unable to take a dozen steps without being exhausted, and finally being hardly able to move at all, nevertheless were better than the villagers who accompanied us, and who live at the altitude of 12,000 feet. In the interior of the country, where the ground is very high, the most dangerous symptoms appear while crossing the moun- tains. Between Ladak and Yarkand, an intelligent servant of M. Moorcroft told me of the fatal consequences of lack of precaution. He says that the passage of the highest range should be made fasting, and recommends frequent doses of an emetic during the journey. He told me the story of a Russian merchant in good health, who was going from Ladak to Lee to see M. Moorcroft, and who died while crossing one of the passes because he ate a good meal before starting. Death, in such a case, should be attributed to the drowsiness brought on by the cold and the extreme rarity of the air which predisposes to inactivity and leads the traveller to his last sleep. (P. 325.) I took a little walk over the cliffs, but the sensation of fullness in my head forced me to return. Since I arrived here, I have been more or less affected by headaches, particularly violent at night; the pain was not like that of ordinary headaches, but as if an over- whelming weight (a dead weight) was attached to all sides of the head, pushing it in different directions. Tea relieved me, but only for a short time. (P. 325.) 138 Historical I suffered greatly at night from headache and from a sort of drowsiness, such as occurs in drunkenness. I have never felt such evident proof of the existence of an agency dangerous to the principles of animal life, and although I suffered much more in the pass of Boorendo, in 1818, the illness did not last day after day, as it did here. All my servants were also affected, some by nausea, others by head- ache; they were not all equally affected, but we could judge that that was only a matter of chance; we should merely say that the natural conditions of energy and action are not always the same .... The extremes of the barometer here were from 17.055 inches to 17.160 inches; those of the thermometer from 41.5°F. to 53°; which gives the pass of Shadool an elevation of 15,500 feet. (P. 326.) Captain Al. Gerard, moreover, has left us in a special chapter of a posthumous work,218 a summary of the data which he observed in his numerous excursions: On lofty mountains, a depression of spirits and a weakness of body, accompanied by cruel headaches, fullness in the brain, oppres- sion of the chest, difficulty in breathing, with pain in the ears from time to time, affect everyone more or less. All these symptoms result from the rarefaction of the air, and of this I have had numerous proofs, having visited thirty-seven places at different times, between 14,000 and 19,400 feet, and thirteen times my camp was pitched above 15,000 feet. It should be noted that the people of Koonawur and the Tartars estimate the altitude of the passes by the difficulty in breathing which they experience when they make the ascents of them. However it should be noted that the difficulty in breathing does not affect everyone equally or at the same time; it certainly depends largely on the state of health. When I was not well, I suffered from headache at 13,000 feet, whereas in good health I felt no effects at 16,000 feet. At Boorendo (15,000 feet) I was very cold, and expe- rienced, even when resting, a greater suffocation than ever happened to me at 19,000 feet, while I was walking. Any fatigue, but especially the ascent of hills, increases these symptoms: from 17,000 to 19,000 feet, the headaches are constant, and no one can take more than a half-dozen steps without resting. When one camps above 16,000 feet (4875 meters), the difficulty in breathing is really terrible, and often for whole hours I thought I was going to suffocate. Persons who have not made such journeys can hardly imagine how much time it takes to cover a distance of twelve or fourteen miles in lofty places. I have gone thirty-four miles on foot in lands which would be called mountainous by those who do not know the difficult parts of Koonawur, with more ease and in less time than I could walk twelve miles in these lofty regions. An ascent of 5000 or 6000 feet is not rare, and when the elevation is more than 14,000 feet, every mile, even when the road is good, requires at least twice as much time as at the height of 7000 to 8000 feet. The prostration of mind and body experienced on lofty mountains affects everyone Mountain Journeys 139 more or less, and one of my friends was more wearied by an ascent and a descent of 5000 feet, in a total walk of nine miles on lofty ground than in going from Nahun to Soobathoo, which is 45 miles. (P. 57-59.) The observations of Captain Hodgson who, in 1817, went to the sources of the Ganges and one of its principal tributaries, the Jumna, deserve to be quoted for the same reason: 219 We experienced a great difficulty in breathing and that peculiar sensation, constant at great elevations where there is no verdure, which I have never felt anywhere as severely as on fields of snow, even when I ascended higher .... The mercury stood at 18.854 inches, at a temperature of 53 °F. so that the altitude was 12,914 feet (3935 meters). (P. 111.) It was May 30; the travellers had reached the source of the Ganges. These countries were visited ten years afterwards by Captain Johnson, whose account-" gives data identical with those of his predecessors. Moreover, the dangerous effect of lofty places is well known to the people of the country. In fact, July 1 and 2, 1827, Johnson made the ascent of the peak of Tazigand or Pendjeoul: The natives, learning of M. Johnson's plan, tried in vain to persuade him to abandon it by exaggerated accounts of the innumer- able difficulties which it presented and of the dangers of the bis or poisoned wind which blows over the snow. (P. 160.) Moreover, a fact which deserves mention and of which we shall subsequently find many examples, the people dwelling in the country suffer much more than the Europeans: On July 2, Captain Johnson occupied the same ground as that where Dr. Gerard had made his barometric calculations at a height of 19,411 feet (5915 meters) above sea level .... The natives who had guided him there found breathing very difficult; they stretched out on the snow, holding their necks in both hands, and the Sepoy nassir, who was the only one to reach the greatest height, complained a great deal also. It is surprising that our compatriots felt no distress. They occasionally experienced diffi- culty in breathing; but they had blisters on the hands and feet and momentary blindness from the glare on the show. (P. 162.) The French traveller Jacquemont seems to disagree with the statements of all his predecessors. At least, he declares that he felt no symptoms at heights often equal or superior to those at which the English travellers suffered so greatly. This difference 140 Historical made such an impression on him that he reported -1 it to the pro- fessors of the Museum of Natural History, and tried to explain it: Kurnaul, February 1, 1831 Several English travellers have crossed the pass of Bouroune (about 15,000 feet), and all complain of the headaches and nausea they experienced there. I have gone through much higher places, because I camped three times above 16,000 feet, and on my way to Beckhur, I had to cross passes at an altitude of more than 18,000 feet. I have never felt any of the painful symptoms of which all travellers on lofty mountains complain, and I have never observed them in even one of the numerous companions of my excursions. I lived seven months in the Himalayas; I have ascended from their feet to their summits; at the time of my journey to Beckhur, four times I ascended to an altitude of 6000 meters, and for almost two months I almost never went below 3000 meters; then I camped at 4000 meters after a stay at 5000 meters. When the ascent is so gradual, the lungs easily become accustomed to working freely in an atmosphere which gradually becomes more rarified. It is a very considerable change of level in a short time that affects them and produces the oppression mentioned by Saussure and all who ascended Mont Blanc after him, long before they reached the summit. (P. 53.) The interesting notes he left, which were published after his death,2-2 contain very interesting observations on this subject, to which he had given particular attention: May 16, 1830, I reached an altitude of 3927 meters .... This was the first time I had ascended to so great a height; it exceeds that at which the effects of the rarefaction of the air begin to be felt painfully in the Alps. I did not feel them at all; I was no more out of breath than I should have been at the lowest level, if I climbed equal grades with the same speed. I saw no real symptoms in any of the people who followed me; no panting, nor drowsiness, nor nausea. It seems to me that in the temperate climates, on parallels like those of the Alps and the Pyrenees, one feels them sooner than on mountains nearer the equator. If this statement stands out uniformly in the testimony of travellers, it is hard to explain. The effect, if it depends solely on the atmospheric rarefaction, should be the same at the same altitude in all the regions of the earth, or even greater in the tropical countries where the temperature rarities the air more at the same elevation. (P. 101.) Jacquemont refers repeatedly to this harmlessness of the heights of the Himalayas compared to the bad effects in the Alps; in the following passage he even offers an explanation of it which has some foundation: I crossed the pass of Rounang, at an elevation of more than 4267 meters, three times, on horseback. Mountain Journeys 111 This elevation is higher than that at which travellers claim to have begun to feel the effects of the rarefaction of the air in the Alps and the Pyrenees. I did not feel them at all. Perhaps the breath- lessness from which Saussure and his guides and all those who followed his steps on Mont Blanc since then suffered was only the result of a long and difficult march on exceedingly steep slopes. Perhaps if one could be carried from Chamounix to the summit of Mont Blanc, one would escape the illness which is generally attributed to the rarefaction of the air at its crest. The Gerard brothers, who are undeniably the foremost travellers in Alpine regions, constantly com- plain of excessive fatigue and violent headaches on all the passes tney crossed, between 4572 and 5791 meters; and this painful condition continued as long as they remained at these heights, where they camped several times. From that fact it would seem that this illness was not merely the passing effect of fatigue caused by a long climb, but really an effect of the atmospheric condition .... The elevation of Mont Blanc is 3780 meters above Chamounix, which is only about 1036 meters above sea level. The ascent is made in thirty hours. There is an enormous change in atmospheric pressure in which one is immersed, and in a very short time. So sudden a transition, independent of the fatigue involved in making it, can definitely affect the respiratory organs. Here, on the contrary, for more than three months, I have been living at an elevation on the average 1829 meters above sea level, and for the last month, at 2743 meters, an altitude at which I feel none of the effects of the rarefaction of the air. When I ascend to an absolute elevation of 4572 meters, I pass through a vertical difference of only 1829 meters, half of that which exists between Mont Blanc and Chamounix, and I have no sensation which I can refer to a respiratory disturbance. Finally, the proof that the annoying symptoms felt by travellers on the summit of the Alps or on the passes of the Himalayas would vanish in time, and that their lungs would find enough oxygen in an air which has lost half its density, is the existence of the farm of Antisana in the Andes, which M. von Humboldt told us about, at an elevation of about 4114 meters, where a family lives, plows, and works. There is no doubt that the lake of Manasarowar exceeds this height by 305 to 457 22;> meters, and yet there are dwellings on its banks, and pilgrims go round it in a seven day journey. M. Gerard himself proves very satisfactorily that a considerable portion of the high country, in which the Kanaweri merchants travel in going from Shipki or Skialkur to Garou (Gortope), is above 4877 meters in elevation, and yet these merchants do not complain there of symptoms by which we see them attacked when crossing passes often at a lower altitude; whence I conclude that in the latter case it is from the fatigue of the journey that they suffer, laden as they are, whereas in the lofty plains of Chinese Tartary, they walk empty-handed on an almost level road. I myself have felt at an elevation of 4000 meters some of the symp- toms in question, that is, fatigue and headache. But I have hardly ever mounted to this height without being exposed to a furious wind, and whatever precaution I took against its cold, I was always chilled, and 142 - Historical this acting first in me upon the digestive tract, caused a disturbance in the digestion, of which the headaches were evidently the conse- quence. (P. 259.) The following observations corroborate the first explanation given by Jacquemont: August 11, 1830, I reached the altitude of 5486 meters on the pass of Gantong; at the summit, I felt absolutely no difficulty in breathing, as long as I remained motionless, carried by my horse, but when I tried to walk on an almost level road, fatigue and panting appeared promptly. And yet I saw my servants, to reach the summit of the pass, walk several hundred steps on very moderate slopes of snow, without stopping to get their breath; only one was sick. (P. 288.) .... August 16, at the pass of Kioubrong (5581 meters), the same immunity; I ascended there rapidly over a very gentle slope, and walked quickly for more than an hour, without feeling any special lassitude caused by the elevation, no pains of the head or ears, no tendency to sleepiness, in a word, nothing particular, perhaps, but a slight panting; and in fact, after a few minutes rest, my pulse rate was 82. (P. 297.) The limit of perpetual snow in this region of the Himalayas is hardly below 6000 meters, according to Jacquemont. Finally, Jacquemont wished to fix clearly the conditions of the problem by a personal experience: I had ridden on horseback to Kioubrongghauti, and since the experiment which I had made there of walking rapidly for an hour in a place with an altitude of 5600 meters, after reaching it without any fatigue, left me without doubt as to the cause of the strange symptoms experienced by travellers who ascend to the summit of Mont Blanc, I wished to climb the pass of Gantong on foot, to see whether the walk, which was prolonged but prolonged moderately for only five hours and very slowly, with numerous intervals of rest, on slopes which are really very steep, but whose vertical height did not exceed 1000 meters, would reduce me to the state of exhaustion descri- bed by M. Gerard as the immediate consequence of the slightest movement, as soon as one reaches the absolute elevation of 4572 meters. That was just the level of my starting point. Stimulated at the beginning of my walk by the morning chill, sustained beside by the freshness of the wind, preoccupied by interest in the objects which I saw at every step, often stopped by them, and taking care after walking three hours to eat a light lunch to ward off any feeling of hunger, which, I have found, always produces in me in lofty places an extreme weakness and headaches, I arrived without weariness, and almost without perceiving it, at the summit of the pass of Gantong, at an elevation of 5576 meters. (P. 302.) But if Victor Jacquemont was almost free from any acute symptom, and did not see any appearing in his travelling com- Mountain Journeys 143 panions and his beasts of burden, it is far from being true that all travellers have enjoyed the same immunity. In fact, in the annals of Berghaus, for March, 1832, we find the following quotation, relating to a passage of the Himalayas on the border of Sutlej; the name of the traveller is not mentioned: At an elevation of 15,000 feet, respiration becomes difficult; the traveller feels great lassitude, vertigo, headaches and unquenchable thirst. It is impossible to describe the sensations produced by extreme rarefaction of the air; one constantly feels as if he were smothering; respiration accelerates in a very painful manner, the elasticity of the skin diminishes. The highest "* point of the pass is at an elevation of 16,500 feet. (P. 547.) Moreover, Lieutenant J. Wood,225 who made a journey to the sources of the Oxus in 1836, 1837, and 1838, gives numerous and interesting details on this subject. February 20, the expedition reached the plateau of Pamir, the altitude of which is 15,600 feet, the mountains surrounding it rising 3000 or 4000 feet higher; the party was at the sources of the Oxus, on the shore of a frozen lake: We began to break the ice to sound the depth of the lake. The ice was 2V2 feet thick, and because of the great rarity of the air, a few strokes with the picks exhausted us so much that we had to lie down on the snow to get our breath. (P. 360.) .... Fifty steps at full speed set us to panting. In fact, exercise brought on pain in the lungs and a general exhaustion which did not improve for several hours. Some of us suffered from vertigo and headaches, but except for these various phenomena, I felt nothing and saw nothing in the others which resembled the sufferings experienced by travellers in the ascent of Mont Blanc. In the latter case, the transition from dense air to rarified air is so sudden that the circulation does not have time to adapt itself to the difference in pressure, so its speed increases in some of the most sensitive organs of the body. The ascent of Pamir, on the contrary, was so gradual that it required "extrinsic" circumstances to remind us of the considerable altitude which we had reached. The effects of the great elevation had, however, been proved to me some time before in a manner for which I had not been prepared. One evening, in Badakhshan, as I was sitting reading by the fire, I had the idea of feeling my pulse, and its rapid and wild beating aroused my attention. I imagined that I had been attacked by a violent fever, and I used the precautionary measures which Dr. Lord had prescribed when he left. The next day, my pulse was as rapid as on the day before, and yet I felt in excellent health. I thought then of examining the pulse of my companions, and to my great surprise I found that theirs were more rapid than mine. The cause of this increase in circulatory activity was evident to me at once; and when 144 Historical we next went toward Wakhan, I counted the pulse of my companions every time I recorded the boiling point of water. The changes in the pulse thus form a sort of living barometer, by means of which a man accustomed to examining himself can, at great altitudes, estimate roughly the elevation. On Pamir, the pulse rate gave the following figures: Myself 110 Scotland fat Gholam Hussein, Munshi 124 Jasulmeere fat Omer-Allah, muleteer 112 Afghanistan thin Gaffer, servant 114 Peshawuree thin Dowd, servant 124 Kabul robust The elevation of the snow line in this region is above 17,000 feet (5180 meters). (P. 352.) Lieutenant Wood was accompanied for part of his journey by Al. Burnes, an envoy to Caboul. October 19, 1837, two others of their companions, Lieutenant Leech and Dr. Lord, went to recon- noiter and cross a pass of Hindu-Koush, going to Caboul. The pass is about 15,000 feet high; the snows would soon render it impassable; the ascent was easy. However, says Burnes:--'6 The horses were in a very pitiful condition, and they had to dismount and walk. No one had any symptoms, but the natives informed them that they themselves were frequently attacked at this point by vertigo, faintness, and vomiting. (P. 152.) Some years later, a French traveller, who travelled over not the Himalayas, but the much less lofty regions of Upper Tartary, made a pitiful story of his sufferings. It is true that one must be on his guard against the statements of Father Hue,-'-7 whose credu- lous simplicity is almost boundless. Nevertheless, the vivid pic- ture which he has left us of the sensations experienced during the passage over Bourhan-Bota, a mountain the height of which he does not give, and which seems to be situated about longitude 95° E. and latitude 40° N., deserves to be reproduced here. The day of the ascent is not specified, nor is the temperature of the air: We prepared to cross Bourhan-Bota, a mountain famous for the pestilential vapors in which, they say, it is continually enveloped .... Soon the horses refuse to carry their riders, and everyone proceeds on foot slowly. Gradually all faces grow pale, nausea comes on, and legs refuse to function; one lies down on the ground, then gets up and makes a few steps more; then one lies down again, and this is the miserable fashion in which one climbs this famous Bourhan-Bota. Good heavens! What wretchedness! One feels his strength broken, his head whirls, all members seem to be disjointed, one feels illness exactly like seasickness, and in spite of that, one must save enough Mountain Journeys 145 energy, not only to drag himself along, but also to beat energetically the animals which constantly lie down and refuse to go on. A part of the group, as a matter of prudence, stopped half-way, in a depression where the pestilential vapors were less thick, they said; the rest, also out of prudence, exerted all their powers to get through with it and not die from asphyxia, in the midst of this air laden with carbonic acid. (P. 256.) The travellers whose accounts I shall now mention agree much better with what the Gerard brothers said than with the extreme statements of Jacquemont and Father Hue. July 14, 1845, Hoffmeister -L'8 reached the highest point of his journey, the pass of Lama-Kaga (Thibet) at the elevation of 15,355 English feet; the temperature was — 50° Reaumur; the snow was falling: About an hour and a hslf passed before our first coolies arrived with our baggage. They were in a very sorry state, and were suffering, as well as our interpreter M. Brown, from headaches which they described as unbearable. Loss of strength, pains, and nausea are the symptoms of this illness which they call here Bies (poison) or Mun- dara. It attacks travellers thus at the line of perpetual snow. In the coolies it appeared halfway up the pass. As a remedy against it they use a sort of paste made of little sour apricots and their seeds. (P. 242.) In the account of Dr. Th. Thomson,-'2'' it was not only the coolies, but the European traveller himself, who was affected by the altitude. September 6, 1847, Thomson and his attendants camped at an altitude of 14,800 feet, and on the 7th, they ascended to 17,000 feet (5180 meters): The whole day long I had never been free of a violent headache, evidently caused by the great elevation. Rest relieved it, but it reappeared at the slightest movement. It lasted all evening, as long as I was awake, and I still had it on the morning of the 8th, when I got up at daybreak to prepare for the journey .... The ascent next day was extremely steep and difficult. The act of raising one's body was very tiring, and the last few hundred yards were covered only after several pauses .... I reached the summit of the pass of Parang at a quarter of eight in the morning; I was . at an elevation of 18,500 feet (5640 meters) ; the temperature was 28° .... the snow was frozen .... the wind blew violently .... We descended without fatigue .... (P. 135.) After living a year in these lofty regions, Dr. Thomson recon- noitered towards the north, as far as the celebrated pass of Kara- korum, at a height of 18,604 feet (5670 meters) . There again, his 146 Historical symptoms reappeared, or to speak more exactly, they became so intense that he was compelled to make special mention of them: August 19, 1848. During these three days of ascent, I suffered greatly from the effects of the rarefaction of the air, being constantly tormented by a painful headache which the least exercise aggravated .... The temperature of the air was 50 °F. The botanist Dalton Hooker is still more explicit.-50 At the height of 16,000 feet, while ascending the pass of Kang- lachem, December 2, 1848, in eastern Nepal, Hooker experienced difficulty in breathing, great lassitude, vertigo and headache. (Vol. I, p. 247.) Some days afterwards, on the mountain of Nango, at a height of 15,000 feet: I found it quite impossible to remain composed because of the increase of the pains in my forehead, lassitude, and oppression. (P. 252.) July 25, 1849, crossing of the pass of Kongra-Lama (15,741 feet) : After two hours, I was chilled and stiff, and was suffering from headache and vertigo due to the elevation. (Vol. II, p. 82.) September 18, ascent of the pass of Sebolah (17,517 feet) : I took the pulse rate of eight persons after a rest of two hours; it varied from 80 to 112, mine being 104. As usual at these altitudes, everyone was suffering with vertigo and headaches. (P. 142.) October 15, night passed at an elevation of 17,000 feet: My coolies were in good health; but those of Campbell were in a very sad condition of pain and fatigue; their faces were swollen and their pulses rapid; some were practically insensible with symptoms of weak cerebral pressure; the latter were especially the Ghorkas (natives of Nepal). I have never experienced bleeding from the nose, ears, lips, or eyes, and have never seen such symptoms in my com- panions on such occasions; nor have I met any recent traveller who has experienced them. Dr. Thomson has noted this too, and when we were together in Switzerland, we learned from A. Balmat, Fr. Cartet, and other guides of experience on Mont Blanc that they had never witnessed these symptoms, nor the darkening of the skin, so frequently mentioned by Alpine travellers. (P. 160.) .... October 17. It is quite surprising to see that Turner nowhere alludes to difficulty in breathing, and speaks only in one place of headache, even at this great elevation. That is probably because he was always on horseback. When I was riding, I never felt any dis- turbance in my breathing, my head, or my stomach, even at 18,300 feet (5580 meters). (P. 167.) We see that it is while they are crossing passes that travellers feel symptoms; ascents, properly so-called, of isolated mountains Mountain Journeys 147 are, in fact, extremely rare. However here is one, in which Captain Robertson,'-31 in October, 1851, reached the summit of Sumeru-Parbut, at a height which he estimates as about 20,000 feet (6100 meters). The preceding night was passed at nearly 4000 meters: The next morning, we left our tent at ten minutes past eight, and at thirty-five minutes past one reached a sloping glacier. At this point, vision and respiration became very painful for Lieutenant Sandilands and several of our guides .... Sandilands reached a spot half an hour's distance from the sum- mit, where he was so affected by the rarefaction of the air that it was physically impossible for him to go any further; he therefore turned back, with the only Rajput who had followed him thus far, the others having abandoned him long before; my Brahmin, a handsome young man of strong constitution, who came with me to the summit, appar- ently felt no effects, but when we reached our tent again, he could eat nothing. As for me, my eyes were painful, and my respiration and my vital force were affected, but yet I had enough energy and physical force left to climb still higher. On my return to my tent, my appetite was not affected at all, and I ate a hearty supper. But the most interesting accounts I have found in my reading are certainly those published by Mistress Hervey. And that is easy to understand; a simple tourist, not heeding politics or geog- raphy, or science, she gives special attention to everything relating to her health and the little incidents of her journey, which she tells obligingly in all their details. Besides, since she has rather a weak constitution, she seems to be easily affected at rather low levels. So it is to mountain sickness that we must attribute part of the following symptoms, although the elevation is very moderate: June 25. We halted (after crossing the pass of Rotung (11,000 feet, 3350 meters) in Lahoul) .... Captain H. came to say good evening to me in my tenf about nine o'clock, and noticed that I was very pale, and that my face and hands were cold and clammy. I was then very sick; I was delirious; I was nauseated, my hands and feet were icy cold. Convulsions came on and I frothed at the mouth. I stretched myself on the ground, and remained there in great distress; they gave me two doses of Luce water, and put my feet in water which, though it was boiling hot, could hardly restore the circulation. Yesterday I was sick all day and unable to get up; my pulse rate was not less than 108. I am better this morning, but my pulse rate is still very high, although less irregular. Captain H. declares that this sudden illness is due to the rarity of the air of the pass .... If I am already affected thus, what will happen at 16,000 or 17,000 feet? (Vol. I, p. 117.) 148 Historical But if doubt is possible in this case, it certainly is not in the following quotations. July 6, crossing of the pass of Bara-Lacha; Mistress Hervey was very ill: I had severe pains in my legs, and felt extreme lassitude, long before reaching the summit of the pass; but I made a violent effort to overcome these sensations, and succeeded in riding to the summit. As soon as we dismounted, a terrible, splitting headache attacked me. Before reaching Yunnumscutschoo, I had suffered from nausea and felt as if my head were going to split. The principal sensations were a very painful and very intense throbbing in my temples, violent nausea, pains in my legs, and a lassitude amounting to prostration. No one else was sick in the camp, except Ghaussie, who had a bad headache. I could not get to sleep at night before one or two o'clock, and was awakened by the throbbing of my heart, so violent that I felt serious fears about it. My pulse was galloping, my head was burning and my temples throbbed, and I was wretchedly nauseated. We did not set out until late the next morning, and if I had not felt better, we could not have moved at all. Captain H. told me that he had had a bad headache during the night, that he had felt tired and ill, but that nevertheless he had not suffered as much this time as the last time he had crossed the pass, for then he had had the same sensations as I ... . The pass of Bara-Lacha is, I think, between 16,000 and 17,000 feet above sea level, according to Captain Cunningham. (Vol. I, p. 133.) Mistress Hervey then relates that the natives of the country attribute all these symptoms to the effect of a poisonous plant; but this time, the plant is a kind of moss. We shall quote this passage in Chapter III. The next day, the road, which still ran along at great heights, several times forced the travellers to ascend small hills: As we ascended (says Mrs. Hervey) I noticed a great many poisonous mosses, two or three species of which were growing on bare rocks. I had a terrible headache, and was shivering with a return of the terrible "pass sickness" or, as the natives say, from being "boottee luggeea", that is, affected by the plants. Tomorrow we shall ascend the Long-Illachee Joth (or pass), and descend it, which promises to me a fine day of boottee. (Vol. I, p. 139.) And in fact, when she reached Rokchin (Ladak) the next day, Mistress Hervey declared that she was so sick and so weak that she could not write. July 9, after a night's rest, she could hardly write and had to remain lying down. Two of her servants were Mountain Journeys 149 very sick. Captain H. suffered during the night from a violent headache. (P. 142.) July 11, passage of a place the height of which Mistress Hervey estimates at about 17,000 feet: I had a worse headache than usual with a terrible oppression of the chest. It is true that since the crossing of the pass of Bara-Lacha, I have constantly suffered greatly from the effects of the rarity of the air; a constant headache, and, especially during the night, a painful pulmonary discomfort, and a very annoying acceleration of the move- ments of the heart. I had hardly an hour of continuous sleep; I had to sit down on my bed, as I could not breathe when I was lying down. These lofty regions do not suit my lungs. (P. 152.) The following night, camp at 14,800 feet on the banks of Lake Choomoreeree: I am now afraid of the night, because, far from sleeping, I suffer terribly. Yesterday, it was really very painful; besides a cruel head- ache, I suffered from great oppression in the chest, and my heart went at a railroad pace, when I moved even an inch in my bed. (P. 153.) These sufferings were so great that they decided her to change her route a little, to avoid great heights (P. 162) . And yet, July 16, when she reached the foot of the pass of Tunglund, she wrote: We saw much poisonous bootie today on the road. I was wretch- edly sick all night. About eleven o'clock in the evening, the respiratory oppression and the suffocation became so unendurable that I had to sit up on my bed to get my breath a little. (P. 169.) The next day, ascent of the pass (between 16,000 and 17,000 feet) : The odious moss of which I have spoken so often covered the pass, and long before I reached the summit, I had a most violent headache. But I had no nausea, perhaps because the pass is very easy. (P. 171.) July 19 of the following year, in spite of her continued resi- dence in the lofty regions of Little Thibet, Mistress Hervey was not acclimated, for, as she crossed the pass of Brarmoorj in Wurd- wun (from 15,000 to 16,000 feet), she said: I suffered from an absolutely unendurable headache, which kept constantly increasing; but I did not have the nausea which I always felt on all the passes of Ladak. (Vol. II, p. 298.) And August 5, 1851, while crossing the pass of Hannoo (be- tween 15,500 and 16,000 feet), in Ladak, a pass of rather easy access, she suffered horribly; it is true that she was already ill. She said the next day: 150 Historical I have crossed many passes, but until today I had never expe- rienced the terrible sensations which almost made me crazy before I was halfway and long after I had left the great heights. My sufferings might have been aggravated by my illness, but in any case, they were crushing. I lay down on the ground at Dora, more dead than alive, and my servants made me a tent of blankets. I was in such a state of prostration that not only was I unable to rise, but I could not bear to be carried in a "dhoolie" .... A violent headache, unbearable nausea, hasty palpitations, and the inability to breathe deeply, such were the symptoms of the well known bootie, which attacked me more severely than ever before I reached the summit of the pass. I am sure that if I had stirred about for a quarter of an hour during these horrible sensations, some blood vessel would have broken and I should have died on the spot. Just speaking was a painful exercise, which brought on copious hemoptysis and increased my pulse rate far beyond 100 per minute. I was terribly nauseated, and the exhausting power of this distress can be compared only with the nausea of sea- sickness. I was also very wretched and my sufferings were intense yesterday. Even today I cannot breathe without pain, and my heart beats violently and irregularly; I have not yet forgotten the rarified atmosphere of the pass of Rannoo. As they were carrying me yesterday about a half-mile from the summit, Ghaussie called my attention to one of my servants, who was lying unconscious on the snow. They woke him easily, but he refused to move, saying that his head "was going to split in two." After a slight struggle between humanity and strongly rooted prej- udices, for the sick man was a sweeper, the lowest class of servants, I sent him my own pony to carry him; if he had been left there, he would certainly have died during the night. While I am speaking of the illness on this pass as a case of bCwtie, I must confess that I did not see a single plant of the particular kind of moss, which, in the passes of Ladak and Lahoul, are considered as poisoning the wind and causing the painful illness which I have described. One of my servants from Cashmere was the only other person among my attendants to be affected; distress in high altitudes is therefore not a rule without exception. (Vol. II, p. 367-370.) And the next day, as she set out from Scheerebookhchun, she wrote: I shall travel by moonlight, for I have been so sick all day that I have had very little desire to move. If I let myself be governed by the painful sensations which have tried me so much, I should not start now, but that might be impolitic. In my opinion there is nothing like exercise to overcome our little bodily and mental troubles. I must practice what I preach, and ride horseback this morning, sending my dhoolie on ahead. (P. 378.) She set out at sunrise, and went on horseback to Kulatsey. I was then so sick and so exhausted that, not finding my dhoolie there, I lay down on my shawl on the ground for several hours. At Mountain Journeys 151 last, towards evening, another dhoolie was ready, and I could get into it .... I have not recovered from the effects of the rarified air on the pass of Hannoo. My heart beats violently and irregularly, and when I breathe, I have severe pains in my chest. My distaste for nourish- ment is so great that I can hardly touch any food all day long. (P. 378.) August 14, crossing a sort of a pass, near Ghia: I have suffered from a very painful headache, but have felt no nausea, although I recognized my old enemy, the bootie, the fatal moss of Ladak-Oojar. When I walked fifty steps to pluck a flower, the throbbing of my heart increased terribly, and repeated doses of digitalis have not quieted its hasty and violent beating. I do not know any sensation that is more alarming and more painful than this exaggerated action of the heart. None of my servants felt any ill effects .... I reached Zurra at sunrise. I am completely prostrated by my splitting headache, although I have escaped nausea, and that is the only consolation I have in my sufferings. (P. 397.) August 18, camp at Choomoreeree, at a height of 14,794 feet (4510 meters) : I passed a miserable night, and this morning I am sick and exhausted. I had to remain thus half the night, absolutely incapable or breathing in a horizontal position; my heart beat violently with terrifying palpitations. I was really afraid of dying in the dark .... In the evening, we camped at an elevation of nearly 15,000 feet. I have the greatest difficulty in breathing, my chest seems loaded with an enormous weight which oppresses me painfully. These distressing sensations increase at nightfall. (Vol. Ill, p. 13.) August 20, camp at the foot of the pass of Parung, at about 17,000 feet (5180 meters) : A terrible height in which to pass the night under a tent, when one suffers from the rarity of the air as I do. Oppression in the chest, extreme difficulty of respiration, frequent spitting of blood have left me no rest during the last sixteen hours .... The cold is intense .... At daybreak, I feel better, although I cannot breathe freely, and although the slightest movement distresses me .... My head has almost recovered, and since my courage has returned, I have decided to cross the pass .... To go on horseback is impossible, to walk ?.s impossible too; I am riding a yak. (P. 19.) Strange thing, that although this pass is the highest our travel- ling lady has crossed, she has little trouble there; no nausea, only a slight headache (P. 26). Moorcroft estimates it as at 19,000 feet (5790 meters), and Mistress Hervey goes to 20,000 feet (6095 meters). She is naturally amazed at this result: 152 Historical It is curious (she says) to note the different effects of the different passes. Although the painful sensations observed undeniably result from the rarity of the air, it is certain that the illness is not proportional to the elevation. On the passes of Bara Lacha and Hannoo, I was wretchedly sick, beyond all description, and on the pass of Parung, 3000 or 4000 feet higher, I had no nausea, hardly a headache. I had difficulty in breathing, but that seems to me a secondary matter. I am far from being able to give a satisfactory reason for this difference. I have crossed so many passes that I have had many opportunities to note how little relation there is between the "pass sickness" and the elevation, of course, beyond 13,000 or 14,000 feet. The "Bischk-ke-B66ttie", or poisonous plant, covered the ground many miles around Tatung. (P. 33.) The journeys of Captain Oliver -33 in the Himalayas also offer an account of impressions connected with our topic. In July, 1859, he crossed the pass of Roopung, at about 15,500 feet (4720 meters) : We camped at the lower line of perpetual snow, at 14,000 feet above sea level. It was very cold .... We set out the next morning over the snow .... The summit of the pass appeared in a wild and desolate scene. But I heeded it little, being occupied with myself, for the rarefaction of the air was acting upon me. I suffered from a painful shortness of breath, and soon I had to stop every two or three steps. The snow was soft, which made walking still more difficult .... I finally reached the last slope, a bank of snow 50 feet high and very steep .... But at the moment I was so completely exhausted that I was quite unable to cross it without assistance. However, after a short halt, I made a desperate effort, and somehow or other I reached the summit, where I stretched myself out on the ground, absolutely exhausted. (P. 84.) .... This pass is much frequented by the Tartars who bring borax and wool to the Indian markets. They suffer greatly, however, from the rarefaction of the air, but attribute its symptoms to a poisonous plant, a fabulous plant, which, according to them, grows at great elevations. They are also subject to violent attacks of colic in the passes .... One of my Sikhs was attacked by it; he lay down on the summit, groaning, and declaring that he was going to die; thirty drops of laudanum restored him. (P. 85.) The same year, another traveller, Cheetam,-'34 took the road from Simla to Srinagar; August 17, 1859, he crossed the pass of Lunga-Lacha at 16,750 feet (5100 meters) : I then had my first experience of the harmful effects which greatly rarified air, bad weather, and fatigue produce at great elevations. Vertigo, violent headache, and nausea, such are the character- istic sensations, to which is agreeably added a feeling of intense exhaustion, a profound physical and mental depression. Happily, in Mountain Journeys 153 me this pleasing complication lasted only a few hours, in the middle of the day, and again intermittently. I noticed that invariably I was better when descending the hills than when ascending them; and that there was a sort of connection between the appearances of the sun and my lucid intervals. The sufferings of my Cashmere servant and the merchants of Caubul were evidently much more continual and acute than mine, particularly because of a general disturbance of which they had been complaining since the day before, at the pass of Bara Lacha. It was impossible to destroy their absolute belief that all these symptoms were due to the poisonous exhalations from a mysterious plant, the "dewaighas" or "medical herb", which they are sure grows in these regions, although they have never been able to find any .... The man from Cashmere was sick two days. P. 137.) A few days after, crossing of a still higher pass, that of Tung- lung, which has an altitude of 17,750 feet (5410 meters). The night camp was made at Larsa, at 16,400 feet: The aacent of the 1350 feet which we had to climb was very rugged; the slightest effort in this rarified air made our breathing very painful. (P. 141.) The account of Semenof 233 is interesting in that it relates to the first journeys made in the high regions of the Celestial Moun- tains. June 25, 1857, after camping at an altitude of 7500 feet, he crossed the pass of Zauku. There thousands of carcasses of camels, horses, oxen, and dogs are to be seen: The horse of M. Kosharof broke down .... mine slipped, cut itself deeply, and died at once; two of the horses of the Cossacks were so exhausted that they could not go on ... . The guide assured us that it was so difficult to breathe at the summit of the Zauku Pass that it would be impossible to live there more than an hour and a half. (P. 364.) We see, in this statement of the guide, an example of the exaggerations usual in all countries where very lofty places are the exception. Unfortunately, Semenof does not give the altitude of the pass of Zauku. But no one could treat this question with more authority than the Schlagintweit brothers, whose expeditions in the lofty regions of Asia are among the most important journeys of this century, and the most fruitful from the point of view of geography, history, and the natural sciences. They have devoted a section, in the official account of their journey,230 to the history of the symptoms of decompression. In it we see that they mounted to the greatest height ever attained by 154 Historical man in mountain ascents, that is, to 6882 meters, on the sides of Ibi-Gamin, August 19, 1855. Here is the summary of their highest ascents: On some very lofty plateaux which serve as pastures, a tempo- rary dwelling for a few months was established at an altitude of about 16,500 feet (5030 meters); it is at this height, probably the highest of the sort in the world, that the shepherds of Thibet pitch their tents and even build permanent dwellings. From personal experience we can say that for ten or twelve days, man can remain considerably above this altitude, perhaps not without distress, but positively without any very serious consequences. In our explorations of the glacier of Ibi-Gamin, from the 13th to the 23rd of August, 1855, we camped for ten full days, in the company of eight men who were our attendants, at really extraordinary elevations. During this time, our camp was pitched at 16,642 feet (5070 meters) at the lowest. The highest point was 19,326 feet (5890 meters); that is the highest elevation at which we passed the night. Another time, we camped at 19,094 feet, later at 18,300, and the rest of the time, between 18,000 and 17,000 feet .... One day we crossed a pass at 20,459 feet (6230 meters), and three days before, August 19, 1855, we had climbed on the sides of Ibi-Gamin to the height of 22,259 feet (6882 meters). So far as we know, that is the greatest height to which anyone has ascended in the mountains .... On the peak of Sassar, August 3, 1856, we reached a height of 20,120 feet. Before us, the brothers Alexandre and James Gerard ascended to 19,411 feet on the peak in Spiti, October 18, 1818 .... So far as the symptoms to be considered in acclimatization are concerned, we can speak from our personal experience. When we crossed passes at an elevation of 17,500 to 18,000 feet for the first time, we first felt serious symptoms. A few days after, when we had traversed the highest points and passed several nights at these alti- tudes, we were almost completely free from these disagreeable symptoms, even at the elevation of 19,000 feet. What the consequence of a longer stay in these lofty regions would have been, we cannot say. But we consider it very likely that a longer residence would have had serious effects on the health .... The effect of the altitude varies with the individual. A healthy man is likely to suffer less. The difference in race is not particularly important. Our Hindu servants, who accompanied us to the highest points, suffered from the cold more than the* Thibetans, their comrades, but they did not feel the effects of the decrease in atmospheric pressure more. For most people, the influence of the altitude begins to appear at 16,500 feet, the elevation of the highest pastures. Our camels and our horses were very definitely suffering at about 17,500 feet. The symptoms produced by the rarefaction are: headache; diffi- culty in breathing; oppression in the chest, which may go so far as to bring on the spitting of blood, and very rarely slight nasal hemorr- Mountain Journeys 155 hages; we never saw blood issue from the lips and the ears; loss of appetite and often nausea; muscular weakness, with a general pros- tration and dejection. All these symptoms disappear almost simul- taneously, in a healthy man, upon return to lower elevations. The effects mentioned are not perceptibly increased by cold, but wind has a very harmful effect on the symptoms experienced. As this was a new phenomenon to us, and as it had not been mentioned by our predecessors, we observed it carefully, and noted circumstances in which fatigue was not a factor. On the plateaux of Karakorum, it frequently happened even to those who were asleep under the tent in rather sheltered places to be awakened during the night by a feeling of oppression which must be attributed to a breeze, even a gentle one. which had arisen during the hours of repose. When we were busy with observations, we took little or no physical exercise, sometimes for thirty-six hours, and our servants even less than we did. And it often happened, in elevations which did not exceed 17,000 feet, that the afternoon or evening wind made us so ill that we lost all taste for food; we did not even think of preparing dinner. In the morning, when the wind was not blowing, appetite generally returned, we were not as ill in the morning as in the evening; this was evidently partly because the strong winds rose usually in the second part of the day. The effects of diminished pressure are considerably aggravated by fatigue. It is surprising how exhausted one becomes; even the act of speaking is a labor, one heeds neither comfort nor danger. Often our servants, even those who had served us as guides, let themselves fall on the snow, declaring that they would rather die at once than take another step. From simple motives of humanity, we were often obliged to intervene in their behalf and tear them by force from the stupor into which they had fallen, whereas we ourselves were hardly in a better condition of energy. (Vol. II, p. 481-485.) The observations of more recent travellers agree completely with what we have just reported. We must even note that, since the existence of discomforts on lofty passes is today well known to everyone, travellers often do not speak of them, or merely allude to them in a few words. So Captain Godwin-Austen,L:;7 who explored the glaciers of Karakorum, in 1860 made the ascent of Bianchu (16,000 feet) and Gommathaumigo (17,500 feet) without speaking of any symptom. In his journey of 1861, he first climbed Boorje-La (15,878 feet) ; his pulse rate was 138, and that of one of his men 104, and he mentions no other symptom (P. 23.) But while he was ascending a peak of 18,342 feet (5590 meters) on August 10 (this is the highest ascent he made) he reports that "many men became ill, had violent headaches, and lay down on the ground." (P. 34.) And in addition, in the account -:!S of the long and important journeys made by two young Brahmins, two brothers, whom the English government sent to visit regions in which Europeans can 156 Historical hardly set foot without risking their lives, there is no mention of the symptoms of decompression. And yet the two "Pundits" cer- tainly visited many lofty places, since they crossed the Himalayas in Nepal, at the foot of Dhawalaghiri, followed the course of the Brahmapoutra from Lhasa to Lake Manasarowar, and pushed on as far as Gartokh. But since they were exclusively interested in geography and politics, they did not heed phenomena which are universally known, or at least they did not think they should give space to them in their narrative. Since this native expedition gave excellent results, a few years afterwards, the Trigonometrical Survey sent an employe, the Mirza, whose journey M. Montgomerie 239 has related, across Hindu-Kush and Pamir to Turkestan. In this account there are a few details which refer to our subject. In January, 1869, the Mirza reached Lunghar, in the steppes of Pamir: The whole company, when they reached Lunghar (12,200 feet), suffered greatly from the Dum, as the Mirza calls it, that is, shortness of breath, etc., the usual effect of great altitudes. The natives gener- ally consider it to be produced by a bad wind; some of the men became almost insensible, but soon recovered when the Mirza had them eat some dry fruits and sugar. (P. 158.) At the pass of Chichik-Dawan (15,000 feet) they suffered greatly; all felt extreme difficulty in breathing, which the Mirza tried in vain to overcome with his sugar candy and dried fruits. (P. 165.) At the same time, an English traveller, Hayward,'40 was also making his way towards Kashgar, but through Little Thibet, across the enormous chain of Karakorum. He too is extremely chary of observations relating to the rarefaction of the air. The journey lasted from October, 1868, to June, 1869. Crossing of the pass of Masimik, at an altitude of 18,500 feet (5640 meters) : It presents no difficulties, is very easy, but loaded horses are slightly affected there by the rarefaction of the air. (P. 36.) Crossing of the pass of Chang-Lang at 18,839 feet (5740 meters) (p. 38) ; ascent of a peak of 19,500 feet (p. 43) , of another of 19,000 feet (p. 55-58), without any physiological observation; he merely says: The chief difficulty at the Chang Lang pass is the distress of loaded animals, as a result of the elevation and the rarefaction of the air. (P. 126.) Mountain Journeys 157 The following year, in 1870, the "Munschi" Faiz Buksh, leaving Peshawar in the Upper Punjab, set out for Kashgar, trying, like so many other more or less clearly official envoys, to open these new ways by which the commerce, the diplomatic influence, and perhaps the arms of England strive to penetrate western Turkestan. His account -41 is very rich in details which interest us. He lays particular stress on Pamir: Pamir has been given the name of Bam-i-Dunya (roof of the world) because of its height. Its great elevation is proved by the absence of trees and the scarcity of birds; grass grows there only in the summer. The air there is greatly rarified, so that breathing is difficult for men and beasts. This difficulty is called tunk by the people of Badakhshan and Wakhan, and ais by the Mogols. The liver and the stomach are irritated. Travellers suffer from headache, and blood flows from their noses. In people of weak constitution, the face, hands, and feet swell. The colder it is, the more marked these symptoms are. The natives use acid, dried apricots, and plums as remedies. At night, if one does not have his head two feet higher than his legs, respira- tion is hampered during sleep. These symptoms appear whether one is afoot or on horseback. I am thirty-four years old. On one of the peaks of Pamir, my pulse rate was 89 per minute; I had a headache, with irritation of the liver and stomach; once I had the nosebleed. One of my servants, named Kadir, a native of Peshawur, aged twenty-seven, had an attack of fever, with difficulty in breathing, irritation of the liver, and swelling of the face and extremities; his pulse rate was 99. Another, named Mehra, a native of Ghizni, aged twenty, felt only slight difficulty in breathing; his pulse rate was 75. Over-feeding increases the difficulty of breathing. (P. 470) .... Between Ak Tash and Sarkol is a lofty peak named Shindi Kotal, the summit of which is always covered with snow; we felt more difficulty in breathing there than on Pamir .... Three days' journey after Sarkol is a lofty peak called Yam Bolak, the summit of which is always covered with snow; we experienced great difficulty in breath- ing there also. (P. 472.) The expedition led by Forsyth the same year from Lahore to Yarkand, through Ladak, had to cross successively the Himalayas and Karakorum. The account which Henderson '-'42 gives of it frequently indicates the observation of symptoms due to the rare- faction of the air. June 27, 1870, crossing of the Namyika Pass, in Ladak: Although the summit of this pass has an elevation of only 12,000 feet, several of our men had great difficulty in breathing, which con- tinued for several hours after we had reached our camp at Karbu, 600 feet lower; some of our men could not even sleep during the night for this reason. (P. 46.) 3ulse Respiration 80 26 100 22 94 92 93 78 158 Historical July 10, crossing of the pass of Chang-La, from the basin of the Indus to that of Shyok, one of its tributaries, at 18,000 feet (5485 meters); little snow: It was the first time that almost everyone in camp suffered from the rarity of the air. The following observations, made after a half- hour's rest at the summit, may seem interesting: Mercury barometer 15.73. Thermometer 61 °F. Water boiling at 181° F. I walked to the summit M. Forsyth, who was on horseback M. Shaw, who was on horseback Mullik Kutub Deen, of Punjab, on horseback A Hindu of Punjab, on foot A Thibetan, on foot Several travellers told me that they and their companions had suffered more while crossing this pass than on others which were higher. We camped for the night near a little lake of sweet water, at 300 feet below the summit of the pass. The painful symptoms caused by the rarity of the air did not disappear until the next day, when we were at a much lower altitude. As for me, even at 19,600 feet, I have never felt great discomfort; mine amounted only to a certain shortness of breath after any exercise, and awakening during the night with a feeling of suffocation which disappeared usually after a few deep inspirations. But in several of our men the symptoms were very serious, and even alarming sometimes. They consisted of intense headaches, with great prostration of body and mind, constant nausea, and such an irritation of the stomach that even a spoonful of water was not tolerated. A great irritability of disposition was another marked symptom; in some cases the lips became blue; in M. Shaw, a clinical thermometer showed a temperature which had fallen 1 or 2 degrees in comparison with that of the preceding days. Having with me a certain quantity of chlorate of potash, I gave a strong solution of it to the patients, rather to please them than in the hope of relieving them. However, it seemed to have a good effect, but why? I should not dare to make a guess. I do not doubt that these symptoms of the lofty mountains are merely temporary and that custom would end them, as it does seasickness. They become much more intense when one makes an ascent when he is already at a great height. July 11, we camped 500 feet below the pass. There the headaches and nausea stopped quickly. (P. 56 et seq.) July 20, crossing of the pass of Cayley, a newly discovered pass, easy of access, which is about 5900 meters high; through it one goes from the basin of the Indus to the plateaux of Yarkand; there was no snow. The travellers found several butterflies there. They do not speak of any physiological disturbance. Mountain Journeys 159 July 21, camp on high desert plains, at an altitude of 5000 meters; they suffered much from the wind: Travellers are frequently killed by this wind, which is sometimes so cold that it checks the vitality very quickly. Men and horses suffered much here from the rarity of the air. Several of our men lay down on the plain, completely exhausted, and could not reach our camp until the next day; some horses which fell were abandoned to their unhappy fate. (P. 77.) They remained several days on these lofty plateaux, and in reference to this, the narrator adds: There are a number of observations which I greatly regret not having made while we were at these heights, and among them changes caused in the pulse, respiration, and body temperature. My travelling companions offered to submit to the boredom of having their temperature taken and their pulse counted at determined times, but I found that I already had too many irons in the fire. The few scattered observations which I made had no great value, but they prove clearly that, in me at least, altitude has only a slight effect, as the following figures show. I should say that numerous observations made on my companions gave similar results: Temperature Pulse Respir. under tongue Ordinarily 80 24 98.2 At Sakte, seated for several hours, 12,900 feet, July 9 90 25 98.3 Summit of Chang-La; 18,000 feet (5485 meters), July 10, after walk- ing to the summit 80 26 Lak Zung, more than 17,500 feet; July 24 (P. 79.) 75 24 97.8 The second part of the book is devoted to natural history. The ornithology is edited by A. O. Hume. I am quoting from it inter- esting observations on the habitat of birds at great altitudes: One of the points which seemed most striking to me in the observations of Dr. Henderson is the ease with which birds seem to live at great altitudes. Our friend the Cuckoo swings on the pendent branches of the birches, uttering his joyous song at an elevation of 11,000 feet, while snow covers the ground. The Lapwing seems at home at 18,000 feet (5485 meters), the "Kashmir Dipper", which lives above 13,000 feet, seeks for insects in half -frozen torrents; the "Guldenstadt's Redstart" hops carefree in the snow at 17,800 feet; the Montifringilla haematopygia seems to live permanently between 14,000 and 17,000 feet, and the "Adams' Finch" is common at 13,000 feet. The long-beaked tufted Lark is in places from 12,000 to 15,000 feet, while the Mongolian "Dottrel" and the "Ruddy Shieldrake" live at 16,000 feet, and the brown-headed "Gull" at 15,000. (P. 163.) 160 Historical I shall end this long series of quotations with an extract from the work which Fr. Drew L'43 recently devoted to the geography of Jumnoo and Cashmere. In the description of the lofty valleys of Ladak, Drew begins with that of Rupshu, the average elevation of which is from 14,000 to 15,000 feet (4270 to 4570 meters) ; the line of perpetual snow there is at about 20,000 feet. A wretched tribe, of one hundred tents, lives there, the Rupshu Champas. In a special section the author discussed the influence of the rarified air: At great elevations, in addition to the oppression and the short- ness of breath, one feels headaches and nausea, as happens at the beginning of fever or seasickness, but with no modification in the temperature of the body. In some persons, at high levels, vomiting occurs, but has no serious consequences, and the patient recovers when he descends to lower regions, provided however, that the organs are not diseased; rarity of the air generally reveals lesions of the lungs or heart. The elevation at which these symptoms are observed varies in a peculiar way, and it is not easy to find the cause of these inequalities. The condition of the health has a great deal to do with it; a man in good condition can endure a much higher elevation than a man who is not accustomed to exercise. That is evident first when one exerts himself a little more than usual, as in running or climbing some hill; under these conditions, in persons who live above 6,000 feet the symptoms usually appear at 11,000 or 12,000 feet. At 14,000 and 15,000 feet, there sometimes appears what may be called an attack of short- ness of breath, even when one is resting. The first time I visited Rupshu, that happened to me during the night, when I had been in bed about a half -hour; but after a week, I overcame this tendency, and since then I have not felt any difficulty in breathing while I was resting, even when I camped 2,000 or 3,000 feet higher. Likewise I knew a native of Punjab, unused to muscular labor, it is true, who had an attack at 11,000 feet. But although one can become accustomed to the rarity of the air to a certain extent, and not feel it at all, the slightest effort will bring on its effects. At 15,000 feet, climbing the gentlest slope makes one more breathless than scrambling up a very steep hill at a lower altitude. Talking or walking, even on a level, soon produces breath- lessness. When one is at great elevations— and here every thousand feet make a great change — climbing a slope is a painful labor. I have crossed a pass at an elevation of 19,500 feet which lower would have caused no trouble; and yet at every 50 or 60 steps, I was absolutely forced to stop, panting, to get my breath; but yet I did not feel any headache or other painful symptom; acclimatization to the mountains for a month or two permitted me to sleep under these conditions. (P. 291.) Mountain Journeys 161 9. Africa. Atlas. — Several summits of the Atlas in Morocco, which were 11,000 to 12,000 feet high, were visited by Dr. Hookes,244 in 1871; he does not mention any symptoms. Kamerun Mountains. — The first ascent was made December 22, 1861, by Burton. In the account 24r> of it which he published immediately he mentions some strange discomforts which should very probably be explained by the influence of the altitude: While I was ascending the volcano, I was so tired that I could not keep my eyes open; I felt a distress which seemed to me to be due to fever. I was obliged to rest, I slept an hour, and at four o'clock I was able to make this ascent. (P. 79.) The general account 24G which he published later of his journeys to the Kamerun Mountains and Fernando Po is no more definite: M. Saker then complained of complete deafness. The burning heat removed all sensation. Perhaps it was aided by the rarefaction of the air. However we were not surprised at suffering so little in the course of our ascent from the discomforts of which so many travellers to Mont Blanc and in the Rocky Mountains complain. (Vol. II, p. 121.) We must note that they were then only at 7000 feet; but the next day they finished the ascent of the great Peak: As we approached the summit, the difficulties of the ascent in- creased. Kharah dropped on the ground, almost fainting under the rays of a burning sun, and was forced to remain there. At half-past one, I reached the summit of the peak. (P. 155.) January 13, 1862, another ascent by MM. Calvo, Saker, and Mann (P. 162-181). No symptom noted. But in the account of it published by Mann,'47 he declares that "he was sick on the Albert Peak and compelled to descend" (P. 23) . Finally, January 29, 1862, ascent of Burton. He camped at 10,187 feet, and reached the cinder cone of Mount Albert: I noted again the complete absence of any suffering due to the thinness of the air. The altitude is considerable, but not sufficient, it appears, to cause the hemorrhages from the ears and lips expe- rienced by von Humboldt in the Andes, or the sufferings of M. Gay- Lussac in his balloon. (Abeokuta, Vol. II, p. 198.) Kilimandjaro. — May 11, 1844, Rebmann -48 saw Kilimandjaro covered with snow. The mountain is "inaccessible, the natives say, because of the evil spirits which had killed a great many of those who had attempted to ascend it." (P. 276.) 1 62 Historical So he could not attempt an ascent. In 1861, Baron de Decken reached an elevation on the sides of the immense mountain which Thornton,"41' his companion, esti- mated as 22,814 feet (6952 meters). November 27, 1862, he was able to ascend high enough to feel some discomfort. Dr. Kersten,250 who accompanied him, reports that they stopped at 4223 meters, because of the cold, before reaching the snow line: The ascent (he says) continued to be fairly difficult, and we were often forced to stop short. Anamouri, one of the men whom we had hired, was also indisposed. (P. 36.) Baron de Decken 250 expresses himself more definitely on the effect of the altitude: When I had reached a height of 4225 meters about quarter past eleven, I stopped, as I was forced to do, since my servants could go no further without danger of pains in the chest. Dr. Kersten also felt the effects of the rarified air. (P. 49.) And last, October 30, 1871, New-'1 ascended Kilimandjaro to the snow line: My men abandoned me, complaining of the cold. I continued with Tofiki alone. All went well for an hour and a half; but then Tofiki collapsed, hardly able to speak. He urged me to go on, telling me that he would wait for me, but that he would die if I did not return. 1 went as far as the ice, broke off some pieces of it, and descended at once. Yes, snow in Africa, he cried with enthusiasm! What ideas this undeniable evidence must have given the learned editor of the Nouvelles annates des Voyages who, in 1849, denied that Reb- mann could have seen snow on Kilimandjaro. 10. Volcanoes of the Pacific. Borneo.— The highest peak of this vast island appears to be Kini-Ballu, the height of which (4175 meters) is almost that of Jungfrau. The first attempt to ascend was made March 11, 1851, by Low.--" He did not get above 2850 meters, and considered that the summit, which he estimates at 13,000 or 14,000 feet, is "inaccessible for any one without wings." And yet, in April, 1858, he reached the summit, accompanied by M. Spencer Saint- John. The latter felt the effects of the rari- fied air very slightly, as his account shows: Mountain Journeys 163 During the ascent (says Spencer)2" I suffered slightly from short- ness of breath and felt some sluggishness in moving. But hardly had I reached the summit when the symptoms left me, and it seemed to me that I was lighter, that I could float in the air. The thermometer at the summit registered 62°F. (Vol. I, p. 271.) In June, 1858, second ascent of the same traveller. This time, he did not say a word about physiological symptoms. In another part of the island, another English explorer, Brooke,-54 ascended Tabalau Indu in March, 1858. It is difficult not to attribute to the altitude a part of the causes of this ikak of which the natives speak and which one of his companions experienced: The climb was hard; the heat was excessive; every step seemed the last one could make .... We reached the summit and rested there with satisfaction. Poor X . . . was in great distress and lay down on his back, while some of his servants went to seek "the friend of the traveller", a very abundant root, from which they squeeze a cool liquid with a slight taste of wood. It is a great mistake to drink, for one has constant thirst, and is attacked by what the natives call "ikak", a painful oppression in the chest, with difficulty in breathing. (P. 305.) Malacca. — In his ascent of Mount Ophir, Braddel 255 experi- enced some discomfort: When I was near the summit, I had a violent headache and severe throbbing in my temples; I bathed my brow with brandy, which relieved me .... But I felt a peculiar fatigue and stretched out on the ground. (P. 87.) Japan. — The first ascent of Fuji-yama of which I have found an account was made in 1860 by Rutherford Alcock.L' '■ He esti- mates at 14,177 feet (4320 meters) the height of this volcano which has been extinct since 1707. It took him eight hours to reach the summit; and he definitely felt the effect of rarefaction of the air: The second half of the ascent was much more difficult .... The air became very rare and evidently affected respiration .... It took more than one hour of struggling, stopping frequently to breathe and to rest our legs and our backs, which pained us; when we reached the top, we were absolutely at the end of our strength. The temper- ature was 54° F. (P. 344.) Gubbins,257 who ascended the volcano August 10, 1872, com- plains only of fatigue. But Jeffreys,-"* whose ascent was on May 4, 1874, mentions clearly real symptoms of decompression, attacking even the natives: 164 Historical As we were painfully climbing, a strong desire to sleep seized us, and the coolies could not resist it when we stopped. One of them was even unable to go on and we had to leave him on the way. We ended the ascent with great difficulty, and reached the summit at noon exactly. (P. 172.) Kamschatka.— The only known ascent of the highest volcano of Kamschatka, Klioutchef (4805 meters), was made by Ermanr":' September 10, 1829. He does not mention any physiological disturbance. Hawaii.— June 15, 1825, for the first time Europeans ascended Mauna Kea, the "White Mountain" (4195 meters); they were a missionary and some officers of the English vessel Blonde. The commander Byron"00 says in narrating this expedition: The lieutenant and the purser were so overcome by sleep that they lay down on the bare rocks to rest. Lord Byron in his turn ascended June 27; but he speaks of no discomfort. January 12, 1834, ascent of Mauna Kea by David Douglas,-61 and January 29, of Mauna Loa, "the Great Mountain" (4250 meters) : no mention of physiological disturbances. Same silence on the part of Loevenstern,-0- who ascended Mauna Loa in Janu- ary, 1839. Anyway, his account contains only a few lines. The great expedition which the government of the United States sent around the world under the command of Wilkes made a long stay in Hawaii. From December 21, 1840, to January 13, 1841, Wilkes and several of his officers camped on the side of Mauna Loa; several times they reached its highest point. It was not with impunity that they lived thus for three weeks at such heights; while they were ascending, they suffered severely: The thermometer had dropped to 18°, and many of our men were severely affected by mountain sickness, with headache and fever, so that they were unable to do anything. I myself suffered greatly from it, with violent throbbing in my temples, and short, painful, and distressing breathing. (P. 149.) Officers, sailors, and natives reached with countless difficulties the foot of the terminal crater, at 13,440 feet (4095 meters) . The next morning, their distress was somewhat abated. The camp was kept at this great height for three weeks, and the detailed account of the geodetic and physical operations in which they were engaged shows that they suffered frequently from mountain sickness: Mountain Journeys 165 Everyone experienced it more or less. Dr. Judd remarked that in the natives the symptoms were ordinarily colics, vomiting, and diarrhea; one or two were affected by the spitting of blood, some had fever and chills. Almost all of us had yellowish skin, headache, and vertigo, some had asthma and rheumatism .... Dr. Judd also found that patients were very hungry without being able to eat. During the day, the least exercise increased the pulse rate of all of us by 30 to 40. (P. 177.) Since that time, I have found in the accounts of the travellers 264 who have ascended the volcanoes of Hawaii or Maui no mention of physiological distress. I See Jourdanet, Influence de la pression do I'air sur la vie de I'hommc. Paris, 1875. Vol. If P- 212. . , -Relation vcridique de la conqnetc du Perou: in Collection de voyages pour servir a Vhistoire de la decouvertc dc t'Amaiquc, by Ternaux-Compans, Vol. IV, Paris, 1837. _ 3 Histoire d,es querres civiles des Es'pagnols dans les Indcs. Translation of Baudoin, p. 200. Paris, 1650. (The original work was published in Cordova in 1613.) Book II, Chap. XX. Vol. I. • 4 Histoire veritable d'un Voyage curicnx dans VAmeriquc, from 1534 to 1554. In the Ternaux-Compans collection, Vol V. 5 Acosta (Jose de) Historia Natural y Moral de las Indias: en que se trata de cosas notables del Ciclo, d.e los elementos, mctalcs, plantas, v animales, etc. (Seville, 1590) ''■Historia general de los Hcchos do los Castcllanos en las islas y ticrra firme del mar Oceano. Madrid, 1615. Decada V. Book X. Chap. V, Vol. Ill, p. 20, I. 7 New edition, Vol, VI, VII, VIII, IX. Paris, 1781. 8 Relation du voyage de la mer dit Sud aux coles du Chily ct du Perou, made during the years 1712. 1713, and' 1714. Paris, 1716. 0 Relation abregce du voyage fait au Perou, par M. M. de I Academic royale des sciences, pour mesurer les degres du meridicn aux environs de I'cquateur, et en conclure le figure dc la terre. Memoires de VAcademie des sciences de Paris, 1744, p. 249-297. 10 Journal du voyage fait par Vordre du Roi, a I'cquateur. 2 vol., Paris, 1751. II Memoires philosophiques. historiqucs, physiques, concemani la decouverte de VAmeriquc. French translation, Vol. I, 1787. 12 Voyage aux regions equinoxialcs du nouvcau continent, fait en 1700-1804. Paris, 1814. 13 Leitre de M. Humboldt adrcssce an citoven Delambre. datee de Lima, November 25. Ann. du Museum d'histoire naturellc. Vol. II. p. 170-180, year XI (1803). 14 Extrait de plusicurs lettres dc M. dc Humboldt. Ann. du Museum, Vol. II, p. 322-337, year XI (1S03). 15 Von Humboldt (Alexander), Notice sur deux tentatives d'ascension au Chimborazo. Annals of Chemistry; second series: Vol. LXIX, p. 401-434; 1838. Translated by Eyries from the Jahrbuch de Schumacher for 1837. 1(1 I could not find this statement in Zumstein's accounts. 17 Tableaux de la nature, translated by Eyries. Paris, 1828, Vol. II. 18 Histoire contemporainc de I'Espagne. 2 vol. Paris, 1869. 19 Gervinus. Histoire du dix-ncuvicme siecle, Mirssen translation, Vol. VII. Paris, 1865. 2" Historia dclla Rcvolucion hispano-amcricana. Madrid, 1830. 21 Carta descricion dc los viages hcchos en America par la Comision cientifica mandada par el Gobicmo Espanol. durante los anos 1862, 1866. Madrid, 1866. 22 Sketches of Bucnos-Axres. Chile, and Peru. London, 1831. 23 Travels in Chile and la Plata. 2 vol. London, 1826. 24 Travels in South America, during the years 1819-20-21. 2 vol. London, 1825. * Travels into Chile over the Andes, in the years 1820 and 1821. London, 1824. 20 Narrative of a journey across the Cordillera of the Andes, in the years 1823 and 1824. London, 1824. 27 Rough notes taken during some rapid journeys across the Pampas and among the Andes. London, 1828. 28 Journal of a passage from the Pacific to the Atlantic. London, 1829. ^Journal of a voyage to Peru. London. 182S. 30 Itineraire de Valparaiso a Buenos-Ayres. published in the second volume of the Journal de navigation autour du globe, of Bougainville. Paris, 1837. 31 Travels in various parts of Peru including a year's residence in Potosi. 2 vol. London, iaso. 32 Observations on the geography of southern Peru, including survey of the Province of Tarapaca, and route of Chile by the coast of the Desert of Atacama. Journal of the Royal Geographical Society. London, vol. XXT. p. 00-130; 1851. 33 D'Orbigny, Voyaqc dans VAmeriquc meridionale, made during the years 1826-1833, 7 vol. Paris, 1835-1847. 34 Reise in Chile, Peru, und auf dem Amdsonenstrome, wahrend der Jahre 1827-1833, 2 vol. Leipzig, 1836. 35 Ascension au Cliimboraco, made December 16, 1831. Ann. de Mm., second series, vol. LVTTT. p. 150-180; 1835. "i; Reise urn die Erde. in den Jahren 1830-32. Berlin 1835. vol. II. "Narrative of the voyages of Adventure and Bcaqle; 1826-1836, third volume; Journal and remarks. London, 1832-1836. 166 Historical 38 Narrative of a journey from Lima to Para. London, 1836. 38 Practical observation on the diseases of Peru, deseribed as thev occur on the Coast and in the Sierra. Edinburgh Med. and Surg. Journal, vol. LIV, LVI, LVII, LVIII, 1839. 1841. 1842, 1843. *" Fragment d'un voyage dans Ic Chile el an Cusco. Bull, dc la Soc. de geogr. Second series, vol. XIX, p. 15-57; 1843. 41 Peru, Rciseskizzen aus den Jahrcn J838-1842. 2 vol. Saint-Gallen, 1?46. 42 Expedition dans les parties centrales de I Amerique du Slid. Hist, du voyage, vol. Ill and vol. IV. Paris, 1851. 43 Voyage a travers V Amerique du Sud, de V Ocean Pacifique a focean Atlantique. Paris. 44 The U. S. naval astronomical Expedition to the southern Hemisphere during the years 1819 - 185(?) 2 Chile, Philadelphia, 1859. 46 Report of a journey across the Andes, between Cochabamba and Chirnore. J. of the royal geographical Society, vol. XXIV, p. 259-265; 1854. *a Voyage dans le nord de la Bolivie et les parties voisines du Perou. Paris, 1853. 47 Voyage dans I' Amerique du Sud, Perou et Bolivie. Paris, 1861. 48 Rclse durch die La Plata-Staatcn. ausgefuhrt in den Jahren 1857-1860. 49 Travels in Peru and India. London, 1862. 50 Description geographique et statisiiquc dc la confederation argentine. 3 vol. Paris. 1860-64. 51 Mouqueron's translation. Paris, 1863. 52 Dc la phthisic pulmonaire dans ses rapports avee I' altitude et avee les races au Perou el en Bolivie. Du soroche on mal des inoutagncs. Thesis of Paris, 18(32. 53 The reference is to Castelnau. r'4 Relatione dclla gita da curico net Chili a sun Raphael nclla Pampa del sur ( febraio 1866). Parma. 1869. 55 Rcise iiber die Cordilleren von Arica bis SaniOrCrus. Extrait in Petermann's Mitthcil- nngen, Vol. XI; 1865. 56 Exploration du cratere du Rucii-Pichincha. Nouv. ami. des voyages, Vol. CVII, p. 106-112; 1845. r'7 Ascension du Pichincha. Chalons- sur-Marne, 1858. 58 Remy (Jules) et Brenchley, Ascension du Chimborazo. Nouv. ann. des voyages, Vol. CLIII, p. 230-238; 1857. 50 Voyages au Chimborazo. a i Altar, et ascension au Tunguragua, letter of April 18. 1873. Bull, de la Soc. de geogr., sixth series, vol. VII. p. 258-295; 1875. '*> Journey of M. Wafer, in which is found the description of the isthmus of America; inserted in volume IV of the Voyage aux tcrres Australes, of G. Dampier. Rouen, 1715. 61 Voyage geographique aux republiques de Guatemala et de San Salvador. Paris, 1868. MAufenthalt and Reisen in Mexico in den Jahren 1825 bis 1834. Stuttgart, 1856. 63 Recherches de Pathologic comparee. Cassel, 1853. 04 Jourdanet, Prcssion dc Vair, vol. I, p. 212. *'"• L. \Y. Glennie, The ascent of Popocatapetl (sic). Proceedings of the geolog. Soc. of London, vol. I, n. 7.3; 1834. m Gros (baron), Ascension au sommet du Popocatepetl. Letter of May 15, 1834. Nouv. ann. des voyages, vol. LXIV, p. 44-68, 1S34. 67 Ascension du volcan du Popocatepetl (mountain of smoke) in September, 1856. Nouv. ann. des voyages, vol. CLIII, p. 304-317; 1857. 08 Recit d'une ascension du Popocatepetl, by MM. A. Dollfus, de Montserrat and Pavie, Archives de la Commission scicntifique du Mexique, vol. II, p. 187-201. Paris, 1866. 69 Reisen in den Vcreinigtcn Staaten, Canada und Mexico. Leipzig, 1S64. 70 Attempted ascent of Orizaba. Alpine journal, vol. Ill, p. 210-214. London, 1867. 71 Report of the exploration to the Rocky Mountains in the year 1842. Washington. 1845. 10 Reports of explorations and surveys to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean. Vol. II. Washington, 1855. 73 Ascent of Mount Hood. Extract in Proceed, of the Roy. Geogr. Soc. vol. Ill, p. 81-84; 1867. 74 Petermann's Mitthcil., vol. XIV, p. 151; 1868. 75 Mountaineering on the Pacific. Alpine journal, vol. V, p. 357-367. London, 1872. 76 Ibid., vol VI, 192-193; 1874. 77 Opere, vol. 4. Venet, 1729. 78 Aetnac topographia; in Thesaurus antiq. sicul. Lugd. Bat., 1728. 70 De Rebus siculis. Catane, 1749. 80 De motu animalium. Pars altera. Rome, 1681. . 81 Voyage dans la Sicile et dans la grande Grece, addressed by the author to his friend, M. Winckelmann; translated from the German (without author's name). Lausanne, 1773. 82 Voyage en Sicile et a Malthe, vol. I, p. 225. Amsterdam, 1775. 83 Voyage pittorcsque des isles de Sicile, de Malthe, et dc Lipari, vol. II, p. 103. Pans. 1784. 84 Voyage en Sicile. Paris, 1788. . . 85 Relation d un voyage fait depuis pen sur ce volcan: in J/oyagc pittorcsque ou description du royaumc de Naples et de Sicile, by the abbe Saint-Non. Fourth volume, p. 91-104. Paris, 1785. 80 Built by Empedocles, according to the legend. (See Fazello, loc. cit., vol. I, p. .) 87 Voyages dans les deux Sidles, translated by G. Toscan, Vol. I, Paris, year VIII. 88 Descrisione dell' Etna. Palermo, 1818. ^Voyage critique a I' Etna, en 1819, vol. I. Paris, 1S20. 90 Souvenirs de la Sicile. Paris, 1823. 91 Note sur les effets physiologiques de la rarefaction de Vair a de grandes hauteurs, boc. philomatique, p. 120-122; 1822. . . 92 "In the midst of it is seen a very steep, round mountain which they call Pico de Teithe. the topography of which is as follows: its peak is very steep and includes 15 leagues, which amount to more than 45 English miles." Description des Canaries, by the Englishman Nicols or Midnal; in Traite de la navigation, by Pierre Bergeron, preface to Voyages faits en Asie dans les douzicmc, trcizicmc, quatorzicmc at qninziemc siccles, vol. I, p. 119. La Haye, 1735.. Mountain Journeys 167 M A Relation if the Pico Teneriffe received from some considerable merchants and men worthy of credit, who went 'to the top of it. History of the Royal Society of London, by Th. Sprat, third edition. London, 1722, p. 200-213. 94 Philos. Transac, Sept. 12, 1670. Vol. XXIX, p. 317-325, 1717. 95 An account of a journey from the port of Oratava in the Island of Teneriff, to the top of the Pic in August 1715. Mem. of the Royal Soc. of London, second edition, vol. VI, p. 1,2-1,7. London, 1745. M Memoirs of the Academy of Sciences of Paris for 1746, p. 140-142 97 The History of the Discovery and Conquest of the Canary Islands. London, 1,64. 9> Relation d'un vovage a la recherche de la Perouse, made by order of the Constitutional Assembly, during the years 1791-1792 and during the first and second years of the French Republic. Paris, year VIII. , .,„._., VT 99 Essais sur les isles Fortunees et I'antique Atlantide. Paris, Germinal, year XI. ^""Voyage aux regions equinoxiaJes du nouveau continent, vol. I, p. 123-145. Paris, I814- 101 Lettre au citoven Devilliers fils. Journal de phvs., de chim. et d'hist. not., vol. LVII. p. 55-63; 1S03. _ . ^Description physique des iles Canaries, Translated by Boulanger. Paris, 1836. 103 Voyage de i Astrolabe, made during the years 1826-27-28-29. Histoire du voyage, vol. I; Paris. 1830. 104 Voyage au Pole Slid. vol. I. Paris ,1841. , i<>5 Voyage around the world of the Astrolabe and the Zelee, under the command of Dumont d'Urville. Paris, 1S42. . 106 Voyage geologique aux Antilles et aux iles de Teneriffe et de Fogo. Paris, 1S4S; vol. 1, p. 65-79. '"'Journal d'un voyage en Chine in 1843, 1845, 1846. Paris, 1S48, 3 vol. 108 Sixteen rears of an artist's life in Morocco, Spain, and the Canary Islands, 2 vol. London, 1859. „„_ _ , . Al . 109 Vie de Jean d'Aranthon eve que d'Alex, de 1660 a 1695; Lyons, 1,67. Quoted in the Guide ■ itineraire du Mont-Blanc, of V. Payot. Geneva, 1S69; p. 161. 110 Eletnenta physiologiae, vol. Ill, p. 197. Lauzanne, 1761. 111 Disquisitiones physicae de meteoris aqueis. Pars prima. Tiguri, 1786. iriDie Bergkrankheit. Le.ipzig, 1854, p. 71. 113 Nouvelle description des glaciercs et glaciers des Alpes, second edition. Geneva, 3 vol.; 1785. 114 Tableaux topographiques, etc de la Suisse, vol. I. Paris, 1,80. 115 Voyages dans les Alpes, 4 vol. Geneva; 1786-1796. 110 The exact height is 3655 meters. "''Narrative of a journey from the village of Chamouni, in Switzerland, to the summit of Mount Blanc, undertaken on Aug. 8, 1787. Thomson's Annals of Philosophy, vol. IX, p. 97-103; 1817. 118 Letter from M. Bourrit to the editor uf the Bibliothequc britannique. Biblioth. but. de Geneve, vol. XX. p. 429-433; 1802. ii» Vovage an Mont-Blanc. Vienna, Gerald Company. 1211 BibHo-thcque universelle de Geneve, vol. IX, p. 84-89, 1818. l* Notice sur un voyage au sommct du mont Blanc, ibid., vol. XIV, p. 219-234, 1820. vsi Relation de deux tcntatives rccentes pour monter sur le mont Blanc. Bibliotheque universelle de Geneve, vol. XIV. \>. 3U1-323; 1820. Hamel has since published a more detailed account of his journey, with historical notes, under the title of Beschreibung zweier Reisen auf den Mont-Blanc. Vienna, 1821. 123 Hamel makes a mistake here; he was still about 700 meters from the summit (Lepileur). 124 Notice sur une nouvelle ascension au mont Blanc. Biblioth. univ. de Geneve, vol. XXI. p. 68-75, 1822. 135 Details dune ascension au sominet du mont Blanc, Ibid, vol. XXIII, p. 137155 and 237-244, 1823. *** D. Clark and Capt. Sherwill, Qitclques details sur leur expedition au mont Blanc. Biblioth. univ. de Geneve, vol. XXX, p. 245-246, 1S25. ,2f Ascension du mont Blanc en 1827. Nouv. ami. des voyages, vol. XL. p. 265-269, 1828. 12s Reise auf die Eisgebirge des kantons Bern und Ersteigung ihrer hochstergipfel in sotnmer 1812. Aarau, 1813. 129 Dr. Parrot. Ueber die Schneegranse auf dcr mittaglichen scite des Rosagebitrges und barometrische Messungen. Schweiggers journal fur chemie und physik, vol. XIX, p. 367-423, 1817. i3o They are told verbatim in the Bibliothequc universelle, vol. XXVIII, p. 66-77, 1825. Zumstein's notes were published in Vienna in 1S24, by Baron von Welden, in a book entitled: Der Monte Rose, which I could not procure. I am borrowing the preceding details from an article published by M. Briquet under the title of Ascnsions aux pics du mont Rose. (Bibl. univ.. vol. XII. p. 1-47; 1861.) 131 Naturhistorische Alpenreise. Solothurn, 1830. lxlApercu sur la topographie medicale de V hospice du mont Saint-Bernard. Nouveau jour- nal de Med.. Chim.. Pharm. etc. vol. VII, p. 29-37; 1820. 133 Ascent to the summit of mont Blanc, Sept. 16-18, 1834. Edinburgh new philos. journal, vol. XVIII, p. 106-120; 1835. 134 Ascension au mont Blanc, translated from the English by Jourdan. Geneva, London, 1838. 135 Influence on the human body of ascents of high mountains, Revue medicale, 1842; vol. IV, p. 321-344. 130 Excursions et sejours dans les glaciers et les hautes regions des Alpes, of M. Agassiz and his travelling companions. Neufchatel, Paris, 1844. 137 Revue Suisse. Neufchatel, June, 1843. 138 Journal d'une course faite aux glaciers du mont Rose et du mont Cervin. Biblioth. univ. de Geneve, Second series, vol. XXVII, lS4fl. 139 Ausflug nach dem Aletsch Eismeer und Ersteigung dcr Jungfrau (4167 m.). Quoted in extenso in Materiaux pour Vetudc des glaciers, by Dollfus-Ausset. vol. IV. 1864. 140 Beobachtungen iibcr den Einfluss der verdunnte Lit ft und des stdrken Sonnenlnhtes auf holier Gebirgen, etc. Osterreich. med. Johrb. N. Folge, vol. XXXII; 1843. 168 Historical »« Travels through the Alps of Savoy.— Edinburgh, 1843. , . . i4aMetn. sur les phenomenes physiologiques, observed on ascending to a certain neiRnt in the Alps. Revue medicate, 1845, vol. II. AT . , 143Z?-24S, 1872. 167 Philosophical transactions, Sept. 12, 1670. las Description des Pyrenees, 2 vol.— Paris, 1S13. urn He even spat blood, according to Gondret (Mem. concernant les effets de la pression atm. sur le corps humain; Paris, 1819. (P. 44.) _ 170 Voyage au sommet du mont Perdu.— Ann. du Museum d'historie naturelle, vol. Ill, 1804. 171 Tableau des Pyrenees francaises, 2 vol.— Paris, 1828. 17- Rapport fait au Counseil des mines sur un voyage a la Maladctta, par la vallee de Bagne'res-de-Luchon.— Journal des Mines, Messidor, year XII, vol. XVI, p. 249-282; 1804. 173 Ueber die Beschleunigung des menschlichen Pulses nach Maaszgabe der Erhohung des Standpunkets uber der Meeresfldche.—Frorieps Notizen, vol. X; 1825. *74 Voyage a la Maladctta.— Paris, 1845. 175 Recueil des ascensions au pic du Nethou, from 1842 (first ascension) to 1868.— Bull, de la Societe Ramond, 1872, p. 15-24, 193-198; and 1S73, p. 49-58. 718 Ford, A Hand-Book for travellers in Spain— London, 1847. 177 Voyage au mont Caucase et en Georgie— Paris, 1823. 178 Voyage a la vallee du Terek. N. Ann. des Voyages, vol. LI, p. 273-324; 1S31. 179 Voyage dans les environs du mont Elbrous dans le Caucase, undertaken in 1829.— Report made to the 'imperial Academy of Sciences of St. Petersburg— St. Petersburg, 1630. 1S0 Voyage dans les rallies centrales du Caucase, fait en 1836 et 1837.— N. Ann. des Voyages, vol. CXVIII, p. 276-328, 1848. w , ^ttt n_ 181 Reisen und Forschungen im Kaukasus, 1865.— Peterm. Mitth, vol. X11I, 1867 182 Journey in the Caucasus, and Ascent of Kasbek and Elbrus.— The joum. of the royal oeogr. Society, vol. XXXIX, p. 50-76; London, 1869.— Itinerary of a Tour in the Caucasus: Alpine Journal, vol. IV, p. 160-166; London, 1870.— The Caucasus, by C. Tucker (Ibid. 421-42f>.) »m Itinerary of a Tour in the Caucasus made bv F. Gardiner, F. C. Grove, A. W. Moore and A. Walker, with Peter Knubel of St. Niklaus.— Alp. Journal, vol. VII, p. 100-103; London, 18(4. 1S4 An ascent of Elbrus.— Alpine Journal, vol. VII., p. 113-124; London, 1875. "-Voyages faits en Asie, dans les XII, III, XIV, et XV siecles— The Hague, 1735. 180 Philosophical transactions, Sept. 12, 1670. 187 Relation d'un voyage du Levant, 2 vol.— Paris, 1717. WReise sum Ararat.— Berlin, 1834. 189 Magasin fur die Litteratur des Auslandes; 1835, no. 34. 190 Gazette russe de I' Academic ; 1838, nos. 21, 23. 191 Journal le Caucase; 1846. nos. 1, 5 7. r-vvv ™* Journal le Caucase; 1850, no. 50.— Translated in Nouv. Ann. des Voyages, vol. CAAA. p. 334-349; 1851. _ , ™3 Reisen im Armenischen Hochland in Sommer 1871— Second part: West— Peterman s Mittheilungen, 1873. 194 Notice d'un voyage dans I'Asic-Mincure, faite en 1837.— iV. Ann. des Voyages, vol. LXXXI, p. 153-196; 1839. 1913 An Account of the Ascent of Mount Demavend, near Tehran, in September, 1837.— Joum. of the R. geograph. Soc, vol. VIII, p. 109; 1838. 1M R. F. Thompson and Lord Schomberg H. Kerr, Journey through the Mountainous Dis- tricts North of the Elbruz, and Ascent of Demavend, in Persia.— Proceedings of the royal geograph. Soc. vol. Ill, p. 2-18; 1859. 197 Great mistake; the height of Demavend is 5620 meters. Mountain Journeys 169 19SiLe livre de Marco Polo, citoyen de Venise, drawn up in French at his dictation, in 1(208, by Rusticien de Pise.— Published by Pauthier. Paris, 1865. 199 Purdon On the Trigonometrical Survey and Physical Configuration of the valley of Kashmir.-], of R. Geogr. S., vol. XXXI, p. 14-30; 1S61. . 200 Memioires stir les contrecs o Ascension du Kilimandjaro, dans I'interieur de I Ajnque oncntale. N. Ann. aes Voyaqes; 1864, vol. I, p. 28. 251 Alpine Journal; vol. Vi, p. 51-52.— London, 1874, issue of April, 1872. *^ Notes of an ascent of the mountain Kina—Balozc (The Journal of the Indian Archi- pelago. Vol. VI, p. 1-17). — Singapore, 1852. 253 Life in the forests of the far East. 2 vol.— London, 18S2. 254 Ten vears in Sarawak.— London, 1866. 255 Note's of a Trip to the interior from Malacca. The Journal of the Indian Archipelago, vol. Vi, p. 73-104.— Singapore, 1853. «" Narrative of a joumev in the interior of Japan, in I860— The Joum. of the R. Gcograph. Soc., vol. XXXI, p. 321-356; 1861. „ tt m n ™ Ascent of Fuji-Yama. Proceedings of the Royal Geogr. Soc, vol. XVII, 1873; p. -8- .9. ** Ascent of Fuji-Yama in the Snow. Proceedings of the Royal Geogr. Soc, March 18.o: '"MReise urn die Erde, in die Jahren 1828; 29 und W.—Historique, third vol., p. 363 et seq. w I'ovage of H. M. S. Blonde to the Sandwich Islands in the years 1824-1825.— London. 1826. 261 Extract from a private Letter addressed to Captain Sabine— Journal of the R. Geograph. Soc. vol. IV, p. 333-344.— London, 1834. 282 Apercu dun viyage autour du monde. Bull, de la Soc. de. Geogr., Second Series, vol. '*»' Narrative of' the United States Exploring Expedition during the years 1838, 39, 40, 41, 42, vol. IV.— Philadelphia, 1844. .. ■ 264 Sawkins, On the I'olcanic Mountain of Hawaii. Joum. of the Roy. Geogr. Soc, vol. XXV p 191-194; 1855. Robert Haskell, On a Visit to the Recent Eruption of Manna Loa. Hawaii. The American journal of science and arts. Second series, vol. XXVIII; 1859, p. 66-71. - Wilmot, Our Journal in the Pacific, London, 1873. Chapter II BALLOON ASCENSIONS At the end of the 18th century, the remarkable discovery of the Montgolfier brothers introduced a new element into the ques- tion of decompression. In this case, the traveller no longer climbs laboriously and slowly to the regions where rarefied aid can act upon his organism; he is carried there without fatigue and with great speed. We are not interested in the montgolfiers, or hot-air balloons, since ordinarily they can mount only to very moderate heights. We shall simply note that the first aeronauts, Pilatre du Rozier and the Marquis d'Arlandes, made an ascent November 21, 1783, and crossed Paris in a montgolfler. But the history of gas balloons is rich in data applicable to our subject. The first of December in this same year of 1783, the physicist Charles, who had just invented the hydrogen balloon, tested his invention under conditions much more stirring and dangerous than the two brave aeronauts just mentioned. This ascension, as we know, was divided into two periods: Charles, who left the Tuileries at 1:45, landed at 3:30 in the plain of Nesles; he let his companion Robert get out of the basket; then, lightened, his balloon rose again with extraordinary speed. In less than ten minutes he rose over 1500 fathoms; the barometer stopped at 18 inches, 10 lines. The story 1 of the clever physicist, filled with justifiable en- thusiasm, shows ,him as "questioning his sensation, listening to himself live, and having no disagreeable feeling in the first mo- ment." But soon: In the midst of the inexpressible rapture of this contemplative ecstasy, I was recalled to myself by a very extraordinary pain in the interior of my right ear and in the maxillary glands; I attributed 171 172 Historical it to the expansion of the air contained in the cellular tissue of the organ, as well as to the cold of the surrounding air .... I put on a woolen hood which was at my feet; but the pain vanished only when I reached the ground. This marvellous invention thrilled the whole world; the most ardent illusions about the practical utility of balloons were cher- ished. Among the strange ideas produced by these experiments in which man took possession of the air for the first time, one of the most curious is that which, less than a year after the first ascent, inspired a thesis sustained in 1784 before the Faculty of Medicine of Montpellier. Louis Leullier-Duche, its author,2 had the idea of using balloon ascension as a treatment of diseases. "The effect," he said, "will be triple: motion, cold, change of air." He insists especially upon this last point: The essential part of air is for man the dephlogisticated air (oxygen). Now in what proportion is it united with the phlogistic in the different regions of the atmosphere? Chemists have not deter- mined. But as the phlogistic is lighter, there must be more of it at a very great height .... The neighborhood of the earth is the proper region of the dephlogisticated air. But we cannot doubt that it is polluted there by different emanations of volatile bodies. And so, in that part of the atmosphere which is the region of dephlogisticated air, the latter is purer the further we go from the surface of the earth. Moreover, as it is colder, the dephlogisticated air is accu- mulated and condensed there. Leullier-Duche attributes the strongest curative virtues to oxy- gen, and considers that it acts even on generation and death: Births at Montpellier coincide with the spring months and deaths with the autumn months; during the spring, the atmosphere is more laden with dephlogisticated air which the growth of plants produces, and during autumn their putrefaction releases a greater quantity of inflammable or phlogistic air (he refers to nitrogen by this double name). Leullier-Duche then proposes to use balloons in the treatment of intermittent, pestilential, or nervous fevers, rickets, scurvy, hysteria, chlorosis, melancholy, slow healing sores, etc. We have seen that the inventor of the hydrogen balloon, in the first and only ascent which he made, experienced painful sensations when he had risen rapidly to a height of about 3000 meters. It was simply a matter of the expansion of the gases of the middle ear, gases which on account of the speed of the ascent had not had time to escape by the Eustachian tube. More serious symp- toms were soon to be observed. Balloon Ascensions 173 On the 12th of Brumaire in the year VII (see the Moniteur, p. 173), Testu-Brissy, mounted on a horse, rose to a considerable height. In a little book,' "dedicated to childhood", a curious engraving represents him on horseback on a platform supported by a cylin- drical balloon. After some details about the ascent of the adventurous aeronaut, the author, who says she knew him, declares that: The purpose of the scientist was attained; he discovered that at a degree of elevation where he himself was not at all affected, the blood of large quadrupeds, apparently less fluid than that of man, was forced out of the arteries and ran out through the nose and ears. Satisfied with this observation, he descended from the considerable height to which he had risen, and gave account of his expedition to the Institute with modest simplicity. (P. 95.) One can hardly attach much importance to this tale. Two years after the ascent of Charles, Blanchard, an aeronaut who died poor and obscure after enjoying prodigious popularity, whose statement, it is true, cannot carry much weight, claimed to have risen November 20, 1785, from Ghent, to a height of 32,000 feet (10,400 meters) : I rose with a rupture of equilibrium of 35 pounds .... In less than two minutes, I was more than 4500 feet from the earth .... The expansion of the inflammable air was such .... that I mounted to an incredible height, which according to the record of my instru- ment was 32,000 feet from the earth .... I sailed in the immensity of the air at the mercy of the winds, experiencing a cold which no mortal ever felt in the severest climates. Nature grew languid, I felt a numbness, prelude of a dangerous sleep, when rising in spite of my lack of strength, I called upon my courage, entered my balloon, and with the handle of my flag .... I broke the lower pole in pieces. (P. 7.) The result of this maneuver was a rapid fall, which ended happily after a series of curious incidents. Blanchard announced his ascent briefly in a letter,5 addressed to the Journal de Paris. It is evident that he mounted very high; but his observation or his calculation was certainly wrong. The astronomer de Lalande, who also dabbled in aerostatics, appeared quite doubtful. He wrote to" the publishers of this curious extract to refute the assertions of the vain aeronaut: 174 Historical Paris, December 7, 1785. Gentlemen: Probably a mistake slipped into the article which you published on the fifth of this month in regard to the ascent of M. Blanchard, made November 21 near Ghent; it says that he rose to 32,000 feet, which would make 5333 fathoms; the greatest height reached hitherto is 2434 fathoms, and the great expansion of the air would probably make it impossible to rise to or to breathe at a height which is more than double that .... At 2430 fathoms height the barometer is at only 16 inches. M. de la Condamine observed it at 15 inches 11 lines, but no man has seen it lower. If one could rise to 5441 fathoms, the barometer would stand at only 8 inches, and it is probable that hem- orrhage and death would soon be the result. De Lalande. There follows a table given by de Lalande, indicating the rela- tions between the barometric pressure and the altitude: 27 inches 158 fathoms 12 inches 11 inches 10 inches 3679 fathoms 4057 fathoms 4472 fathoms 16 inches 2430 fathoms 9 inches 4929 fathoms 15 inches 2710 fathoms 8 inches 5441 fathoms 14 inches 3010 fathoms 7 inches 6021 fathoms 13 inches 3332 fathoms By the way, Lalande reproduces this table in the Yearbook of the Bureau of Longitudes for the year 1805, then he adds: The last numbers will probably be eternally useless; human beings will never see the barometer at 11 inches, unless, by artificial means, they succeed in giving air to the lungs and lessening the pressure of the inner air. (P. 94.) In the Yearbook of 1806, the remark about the impossibility of reaching 11 inches is suppressed. The only statement is: The last numbers are probably useless: M. Gay-Lussac went only to 3584 fathoms. (P. 99.) Prudent correction, for 11 inches correspond according to Lalande to 4057 fathoms (7907 meters) , a height far surpassed since then, as we shall see, by Glaisher and Coxwell and by Gaston Tissandier. But let us return to Blanchard; he did not consider himself conquered, and replied haughtily in the Journal de Paris:7 Gentlemen: If I have not replied sooner to the letter written you by M. de Lalande about a so-called error in regard to my ascent at Ghent, in which I say I rose to the height of 32,000 feet, it is not for want of material; I shall not reply even today, intending to discuss his opin- Balloon Ascensions 175 ion at greater length in the collection of journals of my ascents which I intend to give the public. The nature of your paper, gentlemen, would not permit me so long a discussion. M. de la Condamine, says my illustrious antagonist, is the only man who has observed the barometer at the lowest level, and he observed it, he adds, at 15 inches 11 lines. It would be of no use to remind him that I said that I had seen it at 14 inches in my ascent from Lille with the Chevalier de l'Epinard, and lower yet in England, because, words not being proofs, he would be just as incredulous in the matter. Knowing all M. de Lalande's superiority, I shall take care to contend with him only with victorious arms; and as facts sometimes give the lie to the most careful calculations, I limit myself now to inviting him, as I have just done in a personal letter, to do me the honor of accompanying me in my next ascent; he will then be convinced that the best arguments have no effect against the cer- tainty of a fact. Yours, etc. Blanchard, Citizen of Calais, pensioner of the King. We know that de Lalande replied to the challenge. One should read in the Journal de Paris,8 his curious corre- spondence with Blanchard on this subject. On the 8th of Thermidor in the year VII, they both ascended with the famous flotilla of five balloons invented by the celebrated aeronaut. They hoped, by making use of currents, to go as far as Gotha "to see with delight" said Lalande, "a prince and a princess who, by their learning and their zeal for the sciences, give an example to everyone"; but alas! one of the balloons burst, and the astronomer and the citizen of Calais fell ingloriously into the Bois de Boulogne. But let us drop stories lacking precision and perhaps truth. We enter the domain of scientific attempts with the remarkable ascents of Robertson and, soon after, of Gay-Lussac. The most important ascent of the French physicist Robertson9 took place at Hamburg, July 18, 1803. He started at 9 o'clock in the morning, accompanied by M. Lhoest, his colleague and com- patriot; the barometer marked 28 inches, the Reamur thermom- eter 16°: During the different tests with which we were busied, we felt an uneasiness, a general discomfort; the buzzing in the ears from which we had for some time been suffering increased still more as the barometer dropped below 13 inches. The pain we felt was some- thing like that which one feels when he plunges his head below water. Our chests seemed expanded and lacked resilience, my pulse was hurried; that of M. Lhoest was less so: like mine, his lips were swollen, his eyes bloodshot; all the veins were rounded out and stood up in relief on my hands. The blood had rushed to my head so much that I noticed that my hat seemed too small. The cold increased 176 Historical considerably; the thermometer then dropped quickly to 2°, and stopped at 5V20 below freezing, while the barometer stood at 12 and 4/100 inches. Hardly was I in this atmosphere when the discomfort increased; I was in a mental and physical apathy; we could hardly ward off the sleep which we feared like death. Distrusting my strength, and fearing that my companion would succumb to sleep, I had fastened a cord to my thigh and to his; the ends of this cord were in our hands. It was in this state, not much adapted to delicate experiments, that I had to begin the observations that I was planning. (Vol. I, p. 70) ... . At this elevation, our state was that of indifference: there, the physicist is no longer sensitive to the glory and the passion of dis- coveries; the very danger which results from the slightest negligence in this journey hardly interests him; it is only by the aid of a little fortifying wine that he succeeds in finding intervals of mental clarity and power. As I wish to omit nothing that can cast light on the functions of the animal economy and the operations of nature at this elevation, I ought to mention that when the barometer was still at 12 inches, my companion offered me bread: I made vain efforts to swallow it, but never could succeed. If one considers carefully the state of the surrounding atmosphere, the great rarity of which offered only a slight resistance to my expanding chest; if one considers the small quantity of oxygen contained in the gas in which I was floating, one can believe that my stomach, already filled by a denser gas which was impoverished by the loss of oxygen, was in no state to receive solid food and still less to digest it. I must add that the natural excretions were checked in my friend and myself during the five hours of the journey, and that they were not resumed until three hours after our return to earth .... Seventh experiment. I had taken along two birds: at the moment of the experiment I found one of them dead, no doubt on account of the rarefaction of the air; the other seemed drowsy. After placing him on the edge of the basket, I tried to frighten him to make him take flight: he beat his wings, but did not leave his place; then I left him to himself, and he fell perpendicularly with extreme speed. There is no doubt that birds could not support themselves at this elevation. (P. 76) ... . One can estimate the height of the balloon, taking account of all the corrections, at 3679 fathoms (7170 meters).10 (P. 83.) The number of March 16, 1876, of the journal Les Mondes says on this subject: If, in one passage of his account, Robertson says that he mounted to 7170 meters, in another he says only 7075; calculating by the present tables of the Yearbook of the Bureau of Longitudes on the data of temperature and pressure registered by Robertson, we find only 6881 meters for the maximum height. (Ch. Boissay.) Robertson sent the account of his ascent and of the experi- ments in physics which he performed during it to the Galvanic Balloon Ascensions 177 Society; a report " was made from which we extract the following passage: We have known for a long time that an animal cannot pass with impunity from an atmosphere to which he is accustomed to one much denser or much rarer. In the first case, he suffers from the weight of the outer air, which has an excessive pressure; in the second case, the liquids or elastic fluids which are part of his system, since they are undergoing less than the usual pressure, expand and stretch the surrounding tissues. In both cases, the effects are almost the same, uneasiness, general discomfort, buzzing in the ears, and often hemor- rhages; the experiment of the diver's bell long ago indicated to us what would happen to aeronauts. Our colleague and his travelling companion experienced these effects with great intensity; their lips were swollen, their eyes bloodshot; the rounded veins stood out in relief on their hands, and — a very astonishing fact — they both dis- played a reddish brown complexion which surprised those who had seen them before their ascent. This distension of the blood vessels, in their farthest ramifications, must necessarily produce a hindrance, a constraint in all the muscular movements; and it is mainly to this cause that I think we should attribute the vain efforts made by our colleague to swallow the bread which his companion gave him when they were still at a height marked by 12 inches on the barometer. (Mem., Vol. I, page 106.) An aeronaut who was celebrated for being the first to descend from a balloon in a parachute (October 29, 1797), Jacques Garn- erin, tried to take from his rival Robertson the honor of the highest ascent. As the following extract from the Journal de Paris 1J proves, he claimed to have risen to 4200 fathoms (8186 meters). In the interest of the sciences and the arts, which barbarians have mutilated, M. Garnerin writes from St. Petersburg to Paris the account • of the aerial journey which he undertook at Moscow the third of last October, in which he rose exactly to the height of 4200 fathoms, without having experienced any symptom other than hemorrhage of the nose, and a little discomfort from the cold. Happy opportunity to entertain the public with his quarrels with M. Robertson, whom he calls "the aeronaut of Hamburg", and whose powers of observation and whose truth he questions! "I rose," says M. Garnerin, "521 fathoms higher than the aeronaut of Hamburg, and I did not notice that matter lost weight, nor did I see the sun without brilliancy, nor the sky without azure. I felt neither an extraordinary apathy, nor diffi- culty in swallowing, nor a desire to sleep, etc " Nothing seems less authentic than the statement of Garnerin; the data which we shall presently report show that at the height which he says he reached he would have experienced very serious physiological disturbances. 178 Historical In this same year, a very dramatic ascent took place at Bologna. Count Fr. Zambeccari, of Bologna, Dr. Grasetti, of Rome, and Pascal Andreoli, of Ancona, left during the night of the 7th-8th of October, 1803. They had spent the day in inflating their balloon, which measured 14,000 cubic feet, and intended to start the next day; but they had to hurry on account of the rioting and shouts of the populace of Bologna. The balloon rose with extreme rapid- ity, and they soon reached such a height that Zambeccari and Grasetti, overcome by the cold and exhausted by a series of vomiting, fell into a sort of torpor accompanied by a profound sleep. The brief account, inserted in the Annales de Gilbert,1 '■ tells their sufferings and misfortune as follows: Andreoli, who had retained use of his senses, could not read the barometer because the candle which they had brought in a lantern had gone out. About 2:30 in the morning, the balloon began io descend, and Andreoli heard distinctly the noise of waves breaking on the coast of Romagna. He awoke his companions .... The basket and the balloon fell into the Adriatic Sea with such force that the water dashed up around them to the height of a man. The aeronauts, covered with water, in great haste threw out a bag of sand, their instruments, and all that the basket contained. Then the balloon again rushed rapidly into the air. They tra- versed three strata of clouds, and their clothes were covered with a thick layer of ice; the air was so rarefied that they could hardly hear each other. About three o'clock the balloon descended again. The melancholy German pamphleteer Kotzebue,14 during his journey to Italy, called on Zambeccari, this man "whose eyes are thoughts". The daring aeronaut gave him a detailed account of this terrible ascension of October 7-8, in which he nearly perished: I rose at midnight .... Suddenly we mounted with inconceivable speed. We could observe the barometer only by lantern light, and that very imperfectly. The unendurable cold which reigns in the region to which we had risen, the exhaustion I felt from lack of food for 24 hours, the grief which overwhelmed my soul, this whole combination caused complete torpor and I fell on the bottom of the basket in a sort of sleep like death. The same thing happened to my companion Grasetti. Andreoli was the only one who remained awake and well, no doubt because his stomach was full and he had drunk rum abun- dantly. In fact, he too had suffered greatly from the cold, which was excessive, and for a long time made vain efforts to awaken me. Finally he succeeded in getting me to my feet, but my ideas were confused; I asked him, as if I had been dreaming: "What's the news? Where are we going? What time is it? What is the direction of the wind?" It was two o'clock. The compass was ruined, consequently it was Balloon Ascensions 179 useless to us; the candle in our lantern could not burn in an air so rarefied, its light grew dimmer and dimmer, and finally went out. (Vol. IV, p. 301-303.) They then fell into the sea; then having thrown out everything in their basket, they rose again: With such rapidity, to such a prodigious height, that we could hardly hear each other even when we shouted; I was sick and vomited considerably. Grasetti had the nose-bleed; we both had short respira- tion and an oppression in our chests. As we were wet to the bone when the balloon took us into the higher strata, the cold seized us rapidly and we were covered in an instant with a layer of ice. I cannot explain why the moon, which was in its last quarter, was in a line parallel with us, and seemed red as blood. After rushing through these immense regions for a half-hour and being carried to an immeasurable height, the balloon began to descend slowly, and we fell once more into the sea; it was about four o'clock in the morning. (Vol. IV, p. 305.) The unfortunate aeronauts fell into the Adriatic and remained there, the playthings of the winds and the waves, until 8 o'clock, when a bark picked them up, not without great difficulties. Their feet and hands were frozen, and Zambeccari had to have three fingers amputated. The following year on June 30, Robertson 15 made a new ascent, accompanied by the Russian physicist Sacharoff; but their barom- eter went to only 22 inches and they had no special experiences. This same year of 1804, two young physicists, Biot and Gay- Lussac,111 were given by the Institut de France a scientific mission in the air. They were particularly to investigate variations of magnetic power, which de Saussure thought he had observed on the col du Geant. The two scientists left on the 6th of Fructidor, at ten o'clock in the morning, from the garden of the Conservatoire des Arts. As they did not rise above 4000 meters in a temperature of +10°, they felt no serious physiological disturbances. So they said only a few words on this subject: We observed the animals which we had taken along; they did not seem to suffer from the rarity of the air; however the barometer stood at 20 inches 8 lines, which gives a height of 2622 meters. A violet bee, which we freed, took flight very quickly and buzzing left us ... . Our pulses were very fast; that of Gay-Lussac, which is ordi- narily 62 per minute, was 80; mine, which is usually 89, was 111. This acceleration then was felt by us both in about the same proportion. 180 Historical However, our respiration was not at all affected; we felt no discom- fort, and our situation seemed to us extremely agreeable .... We observed our animals at all heights; they did not seem to suffer at all. As for us, we felt no effect, except this acceleration of the pulse rate of which I have already spoken. There follows the account of what happened to a greenfinch and a pigeon, freed at 3400 meters; the pigeon opened its wings and let itself fall describing circles like the large birds of prey. Gay-Lussac 17 started alone some days after, and rose much higher than the first time. The symptoms of a physiological nature were quite endurable; he speaks of them thus: When I had reached the highest point of my ascent, 7016 meters above sea level, my respiration was noticeably hampered; but I was still far from experiencing such severe discomfort as to wish to descend. My pulse and respiratory rate were much accelerated; and so, breathing very frequently in a very dry air, I was not surprised to find my throat so dry that it was painful for me to swallow bread . . . These are all the inconveniences I experienced. (P. 89.) In regard to this account Robertson made an observation which is interesting because it shows what cause he assigns to the phenomena which he experienced himself: I do not think that there is a professor of physics who has not spoken to his hearers of the weight of the column of air which corre- sponds to the body surface of a man, and who has not shown that this enormous weight is made imperceptible to the body by the equilibrium established between the pressure of the outer air and the reaction of the elastic fluids which are part of its inner system. There is none who has not demonstrated what the effects of the rupture of this equilibrium would be. (Mem., vol. I, p. 107.) But nothing justified Robertson in drawing from these remarks the strange conclusion which follows: I do not think that M. Biot has changed all that. No one can refuse to conclude that the effects experienced by M. Lhoest and my- self, then by M. Sacharoff, are anything but very reasonable; while those experienced by MM. Biot and Gay-Lussac are so contrary to ours that they need to be explained. Now the only explanation possible is that these aeronauts did not rise high enough or that they rose so slowly that there was no rupture of equilibrium for them, otherwise one cannot see what could have kept them from experi- encing the effects which are the inevitable consequences. (Mem., vol. I, p. 108.) This doubt unnecessarily cast upon the truth of the observa- tions of scholars like Biot and Gay-Lussac should have had just Balloon Ascensions 181 reprisals, and it had much to do with the undeserved discredit which has since fallen upon the statements of Robertson. The ascent of Gay-Lussac had a well deserved fame. But people went too far in passing over in complete silence those which had preceded it. Robertson complained justly that the role which he himself had previously played had not been recognized: M. Biot printed in his treatise on physics and repeats in his courses in the College de France that M. Gay-Lussac rose to the greatest height that man had reached up to that time. This assertion, though false, is believed by the youth of today, because I have no one who can say every year to some hundreds of auditors that I had risen to 3630 fathoms more than a year before the ascent of Gay-Lussac; and the time will soon come when no one will know or remember that, before the ascent of MM. Biot and Gay-Lussac, I had made one like it, and like theirs, in the interest of science, but during which the air of those high regions had been less hospitable to me than to those gentle- men. (Mem., vol. I, p. 117.) A few years after, in August, 1808, Andreoli, one of the com- panions of the unfortunate Zambeccari, rose from Padua, and reached, if we are to believe him, a height much greater than that which his predecessors had attained. The correspondent of the Journal de Paris,18 who tells the story, seems to give little credence to the account of the Italian aeronaut, a really very extraordinary account, in which we do not know whether to be more astonished at the ascent or the descent of the daring and lucky aeronauts: Italy. Padua, April 23, 1808. M. Andreoli undertook yesterday in this city an aerostatic journey, which was not very lucky and the account of which arouses unpleas- ant doubts among well-informed people as to the veracity of the physicist. According to this really curious story, which people in Paris may perhaps ridicule, M. Andreoli, accompanied by M. Brioschi, rose at 3:30 in the afternoon, in the presence of a great number of spectators. The barometer having dropped to 15 inches (to 15 inches! Are they quite sure of what they say, and do they know how prodi- giously rarefied the air should be and really is at that height? And in that case, how would the two travellers have breathed?) at this eleva- tion, Brioschi began to feel extraordinary palpitations, without, however, noticing any painful change in his breathing: the barometer dropping next to 12, he felt himself overcome by a gentle sleep, which soon became a real lethargy (they do not say how M. Andreoli felt, and how he resisted the powerful narcotic which overcame his companion). The balloon kept rising and when the barometer was at about 9 inches (that is, a height much greater than that of the highest of the Cordilleras) Andreoli perceived that it was completely expanded and that he could not move his left hand. The mercury, continuing to descend, registered 8V2 inches. Then the balloon exploded with a loud 182 Historical report and began to descend rapidly (I believe it), and then M. Brioschi awoke (not without terror). The fall took place at the castle of Enganca, not far from the tomb of Petrarch and the city of Acqua, 12 miles from Padua; and the most marvellous thing about this story, which was so marvellous from end to end, is that the travellers, no doubt protected by a geni out of the Thousand and One Nights, did not experience the slightest harm, not even the least scratch. Surely that is a miracle which should disconcert all the calculations of ordi- nary physicists. However it may be, the travellers took post horses, and reached Padua at 8:30 to receive congratulations which such a prodigious success deserved on every score. I should note here that the celebrated English aeronaut, M. Glaisher,19 seems disposed to give credence to these extraordinary data; he calls attention to the fact that Andreoli, accustomed to ascents, suffered much less than his companion. And as to the possibility of surviving such a terrible fall, he discusses it with authority and admits it without great hesitation. (P. 161.) August 29, 1811, two Englishmen, Beaufoy and Sadler,-" made an ascent in which they did not rise above 6000 feet, and which holds no interest for us except the sensation felt by Beaufoy "of a slight pressure in the ears and a little deafness", and especially the strange explanation of it which the traveller gives: he attrib- utes this effect to "the dampness resulting from not wearing a hat during the trip." (P. 296.) April 26, 1812, the widow of Blanchard, who was to die so miserably July 6, 1819, on a roof in the Rue de Provence, made an ascent at Turin in which she claimed to have risen to a very great height. The Journal de Paris 21 gave an account of it in the following words: She had taken a barometer with her .... At 15 inches 6 lines, the cold was icy; at 14 inches 1 line, Mme. Blanchard said she had experienced a lessening of the cold; at 12 inches 11 lines, she felt a palpitation of the artery near the outer angle of the left eye and a sort of trembling of the lower lid of the same eye. At 12 inches 3 lines, she had a severe nosebleed. A few minutes later, the barometer marked 10 inches 3 lines, which was its lowest point .... This indicates that the highest elevation of Mme. Blanchard was 3900 fathoms (7600 meters); at this height the cold was unbearable, the Reaumur thermometer was 17° below freezing .... The color of the sky was almost black .... The sun did not have its usual rays and its diameter seemed much smaller than when observed from the earth. A moment after these observations, the thermometer dropped another degree, and Mme. Blanchard, almost stiff with cold, decided to descend. Balloon Ascensions 183 Robertson expressed some doubts about the exactness of Mme. Blanchard's barometric readings. The note he sent to the Journal de Paris -- contains details about the sufferings which he and Lhoest had experienced in their ascent of July 1803, which are not included in the account we quoted above: The elevation to which you state that Mme. Blanchard rose lately at Turin must surprise your readers all the more as it must be regarded as the last degree of human temerity .... First I must admit that I think it impossible for anyone, with an aerostat of 20 feet diameter, which Mme. Blanchard ordinarily uses, to rise high enough to make the mercury drop to 10 inches .... When one reaches the elevation of 3600 fathoms, one yields grad- ually and unconsciously to a lethargic sleep; the mental faculties succumb long before the physical faculties. First one has no memory, no cares for the present or the future; one forgets to supervise the aerostat; soon a soft and gentle sleep, which one cannot resist, lulls all the members and holds the aeronaut in a complete asphyxia, which no doubt is fatal if it is prolonged .... In July, 1803, I made an ascent at Hamburg with M. Lhoest .... The barometer dropped to 12 inches and some lines (while we were still in possession of our faculties). The sky seemed to us to be brown; the sun lacked brilliance; we could gaze at it without being dazzled; we had a slight hemorrhage, and experienced all that Mme. Blanchard has just mentioned. We succumbed to sleep in this ascent; but the lower part of the balloon .... released the gas which was driven out by expansion. We roused from this torpor simultaneously and suddenly, without being able to tell what had happened, except that there had been a break in the continuity of our ideas. Eugene Robertson,-3 one of the sons of the celebrated aeronaut, rose on October 16, 1826, from Castle Garden in New York, to 21,000 feet (6400 meters) ,-* in a balloon of 16,000 cubic feet, inflated with hydrogen: Respiration was painful and difficult, the faculties were blunted, the cold unbearable, especially in the hands. (Therm, at 21 °F.) February 12, 1835, this same aeronaut 25 rose from Mexico to a height of 5928 meters. He examined from close at hand the crater of the former volcano the Chicle and rose "above a nursery of mountains." The famous English aeronaut Green, who made, according to Glaisher,20 more than fourteen hundred ascents, certainly rose several times to great heights; but he seems to have been rather careless about exact measurements, and his figures show evidence of great exaggeration. One of his ascents, which took place in 1821, is curious because 184 Historical of the nature of the gas with which he inflated his balloon; he used oxide of carbon which took him to 11,000 feet.JT But this does not concern our subject. April 20, 1831, Dr. Forster 28 with Green made a balloon trip which did not exceed an elevation of 6000 feet, a height at which they remained for four hours. Their physiological observations referred only to the phenomena of deafness which attack mountain travellers and aeronauts. Forster considers them as having very different causes in the two cases, due in the first to a feeling of fullness in the ears, and in the second to a real weakening of the hearing. The extravagant exaggeration of Green's statements begins to appear in a note of the publisher of Froriep's Notizen,29 which reports naively that Green had made 226 ascents, in which he had several times gone above 6000 fathoms, without experiencing diffi- culty in breathing. The story which Green30 himself gave of the catastrophe by which, September 27, 1836, his companion Cocking lost his life, indicates a height which perhaps should not be considered accurate. We know that Green played a very sorry role in this mad adventure. Cocking had made a parachute wrong side out, the absurdity of which no one could doubt; Green consented nevertheless to take it along. The unhappy Cocking unfastened his parachute just as the balloon reached the height of 5000 feet; he fell like a stone. At the same time, the balloon, freed of his weight, darted upward to great heights: We rose then with such rapidity that we were almost suffocated; with great difficulty I controlled my senses enough to observe the ba- rometer; but M. Spencer observed that the mercury stopped at 13.20, which gives an elevation of 24,384 feet (7430 meters), or about 4*4 miles. But that is nothing beside what he told of an ascent made with Rusch; the pathologist Henle u reports this prodigious statement as a very simple thing, and without making any comment: In his balloon ascents, Green says he never experienced any acceleration of the pulse or of the respiration, except when he rose rapidly after throwing out ballast. In 1838 he rose with Rusch to the height of 27,136 feet (8268 meters), where he saw the mercury drop to 10.32 inches; he passed through the first 11,000 feet (3350 meters) in 7 minutes, without any inconvenience except those mentioned above. (P. 386.) Tall tales are useless! An Italian aeronaut claimed to have Balloon Ascensions 185 surpassed even the fabulous height that the English balloonist said he had reached. We read, in fact, in the Proceedings of the Academy of Sciences of Paris: 32 M. Bonafoux writes that on the occasion of the marriage feast of the hereditary Prince of Savoy, M. Comaschi made a balloon ascent at Turin, in which, if there was no mistake in the barometer readings, M. Comaschi rose to 9474 meters above sea level; but the difference in temperature would seem to indicate a lesser height. The story of Hobard, if it does not give information of great precision, at least appears credible; it is inserted in the Courrier francais of October 9, 1835: August 17, 1835, an aeronaut, M. Hobard, ran the greatest risks in an ascent which he made at Lynchburg, in Virginia; he mounted at seven o'clock in the evening, and in less than an hour landed about 13 leagues from the city. M. Hobard in his account says that a few minutes after his departure he lost sight of the earth completely. At half past seven he made his last observation and judged that he was more than a league high. He saw then two meteors, one in the north and the other in the west; the latter seemed to be approaching rapidly, but it disappeared suddenly, to the great satisfaction of M. Hobard, who feared that it would set his balloon on fire. Shortly after, a squall seized the balloon and whirled it aloft to a height which the aeronaut estimated as not less than 26,000 feet (7925 meters), judging by the difficulty of breathing and the entire loss of hearing. He wished to let gas escape by opening the valve; but not being able to hear, he could not judge, as usual, the escape of the gas by the noise it makes as it issues. He saw nevertheless that the balloon was not deflating much, and he feared it would burst; he feared also that some of his veins would burst, since the rarefaction of the air had made them dilate greatly. The first of his fears was soon realized. Without entirely bursting, the balloon split above and rapidly deflating de- scended with great speed. Happily for M. Hobard, the fall of the balloon was broken by a young fir whose flexible trunk protected him from the terrible shock he would have experienced. However he was thrown out of the basket and considerably bruised, but what were a few contusions in comparison with the cruel death he expected! M. Hobard based his estimate that his greatest elevation was 26,000 feet on the fact that the rarefied air had affected his organs in a more painful way than was experienced by aeronauts who had risen to 25,000 feet, the maximum height hitherto reached in balloon ascen- sions. We must refer to the memorable ascent of MM. Barral and Bixio, July 27, 1850, to find scientific certainty and precision. But from our point of view, this ascent, so useful to meteorology, has only moderate interest. In fact, under the influence of a barometric pressure of 315 mm., corresponding to a height of 7016 meters, in 186 Historical spite of a temperature of 39° below zero, the two brave travellers experienced no physiological symptom which attracted their atten- tion: "Our respiration", they merely said, "was not at all affected." 13 Two years later, ascents no less important from the scientific point of view were made in England by M. Welsh:34 In July, 1852, the Committee of the Kew Observatory decided to institute a series of balloon ascensions for the study of the meteor- ological and physical phenomena which require the presence of an observer in the upper strata of the atmosphere. (P. 311.) J. Welsh, who took Nicklin as companion, was charged with the scientific part; the control of the balloon was entrusted to the celebrated aeronaut Green. The first ascent took place August 17, the aeronauts rose to 19,510 feet (5945 meters) ; in the second (August 26) , they rose only to 19,100 feet (5820 meters) ; and in the third, only to 12,640 feet (3850 meters) . But on November 10, in one hour they reached 22,930 feet (6987 meters) and remained more than 10 minutes above 20,000 feet; the descent took place with extraordinary rapidity: At this height, much greater than all the others we had reached previously, the effects of lowered pressure began to be felt more. M. Green and I experienced very great difficulty in breathing, with increased panting and fatigue after the slightest exercise. (P. 320.) At much lower elevations still, a celebrated English meteor- ologist, M. Glaisher, noted considerable modifications in respir- ation and circulation. The ascents of M. Glaisher constitute the finest series of aerial journeys ever undertaken with a scientific purpose. Some of them took him to very great heights, and one will forever remain famous, that in which he nearly died from the decompression. I am quoting from Voyages acriens 3B the following data which have a bearing on our subject. The first ascent took place June 30, 1862; Glaisher and his balloon engineer Coxwell reached 8000 meters: Between the heights of 4700 and 5900 meters, the thermometer marks 6° above zero. . . . The palpitations of my heart are beginning to become apparent, and my breathing is no less disturbed, my hands are growing blue, and my pulse rate, becoming feverish, is 100 beats per minute. At 6168 meters, we are in a stratum at zero degrees .... my pulse is growing still quicker, and I have increasing difficulty in reading the instruments; I feel a general discomfort, like seasickness, Balloon Ascensions 187 although the balloon is not rolling or pitching .... The blue of the sky has become purer. (P. 47.) The English edition of the work quoted above,:!,i which M. Glaisher published in 1871, gives quite a different account of the symptoms experienced by the learned aeronaut. In the first place, the date of this ascent is given as July 17 instead of June 30: At the height of 18,844 feet (5740 meters), my pulse beat 100 times a minute; at 19,435 feet (5920 meters), I noted the beating of my heart; the ticking of the chronometer seemed very noisy and my respiration began to be affected; my pulse was still faster, and 1 read the instruments with growing difficulty; the palpitations of tho heart were violent. My hands and my lips were a deep bluish color, but not my face .... At 21,792 feet (6640 meters) I felt a sort of sea- sickness, although the balloon did not roll or pitch; I was so sick that I was unable to examine the instruments .... The sky seemed a very dark blue. (P. 44.) Second Ascent, August 18, 1862. The travellers reached 7100 meters, the highest point of the ascent: I felt the pulse of M. Coxwell," which was only 90 per minute, whereas mine was increasing rapidly. From 100 it went to 107 and then to 110, without that of my companion changing appreciably .... As we descended we heard another clap of thunder roaring in the clouds which we were rapidly approaching. Is it the increasing speed of our descent that oppresses me? Is it the electric tension whose increase disturbs the hidden sources of life? .... I do not know, but I experience a sudden distress, a sort of nervous trembling. Happily, after a minute of anguish, a wonderful spectacle helps me triumph over this fleeting swoon. (Voyages acriens, p. 57.) At last came the famous ascent of September 5, 1862; it is the third. The ascent from Wolverhampton took place at 1:03 in a temperature of +15°. At 1:34, the aeronauts had reached an alti- tude of about 5200 meters; the temperature is —9°; there no longer is water vapor in the air. The first physiological disturb- ances then appear: At 1:34, I noticed that M. Coxwell began to be out of breath, which is not surprising, because he was constantly occupied with managing the balloon .... At 1:39, we reached the height of 6437 meters (the altitude of Chimborazo) .... We threw out sand .... ten minutes were enough for us to rise to the height of Dawalagiri; the temperature had fallen to —18.9° .... Up to this time I had taken my observations without difficulty, whereas M. Coxwell, who was obliged to move about in his duties, seemed weary. At 1:51, the barometer marked 11.05 inches. We found out later, by comparison with the standard barometer of Lord Wrottes- 188 Historical ley, that we should lessen this figure by a quarter of an inch. About 1:52, the dry bulb thermometer registered — 5°. Soon I could not see the column of mercury in the wet bulb thermometer, or the hands of a watch, or the fixed divisions of any of my instruments. I asked M. Coxwell to help me get the figures which escaped me, but, because of the rotation of the balloon, which had not ceased since we left the earth, the cord of the valve was tangled. M. Coxwell had to leave the basket and climb on the ring to untangle it. I observed the barom- eter; I saw that it registered 10 inches, and that it was falling rapidly. Its real height, taking care to subtract the quarter of an inch, was 9 and % inches, which indicated a height of 29,000 feet (8838 meters). Shortly afterwards, I leaned on the table with my right arm, which had had its full strength an instant before; but, when I wanted to use it, I saw that it was no longer able to render me any service. It must have lost its power instantaneously. I tried to use my left arm, and found that it too was paralyzed. Then I tried to move my body, and succeeded to a certain degree; but it seemed to me that I no longer had any limbs; I tried once more to read the barometer, and while I was making this attempt, my head fell on my left shoulder. I stirred and moved my body again; but I could not succeed in raising my arms. I lifted my head but only for an instant; it fell once more. My back was leaning on the rim of the basket and my head in one of its angles. In this position I had my eyes fixed on M. Coxwell, who was in the ring. When I succeeded in sitting up, I was completely master of the movements of my spine, and certainly still had great control over those of my neck, although I had lost command of my arms and my legs; but the paralysis had made new progress. Sud- denly I felt incapable of making any movement. I vaguely saw M. Coxwell in the ring, and I tried to speak to him, but could not move my powerless tongue. In an instant, thick darkness seized upon me; the optic nerve had suddenly lost all power. I still was perfectly conscious and my brain was as active as while I am writing these lines. I thought that I was asphyxiated, that I should make no more experiments, and that death would seize me unless we descended rapidly. Other thoughts were rushing into my mind when I suddenly lost all consciousness, as when one falls asleep. My last observation took place at 1:54, at 29,000 feet. I suppose that one or two minutes passed, before my eyes ceased to see the little divisions of the thermometers, and that about the same time elapsed before my faint. Everything leads me to believe that at 1:57 I lapsed into a sleep which might have been eternal. I was not able to move when I heard the words temperature and observation. I perceived that M. Coxwell was speaking to me and that he was trying to awaken me; hearing and consciousness had then returned to me. I then heard him speak louder, but I could not see him; it was much more impos- sible to answer him or make a movement. He was saying to me: "Try now, try." Then I vaguely saw the instruments and soon after- wards surrounding objects. I rose and looked around me, as if I were coming from a feverish sleep, which exhausted instead of resting one. "I fainted", I said to M. Coxwell. "Certainly," he answered, "and I nearly fainted too." I then pulled up my legs, which were Balloon Ascensions 389 extended straight out, and took up a pencil to continue observations. M. Coxwell told me that he had lost the use of his hands, which had become black and on which I poured brandy. He added that, while he had been in the ring, he had been seized by an extreme cold and that icicles hung around the orifice of the balloon, like a terrible candelabrum, worthy of the polar seas. When he tried to descend from the ring, he could no longer use his hands, and was forced to let himself slide on his elbows to get back into the basket, where I was stretched out. He thought, seeing me on my back, that I was resting, and spoke to me without getting an answer. My face was serene and tranquil, without that anxiety which he had noticed before climbing into the ring. Seeing that my arms and my head were hanging down, M. Coxwell understood that I had fainted. He tried to approach me, but could not, feeling unconsciousness overcome him too. Then he wanted to open the valve, but, having lost the use of his hand, could not manage it. He could not have succeeded in controlling our course, if he had not had the idea of seizing the cord between his teeth33 and pulling it two or three times by shaking his head violently. I resumed my observations at 2:07, and the first figures that I registered were 292 mm. for the barometer and 18 degrees for the thermometer. I suppose that 3 or 4 minutes passed from the moment when I heard the first words of M. Coxwell to the moment when I began again to read my chronometer and my other instruments. If this is so, I returned to life at 2:04, and was completely unconscious for seven minutes. (P. 59-64) .... I felt no unpleasant result from my faint .... I walked eight or nine miles after we had landed as easily as if nothing had happened to me .... I made my last observation at 8838 meters. [That is within two meters of the height of the highest peak on the surface of the earth, the Gaourichnaka of Nepal, at the foot of which the Brahmin pil- grims who are seeking Nirvana come to die;39 one may say that no human being ever could drag himself to this height following uneven terrestrial surface, and in spite of their courage the brothers Schlag- intweit did not aspire to mount there. However, I might have continued my observations there, if the continued ascent of the balloon had not taken me higher, where life is still more difficult.] When40 I fainted, we were ascending at the enormous speed of 305 meters per minute, and when I resumed my observations, we were descending at a speed of 610 meters, double our speed of ascent; this circumstance permits me to calculate with a certain exactness the height to which we had really risen. (Voyages aeriens, p. 65.) Calculations based both on the ascensional speed of the balloon and on the temperature marked by a minimum thermometer have led M. Glaisher to judge that the balloon had reached the height of about 11,000 meters. The results of this calculation are, we must say, evidently erroneous. We are surprised to see a scientist of this caliber suppose that the balloon had a uniform speed in 190. Historical ascending and descending, and solve by equations of the first degree a problem which evidently depends on the second. Everything leads us to believe that the balloon soon stopped and soared for some minutes before descending. I should mention a little experiment that is rather interesting: We had taken with us six pigeons to toss into the air successively at sufficient heights. We threw out the first at 4807 meters; he spread out his wings but could not support himself and fell like a leaf of paper. The second, which was thrown out at 6437 meters, did not let itself fall so easily; it whirled about, flying vigorously. Probably it turned completely about each time it dived in spite of itself. Perhaps by yielding to this strange waltz it found a way to resist the terrible suction. The third was thrown out before reaching the level of 8048 meters. It fell like a stone and disappeared rapidly. We kept the three pigeons left for the descent, but we found that one of them was dead in its cage and another was hardly better. When I took it from its cage, it refused to fly away. Only after a quarter of an hour of rest did it begin to peck at a bit of pink ribbon which was around its neck. It was a carrier pigeon which, when once recovered, flew with great rapidity in the direction of Wolverhampton. (P. 67) .... Of all the pigeons thrown out during the journey, only one returned to Wolverhampton, during Sunday (the fifth of September was a Friday). M. Glaisher made several more ascents in which he mounted above 7000 meters (April 10, 1863, to 7300 meters;41 June 26, 1863, to 7100 meters) ; in his accounts he says nothing at all of physi- ological disturbances. But he summarizes, in a separate section, the observations of this sort which he made in these different ascents; I quote from the English edition in which it is much fuller and more interesting than in Voyages acriens: The number of heart beats per minute increases with the altitude, as does the number of inspirations: my pulse was generally 76 before starting, about 90 at 10,000 feet, about 100 at 20,000 feet, and 110 at greater heights; but the increase in the height is not the only element on which the rate depends; the state of health has much to do with it, as does the temperament of the different individuals. The same thing is true of the color of the face; at 10,000 feet, certain persons are of a flaming purplish red, while others are hardly affected. At 17,000 feet, my lips were blue; at 19,000 feet, my hands and my lips were a deep blue; at a height of four miles, one could hear my heart beat and my respiration was much affected; at 29,000 feet, I became unconscious. From all observations one may conclude that the effects of great heights are felt by everyone, but vary in the same individual according to circumstances. (P. 92.) Balloon Ascensions 191 M. Glaisher states that one soon becomes accustomed to the influence of rarefied air, and cites his own experience in this regard. He expresses hopes on this subject that show both keen imagination and scientific understanding: The diminution of pressure .... should act in a very special way on persons who are journeying in the air for the first time. I can make this statement from my own personal experience, which cer- tainly has some value, for I have not always been able to ascend without ill consequences to a height which ordinarily produces great distress, and generally brings on discoloration of the hands and face. I recall having caused great astonishment in a group of scientists by stating that I was accustomed to rising to very lofty altitudes ■ without turning blue. I am really convinced that I have become acclimated to the effects of the rarefied air found at six kilometers from the surface of the earth, and I flatter myself that I can breathe freely in these strata high above sea level. I even have no doubt that this acclimatization can be sufficiently developed to exercise a considerable influence on the scientific use of balloons. At eight or ten kilometers I have tested upon M. Coxwell and myself the limits of our ability to live in rarefied air. Frequent trials would increase this height, and I am certain that it could be extended even more if one used artificial means to aid respiration. Certainly human lungs would find up there their Columns of Hercules, but I do not hesitate to declare that these impassable boundaries are still very far from the regions I have reached. (Voyages aeriens, P. 9.) The learned meteorologist of Greenwich, in another passage of his work, again refers to the future he predicts for ascents to great heights; he expresses with unusual vigor his unlimited confidence in the fruitful efforts of science. We shall show in the rest of this work that these hopes have not been disappointed: As I have already explained in the introduction, I do not doubt that some one will succeed in making observations in regions which I could not attain without fainting. I am persuaded that a day will come when aeronauts will surpass me just as I exceeded the height of Barral and Bixio, who in their turn reached altitudes higher than Sakaroff and Gay-Lussac. I certainly shall not take it upon myself to set the limits of human activity and indicate the point, if it exists, where nature says to the aeronauts: "You shall go no further." (Voy- ages aeriens, p. 67.) For about ten years, there has been no ascent to a great height, and in the scientific ascents to moderate heights, the aeronauts, preoccupied with important problems of meteorology and physics, neglected completely the physiological phenomena whose slight modifications could not be observed without having great attention devoted to them. 192 Historical We must turn to the ascents organized by the Society of Aerial Navigation to find facts that interest us. The first among them, although it did not pass above 4600 meters, gave Dr. Petard, one of the travellers, very interesting physiological observations. He begins by listing briefly the temperaments of his travelling com- panions: M. Croce-Spinelli is blond, of a lymphatic temperament, nervous, he is ordinarily inclined to attacks of bronchitis. M. Penaud is chestnut-haired, of a lymphatic temperament, and he is disposed towards rheumatism. M. Jobert is very dark, of an athletic constitution with bilioso- sanguine disposition. M. Sivel is dark, of a sanguine disposition; he is very strong, and, furthermore, not sensitive to aeronautic influences because of the great number of ascents he has made. Finally, I am dark and of a sanguine disposition. (P. 118.) The balloon rose to a height of 4600 meters (429 mm.) , where the aeronauts found a temperature of — 7 degrees after having passed through a layer at — 20 degrees: I could (says M. Petard) observe that the earth below appeared like a basin, and this illusion makes the hills seem very low and the ravines very shallow. The second phenomenon to be observed is the oppression displayed by M. Croce-Spinelli, at about 3500 meters. I remind you that M. Croce-Spinelli is predisposed to bronchitis. M. Penaud also expe- rienced oppression, but to a much less degree than M. Croce-Spinelli. The other passengers felt none. We next observed the buzzing in the ears which M. Penaud men- tioned first at a height of about 2700 meters. We were all affected at about the same time and in the same way, but with very marked differences in the intensity of the impres- sion. For M. Croce-Spinelli it passed to a state of keen pain, and so persistent that in the train, during our return, he still complained of pains in his ears. M. Croce-Spinelli said that in him the buzzing and later the acute- ness of the pain appeared only during the rapid descents, that is, when the outer pressure exceeded that of the ear. In me, this buzzing was perceptible whenever we had a rapid descent or ascent of some extent, that is, whenever the equilibrium between the inner and the outer pressure in the ear was broken .... Not only did the sounds seem weakened, but they also appeared to come from far away. (P. 119.) The following observations were made above 4000 meters: By aid of the buccal thermometer of M. Sainte-Claire Deville and that of Celsius, I observed a slight drop in the animal temperature, which varied in the experiments made from 35.02° to 35.07°. The Balloon Ascensions 193 acceleration of the respiratory rhythm and of the arterial circulation, very noticeable in all, was in very different proportions in the different subjects. M. Jobert, whose respiratory rate is normally only 10, had a rise to 20; his pulse, normal at 100, reached a maximum of only 130. That of M. Penaud rose from 68 to 104, the respiratory rate from 25 to 45. M. Croce-Spinelli: normal pulse, 72; maximum pulse, 116, at an altitude of 3500 meters. At 500 meters it was only 86. The number of inspirations went from 40 to 64. M. Sivel: normal pulse, 80; maxi- mum, 108; respiration went from 25 to 40. Dr. Petard: normal pulse, 87; maximum, 110; normal respiration, 26; maximum, 35. These data show that the increase in inspirations reached an average of 8/5 of the normal value, but that the increase in pulse rate varied according to the temperaments. While this increase was from 7 to 11 for lymphatic temperaments, it was from 10 to 13 for sanguine temperaments. I could not observe, by the pneumo-dynamometer, any appre- ciable difference in the expansion of the lungs. The pulse was generally full and regular; but it was not possible to make graphs of it, since we were not able to use sphygmographs on account of the drop in temperature, which made exposure of the skin painful. (P. 120.) .... We felt a sensation of peculiar well-being impossible to -describe, although it was expressed by words and mien. The two celebrated ascents to great height (7300 meters and 8600 meters) carried out by my regretted colleagues Croce-Spinelli and Sivel, having been undertaken after the first publication of the results of my researches, their account will naturally be placed in the third part of this book. In conclusion, I shall merely quote an account of an English aeronaut, Simons, who on July 9, 1874, started from Cremorne Garden, in London, taking Groof, the Flying Man, with his compli- cated apparatus suspended under the basket. The balloon contained 27,000 cubic feet; at 1000 feet, Groof disengaged himself, and falling head first, was dashed upon the ground. Groof and his machine weighed 130 kilograms: I looked over the edge of the basket (says Simons), but I was rising so rapidly that I lost consciousness until I was over Victoria Park." But I hasten to add that we should not have too great confi- dence in the ascents of Simons, who certainly deviated from the truth in his replies during the inquest on this painful event. 1 Manuscript preserved in the Library of the Institute, under the title of Second Memoire de M. Charles sur V Aerostatique, 1784. See also L' Art de voyager dans les airs ou les ballons. specifying the means of making aerostatic spheres, following the method of MM. de Montgolher and the procedures of MM. Charles and Robert. Paris, 1784, without an authors name (by Piroux, according to the Uictionnaire des Anonymes de Barbier). -De Aerostation usu medicinae applicando. Theses de Montpelher, LS4. 194 Historical 3 Mme. B***, born de V***, The Olympic Circus, etc. followed by the Aeronautic Horse of M. Testu-Brissy, Paris. 1817. oat,, , I Relation du seizieme voyage acrien de M. Blanchard, dedicated to S.A.S. Mgr. le prince de Ligne; br. in-4 of 17 p. Client, 1786. B Journal de Paris, December 5, 1785. 7 lanuary 5, 1786, p. 18. *: Ibid., December 20. 1785; p. lir.fi. 8 16th and 20th Messidor and 10th Thermidor, in the year VII. _ . 9 Robertson, Relation adressee aji president de V Acad. imp. de Saint-Petersb., in his Memoircs recreatifs, scicntiftques ct anecdotiqucs, 2 vols. Paris, 1810. 10 It is, therefore, by an error that all authors, without exception, have attributed a height of 7470 meters to the ascent of Robertson. II By Izarn (See the Moniteur universel, January 25, 1804). 12 January 20, 1804; year XII, vol. I. o. 73. ™'4bentcuer des Grafe Z . . . bei einer nachtlichen Luftfahrt. Gilberts Annalen der Phvsik, vol. XVI, p. 205-209; 1804. .„-,*■ r v ,„ " 14 Souvenirs d'un voyage en Livonic. a Rome ct a Naples, faisant suite aux Souvenirs de Pans. Translated from the German. Paris. 4 vol.. 1806. . »•• .■'j.vimoiz share this opinion and express it with the greatest clearness. For them, in the first place, the chief effect is due to the removal of the weight of the atmosphere: Whenever one places an animal under the receiver of the pneu- matic machine, or when one mounts rapidly to considerable heights, then not only the sudden expansion of the free elastic fluids, propor- tional to the rapid decrease of the atmospheric pressure, but also the tendency to expansion which exists in the animal liquids them- selves, especially in the elastic fluids which they hold in solution, may be the cause of several striking results, such as a feeling of general discomfort, etc. However, after describing the phenomena presented by travel- lers and balloonists, the authors seem to relegate their entirely mechanical explanation to a secondary place, for they add: These effects are easily accounted for. On account of the decrease in the density of the air there is a lessened quantity in the same volume. This air, therefore, is less adequate for the combinations which it must experience in the act of respiration; consequently, so that in rarefied air these combinations may take place conformably to the purpose of nature, one must breathe proportionately with greater rapidity. This is the cause of this hasty and panting respiration and consequently of the acceleration of the pulse rate which results from it. We even comprehend that at much greater heights the rarefaction of the air would be such that acceleration of the respiration would 218 Historical not suffice to bring to the lungs the quantity of air necessary for the maintenance of life, and that life would finally be extinguished, as it is in asphyxia, for lack of the principal agent of respiration. Death in this case might be preceded by various phenomena unrelated to respiration, such as emphysema and different hemorrhages due entirely to the great expansion of all parts of the body. Here again we find, applied to respiration, the explanation already given by de Saussure; as to hemorrhages, Halle and Nysten persist in attributing them to the decrease of the weight sustained by the body. The same combination of explanations is expressed with greater clearness and moderation in the thesis of Courtois: 27 Most of these phenomena depend at the same time upon changes which occur in the weight of the air and upon the varying quantity of oxygen which this fluid contains in the same volume, depending upon whether it is condensed or rarefied; thus chemical phenomena compli- cate those which depend upon the weight of the air. (P. 17.) At the same epoch there appeared a remarkable work, which deserved more attention from physiologists, and which nevertheless remained almost completely unknown, at least in the part which interests us. I must even confess, not without some embarrass- ment, that I did not know of its existence until I was doing biblio- graphic research necessary for the preparation of the first part of this work, after all my experiments had been completed. In his researches on animal heat, Legallois 2S was led to compare the variations in temperature of warm-blooded animals with the quantity of oxygen which they absorb in a given time. Among the causes which might act upon this absorption, he considers the rarefaction of the air, as a means "of lessening the quantity of oxygen contained in the air in which the animal is confined". Legallois kept the animals in closed vessels (the manometer, as he calls it, measured 41 liters) during the whole experiment; he has nowhere specified the degree of decompression to which he had subjected them, but it is easy to conclude from his accounts that he never reached a half-atmosphere. I summarize in the following table the results of his experiments; the comparative test, made for each animal at normal pressure, lasted the same time, of course: Theories and Experiments 219 Change in Oxygen Carbonic body consumed acid jormed temperature 1. Rabbit, normal pressure 7.05 6.16 + 0.2° Rabbit, rarefied air 6.43 5.02 — 2'°0 2. Rabbit, normal pressure 6.53 6.56 + 0.3° Rabbit, rarefied air 5.97 4.56 — 2.2° 3. Rabbit, normal pressure 12.08 8.55 — 1.3° Rabbit, rarefied air 9.96 7.60 — 1.3° 4. Cat, normal pressure 9.50 — 0.5° Cat, rarefied air 6.93 — 4.2° 5. Cat, normal pressure 8.52 6.20 — 0.3 Cat, rarefied air 7.66 6.12 — 7.°^ 6. Dog, normal pressure 13.26 9.12 — 1.7 Dog, rarefied air 10.91 9.11 — 4.2° 7. Dog, normal pressure 13.19 7.65 — 4. Dog, rarefied air 10.39 6.63 — 6.2° 8. Guinea pig, normal pressure 8.49 6.27 — 0.4 Guinea pig, rarefied air 7.37 6.56 — 2.6° 9. Guinea pig, normal pressure 11.41 9.10 — 1.3 Guinea pig, rarefied air 9.58 8.42 — 4.8 Legallois draws from these experiments, in reference to the subject which interests us here, the following conclusion, which shows admirable sagacity: Since the mere rarefaction of the air, carried far enough to lower the barometer less than 30 centimeters, is enough to chill the animal which breathes it, the result is that the cold experienced on lofty mountains does not depend solely on the coldness of the atmosphere, and that it has in addition an inner cause, which acts through respi- ration. (P. 59.) What a contrast between these clear experiments, these precise conclusions and the confused mass of so-called explanations which, in that same year, Dralet -n gave both of the discomforts and the improved conditions experienced on lofty places! The air on mountains of moderate height is more healthful than that on the plains ... If we consider, moreover, that the pressure of the atmosphere is less as we ascend, we shall not be surprised that the dwellers on the plain are in better health on the Pyrenees, eat with more appetite, and that the elasticity of their lungs gains new strength there. But the man who is approaching the region of snow will not find an air so favorable to the animal economy; since vegetation, accord- ing to the observation of M. Ramond, is practically absent from these wild spots, the nitrogen is not absorbed by the organs of plants, and lessens the wholesomeness of the air by its abundance. MM. Vidal and Reboul have proved that the quantity of vital air in the atmosphere at the summit of the peak of Midi in Bigorre was about 220 Historical one-fourth less than in the valley. Moreover, as the weight of the atmosphere decreases in proportion to the height of its strata, when a man has reached the summit of a lofty mountain, all the parts of his body, since they no longer receive sufficient pressure from the surrounding air, must yield to the heat which expands them in seek- ing its equilibrium in the surrounding bodies. The result is relaxation in the fibre, softening in the solid parts, and excess of fluidity in the liquids. So persons who travel on lofty mountains are subject to hemor- rhages, vomiting, and fainting; but these symptoms rarely appear un- less one ascends to 2000 fathoms above sea level. (Vol. I, p. 36.) Gondret 30 was no more fortunate when he tried to give "an ex- planation, if not complete, at least satisfactory", of the symptoms observed during mountain ascents. This is what he says: The decrease of the weight of the column of air and the elasticity of our organs explain the turgidness of the body, the expansion of the vessels and fluids, and consequently the hemorrhages. The lungs, accustomed to 18 or 20 regular inspirations and expira- tions per minute, suddenly forced to multiplied movements in order to absorb the same quantity of air, are extraordinarily hasty in their labor. The heart immediately feels the effect of the hasty action of the lungs; the result is an accelerated pulse rate and lipothymies. When the two effects which the heart and the lungs exert on the brain are thus accelerated, we can imagine the changes that take place in this organ, and consequently in its functions; it is to these changes that we can attribute the vertigo, dizziness, syncope, and all the dis- orders which follow. The differences noted in different individuals in the intensity of the symptoms are the result of idiosyncrasy. (P. 40.) However, we must admit that he was the first to have the idea of applying rarefied air to therapeutics. From the very evident effect exerted upon us by changes in the barometric pressure, he derives this suggestion: Perhaps chambers may be constructed in such a way that, by the help of the pneumatic pump, we may introduce into them a more or less dense air, according to the requirements of the case. (P. 45.) The rest of the volume is devoted exclusively to the study of the effect of cupping-glasses, simple or combined with scarification. The English travellers who, at the beginning of this century, journeyed over the lofty regions of India, introduced a new ele- ment into the explanation of mountain sickness. According to their stories, the natives of these countries attribute the disturbances which attack strangers and the natives themselves to the effect of Theories and Experiments 221 a poisoned wind; generally, the emanations of certain plants are supposed to give these toxic qualities to the air. Fraser 31 is the first to give us this curious information; we must admit that he makes haste to reject this explanation, and for an excellent reason: I did not suspect that the altitude could affect the strength and the lungs so severely, and yet it was the only cause, no matter how difficult the ascent; for in that respect we had had days before that were at least as bad; and although we were told that the air was poisoned by the odor of flowers, and although there were indeed a profusion of them during the first part of our journey, most of them had no odor, and we could not perceive any in the air. More than that, we were particularly distressed when we reached the lofty gorge of Bamsooroo, where there was no vegetation, and consequently no perfume of flowers. (P. 449.) Dr. Govan,3- who accompanied Captain Al. Gerard on his first journey in 1817, reports the same tradition, without giving it any more credence. But much astonished by the lack of proportion already noted by travellers between the altitude and the intensity of the symptoms, he has the peculiar idea of having electricity play an active part in these phenomena: On the highest peaks of the mountains of Choor there first appear the juniper-tree, the alpine rhododendron, and the tall aconite, the toxic effects of which, when it is used internally, are well known, and seem to have given rise to the belief common among the natives that it poisons the surrounding air; I can find no basis for this opinion, except that in the lofty places in which this beautiful plant grows, travellers often, but not always, experience disagreeable symptoms, usually attributed to the expansion of the air. If the symptoms considered by eminent naturalists as resulting from this expansion should really be ascribed to it, why are they not proportional to the elevation and the rarefaction, and why do these symptoms not invariably appear when the elevation and rarefaction reach a certain degree? On two occasions I passed the night at elevations more than 14,000 feet above the line of perpetual snow; I crossed the Rol-Pass (much above 15,000 feet), accompanied by 40 native soldiers, without anyone of us experiencing these painful symptoms. Now, in the same places, and even at lower elevations, they have been observed in other ascents and predicted in advance by the natives. All of this seems to indicate that these symptoms result from less general atmospheric circumstances, such as the electric force, which, in the case of such lofty conductors, must be in a state of constant fluctuation. (P. 282.) Captain Al. Gerard,13 in the account of his journey of 1818, also mentions poisonous plants: 222 Historical I should note that the inhabitants of Koonawur estimate the height of mountains by the difficulty in breathing during the ascent of them, which difficulty they attribute to a poisonous plant; but in spite of our search in each village, we found no one who ever knew this plant, and judging by our experience, we are inclined to attribute these effects to the rarefaction of the atmosphere, for we have ex- perienced them at elevations where there was no more vegetation. (P. 49.) He alludes again to this hypothesis in his book on the country of Koonawur,34 but always to reject it: Travellers crossing these ranges attribute these painful effects to the influence of poisonous plants; but better informed persons, who customarily pass over these heights where there is no vegetation, know very well that they are produced entirely by the altitude. (P. 37.) But in narrating his expedition and his stay at the pass of Shatool (4830 meters), Dr. Gerard3" does not give any heed to the explanation of the natives. He suffered greatly, as the account which we reported above proves, and naturally sought the cause of his distress, but without success; but in the meantime, he opposed the skepticism of those who for some reason experienced no symp- toms: There I had a lesson which I shall never forget, and I am sure that a man of a more plethoric constitution would have died from apoplectic suffocation. The blood left my extremities, and the pres- sure on the surface of the body was so diminished in that rarefied air that the blood rushed to the head and produced vertigo. (P. 308.) The cause of the symptoms is not very easily seen, and these extraordinary indications of loss of strength, distress, and mental weakness are not satisfactorily explained, and although we cannot hesitate to attribute the principal and immediate cause of them to the rarity of the air, or, more exactly, to the diminished pressure, by which the balance of the circulation is destroyed, nevertheless, the effects are so capricious and irregular that they can hardly agree with the idea of a constant cause. This leads travellers even to deny the existence of the symptoms, and those who have by chance resisted this effect while crossing the mountains remain firm in their convic- tion; but I know that you will believe my reports, although you had only a headache on Boorendo. I too passed the night here without any symptom, except weakness. (P. 320.) . . . As respiration cannot take place in a vacuum, we must consider that, at the elevation of 18,480 feet (5630 meters), the air is nearly half exhausted, and as the whole can have only the sum of the effects of its parts, the progressive action here becomes an arithmetical series, reducible to an experiment in physics, in which the piston strokes of a pneumatic pump seem to draw the hand placed over the opening Theories and Experiments 223 more and more, until the greater pressure is so much more than the lower pressure as to be unendurable to the experimenter. At 18,480 feet, the barometer stands on the average, at 15 inches, so that we then breathe an air only half as dense as that at sea level; who could be surprised at the effects observed? (P. 323.) Captain Hodgson,36 who in his turn reports the statements of the natives, seems not far from believing them himself: The mountaineers, who know nothing of the rarefaction of the air, attribute their weakness to the exhalations of harmful plants, and I think that they are right, for a sort of unwholesome effluvium was exhaled by them here as Well as on the heights below the snowy peaks which I crossed last year on Setlej; although, on the highest snow, the complaint was not of weakness, but of the impossibility of walking for some time without stopping to breathe. (P. 111.) We shall see later, by the testimony of recent travellers, that this idea of wind poisoned by plants is today quite popular in Upper Asia. If now we return to our Alps, about this same time we find Hipp. Cloquet37 republishing the mechanical explanation: The pressure of the air, which weighs constantly upon us from all sides . . . seems necessary to the maintenance of the equilibrium between the living solids and the humors which circulate or float within them; it counterbalances the elastic force of the fluids of our bodies; and since this pressure is considerably diminished here, it is not surprising that the equilibrium is ruptured. (P. 36.) Dr. Hamel,38 when he undertook the fatal expedition on Mont Blanc in 1820, had planned to make experiments there; one of his plans gives evidence of a remarkable sagacity and shows very definite and very scientific hypothetical views about the cause and the effects of rarefied air: I had prepared a flask of lime water to see whether, at the sum- mit, the expired air was laden with carbon in the same proportion as in the regions where at every inspiration about one-third more oxygen enters with the same volume of atmospheric air. I also planned to extract, on the summit, the blood of some animal, to see by its color whether it had been sufficiently decarbonated in the lungs. The account of the ascent of Mont Blanc carried out by Clis- sold 3n in 1882 brings us to an explanation which had not appeared up to that time, and which might serve as type for that physiology of probabilities which has done such harm to science. In the first place, Clissold attributes the symptoms observed to the smaller quantity of oxygen contained in the same volume of air, which compels respiration to be deep and hasty. 224 Historical On the other hand, since muscular energy in general is dimin- ished, the lungs expand less, and compensation must be made by greater frequency of inspirations. Then the editor of the Biblio- thcque universelle adds: Clissold here suggests, without developing it, one of the causes to which we should be tempted to attribute the greatest influence upon one of the effects noted; we mean the expansion undergone by the air enclosed in the abdominal cavity, as one rises in the atmosphere; this expansion, by raising the diaphragm, lessens by so much the capacity of the thoracic cavity, and does not permit the lungs to expand as much as usual, until, by certain slow communications with the ex- terior, equilibrium between the abdominal and thoracic cavities is established again, and the latter regains its ordinary capacity. The French naturalist Roulin,40 who spent several years fn Bo- livia, in 1826 sent to Magendie a letter containing observations on the pulse rate, made on the same persons at Guaduas (average pressure 718 mm.) and at Santa-Fe-de-Bogota (560 mm.; 2643 meters above sea level) . They show a slight increase in the pulse rate in the latter place. The difference is rather slight, and M. Roulin concludes from this: According to that, we may assume that the effects felt when one ascends lofty mountains and attributed entirely to the decrease of pressure, when they are not due to cold or the fatigue of the ascent, must be considered chiefly as nervous phenomena. And yet, a few pages farther on, the author adds: The difficulty in breathing which I felt on the plateau of Bogota was at first attributed to the state of my health; but I observed that several persons, who had recently arrived on the plateau, also com- plained of this difficulty. It is evidently rather because of the name of their author than because of their own importance that I have quoted these observa- tions; they are anything but conclusive. It is also from the standpoint of curiosity that I report here the conclusions from a work of John Davy 41 upon the gases of the liquids and the solids of the body; it is a real step backward from what Robert Boyle and Darwin had taught us. But the reader may judge from that the hesitations between which the minds of physi- ologists drifted. J. Davy carried out numerous experiments with the purpose of finding out whether the liquids or the solids contain gases which the pneumatic pump can extract. The results obtained were always negative, and he concluded from that that there are no free gases Theories and Experiments 225 in the blood, which, moreover, would be "unchemical" and incom- patible with life, for at the slightest increase in temperature or decrease in pressure, nothing could prevent the escape of these gases. It is curious to see, a few years afterwards, a celebrated French physician, Rostan,42 appeal to the very influence of these gases, though vaguely, it is true, to explain the symptoms of decompres- sion. He mingles with his discussion the mistaken ideas, which we have already met and which we shall often find again, about the part played by the decrease of the weight sustained by the body: If one places a living animal in a vacuum, the air within, having nothing to resist it, expands, the animal swells up and dies ... It is the pressure of the air which keeps the fluids in the vessels of animals and prevents them from escaping. When the barometer drops a few degrees, the fluids press towards the periphery; there is difficulty in breathing, disturbance of the circulation, and congestion towards the head. (P. 340.) About this same time there appeared an English memoir which at least had the merit of originality, in the sense of oddness. Cun- ningham,43 as Govan had already done, makes electricity play a principal part, thus explaining the unknown by the unknown; but he adds a strange idea; that there is a radical difference between the effects of the ascent of mountains in the two hemispheres: Apoplectic symptoms characterize the distress of travellers on Mont Blanc, whereas in the southern hemisphere the threatening symptoms are all those which accompany syncope . . . The first have been attributed to the great rarefaction of the air which permits the soft parts of the human body to expand as a result of the reduction in the pressure exerted upon them; but since a similar elevation in the Andes produces effects of an opposite nature, we should seek to explain the latter by other causes than the rarefaction of the air. This cause the author finds in electricity, Which occupies, in the northern hemisphere, the upper part of the body, and, in the southern hemisphere, the lower part, and thus tends to draw the blood towards the head in the former, and towards the feet in the second . . . which also explains why the distress is re- lieved by the horizontal position. We think it useless to continue any farther, and we shall also report without comment the few lines which Burdach,44 in his im- mense encyclopedia, devotes to the effects of a decrease in pressure upon the organism; we see clearly by what he says that he 226 Historical attributes them to the lack of the support of the air upon the blood vessels: The pressure of the atmosphere (he says) upon the human body is equal to a weight of 30,000 to 36,000 pounds; it keeps the mechanical arrangements of the organism in their normal state, and gives con- siderable help to the circulation, restraining the flow of the blood towards the surface . . . Symptoms caused by congestions in various organs have sometimes been noted on lofty mountains, where the air is greatly rarefied. (P. 325.) One of the great difficulties always encountered by authors is the lack of proportion between the severity of the symptoms and the elevation which the travellers have reached, and that not only in different hemispheres, but in the same country, on the same chain of mountains. That is why the German Poeppig,4"' who gave such a complete description of the mountain sickness of the Andes, cannot make up his mind that the cause of it is the decrease of the atmospheric pressure: The idea that the Puna, the Veta, does not depend upon the rare- faction of the air, but upon a change in its composition, finds support in the observation that the illness is not always in proportion to the elevation of a place above sea level. The cabin of Casacaucha is nearly at the same level as Cerro de Pasco, the pass of Viuda is a thousand feet higher, and I have never felt the slightest distress there. (Vol. II, p. 84.) M. Boussingault 46 also was struck by these variations; but bolder than Poeppig, he seeks an explanation of them: In all the excursions I undertook in the Cordilleras, I always felt, at an equal height, an infinitely more painful sensation when I was climbing a slope covered with snow than when I was mounting over bare rock; we suffered much more in scaling Cotopaxi than in ascend- ing Chimborazo. On Cotopaxi we were constantly mounting over snow. The Indians of Antisana assured us also that they felt stifled (ahogo) when they walked for a long time over a snowy plain; and I confess that after considering carefully the discomforts to which de Saussure and his guides were exposed when they bivouacked on Mont Blanc, at the moderate height of 3888 meters, I am disposed to attribute them at least in part to the still unknown effect of snow. In fact, their bivouac did not even reach the elevation of the cities of Calamarca and Potosi. In the lofty mountains of Peru, in the Andes of Quito, the travel- lers and the mules which carry them sometimes suddenly experience a very great difficulty in breathing; we are told that animals have been seen to fall in a state very like asphyxia. This phenomenon is Theories and Experiments 227 not invariable, and, in many cases, it seems independent of the effects caused by the rarefaction of the air. It is observed particularly when abundant snows cover the mountains and the weather is calm. Perhaps this is the place to note that de Saussure was relieved of the distress he felt on Mont Blanc when a light north wind arose. In America, the name soroche is given to this meteorological state of the air, which affects the organs of respiration so greatly. Soroche, in the language of the American miners, means pyrites; this name shows plainly enough that this phenomenon was attributed to sub- terranean exhalations. The thing is not impossible, but it is more natural to see in the soroche an effect of the snow. The suffocation which I felt several times myself while I was mounting over snow, when it was struck by rays of the sun, made me think that air which was evidently foul might escape from it as an effect of the heat. What supported me in this strange idea was a former experiment of de Saussure, in which he thought he observed that the air which escaped from the pores of the snow contained much less oxygen than the atmosphere. The air subjected to examination had been collected in the interstices of the snow on the col du Geant. Analysis of it was made by Sennebier, by nitrous gas and in compari- son with the air of Geneva. (P. 167.) M. Boussingault then repeats the experiment of Sennebier with the snow which he had taken from Chimborazo. Ordinary analysis gave him only 16% of oxygen. But the celebrated chemist him- self declares that objection may "strictly" be made to his method; since the snow had melted in the bottle, the air, in the presence of water only slightly aerated, might have given it part of its oxygen. Evidently that depends upon the quantity of air in pro- portion to the quantity of water, a proportion which is not given in the work from which we quote. But later, M. Boussingault, having taken up this question again,47 showed that the apparent lack of oxygen in the air contained in the pores of the snow results from the fact that the oxygen is dis- solved in greater proportion than the nitrogen in the water of fusion. There is nothing left then of his first hypothesis. These contradictory results, due to the improvement of methods of chemical analysis, remind us of the different opinions expressed in 1804 and 1837 upon the same subject by the illustrious von Hum- boldt. In the letters which he wrote to his brother and Delambre, immediately after his ascents of Antisana and Chimborazo, von Humboldt declared that in his opinion The distress, the weakness, and the desire to vomit certainly came as much from the lack oi oxygen in these regions as from the rarity of the air. He had found only 0.20 of oxygen at 3031 fathoms, on Chimborazo. (P. 175.) " 228 Historical And yet, it appears from his letter to his brother40 that the same symptoms attacked him on the summit of Antisana, where, however, analysis showed them the normal proportion of 0.218 of oxygen in the air. But when, in 1837,50 he refers to the details of his account, he no longer speaks of the chemical composition of the air, but only of the lessened quantity of oxygen in the same volume; further- more, he introduces into science a new explanation of the fatigue on mountains, an unsatisfactory explanation, which, however, was long accepted without contradiction: According to the present state of eudiometry, the air seems as rich in oxygen in these lofty regions as in the lower regions; but in this rarefied air, since the barometric pressure is less than half what we are ordinarily exposed to on the plains, a smaller quantity of oxygen is received by the blood at each aspiration, and we understand perfectly why a general feeling of weakness would result. This is not the place to inquire why this asthenia, on the mountains as in vertigo, usually causes uneasiness and a desire to vomit, nor is it the place to demonstrate that the issue of blood or bleeding from the lips, the gums, and the eyes, not experienced by everyone at such great heights, can by no means be explained satisfactorily by the progressive removal of a mechanical counterweight which compresses the vascular system. It would be better to examine the probability of the effect of a lessened air pressure upon weariness when the legs are moving in regions where the atmosphere is greatly rarefied; since, according to the memorable discovery of two clever scholars, MM. Guillaume and Edouard Weber, the leg, attached 51 to the body, is supported when it moves, only by the pressure of the atmospheric air. (P. 419.) If M. Gay-Lussac, who on September 16, 1804, reached the prodi- gious height of 21,600 feet, which consequently was between that of Chimborazo and Illimani, did not suffer from bleeding, perhaps that should be attributed to the absence of all muscular movement. (P. 418.) About this time, a French physician, Dr. Junod,"'2 conceived and carried out the idea, already glimpsed by Gondret, of lowering the pressure artificially in apparatuses large enough to accommodate a man. M. Junod had been led to make his experiments by the effects "he felt from the expanded air in the Alps, in the Pyrenees, and on Mount Etna. His apparatus consisted of a copper sphere 1.30 meters in diameter, in which a man could sit: When a person is placed in the interior of the receiver, and the natural pressure of the air is lessened one-quarter, this is what one observes: 1. The membrane of the tympanum is distended, which causes a Theories and Experiments 229 rather uncomfortable sensation, which disappears as equilibrium is reestablished; 2. Respiration is hampered: the inspirations are short and fre- quent after 15 or 20 minutes. A true dyspnea follows this difficulty in breathing; 3. The pulse is full, easily depressed, frequent; all kinds of super- ficial vessels are in a state of manifest turgescence. The eyelids and the lips are distended by the superabundance of fluids. Not infre- quently hemorrhages occur, with a tendency to syncope. The skin is the seat of distressing heat and its functions are increased; 4. The slackened formation of blood, the expansion, more or less great, of the gases which circulate with the blood, and the super- abundance of this liquid in the different classes of superficial vessels, explain well enough the failure of innervation which is characterized by lack of energy and a complete apathy; 5. The salivary and renal glands secrete their fluids less abun- dantly, and this effect seems to extend over the whole glandular system; 6. The weight of the body seems to diminish perceptibly. The memoir ends with the description of the large cupping- glasses and of some pathological cases treated with them. To the application of this method of treatment, to which he has given the name of hcmospasie, M. Junod has devoted his efforts since that time.53 It really has no connection with our subject, since it con- cerns a rupture of the equilibrium of pressure between different points on the body, by the application of a partial vacuum on one or several members. Magendie first made this evident in the re- port 54 which he was requested to present to the Academy of Sci- ences upon the work of M. Junod. The celebrated physiologist first reviews the history of cupping- glasses, which date from the time of the Egyptians, and passes to the barometric chambers of M. Junod by a transition which shows that, in spite of himself, he still compares them with these cup- ping-glasses: These apparatuses (he says, in fact) were constructed with the purpose of varying, upward or downward, the pressure which the body of man sustains through the extent of its cutaneous and pulmo- nary surfaces . . . It is by acting upon the two surfaces at the same time that this apparatus differs from those which were devised in England by MM. Murray and Clanny; these apparatuses last mentioned act exclusively upon the skin, the lungs having free communication with the outer air, through a separate tube.65 Then, to come to the part of M. Junod's work which has some interest for us, Magendie quotes the report of the phenomena pre- 230 Historical sen ted by a man subjected to the action of compressed or ex- panded air; we have just taken from the original memoir what relates to this last point. We regret to add that Magendie did not display much fore- sight when he said: From a medical point of view, these apparatuses as yet do not seem to offer any application . . . That is not true, however, of those which M. Junod designs to use for rarifying or compressing the air around members. It is not surprising to note that after these discouraging re- marks M. Junod gave up the use of expanded air as a general medium, and limited himself to improving 56 the large cupping- glasses which bear his name, a very powerful therapeutic agent which has very unjustly been neglected by physicians. But through a strange confusion, explanations which were very appropriate when it was a matter of the local rarefaction by the large cupping- glasses continued to be applied to the general action of decreased pressure. As an example of this mistake, I shall quote the remarks of Dr. H. Favre: 57 The principles upon which the Junod method rests are very simple: M. Junod, born in the Alps, had himself felt the difference in pressure as one ascends or descends in the mountains. He resumed the experiments of de Saussure and Gay-Lussac with the most laud- able discernment. If one ascends to the summit of Mont Blanc, or rises in a balloon to a height of 7000 meters, he feels remarkable effects, resulting solely from the lack of pressure exerted at these heights by the more and more rarefied atmosphere. Artificially, we know how, by making a vacuum, to rarefy the air, that is, to lessen the pressure on a circumscribed area. If we are dealing with a living body, certain effects produced by an ascent in the atmosphere will then appear: such is the purpose of hcmospasie; Dr. Junod attains it by the creation of his large cupping-glass. (P. 7.) Returning now to mountain travellers, we find again the series of mistaken preconceptions and apparent contradictions which we have already noted. The difficulty of explaining the facts brings many of these travellers to deny them. An example of these theoretical protests is furnished us by the editor of the Biblio- thcque universelle of Geneva, who reviewed the account of the ascent of Mont Blanc by Dr. Barry: The circumstances observed by M. Barry are so unimportant that they confirm us in the opinion that fatigue plays a greater part than Theories and Experiments 231 the rarity of the air or the supposed influence of snow . . . We can assert that these are the same sensations felt by ordinary travellers when they approach the summit of any mountain whatsoever. I beg the reader to refer to the actual words of Barry, which I quoted previously (See page 95) ; he will find, I hope, in them a proof of the necessity of verbatim quotations. It is interesting to note that M. Martins,59 who was later to become so sick on Mont Blanc as if by a kind of punishment for his skepticism, at that time shared these sentiments. Accounts of mountain sickness left him very incredulous: As for us (he says), occupied night and day with our observa- tions, we also tried to test our sensations to find out whether this lofty habitation (2680 meters) had any physiological effect upon our organs. But it was in vain . . . Since my sojourn there, I have read again all the accounts of ascents of Mont Blanc, from de Saussure to Mile. d'Angeville, and the sensations felt by these travellers can be explained very easily by fatigue . . . Of course the air of the mountains is more rarefied, but it is also more alive . . . The liveliness of the air, added to its rarity, refreshes the traveller and doubles his powers; for the chemical composition is the same. (P. 213.) I confess that I am surprised that a man with so clear and so perspicacious a mind could have used such expressions. What do the words "a more alive air" mean.? The Swiss peasants who saw the celebrated professor of Montpellier collecting air in balloons and sending it to Paris, and who thought that he would make some illustrious patient breathe it, shook their heads and said: "Our air will be dead when it gets there." We see that essentially they thought like M. Martins. Dr. Rey,G0 whose work is often quoted, and who, without seem- ing ever to have made an ascent, wrote a dogmatic article about mountain sickness, reaches the theoretical explanation after an enumerative description. He sees, and in this he does not have the merit of invention, that rarefied air is the cause of all these symptoms: It is neither the fatigue which removes the power of breathing, nor the difficulty of breathing, nor an incomplete respiration which cause the exhaustion, as has sometimes been said; it is the decrease in the density of the air . . . These effects are due to the relaxation of the fibre caused by the decrease of the compressing power of -the air, the explanation of which follows. (P. 334.) The usual calculation on the difference in the weight sustained by the body at different altitudes follows. At the Saint Bernard 232 Historical pass, "the action of the atmosphere is diminished one quarter or 5500 pounds, which expands the vessels in a similar proportion". Then, to the explanations "furnished by science" Rey adds one, which I cannot help finding rather queer: We can hardly climb to the top of a very lofty tower without making frequent pauses on the way, and usually we reach the top only with great effort. Certainly that is not because of the rarefaction of the air, nor even because of weariness. Is it not because we have had to lift our legs many times consecutively, by a law quite different from that of walking and much harder to obey? In fact, all the muscles of our organs of locomotion, set to work at the same time by an ascensional movement to the continuity of which they are not accustomed, experience from it a fatigue which forces us to pause frequently, which increases as long as we continue ,t° mount, but which ceases as soon as we have reached the top and does not return while we are taking the same way downward. Well, that which takes place in a man climbing a stairway he experiences with greater reason on the side of a rugged mountain, because here there is a combination of a long walk on trails often requiring violent and unaccustomed use of muscular powers and a great rarefaction of the atmospheric air. If we could wind around Mont Blanc and reach its crest by a gradual slope as we wind around the Saint Gothard or the Simplon pass, it would no longer be necessary to make the unnatural movement of the legs, members which become heavier to raise in proportion to the contraction of the column of the air, and consequently we should no longer feel this distress which we mistake for fatigue. (P. 335.) Tschudi,61 the celebrated. German traveller whose complete de- scription of the mountain sickness in the Cordillera of the Andes we have already quoted, explains the extreme weariness of the lower limbs which one experiences in ascending, like von Hum- boldt and the Weber brothers: Since the head of the femur, according to the researches of Weber, is held in its cavity by atmospheric pressure, when this pressure di- minishes, a continuous muscular contraction must replace it. (Vol. II, p. 66.) He then reports, but without seeming to believe it, the explana- tion given by the Indians about metallic emanations: There are places where it is known that the Veta is more severe than elsewhere, and they are sometimes lower than others where it is much less evident, so that it does not seem to be caused entirely by the rarefied air, but also by some unknown climatic influence. Usually these places are rich in minerals, whence comes the general belief of the Peruvians that these effects are due to metallic emanations. Dr. Archibald Smith G2 does not consider these differences; but Theories and Experiments 233 he gives some very strange information about the symptoms of the Veta and their possible causes: The inhabitants of the coast, when they climb the chain of the Andes, feel their respiration oppressed in places where the Indians do not experience this distress, because of the much greater develop- ment of their respiratory organs .... The pulse accelerates and the lungs act much more rapidly than normally. Their free play is hindered, however, by the accumulation of blood and a considerable degree of congestion, resulting, in my opinion, on the one hand from the lessened atmospheric pressure, which causes an expansion of the fluids in circulation, and on the other hand from the resistance of the cutaneous and pulmonary capillaries enlarged by the cold. The result of this is that strangers to these climates are very subject to stomach disturbances, dyspnea, apoplexy, or other hemor- rhages when they cross the passes of the Cordilleras . . . Cats which have been taken to the snow line and have been well-fed are very subject to sudden death ... I have heard that at Cerro de Pasco a terrier suddenly fell dead, probably from apoplexy, while he was jumping with joy and caressing his master. (P. 356.) An English traveller, Hill,03 who was quite sick while crossing the Andes, and who saw two children stricken with the soroche so violently that they "were almost lifeless in the arms of their father", lays stress upon the effect of different temperaments in reference to the severity of the illness: The illness, in its most serious form, is accompanied by very alarming symptoms and is generally fatal; in a traveller of a plethoric constitution it is usually very serious; it is characterized then by vertigo, weakness of vision and hearing, and very often by a flow of blood from the eyes, the nose, and the lips and by violent headaches and vomiting.- But in thin travellers, not very strong in constitution, it is more likely to cause fits of weakness, accompanied by the spitting of blood. In persons who enjoy good health, vomiting is one of the most frequent symptoms, and the others generally consist of lassitude and difficulty in breathing, such as appeared in my companions and myself. (P. 68.) Coming to the causes of the symptoms, he repeats, without seem- ing to attach real importance to it, the opinion of the natives about metallic emanations: This illness has been noted to be more common in the provinces where metals abound; so the general opinion among the natives is that it owes its appearance or its increase of violence to the metallic exhalations which are supposed to saturate the atmosphere of those regions. This opinion is undeniably based on the fact that the disease particularly attacks prospectors for metals, men who are usually not 234 Historical accustomed to the air of the mountains, and who endure great fatigue. We can hardly doubt that, whatever the form under which it presents itself, its appearance is due to the decrease in the weight of the air, whose effect everyone feels in very lofty places. (P. 69.) Hill does not hesitate to declare that animals can become almost completely acclimated to lofty places: The effects of the rarefied air are not limited to man; they exert equal, if not greater, action upon the other animals of creation. The horses and the mules of the plains cannot cover the same distance in a given time on the mountains as on the plain; they are not capable of carrying as heavy burdens on the Sierra as in the climates in which they are accustomed to living. However, these animals, when they have been taken to consider- able heights and are well cared for, become acclimated, in most cases, after a few months, and they become fit to do almost the same work as animals born in these lofty regions. (P. 69.) The physiologists continued, nevertheless, but without great success, to seek for the causes of these symptoms noted, explained, or denied by travellers. One of them, M. Maissiat,64 whom his pro- found knowledge of physics has often inspired to better result, tak- ing up an explanation which we have already seen mentioned by Clissold, in 1822, gives an important part to the abdominal gases, expanded by the decrease in pressure: Their pressure stimulates the diaphragm and regulates the fre- quency of its contractions; therefore, the circulation is linked with the production of the intestinal gases. (P. 253.) If the pressure enveloping the animal diminishes, there will be acceleration of the circulation and respiration and congestion of the skin, and if the pressure continues to diminish, delirium or even death may result; since the pressure of the abdominal 'gases increases in its effects proportional to the decrease in the outer pressure, these gases expand and distend the entire abdomen even to the point of rupture, if the drop in external pressure is very rapid .... The accelerated circulation and respiration tend to speed up the abdominal action, and thus to restore equilibrium and quiet regu- larity. (P. 254.) The German physician, Flechner,*55 reports an opinion quite con- trary to that of Boussingault and von Humboldt upon the compo- sition of the air of lofty places; he opposes it, it is true, and pre- fers the last idea suggested by de Saussure. I quote from the review in Schmidt's Jahrbuch: According to the general opinion, the air in the mountains is richer in oxygen, from which inflammatory diseases result .... Theories and Experiments 235 Flechner has found that that is not correct .... But if, in lofty places, the air is rarer while the composition remains the same, the oxygen will weigh less: it will furnish less oxygen to the blood. The light of the sun has no effect. All the rest of the work is devoted to considerations of the diseases which are prevalent in the mountains. The professor of Lyons, Brachet,00 in the special work which he devoted to our subject, begins by repeating the common idea of the decrease of the weight sustained by the body when the air expands: A column of air which raises the barometer only to 13 ¥2 inches must exert upon the body and all the surfaces with which it is in contact an infinitely smaller pressure, the effects of which we can compare to those of the immense cupping-glass of Dr. Junod and which we might, consequently, consider as a sort of suction. The capillaries, which are less compressed, must therefore react less energetically upon the blood and the other liquids which circulate through them; they must therefore be distended and congested by a sort of stasis .... The rarefaction of the air explains very well the difficulty and trouble in breathing, but it does not explain the panting and the extreme prostration which the slightest movement causes. To explain this new element, Brachet, who has just fallen into so strange an error in physics, expresses the most suitable ideas: The panting (he says) results from the darker blood which reaches the lungs and does not find, in the rarified air which enters there, a sufficient quantity of oxygen to revitalize it quickly enough. The lassitude results from the fact that the blood, which is therefore not well aerated, no longer gives the muscles the normal stimulus which they need to contract. This view, which is so simple, so clear, and, let us add in ad- vance, so true, did not end the controversy, however. In fact, a few months afterwards, Castel,G7 a member of the Academy of Medicine, discussing the question theoretically, ex- presses himself on the subject in the vaguest terms; no doubt, for him, the physiological phenomena observed on lofty mountains are due to the decrease of atmospheric pressure, but, he adds: Not that this pressure is, as certain authors have maintained, the immediate agent in the movement of the blood in the most remote arterial ramifications and the veins, but it exerts a direct and constant influence upon contractility, of which the flow of animal liquids is never independent. The contractility is checked to a degree propor- tional to the amount of decrease of atmospheric pressure. Finally, in this same year, the celebrated German physiologist Vierordt os made a certain number of experiments upon the effect 236 Historical of slightly expanded air upon respiration. He gives no informa- tion about the manner in which he carried on his experiments, which dealt only with pressures included between 340 and 330 lines of Paris (767 and 744 mm.) . Their chief purpose was to find out whether variations in pres- sure have an effect on the exhalation of carbonic acid; their results are not very clear, in spite of the profusion of tabelles in which they are expressed and the wealth of decimals of doubtful deriva- tion which accompany each number. All conclusions based on these experiments would seem to me extremely rash. Besides, the slight barometric oscillations within the limits of which they are kept prevent them from having any interest for us. It was also at this same period that M. Lepileur's C9 memoir appeared, the interesting narrative of which we have quoted in the proper place and in considerable detail (See page 98 et seq.). This work is not only rich in precise and shrewd observations, but it also contains theoretical views, the importance of which deserves our full attention. M. Lepileur first gives credit to the explanations of de Saussure and those of Brachet; but they do not satisfy him: The phenomena relating to hematosis do not seem to us the only causes of the panting and lassitude on lofty mountains .... One gradually becomes used to the rarefied air so that he no longer feels its effect. If it depended only on the more or less com- plete stimulation of the muscles by a blood which is more or less arterial, would this fatigue be accompanied by pains of back and limbs, and would it be likely to disappear thus through habit in so short a time? We should be tempted to consider this painful fatigue as resulting chiefly from the congestion of blood taking place in the muscles during their action, in proportion to their efforts, and the whole group of phenomena due to the rarefaction of the air seems to us to agree fairly well with this idea. The more active the circulation is, the more easily congested the organs are. Now the pulse, without losing strength, becomes considerably more rapid when one is ascending a mountain, and the tendency to congestions is completely demonstrated by the facts which we have given .... When one remains motionless, equi- librium is maintained .... but as soon as one begins to move, the contracted limbs become the seat of a congestion which occurs with a rapidity proportional to the increase in the speed of the circulation. (P. 62-64 of the separate printing.) Beside the congestion of blood in the muscles, which, according to him, explains the lassitude, M. Lepileur places exertion, which would explain the nausea, the impending syncope, and the head- ache: Theories and Experiments 237 During exertion, there is a stasis of blood in the capillaries and congestion in the brain, the lungs, and the muscles. When one makes a series of almost uninterrupted efforts, .... when one runs up a stairway, .... vision is dimmed, vertigo occurs, a painful fatigue is felt in the limbs, and muscular strength fails. But if one stops to get his breath before the effects of the cerebral and pulmonary congestion have reached this point, the blood then flows back towards the heart, the face grows pale, and a well denned sensation of fainting is felt; sometimes the syncope occurs even when one has not taken care to place himself immediately in a horizontal position .... If now we consider the phenomena observed in the organism at great heights, we find exactly the same course and the same signs. Except that the rarefaction of the air, by making respiration more frequent and the panting more rapid, necessarily hastens the rest of the ordinary effects of exertion .... The slight hemorrhages of the gums, the imminence of hemoptysis, and the epistaxis are explained by the congestion, as a result of exertion .... As to the distress in the stomach, must we not consider the grad- ual expansion of the intestinal gases under a constantly decreasing pressure of the atmosphere as contributing greatly to this phenomenon and to those which accompany it? ... . And yet we have not observed any increase in the volume of the abdomen. (P. 65-68.) We see that M. Lepileur considers that everything is explained by congestions of the muscles and the nervous centers, due to exertion and increased by the panting, about the cause of which he says absolutely nothing. It appeared very difficult, after so complete and detailed an observation, to deny the harmful effect of altitude under certain circumstances. And so, following the account of his ascent of the Wetterhorn (3707 meters), on August 31, 1845, A. Vogt 70 protests against denials which are at least unwise; moreover, he tries to explain them, but he is not very successful in this attempt: We see (he says) in the narratives of travellers who have climbed lofty mountains strange contradictions; some mention frequent and more or less serious disturbances, others deny them completely. It seems to me that three factors act upon the human organism at great altitudes: 1) The decrease of weight of the atmosphere and the consequent expansion of the air; 2) the dryness of the air; and 3) the light reflected from the stretches of snow. Martins, Barry, Agassiz, Desor, Escher von der Linth, etc., who felt no symptoms, blame the imagination of their predecessors. I can contradict them on one point. During the night which we passed at the Aaresattel, I was astonished at the rapidity of my breathing; my respiratory rate was twice as great as on the plain, although I did not feel the slightest discomfort. 238 Historical It is natural for one to breathe more air in a rarefied atmosphere, in order to bring the same quantity of oxygen to the blood, since in a given volume of air there is less weight of it than on the plain. If there are many mountain climbers who have not noticed this phe- nomenon, that is because the diminished atmospheric pressure is a great help in the expansion of the thoracic cavity, and thereby makes respiration easier. Father Hue 71 is not a skeptic, far from it. His well-known credulity even robs his accounts of much authority. Nothing is so strange as this simplicity which very lightly borrows the language and the aid of science. In fact, he adopts absolutely the idea of poisonous emanations or vapors; but, more daring than his prede- cessors, he even specifies the nature of them, and considers that they are formed of carbonic acid: The mountain Bourhan-Bota has this very strange peculiarity, that the harmful gas exists only on the part that faces east and north; on the other side, the air is pure and quite respirable; it seems that these poisonous vapors are nothing but carbonic acid gas. The people attached to the embassy told us that when it was windy, the vapors were hardly noticeable, but that they were very dangerous when the weather was calm and serene. Since carbonic acid gas is known to be heavier than atmospheric air, it must condense on the surface of the ground and remain there until a great agitation of the air sets it in motion, scatters it through the atmosphere, and neutralizes its effects. When we crossed Bourhan-Bota, the weather was quite calm. We noticed that when we were lying down on the ground, we breathed with much more difficulty; if, on the contrary, we mounted our horses, the influence of the gas was hardly felt. Because of the presence of carbonic acid, it was very difficult to light a fire, the argals burned without flame, shedding much smoke. However, it is impossible for us to tell how this gas was formed and whence it came .... A terrible quantity of snow fell during the night; those who, on the day before, had not dared to keep on, joined us in the course of the morning; they told us that they had finished the ascent of the mountain with ease because the snow had dispelled the vapors. (P. 265.) These regions, so rarely explored, were crossed in 1873 by Cap- tain Przevalski.72 He rejects absolutely the explanation which we have just reported: The great elevation of northern Thibet causes marked difficulty in breathing, especially if one walks quickly; then come vertigo, trembling in the legs, and even vomiting. The fuel of the country (argal) is hard to burn because of the rarefaction of the air and the rarity of the oxygen. The missionary Hue explains the same phenomena, which he observed on the mountain of Burchan-buda, by emanations of carbonic Theories and Experiments 239 gas; but that is a mistake, for many Mongols from Tsaidam remain there during the summer with their cattle, which would not be pos- sible if asphyxiating gases escaped there .... Father Hue should not be believed when he speaks of the harmful gases of Burchan-buda. (P. 174.) Dr. Pravaz,73 a physician of Lyons, a few years before, had founded an establishment in which he used a stay in compressed air for the treatment of different diseases. The book which he devoted in 1850 to the exposition of the data which he had ob- served contains, in its first part, interesting remarks on the different causes of mountain sickness: 1. Respiration is mechanically restrained in its extent by the lack of elasticity of the atmosphere, which presses upon the interior of the lungs and by itself causes their development when the thorax expands through the effort of the inspirating muscles. 2. This function is insufficient for hematosis, because the oxygen, or the vivifying principle of the blood, is present in too small an absolute quantity in the volume of air introduced by each movement of the inspiration, in addition to the fact that the lack of pressure makes the quantity of this gas dissolved in the blood less abundant. 3. The arterial circulation is accelerated as a result of the rapidity of the respiratory movements caused by the instinct of self-preserva- tion, while the capillary circulation slackens, because the recall of the venous blood to the right cavities of the heart has become less ener- getic on account of the decrease of the constriction exerted on the periphery of the organs. (P. 57.) Farther on, while discussing at length these congestions of the mucous membranes which have attracted so much attention from the observers, he explains them by saying: One of the motors of the venous circulation, and consequently of the capillary circulation, namely, the atmospheric pressure, decreases as one rises above sea level. The greater the altitude, the less active will the recall of the blood into the right cavities of the heart be, and the greater tendency will the blood have to congest the parts where aspiration is ordinarily most effective. We may then compare the action of the heart with that of a pump working in a medium where the air is very much rarefied, and which can draw water only at a depth much less than under the ordinary pressure of the atmos- phere .... Hence the tendency to hemorrhages and apoplexy on lofty moun- tains. Mountain sickness presents another symptom which no one has tried to explain physiologically. It is evidently produced by a disturb- ance of the circulation in the portal vein system; it is characterized, in fact, like congestions of the liver and the abdominal viscera, by vomiting, cramps in the stomach, and intestinal pains. (P. 82.) 240 Historical As to the differences presented by different individuals with reference to the altitude at which mountain sickness attacks them, Pravaz finds reason for that in the inequality of "the resistance of their tissues and in the vital contractility of their lungs". The sudden appearance of symptoms, a suddenness which our author exaggerates, is due to the fact that "in an almost indi- visible moment, the atmospheric pressure becomes less than the reaction of the lung, and ceases to be able to struggle successfully against it. . . . The decrease of the quantity of oxygen contained in the air breathed would not be great enough to explain this fact, for this decrease . . . could bring on dyspnea only gradually". (P. 76.) Be that as it may in regard to this last restriction, up to that time the alternative explanation given by de Saussure had been accepted without dispute, an explanation which tends to attribute the discomforts of decompression chiefly to the insufficient quan- tity of oxygen which the respiratory acts bring into the lungs. But in 1851, Pay erne,74 an engineer who gave much attention to diving- bells, raised an objection to this hypothesis, the worth of which we shall discuss later: Upon the highest summits ever ascended, the pressure is equal at least to 32 cm. of mercury. The air there contains still 125 gm. of oxygen per cubic meter, or 100 gm. per 800 liters which a man- breathes per hour. Now experiments, the accuracy of which no one could question, have recently shown that a man while resting con- verts only 50 gm. of oxygen into carbonic acid. Assuming that while at work he would convert 5 and even 10 gm. more, he will be far from lacking it in a place where the barometer stands at 32 centi- meters .... The weariness and the panting in lofty places therefore do not seem to me to come from an insufficiency of oxygen, but from the rupture of the equilibrium between the tension of the fluids contained in our organs and that of the ambient air, no matter in which direc- tion the rupture operates. The authors who followed Payerne seemed not to have known of his objections. Marchal de Calvi,75 among others, reproduces purely and simply the former explanation; this is shown by the extract from his work, published by the Proceedings; this extract we quote in full: The author thinks that he can conclude from the experiments reported in this Note that the variations in the atmospheric pressure are far from exerting the influence attributed to them. According to him, the mistake comes from the fact that in most cases which have been considered, when there is a decrease in pressure on the surface Theories and Experiments 241 of the body, there is at the same time rarefaction of the air entering our lungs, and consequently decrease in the quantity of oxygen nec- essary for the normal accomplishment of hematosis. In 1853, Speer,76 an English physician, published a special work on the nature and causes of mountain sickness. He begins by tell- ing that he himself, on the main peak of Mont Blanc, began to feel the following symptoms when he had reached 9000 feet: Congestion in the head, throbbing of the carotids, palpitations of the heart, distaste for food. At 10,000 feet, he felt a constriction of the chest, and shortly after, the taste of blood in his mouth, which was caused by a slight exudation from the gums. He then reviews the different explanations suggested, dwelling on that of Brachet, which he finds "too exclusive". To his mind, the great fatigue of the muscles is caused by "the congestion of blood which follows their repeated contractions", and as for the other symptoms of mountain sickness, they are due chiefly to "the irregularity of the circulation, with congestion of the brain and the abdominal viscera". The following conclusions indicate clearly the author's line of thought: Mountain sickness is characterized by the following symptoms, the union of all of which, however, is only rarely seen, if ever, in the same person: vertigo, headache, drowsiness, dyspnea, constriction of the chest, palpitations, tendency to syncope, oozing of blood from the mucous surfaces, increased rapidity of the pulse, anorexia, nausea and vomiting, thirst, feverish tongue, muscular pains, sensation of extreme weakness in the lower limbs, general prostration. These symptoms should be attributed to three causes: gradually increasing congestion of the deep portions of the circulatory apparatus; increase of venous plethora of the blood; loss of equilibrium between . the outer air and that of the gases present in the intestine. These determining causes of mountain sickness are themselves the result of the considerable and rapid change in the pressure and the temperature of the atmosphere. The next year, Dr. Conrad Meyer-Ahrens," a physician at Zurich, devoted to the study of the symptoms of decompression a long work far more important than that of Speer. This memoir is composed of two parts; in the first (p. 1-99) the narratives of a great many travellers are reported with details; the second summarizes the symptomatology (p. 99-123) and indi- cates the etiology (p. 123-136), the prophylaxis and treatment (p. 136-139) of mountain sickness. In the preceding chapters, we have given all the data quoted 242 Historical by Meyer-Ahrens and many others besides; since this part of his work contains no personal observation, I shall not speak of it. But from the part devoted to symptomatology, I extract a very good summary of the symptoms from which mountain travellers have suffered in different degrees: The principal symptoms or at least those which occur oftenest in man are: discomfort, distaste for food, especially distaste for wine (however, the contrary has sometimes been noted), intense thirst (especially for water, which quenches the thirst best), nausea, vomit- ing; accelerated and panting respiration; dyspnea, acceleration of the pulse, throbbing of the large arteries and the temples; violent palpi- tations, oppression, anxiety, asphyxia; vertigo, headache, tendency to syncope; unconquerable desire for sleep, though the sleep does not refresh but is disturbed by anguish; finally, astonishing and very strange muscular fatigue. These symptoms do not always appear all together .... Others are observed, although less frequently, such as pulmonary, renal, and intestinal hemorrhages (in animals also); vomiting of blood; oozing of blood from the mucous membrane of the lips and the skin (due merely to the desiccation of these mem- branes), blunting of sensory perceptions and the intelligence, impa- tience, irritability, .... finally, buzzing in the ears. (Pages 100-101.) But the chapter most interesting to us is that on etiology. I quote here the principal passages: All that we have just said about the etiology of mountain sickness shows: 1) that it appears at varying altitudes; 2) that meteor- ological conditions, temporary or general personal characteristics, and the speed of walking vary the altitude at which one is attacked and the severity and number of the symptoms. When one sees the appearance of mountain sickness correspond to varying altitudes, he asks himself what circumstances depending upon the altitude are capable of causing the phenomena which con- stitute it. In my opinion, the principal role belongs to the decrease of the absolute quantity of oxygen in the rarefied air, the rapidity of evaporation, and the intense action of light, direct or reflected from the snow, whereas the direct action of the decrease of pressure should be placed in the second rank. I find the immediate causes of mountain sickness in the changes made in the composition and the formation of the blood by the decrease in oxygen and the exaggerated evapora- tion, changes to which are added others due to the action of light on the cerebral functions, an action which affects the preparation of the blood liquid. These suppositions permit us to include — if we also take into account individual constitutions — all the phenomena of mountain sick- ness, without needing to appeal to the -direct action of the decrease in the weight of the air. This explains the acceleration of the respira- tory movements and the circulation, the congestions, the hemorrhages, the functional disturbances of the brain and the extraordinary fatigue of which almost all travellers complain. "We see too why mountain Theories and Experiments 243 sickness attacks not only travellers on foot, but also horsemen; why the former are stricken much more severely (twice as severely, ac- cording to Tschudi); why exertion aggravates it; why it disappears when the traveller stops walking for a moment and reappears imme- diately when he starts again; why, however, just as horsemen themselves feel its painful symptoms, so at very great heights rest does not completely free travellers from it (de Saussure, A. Vogt) ; why walking on a level at great heights is often accompanied by distress which increases when one walks more quickly or begins to climb; why aeronauts are not exempt from disturbances of respiration and circulation; why patients stricken by the disease of the Puna are advised to sit quietly in rooms which are warm and well closed, etc. (Pages 131-133.) .... Other phenomena can in part be attributed to the immediate action of the diminished pressure, as, for example, the strange sensa- tion of lightness of which many travellers speak, the violent beating of the heart, qualms, nausea, vomiting, and oppression. In fact, the lessened pressure of the air, by lowering resistances, aids rapid walk- ing, respiratory movements, and the action of the heart, while at the same time it tends to increase the volume of gases contained in the intestinal canal; so that distention of the stomach and the crowding upward of the diaphragm may bring on nausea and oppression. But these phenomena of direct action may be relegated to the second rank, as I have already said. (P. 134.) We know, from the experiments of the Webers, that the great lassitude of mountain travellers is due to a direct action of the diminished atmospheric pressure; but we must understand that not only the large muscles, those that move the large bones and hold them in their articulations, become weary, but the same thing is also true of the small muscles, like those of the tongue and the larynx (Parrot and Hamel) ; a phenomenon which must be general and keep increasing, as A. Vogt asserts, if it is the consequence of the decrease in pressure, and that really does happen. Here too, we must make allowance for individual peculiarities. (P. 135.) So, in the eyes of Meyer-Ahrens, the immediate causes of mountain sickness are, in the first place, the decrease in the abso- lute quantity of oxygen in the rarefied air; then come the rapidity of evaporation, the intense action of the light, the increase in vol- ume of the intestinal gases, and a weakening of the coxo-femoral articulation. Dr. Lombard,TS who almost at the same time wrote for the Bibliotheque de Geneve excellent articles which he soon afterwards collected and published in a brochure, returns purely and simply to the two old explanations of de Saussure: diminution of weight sustained, diminution of the quantity of oxygen contained in the same volume of air; then the theory of the Webers appears again: 244 Historical There is a very important element in mountain climates; it is a lessened atmospheric pressure and consequently an air which is less dense, as well as a decrease in the quantity of oxygen which is necessary to maintain life by means of respiration. To these last two circumstances are due in great part the phenomena observed on lofty mountains, and to these two I wish to call the attention of my readers for a few moments. If we question physics, we shall see that the total weight of the atmosphere represents as many times one hundred three kilograms as there are square decimeters on the surface of our body, so that, depending upon the height of different persons, the total weight sus- tained by our organs will vary between fifteen and twenty thousand kilograms. If then we leave a country more or less near sea level for a higher elevation, our bodies will sustain a pressure which will diminish in proportion to the increase in altitude. We can understand what a shock it must be to our organs when the enormous weight to which they are usually subjected is diminished by a sixth, a quar- ter, and even a third, as is noted on the Righi, the Saint Bernard, or the summit of Mont Blanc. And if we add to this decrease in pressure the no less important change which takes place in the density of the air, and consequently in the quantity of oxygen, we shall not find it difficult to explain the various disturbances which occur in the respi- ration, the circulation, the locomotion, and the digestive processes of those who climb the lofty peaks of our Alps, or dwell there for a time. In the appearance of the symptoms of which we are speaking, what part is played by a low pressure, and what part by an insufficient quantity of oxygen? That question is hard to answer, since both respiration and circulation should be equally modified under these two influences and should react on the muscular strength; on the other hand, now that recent researches have shown that the head of the femur is kept in the cotyloid cavity by means of the atmospheric pressure, it is clear that a decrease in the weight of the air should make movements more difficult; so that we reach the conclusion that the phenomena produced in living bodies, transported to great heights, are the result of the two meteorological conditions of which we have just spoken: a decreased pressure and a smaller quantity of oxygen. (P. 273.) But shortly after this, M. Giraud-Teulon, a French physician who was very competent in matters relating to physics, completely exposed the fundamental error upon which M. Lombard, along with so many others, was relying. Long before this, Valentin,71' calculating the amount of the changes in the weight of the atmosphere on the surface of the human body at different heights above sea level, and admitting that organic matters are compressible to the same degree as water, had shown that: Theories and Experiments 245 For one atmosphere of added pressure, the decrease of volume would be about 0.2 of a cubic inch, that is, 1/22522 of the total volume of the body. We see then that the volume of a man who was on the summit of Mont Blanc and let himself slide down would contract only seven one-hundred-thousandths. (Vol. I, p. 84.) However, this clear demonstration of the lack of importance of changes in pressure considered from the mechanical point of view had not kept a very eminent author, Heusinger,80 from repeating with many details the explanation carelessly approved by so many travellers: The pressure of the atmosphere upon the body diminishes .... At sea level, it has been calculated that an adult man would sustain a pressure equal to 33,893 pounds; if he ascends to the height of Mont Blanc, the pressure will be only 19,334 pounds .... The bones will no longer be held in their articulations with the same strength, the muscles will have to exert greater force, fatigue therefore will be greater, .... the blood will be held with less force in the vessels, it will have a tendency to transude and to form hemorrhages where the walls are thin enough, and the blood will accumulate in the less contractible organs, where the capillary vessels can be expanded more easily, for example, in the mucous membrances, the lungs, and the brain; there will be congestion in these organs; the heart, which has fewer obstacles to overcome, will contract more often and the pulse will become more frequent. (Vol. I, p. 252.) We must note that to this erroneous cause a number of others are added, which are more or less justified, according to the vagaries of the eclectic method. First come evaporation due to decreased pressure and dryness, lower temperature, the action of the rays of the sun, which is stronger and "penetrates the body more deeply, and irritates the eyes, the brain, and the spinal cord", then electricity, "probably stronger and less often negative", and finally the lessened quantity of oxygen in the rarefied air, which "counterbalances the frequency of the respiration and the circu- lation". To return to the mechanical explanation, it was absolutely demolished by the work of M. Giraud-Teulon, and we are surprised that after such a thorough refutation, it has appeared again in books and even in the academies. M. Giraud-Teulon S1 first lays down two principles which have been too much forgotten by physicians and physiologists, before and after him: 246 Historical 1. All pressures exerted by the ambient atmosphere upon the human body naturally oppose each other and balance each other perfectly. 2. The force exerted by the weight of the atmosphere is, more- over, counterbalanced by the incompressibility of the liquids with which all our organs are imbued, and by the tension of the gases and vapors in the splanchnic cavities and interstices. Thus the skin is placed between two forces which strive in opposite directions and cause an equilibrium. Then he asks himself: Whence comes the difference (a difference, the nature of which he unfortunately does not explain) observed between the corpse and the living body in the reaction of the two to outer pressure? Should we attribute it entirely to the difference in temperatures? But the temperature of the human body is not high enough to give a tension of more than 3 or 4 centimeters of mercury to the vapors of the liquids which it contains. Should it be attributed to the gases dis- solved in these liquids? But the experiments of Magnus prove that if their quantity, merely for some of them, reaches proportions suffi- cient to carry the tension of the liquids containing them to a figure which equals or surpasses the atmospheric pressure, their action and their reaction, with reference to the atmosphere, would be purely physical. Now Magnus has shown, on the contrary, that the gases dissolved in the blood are retained there by quite other forces than simple pressure. For it is not enough to raise the temperature or to lower the outer tension, even to just a few centimeters, to expel the gases dissolved in the liquids of the body; it requires the presence of other gases for which the blood has a greater affinity than for the normal gases which it contains. Where then shall we find the inner force which balances the ambient pressure? In the study of the laws of circulation and pressure in the great vascular systems. The author then shows that, in the living animal, because of the circulation of the blood, the tissues are always in a state of tension which he estimates at from 8 to 15 millimeters of mercury. Since this tension is constant, the result is, he says: That the organic system of the living being is never endangered by even a great variation, if it is gradual, of the outer pressure and that the circulation would continue as it was before the variation. And this explains the data collected by M. Poiseuille and by M. Tingu, in regard to the continuation of the vital functions, in spite of a considerable increase of the ambient pressure. The dangerous power of the gases of the blood, freed by the decrease of pressure, a hypothesis which Robert Boyle was the first to express and which M. Giraud-Teulon strongly opposed, as we have just seen, found an able defender in Felix Hoppe.82 The work of this chemist is of a purely experimental type; it was Theories and Experiments 247 undertaken with the purpose of explaining the symptoms which attack laborers working in compressed air; and as everyone has observed that these symptoms occur at the moment of decom- pression, Hoppe hoped to find their cause by studying death in rarefied air. Here first is the summary of his experiments: A rat was subjected to a rapid decrease of pressure. Convulsions occurred at about 50 mm. of mercury .... and death between 40 and 50 mm. On opening the thorax, .... there could be seen through the walls of the vena cava, and the right auricle and ventricle, a considerable quantity of gas which could be released by puncture .... In a cat ... . which died at about 40 mm., .... I found about 0.3 cubic centimeters of air in the vena cava and the right cavities of the heart; there were a few bubbles of air in the left auricle. The veins and the right heart were full of blood, the left heart almost empty; the blood was completely liquid, the arteries contracted spontaneously, the ventricles only under stimulation; the lungs were empty of air and healthy; there was no rupture of vessels; the brain was normal .... Two swallows died .... at a pressure between 125 and 120 mm.; I found a few small bubbles of air in their blood In birds as in mammals, the blood of the left heart was bright red, and consequently still contained oxygen .... Two frogs taken to the point of complete collapse were opened; there was no gas in their hearts .... A slow-worm taken to a pressure of 22 mm. swelled and remained motionless; then, a few minutes after being returned to normal pressure, it seemed as well as before. Summarizing: 1. Birds die long before the point of effervescence of their blood; mammals die at a pressure hardly above this point; amphibians do not die even below this point; 2. In warm-blooded animals, gas escapes in the interior of the vessels as a result of rapid decrease of pressure. This is not true of amphibians. F. Hoppe then asks himself whether death should be attributed to this escape of the gases of the blood, or to the lack of oxygen in the blood. It is very difficult to answer this question, he says: "For, in the autopsy, the arterial blood is still bright red, and very different from the blood of animals dying of asphyxia" (P. 67) ; an observation which is accurate, but due to an experimental error which we shall demonstrate later. At any rate, the sudden death seems to him to be certainly due to the obstruction of the vessel by the gases liberated: The heart exerts upon its contents a pressure of 100 mm.; if the air in the large venous trunks has a pressure of only 50 mm., it must 248 Historical be compressed a third of its volume to enter the arteries; the result is a great slackening of the circulation. If this slackening, joined to the small quantity of oxygen contained in the blood and the unequal power of the right and the left heart, can cause death, it can be only an instantaneous death. This death can be caused only by the obstruction of the capillaries of the lungs by bubbles of air, whence comes the stoppage of the circulation. He does not limit himself to this theoretical demonstration, and tries to prove experimentally that it is not the lack of oxygen, But the decrease of the pressure which kills animals placed under the bell jar of the pneumatic machine. To make this proof, he uses a method which, long before I knew the work of Hoppe, one of the last I found in my bibliographical research, I frequently used, and from which, as will be seen, I have drawn conclusions diametri- cally opposite to his. It will be interesting to discuss the reason for these differences; but this is not the place to do so. At any rate, Hoppe said to himself: if it is the decrease of pres- sure which brings death, and not the lack of oxygen, death will necessarily occur at the same pressure, even if pure oxygen is used: A guinea pig fell in convulsions at 77 mm.; pure oxygen was admitted into the b'ell, and it rose at once. When the pressure had been lowered again, it experienced the same symptoms at 75 mm.; sec- ond admission of oxygen, third lowering of pressure: symptoms at 75 mm.; another admission of oxygen, collapse at 75 mm. Return to normal pressure; the animal survived. (P. 69.) .... So the symptoms of sudden asphyxia came at the same pressure, whether the animal was in air or in oxygen. From this he draws the definite conclusion that the cause of death lies in the appearance of free gases; the moment of their escape varies with "the pressure, the temperature of the animal, the power of absorption and the affinity of the blood for gases, and the quantity of blood corpuscles". The important researches of M. Fernet 83 this same year brought to the question a new element which, during later discussions of the cause of mountain sickness, seemed to support mistaken theories. Ever since the early experiments of Robert Bojde, it had been known that gases in considerable quantities are present in the blood. More recent chemists, particularly Magnus81 in 1837, had shown that oxygen forms a very large proportion of the gases. From these experiments physiologists had been led to conclude that respiration is only a simple exchange of gases between the Theories and Experiments 249 carbonic acid of the blood and the oxygen of the air, an exchange regulated by the laws of physics. 85. The work of M. Fernet made them change their minds. This physicist, by a series of experiments carried on with unusual shrewdness, showed that carbonic acid and oxygen are kept in the blood chiefly by a chemical affinity. The method of demonstration which he used is directly connected with our subject, since he utilized the effect of changes in the barometric pressure. The method used by M. Fernet involved removing from the blood the gases which it contained, agitating it in closed vessels, with oxygen or carbonic acid under various pressures, and meas- uring the quantity of gas which it absorbed under these different conditions. He thus showed that: The volumes of oxygen chemically absorbed and independent of the pressure have a relative value so great that these experiments are immediately distinguished thereby from those which relate to saline solutions and even to serum. Not only is the progress of the phenomenon almost completely freed from the law of simple solution, but the volumes absorbed seem from the very first to be independent of the pressure, since the volume, when chemically combined, is almost five times as great as the volume when dissolved under atmos- pheric pressure. (P. 209.) .... In respiration, the oxygen of the air exerts a pressure which amounts to only one-fifth of the pressure of the atmosphere, so the volume dissolved in the blood of the respiratory apparatus must be reduced in the same proportion. The volume of oxygen absorbed in the state of combination by the corpuscles will then become about twenty-five times as great as the volume which actually enters the serum in the state of true solution. (P. 211.) From this well established fact, in his actual experimental conditions, M. Fernet thought he could draw the following con- clusion: This is the explanation of this result, already verified by a great many observations, that the absorption of oxygen is practically the same, on the summits of mountain and on the plains, whatever the atmospheric pressure; however, observation, here agreeing with theory, has already noted slight differences corresponding to differ- ences in pressure; but they can be demonstrated only by measuring methods capable of great accuracy. (P. 211.) We should make reservations about this conclusion, which does not seem to us to be included in the experimental premises. But we shall see that certain physiologists let themselves be drawn far beyond that. In this number is Longet. 250 Historical Longet SG rapidly reviews the observations of mountain trav- ellers and aeronauts; he lists the different explanations which they have given of the symptoms felt. He agrees that sudden changes in the pressure can decrease the oxygenation of the blood, because: A certain lapse of time is always necessary for the equilibrium between the gases of the blood and the outer gases to be completely established, and also for the more active movements of respiration to be put in harmony with the new conditions, so that the lungs absorb, in a given time, almost the same quantity of oxygen as the normal state requires. (First edition, p. 474; third edition, p. 560.) But if one stays a long time, a complete equilibrium is estab- lished. In fact, he says: If, at each breath, the mountain dweller necessarily draws less oxygen into his lungs than the plain dweller does, he compensates for that by more frequent inspirations, so that, after all, in both of them the same quantity of oxygen can be absorbed in the same time. (First edition, p. 475; third edition, p. 561.) And farther on, speaking of the oxygen of the blood, he writes this quite explicit passage: We know that the quantity in weight of a gas dissolved in water is always proportional to the outer pressure; applying this law to the case in question, we would reach this conclusion that the blood of dwellers in regions where the atmospheric pressure is hardly 0.380 meters would contain one-half less oxygen than the blood of dwellers by the seashore, where this pressure is 0.760 meters; but no doubt the preceding law does not apply here, because some chemical affin- ity interferes. (Third edition, p. 592; first edition, p. 493.) That was also the opinion of M. Gavarret,ST who, in 1855, expressed himself as follows: It would be false to say that the absorption of oxygen by venous blood is a purely physical fact; everything proves, on the contrary, that chemical forces play an important part in this fixation of oxygen. If, in fact, its absorption was a simple physical solution, while the outer pressure remained the same, the quantity of oxygen absorbed should increase in direct ratio to the proportion of this gas in the air breathed by the animal; now the experiments of Lavoisier had already shown and those of M. Regnault had proved indisputably, that how- ever great is its proportion in the artificial atmospheres created around the animals, the consumption of oxygen remains the same. In the second place, if the composition of the air remains the same, the ponderable quantity of oxygen dissolved physically by a liquid varies proportionately to the outer pressure. In the hypothesis that the phenomenon took place entirely through physical forces, the mass of oxygen absorbed by the residents of cities situated on the Theories and Experiments 251 lofty plateaux of the New World would necessarily be reduced to very small proportions; the animals which live permanently at the dairy farm of Antisana, where the barometer stands at only 47 centimeters, would absorb a weight of oxygen less than two-thirds as much as they consume at sea level. Such a variation in so important a function would certainly cause great changes in their mode of exist- ence, which surely would not have escaped observation. If the oxygenation of the blood in the pulmonary capillaries was a purely physical fact, in birds of lofty flight which pass instantly from the surface of the earth to the highest regions of the atmosphere, the consumption of oxygen would undergo variations too sudden and too extensive not to endanger seriously the lives of these animals. (P. 262.) Moreover, in 1868, in his third edition, Longet borrowed this last objection from M. Gavarret, and added to the passage which I quoted above the following remark: How can we admit that observers would not have been struck by the profound changes which such variations would not fail to produce in the mode of existence of these populations? After that, is it not strange to see that when M. Jourdanet, as an "observer", noted "these variations in the mode of existence of the populations of lofty places", his conclusions were rejected by an exception drawn from the fact that by virtue of chemical laws oxygen cannot be removed from the blood by decrease of pressure? In 1858 there appeared the second edition of the book of M. Lombard,88 of which we have already spoken; in announcing it, the editor of the Bibliothcque XJniverselle, Dr. Duval, 89 expresses himself in these characteristic terms: The researches on mountain sickness have been completed and better coordinated; perhaps the author made the possible symptoms of the digestive functions at an altitude of 1300 to 2000 meters seem a little too common. Many tourists will state that at that height they feel neither lack of appetite, nor nausea, nor vomiting, but on the contrary, an excellent and hearty appetite; some will also deny this distaste for wine and alcoholic liquors which would be experienced under the same circumstances; but that is only a question of a few meters more or less, and the reality of the symptoms described is none the less constant at an elevation which varies with the indi- vidual. De Saussure, who did not begin to be perceptibly affected until he had reached a height of 3800 meters, may pass as an exception. As for M. Lombard, he thinks much less of the direct effect of the diminished weight of the air; he also brings up the objection of Payerne, but none the less he gives great importance to the les- 252 Historical sened quantity of oxygen contained in expanded air, of equal volume: MM. Barral and Bixio, .... in spite of the fact that more than 9000 kilos were taken from the pressure to which their bodies were accustomed, felt no very pronounced sensation .... On the other hand, workmen in diving bells endure a double, triple, or even quadruple pressure without serious change in the functioning of the organs; and by this we are naturally led to consider the differences of atmospheric pressure as less important than one would be inclined to think from the purely scientific point of view. On the other hand, we have recognized that as one ascends heights, the air becomes less dense and consequently contains less oxygen, so that the respiration must be more frequent and more com- plete to bring into the lungs the quantity necessary for the oxygenation of the blood. From this physiological necessity there must result a considerable difficulty in breathing and consequently in the circulation also; and this we see in the dwellers in the lofty regions of our globe. Yet we must not believe that the rarefied air of our mountains does not contain a sufficient proportion of oxygen to maintain life; experiments made on the quantity of oxygen necessary for respira- tion have, in fact, shown that a man at rest in one hour converts 50 grams into carbonic acid, and if we add five or even ten grams for the increase produced by movement or work, we shall see that, assuming that the stay is in a place where the barometer stands at only 315 mm. (7000 meters), the air still contains 100 grams of oxygen in the 800 liters that a man breathes per hour. So that we see definitely that, even at great heights, the atmosphere can furnish man a sufficient quantity of oxygen to sustain breathing. Does it follow, nevertheless, that this great decrease in an element so essential to life has no effect upon our principal functions? We do not think so, quite to the contrary; it is visibly evident that the withdrawal of a considerable portion of oxygen must make respiration incomplete and react upon the other vital functions which, like the circulation, are very intimately associated with respiration. But even that is not all; when an incompletely oxygenated blood reaches the different organs, such as the brain and the muscular system, it is evident that their functions will experience a disturbance proportionate to the incompleteness of the oxygenation; so that one must attribute to the decrease of oxygen a considerable portion of the disturbances which occur in innervation and motility. (P. 47.) M. Lombard then admits in part the explanation which the Weber brothers had given and which von Humboldt had accepted in regard to the role of the pressure on the cotyloid cavities. Among the symptoms experienced by travellers attacked by mountain sickness, the sensation of extreme cold is neither the least strange nor the least painful. M. Ch. Martins,™ who had felt it in his ascent of Mont Blanc in the company of Bravais and M. Lepileur, made a special study of this physiological cold, an Theories and Experiments 253 expression which indicates, in the mind of the learned professor of Montpellier, not a drop in the body temperature, but the sen- sation of cold which may be produced by various causes. After studying these causes in a man at sea level, M. Martins declares that others exist in the mountains. Some act indirectly by changing the temperature of the air to which the sun gives less heat as a result of its decreased density, and which receives very little heat from the much reduced contact surfaces of the ground. Let us add that its constant renewal does not give it time to become warm, and that the expansion of ascending currents tends to chill it. Other causes act directly upon the living body. First is the power of radiation, which is twice as great on the Grand-Plateau of Mont Blanc as at Chamounix; next, pulmonary and cutaneous evaporation, stimulated by the low pressure, by the wind which blows almost constantly in lofty regions, and by the dryness of the air; finally, on lofty summits, the contact with a frozen soil. These are the physical causes which tend to chill the body. After explaining them in detail, M. Martins next comes to the physiological causes of the chill, which are peculiar to high mountains. Here we quote verbatim: Everyone knows that, at elevations which vary according to the individual from 2000 to 4000 meters, one begins to feel painful sensa- tions, namely: extreme panting accompanied by headache, desire to sleep, nausea, and great lassitude. This is the phenomenon called mountain sickness, a complex result of fatigue, abrupt decrease in pressure, and especially the rarefaction of the air. Physiologists consider that man draws into his lungs in an ordinary inspiration on the average a half-liter of air; the oxygen of this half-liter of air combines with the blood. At sea level, at a pressure of 760 mm. of mercury, a half-liter of air weighs 0.65 gm. and contains in weight 0.16 gm. of oxygen; at a decreased pressure, 475 mm. for example, to which we were subjected for three days at the Grand-Plateau, the volume of air inspired is still the same; but its weight differs, for it is reduced to 0.40 gm., and the oxygen contained by this half-liter of air is only 0.10 gm., and on the summit of Mont Blanc, at a pressure of 420 mm., only 0.09 gm The oxygen of the blood and consequently the heat production are therefore less than at sea level merely because the quantity of oxygen drawn into the lungs is much smaller. Respiration is less perfect, just as it is in foul air in which the proportion of oxygen is lower than in normal air. This entirely physical cause had already been pointed out by Halle, Lombard, and Pravaz junior. Like them, I attribute to it the symptoms of panting which are noted in rapid ascents on lofty mountains. The objection that on lofty mountains the number of inspirations 254 Historical compensates for the lessened proportion of oxygen in the air inspired is not valid. Anyone who has himself experienced the short and hasty inspirations, without proper expansion of the thorax, which accom- pany the breathlessness during and immediately after an ascent, realizes that these hasty inspirations cannot have the calorific effect of regular inspirations. So panting ceases the moment one stops walk- ing, and a regular respiration, more frequent than on the plain, partly compensates for the lessened quantity of oxygen; I say partly, for to make complete compensation, on the Grand-Plateau, for example, the number of inspirations would be to the number on the plain as 8 is to 5, that is, proportional to the quantities of oxygen inspired. Now that is not the case; panting, in a state of rest, certainly does not add one-third more. The lessened oxygenation of the blood is therefore not counterbalanced by the frequency of the inspirations, and becomes a physiological cause of cold which is peculiar to lofty regions, and probably the principal one of all those causes which bring on the symptoms known under the name of mountain sickness. This explanation, we see, is only the one already envisioned by de Saussure; we see also that M. Martins is much less optimistic than Longet, who asserted that on the mountains one could make up for the lessened oxygen content of the inspirations by their number. The same ideas also occur to the mind of Guilbert,!U when he gives an account of the soroche of the Cordilleras: Upon the plateau of the Cordilleras, the air contains only 3/5 of the quantity of oxygen which it contains at 0.76. When one ascends, he reaches colder and colder regions, where man must produce more heat, to maintain his normal temperature. To expedite combustion, he needs a greater quantity of oxygen, and the air contains less. Here are two causes working in the same direction, which are suffi- cient to explain the disturbance of the respiration and the circulation. The experiments of Magnus have shown the presence of free gases in the state of solution in the blood. The tension of these gases increases as the pressure diminishes. Then these gases exert a pressure against the walls of the vessels in which they circulate with the blood, and distend them; hence come compression of the brain, and consequently violent pains in the head, etc Perhaps too hematosis is incomplete; in this case, it could claim part of the effect on the nervous system; the blood, which has lost part of its stimulating qualities, could no longer be a sufficient stimulus; hence the tendency to syncope, etc The decrease of the atmospheric pressure also explains the hemorrhages. The free gases of the blood press against the walls of the vessels; a moment may come when these walls, unable to resist, longer, are ruptured and let the blood escape The action of the heart is no longer counterbalanced by the atmospheric pressure, and the result is a stasis of blood in the capil- laries which are therefore distended. This phenomenon is evident Theories and Experiments 255 in the face and the hands, and especially in the conjunctiva. The same thing must take place in the capillaries of the lungs, and the exaggerated contraction of the heart also has a share in causing the difficulty in breathing. Let us note, in addition, that Guilbert adopts the explanation of the Weber brothers in regard to the connection between decom- pression and the firmness of the articulation of the head of the femur. Finally I shall report the conclusions of Guilbert with reference to pulmonary phthisis. This disease is very common on the Pacific coast, except among the Indians. But in the Cordillera, according to this physician, one observes: 1. The absence of phthisis among the natives, without any racial distinction; 2. Curability by a prolonged sojourn, and in such a proportion that this curability cannot be considered as the exception; 3. The constantly delaying effect of the climate upon the progress of the disease in those who cannot be definitely cured, and the not infrequent remissions. In the year 1861 the first book of M. Jourdanet 92 appeared. This work had a double merit; first, by actual observation, he recog- nized certain signs of harmful effect from prolonged sojourn in lofty places, although no one before him had suspected it; second, by his explanation, he revived for science the idea glimpsed by Pravaz, but rejected through the work of M. Fernet, of a lessened solubility of the oxygen in the blood, in consequence of a dimin- ished barometric pressure. The true doctrine is completely ex- pressed in this volume. In the beginning, M. Jourdanet takes up and develops the calculations of M. Martins: The barometric pressure of Mexico is 585 mm. Consequently a liter of air weighing, at sea level, 13 decigrams, weighs only about 1 gram in this capital. In both cases, oxygen figures in the proportion of 23.01%. That gives us 299 milligrams as the weight of a liter of oxygen at sea level, whereas this figure is reduced to 230 milligrams for the altitude of Mexico. Let us declare then a difference of 69 milligrams per liter to the disadvantage of this locality. Admitting now as correct the calculation which rated at 16 the number of inspirations made by a man per minute, we observe that the consumption of air is 8 liters in this interval of time, and consequently is 480 liters in an hour. But we have already noted for Mexico a loss of oxygen of 69 milligrams per liter. It is therefore indisputable that in this capital one loses the benefit of 33 grams per hour or 794 grams of oxygen per day. (P. 65.) 256 Historical After explaining thus the chief condition of the physico-physio- logical problem, M. Jourdanet states that the ardor of the sun on the heights of Anahuac must also act to diminish considerably the density of the strata of air near the ground, and consequently the intrapulmonary gaseous endosmosis. When this has been established, he shrewdly compares respira- tion in a pure air, but under low pressure, with respiration in air with low oxygen content, but at normal pressure. Then answering the objection taken from the work of MM. Regnault and Reiset by M. Gavarret, an objection which had just found new strength in the experiments of M. Fernet, he comments with reason that if the chemical combination of the oxygen and the blood was abso- lutely independent of pressure, one should live with ease not only at the lowest barometric pressures, but also in air with very low oxygen content, which no one will admit: According to the opinion of M. Gavarret himself, the solubility of oxygen in the blood is diminished when the quantity of oxygen inspired is lessened. It is therefore indisputable that, however effec- tive and necessary the affinity of the corpuscles for oxygen in the act of respiratory endosmosis may otherwise be, the mere fact of the rarefaction of this gas lessens the absorption of it at high altitudes and thus causes real disturbance in the phenomena of respiration. (P. 69.) M. Jourdanet then adds the following interesting observation: If the convictions which we have just expressed were to be shown inaccurate in the results, compensation for the rarefaction and the lightness of the atmosphere in Mexico would have to be made by deep inspirations and by a respiration which in general was more active than at sea level. It is commonly believed that this is the case and this opinion is based upon the observation furnished by persons who make a rapid ascent in the atmosphere or who make only a short stay at high altitudes. It is completely erroneous. The truth is that those who dwell at great elevations breathe less quickly than men whose abode is near sea level. The rarity of the air, as we shall see later, produces apathy of the muscular system. The chest also feels its effects. I have often surprised the functions in the very act by counting the respiratory movements of persons who were unaware of it and who were in a state of complete repose. I almost always noted a decrease in the number of expansions of the chest. Some- times, fairly often, in fact, one forgets to breathe and is forced to make up for lost time by taking deep inspirations. (P. 76.) .... But this respiration, so calm in absolute repose, easily gains amplitude under the influence of movement. (P. 87.) The consequences of this decreased absorption of oxygen are easily foreseen. The first is a decreased activity in the production Theories and Experiments 257 of animal heat, at the very time when, on account of the altitude, this production should be increased. In fact, our author says very fittingly: Prudent Nature at sea level has established laws which assist, through the atmosphere, these variations in the production of human heat. For in winter the cold air is denser, and contains a greater part of the vivifying principle in a certain volume. The warmth of summer, on the contrary, by expanding the atmosphere, gives the lungs a proportion of oxygen in keeping with the small amount of heat which the body must produce. Thus the source, from which we draw the elements of our respiration, itself varies in a certain measure, which, at sea level, is a kindness of Providence. This is not true at high elevations, where the density of the air, lessened by the decrease of the barometric pressure, is no longer proportionate to the temperature surrounding us, but to the altitude which we have reached. And note particularly this extremely impor- tant fact: whereas at sea level the exterior causes which chill us take care to give us the means of combatting this drop in temperature, in Mexico, on the contrary, the decrease of pressure which produces cold in the air alters the source of heat for us by compelling us to breathe a rarefied atmosphere. So that, on the one hand, the increased expan- sibility of the air and the easier evaporation chill us constantly, while, on the other hand, the increased rarity of oxygen refuses us the normal means of calorification. Upon these data, so clear and so exact, the physiological pecu- liarity of altitudes rests entirely. (P. 83.) It is, therefore, not surprising to see that: Persons in a state of repose chill very easily. Their lower limbs are almost never warm. Muscular exercise would stimulate the circulation and the respiratory movements; but the blood, deprived of oxygen, produces apathy of the muscles and makes one prefer repose. Here then appears the result of the experiment made by M. Becquerel upon the muscle fiber which loses its contractility and becomes ener- vated when it lacks contact with the arterial blood. (P. 86.) Here M. Jourdanet meets the phenomenon described by all mountain travellers, of exaggerated fatigue, pain in the thighs, and heaviness of the lower limbs; he protests energetically against the explanation of the Weber brothers, which was accepted by von Humboldt and almost all later authors, although this explanation, to use his apt expression, "does not bear careful examination": In fact, if we estimate in square centimeters the surface on the plane of opening of the cotyloid cavity, the diameter of which is 54 millimeters, we get a result of 22.89 square centimeters, which, multi- plied by 1003 grams, a weight equivalent to a square centimeter of surface, give us 23,645 grams, to represent the real weight in the cavity of the joint. If we remember that many travellers have felt 258 Historical the muscular fatigue which we are discussing when they had hardly gone beyond a fourth of the atmospheric pressure, we shall see that this phenomenon appeared when the thigh was still supported by a weight of 17 kil. 734 gm. We do not understand why a member, which may weigh at most 15 pounds, would have so little respect for the 21 pounds surplus which it would drag along in its fall. (P. 89.) The real reason, according to M. Jourdanet, is expressed thus: This phenomenon appears when the blood, incompletely oxygen- ated, causes the contractile power of the muscular fiber to be considerably diminished. The abdominal member then refuses to carry out its normal functions and warns by pain that the task is beyond its powers. The same thing would happen to the other muscles of the body, if one required of them the exaggerated efforts which ascent demands from the muscles of the thigh. (P. 89.) Summarizing: The symptoms of the famous mountain sickness: vertigo, swoon- ing, vomiting, — what do they amount to but cerebral anemia, for want of the stimulus of arterial oxygen; congestion of the venous system, and especially the portal vein and the liver; but, above all, enervation of the muscular fiber for the same reason. Always and everywhere: lack of the normal quantity of oxygen in the circulation of the arterial blood. (P. 90.) Most of the book is devoted, as its title indicates, to the study of the diseases of Mexico. Everywhere there M. Jourdanet finds predominant the effect of this anemia of a special type, "result of an imperfect respiratory endosmosis". It is indeed, as he says clearly in his subsequent works, this strange syndrome which, awakening his medical shrewdness, caused him to reflect upon the conditions harmful to respiration and metabolism presented by a prolonged sojourn on the lofty plateaux of Anahuac. I shall merely quote the following passage because it offers a sort of summary of this remarkable work, and because we find in it a part given to the pressure as a mechanical agent, simply assisting its chemical action: We have already seen the blood, feebly welcomed and lazily expelled by the nervous centers, congesting the brain and the spinal cord of weak persons, already injured by the climate. We shall mention the disturbances of more than one sort of the alimentary canal, several of which are due to the circulatory slackening and to the capillary congestions of the intestinal venous system. The uterus has attracted our attention by phenomena of the same nature. We shall take the opportunity to say here that pulmonary congestions are frequent in Mexico and too often are fatal. Finally, more frequently than all the other organs, the liver imbibes blood and from this source draws countless symptoms, the unfortunate consequences of which are frequently reckoned among the causes of death. Theories and Experiments 259 And so, beyond any doubt, altitude favors venous stases. When they are superficial, one cannot deny that the decrease of the air pressure acts in a purely mechanical sense towards this result. The superficial capillary networks, deprived of their natural external support, expand with an ease in proportion to the decrease in the weight. If to this first cause you add a blood not sufficiently stimu- lating for the arteries and too abundant in general for the veins, you reach the etiological trinity: lessened external adjuvant, organic sluggishness, general congestion of the venous system; a trinity the effects of which will be directed by turns to different parts of the organism, depending upon where the disturbances in innervation have previously prepared for them. (P. 254.) Two years later, there appeared a long memoir by the same author.93 The mere title of this second work, The Anemia of Altitudes, indicates the idea of M. Jourdanet: in his opinion, "the dwellers at great elevations, above 2000 meters, are generally anemic", and this condition is particularly evident to the eyes of the practitioner by the syndrome. And yet the chemical analysis of the blood strangely contradicts what the clinical observation revealed: In 1849, while I was in Puebla, I wished to ascertain by analytical examination of the blood whether the proportion of corpuscles was reduced. I made my first investigation on a young man twenty-five years old whom I knew to be suffering from gas- tralgias and vertigo. He fell from his horse, and the consequences of this fall made bleeding necessary. My analytical tests were made on blood obtained in these circumstances. They showed me that the proportion of corpuscles was 151/1000. I repeated my experiments upon four young women who were bled following accidents. Their pallor, their general prostration, and their nervous condition showed that they were suffering from chloro-anemia, although auscultation revealed no arterial murmur. Their blood furnished the normal proportions of corpuscles. (P. 8.) What is the explanation of this apparent contradiction? It is that: The principal duty of the blood corpuscles is to serve as aid to the real agent of our life. When their proportion is reduced in the blood, it is no doubt correct to say that the sickness is the result of the decrease in corpuscles; but we would fix the immediate cause -of the symptoms of the disease more accurately if we attributed its existence to the decrease in oxygen. I think I am more justified in expressing myself in this way because if, in the case of anemia, we call attention, as it is natural to do, to the reduced proportion of this gas in circulation, we see several causes which may produce this circulatory anomaly, without finding it necessary to explain it by a decrease in the number of corpuscles. That, exactly, is the case in the anemia of altitudes. (P. 10.) 260 Historical M. Jourdanet summarizes his opinion in the following proposi- tions: 1. The corpuscles and the barometric pressure regulate the quan- tity of oxygen in the blood; 2. Disturbances in either of these two forces must necessarily affect hematosis; 3. Since oxygen is the chief vital agent, its decrease for lack of corpuscles causes the weakness of anemic patients; its decrease in the blood for lack of pressure must produce the same result; 4. For this reason persons breathing the atmosphere of great elevations must have their health affected in the same way as those suffering with anemia at lower levels; 5. The anoxemia of altitudes is therefore analogous to the hypo- corpuscular anemia of the sea level. (P. 21.) Since plethoric persons have a large proportion of corpuscles in their blood, it is not surprising, as M. Jourdanet says, to see them often: Climbing the rugged sides of Popocateptl and at an altitude of 17,700 feet imbibing the complete elements of life, whereas their travelling companions, of less sturdy constitution, succumbed to mountain sickness. (P. 22.) Then making a more detailed study of the chief phenomenon, the general trend of which he indicated previously, and taking into account the experiments of Magnus and M. Fernet and his own, M. Jourdanet reaches the remarkable conclusions which we give verbatim: 1. From 76 to 65 centimeters, partial vacuum acts only upon the part of the gases of the blood which is held in true solution; 2. Under the influence of this first barometric decompression, the release of carbonic acid is mmh greater than the loss of oxygen, the result of which is greater freedom of action for the oxygen; 3. It is possible then that, since a moderate elevation does not noticeably decrease the quantity of the oxygen in the blood, whereas it removes a considerable portion of carbonic acid, it may act upon man with a tonic and strengthening effect; 4. As to the portion of oxygen which a weak affinity allows us to consider as being held by chemical action, its escape from the blood results from lowered barometric pressure only when the pres- sure approaches 60 centimeters; 5. We therefore should consider that the quantity of oxygen in the blood is seriously diminished beginning in the neighborhood of this limit, and it is then that the anemia of altitudes begins; 6. We can therefore understand that a moderate altitude may be a powerful means of curing anemia, whereas this same disease is a natural consequence of sojourn at a considerable altitude. (P. 37.) Theories and Experiments 261 Finally, in 1864, a third 04 work repeats with new develop- ments the ideas expressed in the works from which I have just taken numerous quotations. However, I cannot refrain from ex- tracting from one of his chapters on mountain sickness his clear explanation of this syndrome, an explanation in which we need to make no important change for the conclusions of the present book: A man who rapidly ascends to a very lofty point is deprived of a certain quantity of oxygen from which he was accustomed to receive a stimulating effect necessary for the full exercise of his strength. Certainly, what is left him after his ascent is still capable of maintaining life and even the regular action of the functions. But man cannot endure without temporary symptoms a sudden reduction which lessens the resources from which the nervous system is accus- tomed to draw its power. The muscular fibers also refuse to perform their task when their oxygen supply is decreased. We then see appearing those phenomena which hemorrhages have made familiar to us. As a result of the loss of blood, the organism, we know, sud- denly loses an important part of its normal stimulus; the patient has vertigo, his muscles weaken, nausea attacks him, and the more nearly vertical his position is, the more quickly he is seized by syncope .... The weakness produced by bleeding is evidently the consequence of a sudden lack of oxygen through the loss of a certain quantity of corpuscles, just as mountain sickness results from a more direct with- drawal of the same gas. So that, beyond a doubt, an ascent beyond 3000 meters amounts to a barometric dis oxygenation oj the blood, just as a bleeding is a disoxygenation oj the blood through the lack of corpuscles. (P. 92.) These works soon stirred up a controversy which was very bit- ter. A French expeditionary corps had just been sent to Mexico, and the conclusions of M. Jourdanet were anything but encourag- ing for those who dreamed of the establishment of a Latin empire supported by a French colony established on the lofty plateaux of Anahuac. Michel Levy, then director of the School of Military Medicine and Surgery, was aroused and thought he should open a sort of investigation of the accuracy of the data given by M. Jourdanet; Dr. L. Coindet, head of the medical service of the second division of the French army, agreed to take charge of this investigation. The first letter sent by this observer to his hierarchic chief censured the statement of M. Jourdanet about the slackening of the respiratory movement: A statement (said Michel Levy) which contradicts the opinion accepted hitherto that, under the influence of reduced atmospheric pressure, respiration is accelerated to compensate by the number of 262 Historical inspirations for the diminished quantity of oxygen in the same volume of air.95 In this document, L. Coindet 96 reports the results of 1500 obser- vations made on Mexicans and Frenchmen on the high plateaux, in which he counted the number of respiratory movements. I give here the summary of his tables: Frenchmen Mexicans Below 16 inspirations per minute 54 25 16 inspirations 70 54 Above 16 inspirations 626 671 750 750 General average of inspirations per minute 19.36 20.297 In the presence of this mass of data (adds our author), doubt is no longer possible, and it is certain that those dwelling here do not breathe less quickly than men whose dwelling is 2277 meters lower. Farther on, Coindet declares: That, independently of the greater activity of the respiration, the inspirations are generally ample, deep, and profound, and-that all the more because they are less numerous. He then states, without having made any exact measurement of this point, however: That thus equilibrium is always established, and that the function constantly tends to adapt itself to the rarefaction and lightness of the atmosphere. Then, in a very sudden decision, which seems to indicate on the part of our author a very great desire to be easily convinced, Coindet does not hesitate to draw at once this important conclu- sion from these observations on the respiratory rhythm: That what has been written in regard to the insufficiency of the oxygenation of the blood at great altitudes, as a consequence of an alleged slowing of the respiration, should be considered unfounded . . . It may very well be that the so-called Mexican anemia is merely the yellowish complexion characteristic of the natives! Next come observations on the pulse rate and the comparative measurements of the chest capacity of Frenchmen and Mexicans. We shall return to the second of these later. In regard to the pulse: I have felt it repeatedly (says Coindet) without any prejudice, and I have even counted the heartbeats, which agreed with those of the arteries. In short, he finds as the average pulse rate, 76.216 for French- men, and 80.24 for Mexicans. Theories and Experiments 263 The second letter''7 treats of "acclimatization on the heights of Mexico"; it contains only a summarizing description of the races of Mexico and a little meteorological information. However, I quote the following passage, which is rather interesting: After crossing Cumbre, when we reached an elevation above 2000 meters, first respiration and circulation, and afterwards absorption, exhalation, and metabolism underwent noticeable changes. We per- ceived a tendency of the fluids of the body to move towards the periphery, the result of which was derangement of the circulation, various congestions, cerebral, pulmonary, and nasal hemorrhages, several examples of which I have given; difficulty in breathing, which made us pant; general discomfort, which made us consider the weather heavy, although it was really lighter; difficulty in moving and greater fatigue, and these symptoms were particularly marked in the men of the 95th of the line, who had not remained long at Orizaba, like us, and who had been transferred rather suddenly from sea level to a fairly high elevation. Little by little, the organism of everyone, at first in conflict with a medium for which it had not been created, adapted itself progressively to this medium, and today, after a ten month sojourn on Anahuac, it has been so transformed that it resembles that of the Indian. (P. 817.) The third letter 98 is much more important to us. In it is the report of the analyses made in the laboratory of the School of Mines of Mexico under the supervision of Professor Murfi, with the purpose of measuring the quantity of carbonic acid formed in a given time by dwellers on the lofty plateaux. Twenty-five per- sons, 10 of whom were French, 10 Indians or half-breeds, and 5 Mexicans of European origin, were the subjects. The average re- sults, for the French, for example, are given in the following table: Number of inspirations per minute 19.6 Pulse rate 78.2 Quantity of air expired in one minute 5.90 liters Average percentage of carbonic acid per minute 4.24 If we set aside the discussion which Coindet gives about the petty differences of details noted among the representatives of the different races on whom he experimented, we find that these observations inspired the following reflections in him: The average quantity of air expired per minute according to M. Dumas is 5.3 liters at sea level; here generally we have about 6 liters, when once the man is acclimated. This is logical, for since the air of altitudes contains in a given volume less oxygen at a barometric pressure of 0.58 or 0.59 meters than at 0.76 meters a greater quantity of this air must be absorbed to compensate for the difference: this is at- tained by a more active respiration; so that the air which is drawn into 264 Historical the lungs and exhaled from them is always about a third of a liter for each inspiration and each expiration. While the air expired by man at sea level contains from 3 to 5 parts of carbonic acid per 100, our experiments show that on Anahuac the average is just as high, since it is 4.36 for 25 subjects. It has been shown by 103 observations made at sea level by MM. Brunner and Valentin that the quantity of carbonic acid contained in the expired air is 4.267%. M. Vierordt," who made nearly 600 experiments on this subject, reached nearly the same results. The expired air contains on the average 4.336%. Our average does not differ from the latter, if we take into account the decrease in atmospheric pressure which, as is well known (?), increases 'a little the proportion of carbonic acid exhaled. We are not surprised, after this long enumeration of data, to see Coindet cry out with an accent of triumph: Absorption of oxygen, exhalation of carbonic acid constitute two connected expressions, from the chemical point of view. On the other hand, modification in the qualities of the expired air and the corre- sponding changes in the composition of the blood are the two terms of the physico-chemical problem of respiration. There can be no doubt then about what one should think of the alleged insufficiency of the oxygenation of the blood at high elevations. The Gazette hebdomadaire contains another series of letters addressed by Coindet to Michel Levy,100 under the general title: "Statistical Studies of Mexico", devoted to pathology, meteorology, etc.; they only rarely treat questions which are purely physiologi- cal. We see that for this physician everything is settled by his preceding researches, and that it is quite proved, as he says frequently, that at high elevations man compensates exactly, by the number and amplitude of the respiratory movements, for the loss in oxygen caused by the lessened density of the air; so that equilibrium is regularly maintained. I can find to be quoted verbatim only the following passage, in which our author's opin- ion about the cause of mountain sickness is shown. June 5, 1863, (he says) in the company of Dr. Laval, I ascended almost to the summit of Iztaccihuatl (4686 meters) .... Our mouths and throats were dry; our legs were exhausted; our respiration was panting, hasty, deep, often broken; our pulse, which was small, had a rate of 128. But we did not yet feel the distress, headache, or nausea, which constitutes mountain sickness, in which, by the way, acceleration of the circulation no doubt plays a great part by its congestive effect. M. Jourdanet did not fail to answer the letters which con- tradicted his physiological and medical statements on almost all points and which gave the impression that there could be nothing Theories and Experiments 265 accurate "in a book", these are the very words of Coindet, "so opposed, I am proud to say, to all I have written". Without dis- cussing what relates to pathology, we shall go straight to the convincing reply which M. Jourdanet 101 made in opposition, not to the data reported by Coindet, but to the conclusions which this doctor drew from them: M. Coindet states that the respiration is not merely accelerated, but that it is ample, deep, profound. Now what do this amplitude, this depth, and this profundity amount to? We find the definite measure of them in the passage of his correspondence in which we see that 25 subjects gave an average of 6 liters of air breathed per minute, in 20 respirations. That is therefore an average of 30 centi- liters of air for each respiratory movement. It is evident that this volume of air represents only a very moderate thoracic amplitude . . . Our colleague is no more fortunate when he states that, on the great elevations of Anahuac, more air passes into the lungs in a given time than at sea level; for the 6 liters which he collected in the sub- jects of his observations are not above the very ordinary average furnished by men from 20 to 30 years old at the pressure of 76 centi- meters. And we should also note that, considering the rarefaction of the air of Mexico, these 6 liters weigh only 6 grams, instead of 7.8 grams, the weight of the same volume of air at sea level .... So, according to M. Coindet himself, at an altitude of 2277 meters, respiration is not ampler, or deeper, or more active than at sea level. (P. 150.) The reply appears incontrovertible on this phase of the ques- tion. The chemical considerations remain. Here M. Jourdanet criticizes an obscurity in Coindet's wording, which no doubt has already impressed our readers, but which makes the reading of the different observations contained in the memoir itself quite incomprehensible. In the table reproduced above, we have copied verbatim these words: Average percentage of carbonic acid per minute: 4.24. What does this information mean? Does it refer to a percentage calculated in volume or in weight? This question is asked in regard to each of the observa- tions. We are quite surprised (M. Jourdanet says naturally) at the obscurity which reigns in the report of M. Coindet. Let us take, for example, the first experiment: "H. Staines .... Number of inspirations per minute 22; number of liters of air in one minute 6.4; carbonic acid 4.64%." Considering these 6.4 liters of air breathed by the subject of the experiments, we cannot help thinking that the 4.64% of carbonic acid indicates the proportional quantity of this gas in volume also. But further on (Gaz., 1864, p. 36, first column), these figures are repeated under the heading: Weight per 100 of carbonic acid expired in one minute. Evidently the wording is not clear. 266 Historical We repeat with M. Jourdanet: Evidently the wording is not clear; but an important circumstance throws complete light on it. It is the comparison which Coindet makes between the figure he obtained and those of Vierordt, Brunner, and Valentin. These physiologists very certainly meant the percentage in volume, and Coindet could not have been confused about that, because the passage we copied above is the word for word reproduction of a new paragraph of the deservedly popular book of M. Beclard,10- from which only the words "percent in volume" have been left out. To M. Coindet, then, the matter concerns a proportion in volume, and his own experiments would show, if this were the case, a considerable decrease in the intra-organic combustions on the Mexican plateau, since, the quantity (in volume) of carbonic acid exhaled there being the same as at sea level, the quantity in weight would evidently be much lower, in a proportion meas- ured by the very decrease of the atmospheric pressure. But here is another thing. M. Jourdanet, who was then in Mexico, desirous of settling this doubtful question, asked M. Murfi, "true author of these analyses", and obtained from him an answer showing clearly that: The experiments of the College of Mines gave an average of 4 grams and 51 centigrams of carbonic acid per 100 liters of air expired, measured at a temperature of 14 degrees and at a pressure of 58 centimeters. The contradiction is glaring: Coindet specified volumes, M. Murfi states that it is a matter of weights, and M. Jourdanet, naturally giving more credence to the statements of the Mexican chemist, draws from them a really crushing conclusion for his adversary: It is therefore unquestionable (he says) that the subjects of the experiments of the College of Mines produced 4.51 grams of carbonic acid per 100 liters of expired air. On the other hand, the report of M. Coindet, agreeing in this with the statement of M. Murfi, says that the quantity of expired air was on the average 6 liters per minute. Who can doubt then that if 4.51 grams of carbonic acid correspond to 100 liters of air, the 6 liters expired by the subjects of the experiments contained 27 centigrams. It is therefore certain that the quite unde- niable result of the respiratory proportion of the College of Mines was that the subjects from twenty to thirty years old produced 27 centigrams of carbonic acid per minute, that is, 16 grams and 20 centi- grams per hour. The conclusions of M. Coindet do not agree with these figures; for not only did these alarming figures not authorize him to say that respiration in Mexico is identical with that at sea level, but they Theories and Experiments 267 indicate a danger which would justly make one fear sojourn in lofty Anahuac; since, according to these experiments, the carbonated respir- atory combustions would not be half there what they are at sea level. The analyses of the College of Mines therefore leave us in great anxiety. I notified my colleagues of the Society of Medicine of Mexico, who were sufficiently affected by them to vote new surveys. (P. 151.) To this undeniable conclusion, Coindet 10:! tried to reply in his turn. Let us set aside the mere assertions and the digressions of acrimonious polemics, although they are numerous, and come to the root of the matter, the contradiction which we revealed above: M. Michel Levy (he says) and the members of the Society of Medicine of Mexico know the reply which I made to the statements of M. Jourdanet. I proved that the volume 3.90 per 100 of air at a temperature of 14 degrees and a pressure of 58, which was given me by the weight 4.51 per 100 of air also at a temperature of 14 degrees and a pressure of 58, furnished, because of the greater quantity of air expired (6 liters instead of 5.3 Dumas), 295.13 grams of carbon con- sumed in 24 hours, or 12.30 grams in one hour, and we know the averages established at sea level by MM. Dumas, Andral, Gavarret, Valentin, Brunner, Vierordt, etc. It is quite certain, I assert, that my subjects would not have expired more than 3.3 liters of air at sea level. I confess for my part that I do not understand this very well, and it would have been desirable that Coindet should copy in his letter the proofs which he had sent to M. Michel Levy. First, let us note that this time the 4.51 are no longer for him a measure 104 of volume, as that resulted evidently from the new paragraph which we mentioned, but a measure of weight; it is, as M. Murn said, the weight of carbonic acid contained in 100 liters of air expired at 14° and 58 cm. But from that point, the reasoning and the calcu- lation of M. Jourdanet are unassailable. If 6 liters of air per min- ute pass through the lungs, that makes 360 liters in an hour, con- taining 360 x 4.51 grams = 16.23 grams of carbonic acid. The re- searches of Andral and Gavarret 105 give an average, between the ages of 20 and 40, of 12.2 grams of carbon consumed, which corre- sponds to 44.07 grams of carbonic acid. The difference is enor- mous, so enormous that, for my part, I think that there is a funda- mental error in the analyses which are the basis of his reasoning. Let us see now what Coindet's reasoning is. And first, let us note that he takes a strange cross-road: "I have proved", he says, "that the volume 3.90 per 100 of air at a temperature of 14 degrees and a pressure of 58, which was given me by the weight 4.51 per 100 of air also at a temperature of 14 degrees and a pressure of 58 . . ." 268 Historical These are painful and useless calculations; why change a weight into volume to find again a quantity in weight? Let us, however, make them again, because, if their apparent result is favorable, we shall find considerable errors in them. A liter of carbonic acid at 0° and 76 cm. of pressure weighs 1.966 grams. Therefore, 4.51 grams of this gas represent under these 4.51 conditions of temperature and pressure liters, and at 58 cm. 4.51 liters x 76, 4.51 liters x 76 (273 + 14) and at 14° = 3.160 liters. 1.966 x 58 1.966 x 58 x 273 So the expired air contained in volume 3.16% of carbonic acid, and not 3.90 as Coindet said, so that all his subsequent results are decidedly wrong. Better still: accepting the figure of 3.90% (a proportion, which, by the way, does not vary, as Coindet seems to think, with the pressure and the temperature) we get final results very different from those he records. In fact, the men whom he observed breathed per hour 360 liters of air, which consequently contained, according to him, 360 x 3.9 liters = 14.04 liters of carbonic acid, at 14° and 58 cm., representing at 76 cm. and 0°, 14.04 liters x 58 x 273 = 10.19 liters. 76 (273 + 14) Now since 1 liter weighs 1.966 grams, we would have for the production per hour only 1.966 grams x 10.19 = 20.03 grams; and as there is a weight of 27.68% of carbon in carbonic acid, the weight of the carbon consumed per hour would be 1.966 grams x 10.19 x 27.68 = 5.54 grams; 100 * which is far from the 12.30 grams announced by Coindet. On the contrary, the calculation of M. Jourdanet here finds a complete verification by counter-proof. In fact, it results from what we have just said that really, according to the experiments of Coindet, his men exhaled per hour 360 liters x 3.16 = 11.376 liters of carbonic acid, representing at 76 cm. and 0°, 8.258 liters, which weigh 16.23 grams, a number exactly like the one we found before according to M. Jourdanet. Theories and Experiments 269 It is for the reader to decide whether, after such a surprising argument, one should jeer, as Coindet did, at the "competency" of the man who very courteously criticized his mistake. At any rate, we can now easily evaluate the following conclusions, which he boldly 10° formulated: 4. The average of the carbonic acid expired on Anahuac, with diet and conditions equal, is not lower than at sea level. 6. The quantity of oxygen circulating in the blood is the same at high elevations as at sea level; and with similar and equally satis- factory hygienic conditions, the efficacy of hematosis is the same also. 17. Under ordinary conditions, residence in Anahuac does not seem to lessen permanently and injuriously the total of the gases which circulate in the human body. As for me, I do not hesitate to say that in the work of Coindet nothing justifies this last conclusion, and everything in it contra- dicts the first two. To tell the whole truth, I confess that I can- not accept as accurate even the analyses which are the foundation of them; there must be some mistake in the experimental method or in its application. I shall merely say that the quantity of air upon which the analysis was based was much too small; M. Murfi had the respiratory movements carried on in his apparatus for a half -minute ; Andral and Gavarret had them continued from 8 to 13 minutes. Furthermore, no one took care to collect the air which passed through the nostrils. However disposed I am to think that in Anahuac the intensity of the organic combustions is really les- sened, I refuse to believe that it is one-half less, as would be demonstrated if we considered as accurate the figures furnished by the work of Coindet himself. To sum it up, from the point of view of the chemical phenomena of respiration, there is absolutely nothing left of this work. One of the surgeons of the Mexican expedition, M. Cavaroz,107 shortly afterwards published a memoir, the observations and con- clusions of which are exactly like what M. Jourdanet had already said. He first made a great many measurements on French soldiers and found that at an altitude of 1712 meters the general average of respirations was 19% and the pulse rate 65 %•: He first draws this conclusion that: on the lofty plateaux of Anahuac, there is established in the European a supplementary respiration, intended to compensate by the number of respiratory movements for the loss of oxygen for hematosis resulting from the rarefaction of the atmosphere .... 270 Historical But, he soon adds, we need to know whether this compensation is complete, and whether, after all, there is no loss of oxygen, and whether the hematosis is as normal and perfect as at sea level. I do not think so, for according to the average ratio of 18 respirations for 67 heartbeats, the number of heartbeats for 19% respirations should be 67 V2. It is only 65x/4; therefore there is a loss of 2V4 heartbeats; therefore the circulation is slackening to a certain degree, and the physiological condition is disturbed. The rest of the work of M. Cavaroz contains observations tend- ing to prove that on the lofty plateaux the European loses his liveliness and strength, and that if he falls ill, he rapidly passes into a state of prostration. So, in his opinion, perfect acclimatiza- tion is by no means proved. The resemblance between these ideas and those of M. Jourdanet is quite striking. However, no one has paid any attention to it, and henceforth authors will speak of no one but Coindet, and we must confess that without exception they will side with him against M. Jourda- net, which proves, among other things, that it is much easier to read conclusions than to discuss a memoir. So in the article Air which M. A. Tardieu ln" wrote for the Dic- tionary of Practical Medicine and Surgery, the learned hygienist devotes a page to the study of the physiological effects of rarefied air. It is filled by a rapid review of the ideas of M. Jourdanet and the works of Coindet; I take from it these characteristic lines: After what has just been said, we see what we should think of the alleged insufficiency of oxygenation of the blood at high altitudes. Moreover, M. Tardieu gives no explanation. The article Altitudes which M. Leroy de Mericourt wrote for the Dictionnaire Encyclopcdique two years after deserves the same reproach. But before discussing it, I must say a few words about a very odd book, published in 1863 by Dr. Foley.109 When we come to the study of compressed air, we shall have to give a lengthy review of it. We shall see that in the opinion of this physician, the compression exerted by the air plays the principal part: "When one enters the caissons", he says, "he is flattened." He naturally brings the same preoccupation of a me- chanical type to the study of mountain sickness: A traveller climbs a mountain. The higher he ascends, the weaker he feels, and the more his subcutaneous veins distend. He finally becomes ill. Why? The periphery of his body is no longer compressed. A comparative vacuum has been formed around it. The blood has accumulated there. The brain has therefore failed. The aeronaut has fainted. (P. 63.) Theories and Experiments 271 Let us add that farther on M. Foley declares that nausea, cramps, etc., are the sign of "insufficient hematosis". In his opinion, it is the presence of the air sacs which saves the bird from the symptoms of decompression; the shocks* with which he would be threatened on his return as workmen are when they leave the caissons (see later, Title II, Chapter III) are spared him because of the elastic tension of the gases contained in the sacs. For that, the bird that is mounting needs only to close its beak and its nostrils; but perhaps we may be permitted to ask how it can breathe then. A distinguished veterinarian, M. Liguistin,110 who was in com- mand of this service during the Mexican expedition, found himself confronted with the same problems as the military physicians. He seems not to have known of the heated discussion the principal points of which we have just summarized: "In his opinion, moreover, the effect of the decrease in the density of the air is very well known." (Vol. Ill, p. 583.) As to symptoms observed in animals, he states that the respira- tory disturbances noted by doctors seem not to have attacked beasts of burden: Would the large solipeds bear more easily than men the effect of an air with low oxygen content? Would the lymphatic temperament with which they are endowed explain sufficiently the less urgent need of a denser air? However we know very well, and have already said so, that the atmospheric pressure most favorable to animals Is also that found at sea level and in places of moderate elevation, where the mercury column registers about 76 centimeters on the barometer; that, if we place a living animal in a vacuum, the air within it, no longer meeting any resistance, expands, the animal is distended and dies; that it is the air pressure which keeps the fluids in the vessels of animals and prevents them from escaping. Therefore, when the barometer drops a few degrees, the blood must evidently flow towards the periphery; then we observe difficulty and acceleration of respira- tion, slackening of the circulation, weariness, prostration, and lack of interest. If in this situation our animals were endowed with the power of speech, they would probably tell us, as men do, that the weather is heavy, thus taking the effect for the cause, for we know that the rarer the air is, the lighter it is. It is unnecessary to explain why the respiration is more hasty. We know well enough that, since the air necessary for life is extremely rare, the respiratory acts must be more frequent to produce the same result. It is still more unnec- essary to add that when the air becomes rarer, one might die of asphyxia. In a rarified air, thoracic inflammations and hemorrhages must necessarily prevail. And yet we have not observed this, and that is why we think that we are authorized to assert that the reduced atmospheric pressure on the lofty plateaux of Mexico does not have 272 Historical the peculiar influence upon our animals which we have observed in men living in the same medium. We mention the effect of the rare- faction of the air only in explaining the exaggerated distention accompanying the numerous indigestions observed in our horses and mules during the period of the siege. (Vol. Ill, p. 658.) In a special work, this same veterinary gives an account of a series of very unusual symptoms, observed in the animals of the expeditionary corps, in the crossing of Rio-Frio (3300 meters) . The animal passes from health to sickness without any preliminary symptoms. The system is in a state of general tension, especially the muscular system. The eyes are fixed, wild, brilliant, the face con- tracted and the pupil dilated. The hind limbs and the whole hind- quarters are the seat of spasmodic movements which are very definite and easily detectable. The muscles of the stifle and the thigh display partial quiverings. The mouth is filled with a white, foamy, and very abundant saliva. The jaws are in a state of permanent contractility. There is certainly an over-stimulation of the salivary glands. There is a mani- fest desire to vomit. Frequent efforts with belching are easily observed. The belly is not distended. There are a few slight colics shown by a little uneasiness, but the animals do not lie down, aroused instinctively by the desire to urinate or defecate. The genito-urinary system is over-stimulated: there is a stubborn and painful erection of the penis. The conjunctiva is in its natural state and shows no very perceptible changes; it is moist and very slightly bloodshot. The capillary blood system is not visibly changed. The heartbeats are strong and tumultuous. One can see at a distance, without resorting to auscultation, the hasty movements of diastole and systole, and can count the throbs of this organ by looking from behind the knee; . . . and yet, strangely enough, the state of the pulse is not appreciably modified in its normal rhythm. The nostrils are dilated. The expired air is hot; respiration is accelerated. The inspiration is shallow and the expiration deep. The respiratory muscles are contracted and tense, and the flanks, drawn upward, are separated by extremely pronounced projections. They rise and fall up to twenty or twenty-five times per minute. There is rather general prostration of the nervous system than evident over-stimulation of the brain. The symptoms which we have just listed continue for several hours without increasing and then disappear evidently as the effect of suitable measures. (Vol. IV, p. 258.) This strange series of symptoms apparently so dangerous, which, however, never brought on any serious consequences, sug- gested to M. Liguistin the idea of poisoning. Not all of his col- leagues shared his opinion; "some explained the symptoms in ques- tion by blaming chiefly the rarefaction of the air, slow asphyxia Theories and Experiments 273 M. Liguistin himself realized that this element might have an important etiological part: Certainly there is no doubt (he says himself) that at the season when we crossed Rio-Frio, the period of great heat, that a consider- able increase in the temperature, causing evident rarefaction of the air, added to an elevation of 3302 meters above sea level, and producing by this altitude a decrease of 3 ¥2 kilometers in the height of the atmospheric column, had the immediate result of decreasing considerably the quantity of respirable air and producing symptoms characteristic of such causes. We should have liked to be able to prove this physical point by the barometer, during the different conditions of the atmosphere; for that alone would have furnished the real explanation of the swelling of the abdomen frequently appearing in the animals of the expeditionary corps during our crossing of Rio-Frio. However, although this rarefaction was not demonstrated experimentally, its existence is nevertheless undeniable. In Mexico City, observation showed that the atmospheric pressure was only 58 degrees. We may therefore estimate it for Rio-Frio at approximately 55 or 56, which would cause a decrease of 20 degrees from normal atmospheric pressure. Is it illogical to suppose, after that, that animals cannot be placed for even an instant in such a medium without their organism feeling some effects of it? Evidently not; and we were all the distressed, but not surprised, witnesses of the harmful effect which so rarefied an atmosphere can produce upon the health of large solipeds; I mean this second pathological scene, which appeared again more definitely at Rio-Frio, and which brought a moment of turmoil and confusion (indigestion with distention). (Vol. IV, p. 262.) In short, M. Liguistin persists in the idea of poisoning, the harmlessness of which he explains by the partial neutralization produced by other plants simultaneously ingested. By searching in the vicinity, they found a sort of scilla, to which they attributed the symptoms. Experiments made with the leaves suspected gave, however, only one interesting result: the firm refusal of the horses to taste them, even after a fast of 48 hours. As for poisoning obtained by aqueous extract, ingested in the animals by force, they by no means resemble the symptoms observed during the crossing of Rio-Frio. Whence we conclude, in direct opposition to our author, that these symptoms were due exclusively to the rarefied air. I now come to the article of M. Leroy de Mericourt,111 an article to which the name and the special qualifications of its author gave much credit, and which is still quoted constantly. However, it does not contain any personal observation, and the only really original idea in it is due to Professor Gavarret; but it gives, in an elegant style, a summary of the data previously 274 Historical observed and the theories put forth. The most interesting part consists of a very harsh criticism of the works and opinions of M. Jourdanet, whom he considers completely vanquished by Coin- det. According to him: The proportion of carbonic acid in the air expired, as indicating the activity of hematosis on altitudes of more than 2000 meters, showed that the average exhalation of this gas is not less than it is at sea level. We have already shown what one should think of this asser- tion, to which the very figures of Coindet would give much too complete a contradiction, in our opinion. Then, finding the comparison made by M. Jourdanet between mountain sickness and bleeding, and expressed in these striking and accurate terms: "An ascent above 3000 meters is a baro- metric disoxygenation of the blood, just as a bleeding in a cor- puscular disoxygenation", M. Leroy de Mericourt finds nothing better to say about it than to qualify it as strange: Moreover, (he says) a priori, the objection may be raised against M. Jourdanet that the absorption of oxygen by the venous blood is not a purely physical fact, the result of a simple solution, but that chemical forces play an important part in this fixation of oxygen. I was very desirous of reporting this opinion because it shows well what the sentiment of the most learned and the best authori- ties was in 1866. We must, in fact, wait for the theory expressed by M. Jourdanet, the accuracy of which I have demonstrated ex- perimentally, to be considered soon as a thing so simple and evi- dent that everyone will claim to be its originator, or at least will refuse it any merit of originality. I now come to the passage penned by M. Gavarret. After reviewing a few principles of elementary physics, the learned professor of the Faculty of Paris continues in these words: When he ascends a lofty mountain on joot, man accomplishes a quantity of mechanical labor which varies with the weight of his body, the height of the ascent, the nature and the disposition of the ground on which he walks. To the mechanical force which he thus expends there corresponds a consumption of a determined quantity of the organic materials of his blood, the combustion of which pro- duces no thermic effect. Independently of the quantity of heat necessary for the maintenance of his own temperature, the respiratory combustions must therefore furnish the calorific equivalent of the mechanical force expended during the ascent. To understand thor- oughly the consequences of this forced increase of the respiratory activity, let us give our attention to a specific example. Theories and Experiments 275 An adult man, of good constitution, weighing 75 kilograms, has ascended, on foot, to an altitude of 2000 meters on the side of a mountain. He has thus accomplished a useful work of 150,000 kilo- grams, representing 353 units of heat, the thermic effect of which is zero, since they are transformed entirely into mechanical force, and which are furnished by the respiratory combustions. Since eight tenths of this transformed heat comes from the combustion of carbon, the creation of the mechanical force corresponding to the useful work accomplished during the ascent requires the production of 65 liters of carbonic acid, above 22 liters of this gas which the man forms per hour in his general capillaries to maintain his own temperature. The consequences of the production of so great a quantity of carbonic acid in the body are apparent. The consumption of the organic materials of the blood is excessive, and the powers are rapidly ex- hausted. The respiratory and circulatory movements are considerably accelerated, on one hand to render possible the absorption of all the oxygen necessary for such active combustions, and on the other hand to rid the blood of such a proportion of dissolved carbonic acid. When the pace is slow, the force expended in a given time is slight, and the functional disturbances are not great. But if the ascent is rapid, the exhalation of gas, though very much activated, is not enough to maintain the normal composition of the blood, which remains saturated with carbonic acid; then respiration becomes uneasy; the dyspnea is extreme, and is accompanied by head- ache, vertigo, and drowsiness .... We easily understand why a halt of a few instants is enough to dissipate all these symptoms. As soon as the man is resting, the expenditure of energy ceases, the activity of the respiratory combustions drops rapidly to the degree strictly necessary for the maintenance of his temperature, the utili- zation of oxygen is only 22 liters per hour, the blood is very quickly freed of the excess of carbonic acid which it contains, and all the disturbances of the respiratory and circulatory functions disappear at the same time .... As a result of these considerations, we think that we are author- ized to say that the larger part of the functional disturbances characteristic of mountain sickness should be attributed to a true intoxication by carbonic acid dissolved in too great proportions in the blood. To express our ideas completely, we shall add that an intoxi- cation of the same sort, the inevitable result of too great an expendi- ture of energy, is one of the principal causes of the serious symptoms observed in overdriven animals. This interesting and original theory, supported by indisputable calculations and the great authority of the learned professor of medical physics, should gain great success and be epoch-making in science. Henceforth, all will vie with each other in repeating it; already Dr. Aug. Dumas 112 has been the first to do so in his inaugu- ral thesis. But the theory of M. Gavarret does not satisfy him; he ac- cepts and supports with well-made calculations the theories of the 276 Historical Weber brothers on the tendency of the head of the femur to sepa- rate from the cotyloid cavity in expanded air. The objections of M. Jourdanet do not affect him, as we see. That is because he does not consider the work of this learned physician very impor- tant; in his opinion, Coindet has completely refuted such errone- ous statements: What becomes then (he cries) of the alleged insufficiency of oxygenation of the blood at high altitudes? and what shall we say of all the theories which M. Jourdanet has based upon this idea? As to the headache, vertigo, and loss of consciousness experi- enced by von Humboldt and other travellers, Dumas explains them "in a wholly mechanical manner"; to tell the truth, he merely copies an explanation already given by Pravaz: Barry has shown that at each expiration, the course of the blood is slackened in the jugular veins. Therefore it is easy to understand that, in a person who has reached the summit of a lofty mountain, where his hampered respiration forces his thorax to make hasty movements, his venous blood experiences a stasis in the jugular veins and even flows backward, possibly causing a congestion of the nervous centers and all the symptoms which result from that. M. Scoutetten,111 whose work appeared the next year, is satis- fied with copying the principal parts of the article Altitudes, and particularly the quotation from M. Gavarret, whose opinion he adopts wholly. As he seems besides to attach much importance to the varia- tions of the weight sustained by the human body under different barometric pressures, he took the trouble to draw up a long table in which are listed the amounts of this weight in all the mineral water spas. We learn from this that a man who sustains 15,345 kilograms at sea level is relieved of 406 kilograms at Vichy, of 1015 at Saint Gervais, of 1905 at Mont Dore, and 2744 at Cauterets, the highest of the spas. Is it among such ideas that an author takes his stand whose Proceedings for 1867 publish a note which is not conspicuous for clarity? I do not know and leave the reader the task of decid- ing: 114 M. Kaufmann submits to the judgment of the Academy a memoir on the mechanical effect of the air upon certain physiological functions in which it does not usually play a part. To ascertain, the author says, the mechanical effect exerted upon different parts of the organism by the pressure of the air, I began experiments to measure the air; some in which I measured the Theories and Experiments 277 changes produced in different physiological or pathological states by variations in the weight of the atmosphere; others in which I produced these variations artificially. Those whose results I am submitting to the Academy today refer to the different periods of generation in mammals from conception to the time of delivery. In the book which he published at the time of his return to France, Coindet lir' returns to the question of the quantity of car- bonic acid formed by men who live on the lofty plateaux. Evi- dently he felt ill at ease on this ground, for in a work of two vol- umes, containing more than 650 pages, he devotes only 5 to this important subject. And yet what could be more convincing in favor of his point than to dwell upon this demonstration that the intra-organic combustions are as active at high altitudes as at sea level? Anoxemia, against which he was battling, would be com- pletely disproved. I confess that at first I expected to find new experiments in this book; there are none, and the explanation of the data is infinitely less complete and detailed in it than in the letters addressed to Michel Levy. This is soon explained, for first we record a valuable confes- sion; "I was mistaken", says Coindet (Vol. II, p. 90), "when I formerly wrote weight instead of volume." There is a point gained, and, as I had shown when I recalled the passage copied by Beclard, the notorious 4.51% in 1864 represented to Coindet a proportion in volume, although he said the opposite in his 1865 letter. But then, if there is 4.51% of carbonic acid in volume in the air, since the subjects were breathing at the rate of 6 liters per minute, or 360 liters per hour, that makes in one hour 360 liters x 4.51 — 16.23 liters of carbonic acid expired. Since we are working at 14° and at 58 centimeters, this volume corresponds., at 0° and 76 cm., to 11.77 liters; and as a liter weighs 1.966 grams, the production of carbonic acid per hour would be 23.14 grams, giving 6.40 grams of carbon consumed. Once more we are far from the 12.30 grams announced triumphantly by Coindet. But he thinks better of it: We must not lose sight of the fact (he says) that 4.52% in volume, the average amount of carbonic acid exhaled in one minute, has been removed from an air at a temperature of 14°, and a pres- sure of 58 cm., brought to a temperature of 0°, and a pressume of 76 cm. ... so that 6.125 liters, average amount of air expired in one minute, disregarding the Frenchmen who had lately arrived and were not acclimated, give us 367.55 liters in one hour . . . When the average of 4.52% of carbonic acid exhaled in one min- ute is accepted, we can establish the following proportion: 278 Historical 100 : 4.52 : : 367.55 : x = 16.62 liters of carbonic acid per hour. At sea level, 1.85 liters of carbonic acid contain 1 gram of carbon, which gives us 9 grams very approximately consumed in one hour. . . . This figure is quite different from the 12.30 grams of the first work. And yet how was it obtained? First by taking the quan- tity of air expired from 6 liters to 6.125 liters; then by declaring that in the calculations the air was reduced to 0° and 76 cm.; but Coindet forgets that he said exactly the opposite before: I have proved that the volume 3.90% of air at 14° and 58 cm. fur- nished me by the weight (let us not forget that now it is the vol- ume) 4.51 of air also at 14° and 58 cm In another passage, he is no less explicit Since the quantity of air expired per minute, as admitted by M. Dumas, is 5.3 liters at sea level, in Mexico City . . . we have about 6 liters. This was logical, for since the air at high altitudes contains less oxygen in a given volume, a greater quantity of this air had to be absorbed to make up the difference. It is not therefore, in our opinion, 9 grams, but 6.40 grams of carbon consumed in an hour that are given by the figures of Coindet himself. But even with 9 grams, we must realize that we are far below the average figure of 12.2 grams found by Andral and Gavarret. Coindet cannot conceal it, but he does not seem at all disturbed by it: Our average of 9 grams (he says calmly), lower than that found by some authors, does not cause us, for reasons given above, to con- sider the respiratory combustions of carbon as perceptibly lower on the lofty plateaux than they are at lower levels. What are these reasons then? First, we see, is that Our Creoles were students in the School of Mines, on the day before their final examination for the year, sitting studying all day long, and under these circumstances the expired air has undergone little change; And second, that The Indians had an insufficient diet and used alcohol habitually; And third, that There were losses through the nostrils! I think it would be useless to continue. I can only repeat what I said above: from the chemical point of view, there is nothing, absolutely nothing, left of the work of Coindet; and as the experi- ments which we have just shown to be so unsatisfactory are the Theories and Experiments 279 basis of his whole physiological argument, we see that his position is untenable. I should certainly not have spent so much time on a work which has had far too much publicity, if it was not still quoted as an authority by persons who preferred to trust to its peremptory conclusions rather than to make the painful analysis through the meanderings of which we have led our readers. And the latter have had the opportunity to see that even if the a priori asser- tions and the statements of conclusions are clear, the experiments themselves and the calculations based on them contain only ob- scurity, confusion, or error. M. Gavarret 116 did not adhere to the theory which we reported above, and which he had given in the form of advice to M. Leroy de Mericourt. When he wrote the article Atmosphere for the Dictionnaire Encyclopcdique, he was led to investigate the effects of decreased pressure, without the addition of fatigue, exertion, and the production of carbonic acid imposed by mountain ascents. Reaching the study of causes, as an experienced physicist, he first opposes the opinion that the lessening of the weight sustained by the body may have some effect; he properly invokes against this error the principle of the incompressibility of liquids, and conse- quently of the body. But in giving his attention to this point, strangely enough, he returns to the ideas of Robert Boyle: The disturbance which accompanies the decrease of the barometric column is really the effect of the pressures from within outward exerted by the vapors and the gases imprisoned with the body .... We must fix our attention upon the gases of the blood which, under the effect of a considerable and very rapid drop of the barometric column, may cause serious symptoms. The blood, in fact, contains oxygen, nitrogen, and carbonic acid in the state of simple solution. When the outer pressure diminishes, these gases tend to separate from the blood, push the walls of the vessels from within outwards, and distend the pulmonary and general capillaries, the walls of which may be ruptured because of their thinness and lack of resistance. Such is the mechanism of the production of hemorrhages, sometimes slight and temporary as their determining cause when they appear on ex- ternal surfaces, sometimes serious and even fatal, when they have the interior of some vital organ as their seat. (P. 153.) But M. Gavarret makes haste to apply a proper restriction to this: Symptoms of this sort may no doubt be produced in persons who are very rapidly moved to great altitudes; but that is not the case with travellers who gradually ascend from sea level to the highest plateaux on earth. In the latter, the laws of physics governing gases and their solubility .... reestablish harmony .... (P. 154.) 280 Historical In other words, the explanation given by the learned professor can be applied, according to him, only to laboratory experiments performed on animals; mountain climbers and aeronauts are not amenable to it. The argument brought by M. Gavarret against the part which so many authors had given to the decrease of the weight sustained by the body seemed to have exposed this error; the important ex- periments of Rudolph von Vivenot 117 seemed, on the other hand, to give it new authority. In fact, the Viennese physician proved very clearly that in rarefied air the depth of the respirations and the respiratory capacity diminish considerably. These experiments were made at the Johannisberg establish- ment, in the apparatuses set up by Dr. Lange; some had as their purpose the study of compressed air, and those we shall discuss later; the others, of which we shall speak now, related to rarified air. When we take into account the altitude of Johannisberg, where the average height of the barometer is 742 mm., we see that if the decompression reached in the apparatus was 318 mm., the actual pressure was 424 mm., which corresponds to an altitude of 4470 meters above sea level. Under these conditions, as I said a moment ago, the amplitude of the respirations diminished considerably: Dr. Lange and Dr. Mittermaier, whose pulmonary capacity shortly before at normal pressure had been 3942 cc. and 4237 cc, could only with the greatest efforts expire 3448 cc. and 3842 cc, of air which was admitted to the receivers of the spirometer. Their respiratory capacity therefore had diminished 494 cc. and 394 cc. respectively. On an average, we can deduce from the above figures as a normal average respiratory capacity 4090 cc, as respiration in rarefied air 3646 cc, consequently as average decrease of pulmonary capacity 444 cc, to which we must add that these 3646 cc. of rarefied air represent only 2084 cc. of normal air. (P. 7 of the separate printing.) The frequency of the respirations has considerably increased, working inversely: The number of respirations rose in me from 14-15 to 18; in M. de G. . . ., from 17 to 21, and at another time, from 17-18 to 19; in Dr. Lange, from 15 to 21; in Dr. Mittermaier, from 7.5 to 9.5 per minute. As to the consecutive duration of this effect, it could not be noted, because no observations were made following the experiments in rarefied air. (P. 11.) . . . As to the depth and rhythm of respiration in rarefied air, an in- crease in the depth of the inspirations is noted. This, then, is the first case in which the effect of rarefied air seems to agree with that Theories and Experiments 281 of compressed air, although the causes are opposite. Whereas in com- pressed air there is a deeper inspiration spontaneously, as a mechani- cal effect of the increase in pressure, it is, on the contrary, the need of getting air, which, since it cannot be satisfied in rarefied air by normal inspirations, necessarily produces deep and forced inspirations. One experiences at the same time a feeling of uneasiness, oppression, during which the inspiration is especially difficult, because, even in atmospheric air, it requires more energy than the expiration, whereas the latter, in rarefied air, is made more easily and more quickly. (P. 16.) Vivenot also made observations on the pulse rate. It rose from 78 to 80 in Dr. M., from 73 to 82 in Dr. L., from 61 to 76 in M. de G., from 80 to 105 in Vivenot himself. A veterinarian of the Royal Corps of English Engineers, Fleme- ing,118 published in 1867 a work in which he reports a fairly large number of travellers' observations, and at the head of which he expresses his theoretical opinion about the effect of decompres- sion: If the pressure is reduced artificially, as when one climbs a moun- tain or ascends in a balloon, one notes the same phenomena as in fish taken from the water. The body swells, the inner fluids distend the tissues outwards, exerting a vigorous pressure on them, burst the vessels, and often cause hemorrhages. Rarefied air contains less oxygen in a given volume, so that respiration, being incomplete, is accelerated to compensate for this deficiency; the inspirations are proportionately more numerous; the heart contracts vigorously and more frequently, the blood circulates with difficulty, the lungs are congested, the blood vessels are dis- tended, and aneurisms are formed. (P. 9.) In summary, according to Flemeing, the effect of altitude can be produced in several ways: 1. By the decrease of the atmospheric pressure: the muscles and the articulations tend to relax, the blood stops or transudes through the walls of the vessels, especially the mucous membrane of the air passages, the lungs, and the brain envelopes. 2. By cutaneous and pulmonary evaporation .... 3. The frequency of the circulation and the respiration is coun- terbalanced, or better, caused by the small quantities of oxygen which the inspired air contains. 4. The lowered temperature .... 5. The more powerful rays of the sun ... . which cause irrita- tion of the eyes, the brain, and the spinal cord. (P. 12.) M. Bouchard, in his noteworthy thesis .on the pathogeny of hemorrhages,110 is led to express his opinion about the cause of the symptoms, noted both in persons subjected to a considerable 282 Historical decrease of pressure and in workmen who are being decompressed when they leave the caissons of bridge piers. In his opinion, as we shall see at the proper time, hemorrhages are due partly to the escape in the vessels of the carbonic acid of the blood, which has been stored up there in exaggerated proportions during the compression. Decompression by ascent would produce the same effect; and if hemorrhages have been noted particularly in mountain climbers, the theory which he suggests may explain the difference in these effects: The man who rises in an aerostat performs practically no work except that required by the respiratory movements. The man who climbs a lofty mountain, on the contrary, makes a considerable muscu- lar expenditure and must load his blood with carbonic acid. Is it not, moreover, to this accumulation of carbonic acid in the blood that certain authors attribute this peculiar dizzy state called mountain sickness? (P. 102.) Errors are hardy. It is strange to note that in spite of the authoritative answer made by M. Jourdanet to the theory of the Weber brothers, it continues to be taught almost universally. M. Beclard,120 in the last edition of a book which should be in the hands of all students, says, in fact: When man rises in the air, climbing very high mountains on foot, as the rarefaction of the air increases, he experiences a very peculiar feeling. It seems to him that his limbs are heavier; the lower limbs especially soon become the seat of a fatigue which urges him to rest. Hardly has he stopped an instant when this fatigue disappears to reappear after a short time; and so on. This is what happens; the atmospheric pressure is no longer sufficient by itself to keep the head of the femur firmly against the cotyloid cavity, and thus counterbalance the weight of the lower limb, and muscular effort must keep the limb in its articular relations. This unusual muscular effort is promptly followed by need of rest for the muscles .... This effect is felt even when the differences in pressure of the barometric column are not very great. When the barometer falls, since the muscles have to move heavier organs, we say that the weather is heavy, although in reality the pressure exerted upon the surface of the body by the atmospheric column is less. Likewise, when the barometer rises, movements are made more easily. (P. 697.) As to the symptoms of decompression other than heaviness of the limbs, M. Beclard attributes no importance to them when the transitions are made rather slowly: At Potosi (4000 meters), at Deba (5000 meters) .... the functions of metabolism, respiration, and circulation of the mountain dwellers Theories and Experiments 283 go on as in dwellers on the plains, and they are in just as good health .... Men and animals therefore can endure very considerable varia- tions in pressure without disturbance of the functions of life. It is true that, since the density of the air is lessened, the air drawn into the lungs contains in each inspiration less oxygen than on the plain in the same volume; but the movements of respiration harmonize with these new conditions. Moreover, pressure is still exerted in all directions, the air penetrates all the open cavities (alimentary canal, respiratory passages), the gases of the blood are put in equilibrium of tension with the atmospheric air, and the normal conditions of gaseous exchange are not altered in the lungs. The variations in the pressure of the atmospheric medium in mountain ascents or in balloon ascensions are not likely either to cause painful symptoms in regard to metabolism. But this is not true when the decompression takes place rapidly, as happens in aerostatic ascensions: Then a certain time is needed for the equilibrium between the inner gases and the outer gases to be established. When the ascen- sion has been to a considerable altitude, sometimes there appears a difficulty in breathing, suffocations (from expansion of the intestinal gases which press upon the lungs, crowding the diaphragm upwards) and local hemorrhages in the mucous membranes (probably from, sud- den expansion of the gases contained in the vessels, and from rupture of the capillaries). (P. 696.) Beside the ideas of physicians with theories we should place the opinion expressed by mountain climbers. After the theories and the discussions which we have just reported, it is somewhat surprising to see certain travellers almost deny the effect of de- compression. For instance, Hudson,1-1 who scorning "the easy beaten path which usually leads to Mont Blanc," ascended the mountain by a new route, starting from Saint Gervais, states that: If one is careful to save his strength, he can cross the highest summits without experiencing any serious inconvenience. Several persons have complained of discomfort experienced at great heights, nausea, drowsiness, bleeding from the nose, the eyes and the ears, and I do not doubt that such symptoms are possible; but my long training in mountain journeys has proved to me that they should be attributed only to fatigue, to which no doubt may be added cold and the rarity of the air, or rather the unusual precautions required by these two circumstances. In fact, there were five of us in the group, and thanks solely to care not to get tired, none of us had an instant of discomfort; the same thing was true at the time of my ascent of Monte Rosa. (P. 85.) Dr. Piachaud,1-2 whose interesting observations we have already 284 Historical summarized, made during his ascent of Mont Blanc in 1864, also attributes to fatigue alone the disturbances of circulation and respiration; according to him, the drowsiness is due to cold, the muscular fatigue to the cause indicated by Brachet, and the heavi- ness of the lower muscles to the cause specified by Weber and von Humboldt. But these not very original estimations have hardly any im- portance beside the new and very ingenious theory advanced by Dr. Lortet.1-3 We have reported at length the observations made with all the precision required by modern physiological research by this learned physician during his ascent of Mont Blanc. The discovery to which he gives most importance is the decrease of the body temperature during the act of ascent. In his opinion, this is the true cause of the symptoms experienced, and to explain it, M. Lortet relies upon the elementary notions of the mechanical theory of heat: In a state of rest and fasting, man burns the materials of his blood, and the heat developed is wholly employed in maintaining his temperature constant in the midst of atmospheric variations. On the plain and during moderate mechanical work, the intensity of the respiratory combustions, as M. Gavarret has shown, increases propor- tionately to the expenditure of energy. There is a transformation of heat into mechanical energy, but because of the density of the air and the quantity of oxygen inspired, there is enough heat formed to make up for this expenditure. In the mountains, especially at great altitudes and on very steep snowy slopes, where the mechanical work of the ascent is great, an enormous quantity of heat is needed to be transformed into muscular energy. This expenditure of energy uses up more heat than the or- ganism can furnish, hence the perceptible chilling of the body and the frequent halts which must be made so that one can gain warmth. Although the body is burning hot, although it is often covered with perspiration, it becomes chilled during the ascent, because it uses up too much heat and because the respiratory combustion cannot furnish a sufficient quantity of it because the air lacks density; because of the rarefaction of the air, at each inspiration less oxygen enters the lungs at a great height than on the plain. (P. 33.) M. Lortet then shows, by a simple calculation, that while he is ascending 1000 meters, a man weighing 75 kilograms would find that the temperature of his body would drop 2.3°, if he furnished no restorative heat. Hence he draws this conclusion that the drop of 4° to 5°, which he noted in ascending to 3800 meters, is quite natural and within the limits indicated by his theory: Let us take, for example, a human body weighing 75 kilograms, and let us assume that during the ascent no combustion repairs the Theories and Experiments 285 loss of heat undergone; let us assume also that all the mechanical work is usefully employed, that is, that none of it is lost in slipping, false steps, etc. When the body has been raised 1000 meters, the quantity of work accomplished will be represented by 75 x 1000 or 75,000 kilogram- meters. As the mechanical equivalent of heat is 425 kilogram-meters for each unit of heat, to get the quantity of heat absorbed during this 75,000 work of ascent of 1000 meters, we shall have =176 units of 425 heat. If we assume that the specific heat of the human body is equal to that of water, that is, equal to 1, and if we represent this specific heat by C; if we call the drop in body temperature X, we shall have: quantity of heat lost by the body 75 (C + X) or 176 = 75 x X, whence 176 X = , or X = 2.3 75 Therefore the drop in body temperature resulting from the heat absorbed by a work of 75,000 kilogram-meters, performed in an ascent of 1000 meters, would be 2.3° centigrade, assuming that no combustion repaired, at least in part, this loss of heat. But it is evident that in reality this combustion exists and that a part of the heat expended is restored while it is being absorbed. But we have seen, by the study which we have made of the respiratory and circulatory disturb- ances, how much this combustion is hampered at a certain altitude, and how incomplete it is. Furthermore, it is evident also that all the energy expended is far from being useful because of false steps and the softness of the snow. The quantity of heat used must therefore be enormous, and the drop in temperature must be great and hard to meet by respiratory com- bustion. We see then, when these different elements of the problem are well considered, that this drop of four and some tenths degrees centi- grade, in the ascent of Mont Blanc, is not at all extraordinary because this figure gives one and some tenths degrees centigrade for each thou- sand meters of elevation, a quantity which is very near the 2.3° centi- grade given us by the physical theory, when we do not take into account the respiratory combustions. (P. 36.) However, when one is digesting, there is almost no drop in tem- perature, probably because of the acceleration of the circulation, either general or capillary, and perhaps also because of an extremely rapid absorption of alimentary material. This explains the practical habit of the guides of giving out food about every two hours. Unfortunately, above 4500 meters, distaste for food is so great that it is almost im- possible to swallow a few mouthfuls. (P. 37.) To this chief cause others are added, which M. Lortet stresses. First: The rapidity of the circulation is another cause of the drop in 286 Historical temperature, since the blood does not have time to become suitably oxygenated in the pulmonary vesicles. (P. 34.) In addition, as M. Gavarret has shown: The creation of mechanical energy corresponding to useful work, accomplished during the ascent, requires the production of 65 liters of carbonic acid above the 22 liters of this gas which man forms per hour in his capillaries to maintain his temperature. The consequences of the production of so great a quantity of carbonic acid in the body are apparent. At a great height, the respiratory and circulatory movements are accelerated not only to make possible the absorption of an adequate quantity of oxygen, but also to free the blood of the carbonic acid which it holds in solution. But this exhalation of gas, though very active, is not sufficient to. maintain the normal composition of the blood, which remains supersaturated with carbonic acid; hence the occipital headache, the nausea, an irresistible drowsiness, and a still greater drop in temperature, from which travellers and guides usually suffer above 4000 to 4500 meters. (P. 35.) And he concludes by saying: The symptoms known by the name of mountain sickness are due chiefly to the great chilling of the body, and perhaps also to a cor- ruption of the blood by carbonic acid. (P. 37.) M. Lortet was accompanied on his ascent by an English physi- cian, Dr. W. Marcet,1-4 who made the same experiments, and gave an account of them in a special work. The observations were made with a thermometer placed in the mouth, without pausing in the ascent, because: The pause in the progress upward, however short its duration, was nevertheless enough to permit the body to produce heat momentarily to replace that which had been expended during the act of ascent. The results which M. W. Marcet reached are identical with those of M. Lortet: 1. The temperature of the human body in a state of rest does not seem usually to be less at great heights than at sea level. 2. The temperature of the body invariably tends to drop during the act of ascent. The amount of this drop depends almost exclusively upon the time of the last meal. This drop is due to the muscular movements and not to the effect of rarified air .... A rapid ascent of only 328 meters was enough to cause a drop of 1.4°. 3. The general discomfort, particularly the nausea, often experi- enced at great elevations, is accompanied by a considerable drop in body temperature. It is the result of the fact that the body has be- come unable, because of the physiological circumstances in which it is placed, to replace the heat which it has expended during the act of ascent. Theories and Experiments 287 And so, according to M. Lortet and M. Marcet, who expresses himself even more definitely than his travelling companion, there is a considerable drop in body temperature, and this drop is due "not to an effect of the rarified air", but to the muscular move- ment, to the transformation of heat into work. But these physiologists found in M. Forel an adversary worthy of them. The excellent work of the professor of Lausanne is divided into three parts published, one in 1871, the last two in 1874. It was undertaken first as a criticism of the memoirs of MM. Marcet and Lortet. M. Forel 125 begins with very just criticisms of the use of the buccal thermometer, as an indicator of the real temperature of the body. I copy here his observations, to the complete accuracy of which I can testify in many circumstances: First, it is very difficult to keep the lips hermetically closed for a sufficient time, and only after a rather large number of attempts and experiments could I become completely enough accustomed to it so that I could be sure that not even one bubble of air was admitted during the experiment. What is difficult in a state of repose becomes unendurable while one is climbing, when one begins to pant, when all the openings together are not enough to admit a sufficient quantity of air into our lungs, especially when the rarefaction of the air demands imperiously a larger volume than we need on the plain so that our system may be supplied with enough oxygen; then it is regular torture to close for ten minutes the mouths which we should like to be able to enlarge, and the experiment becomes terribly painful. Another difficulty is to keep the thermometer exactly under the tongue, and as much as possible always in the same place. The tongue is very flexible and fairly docile; it can, if need be, surround the bulb of the thermometer closely enough not to permit contact with the air of the mouth; but the thing is very difficult, as one can convince him- self before a mirror, and what is difficult when one is at rest becomes almost impossible under the painful conditions of the experiment. Now if any portion of the surface of the bulb is in contact with the air of the mouth, the results are greatly modified. In fact, the buccal cavity is not closed at the back, the opening of the palate per- mits a constant mixture of the air contained in the mouth and the air which circulates with violent impetuosity in the canal of the pharynx; even if there is no current of air in the buccal cavity properly so- called, this mixing necessarily takes place, and in proportions which are greater, as the current of air in the pharynx is more violent and the differences of temperature and humidity between the pharyngeal air and the buccal air are greater. In our conditions of experimenta- tion on lofty mountains we are as unfavorably placed as possible from this point of view. The respiration is panting in a very dry and very cold air. The mixing of air must necessarily increase in amount with the altitude and with the muscular movements which accelerate the respiration. 288 Historical The cold air drawn into the mouth might perhaps be warmed quickly enough not to cause very considerable changes in temperature: but as this air is very dry, there is evaporation of a certain quantity of saliva, and therefore a chilling and a lowering of the temperature. (P. 12.) Besides this quite general criticism, M. Forel rightly considers one of the statements of MM. Lortet and Marcet strange and in- explicable, unless we admit a serious mistake in the observation: Both say, in fact, that they had to observe the temperature while walking, during the very act of ascent, for as soon as they stopped, or merely slackened the speed of their progress, the ther- mometer, relatively very low during the ascent, rose almost suddenly to the normal body temperature .... Now the human body cannot grow warm so instantaneously. If the temperature is assumed to be 35°, if the body weighs 60 kilograms, 60 calories must be produced for the temperature to rise to 36° .... Helmholtz estimates the production of heat of a man weighing 60 kilo- grams at 1.5 calories per minute; it would therefore take 40 minutes to produce the 60 calories .... which is very far from the instantaneous- ness described by Lortet and Marcet. (P. 15.) The first part of M. Forel's work ends with conclusions from which I take the two following, which are the most important: 1. The act of ascent normally produces an increase in body tem- perature of some tenths of a degree; I reserve my opinion in regard to the effect of ascent upon the heat production of the body in the condition known by the name of mountain sickness. (P. 28.) 12" These conclusions appear again at the end of the second part, in which physicians and physiologists will read with the greatest interest experiments investigating very exactly the determination of the temperature in different parts of the body (hand, armpit, groin, mouth, auditory canal, urine, rectum) . The third part is subsequent to the publication in the Annals of the Natural Sciences of my Memoir, the results of which M. Forel approves. In it is an anecdote which is very interesting from the point of view of the theory which I have formulated, and the accuracy of which the present work will show, I hope, to those who are the hardest to convince; I shall relate it in the third part of this work. Finally, M. Forel ends with a detailed account of an ascent of Monte Rosa in which he experienced mountain sickness, although only slightly. On this occasion he makes this remark, — which ex- plains both certain exaggerations and certain doubts — namely, that attention given to observation of the symptoms one feels dispels Theories and Experiments 289 mental depression and lessens fatigue. This is true of danger as well as of scientific interest; no one suffers from mountain sickness on dangerous passes. On this ascent, M. Forel noted that his temperature was always increased by walking, even above 4000 meters; he himself is sur- prised at that, considering the very pronounced state of anoxemia in which he must have been. But as he was not seriously af- fected, he merely states the fact, and, true to his prudent method, still reserves the case of ascent during an established state of mountain sickness. These conclusions were corroborated by the researches of an English physiologist who did much research on variations in tem- perature of the body in health and in sickness. Cliff ord-Allbutt 127 made a series of ascents, one of them on Mont Blanc in very bad weather, to study the effects of walking and climbing on the temperature of the body. It was measured under the tongue during the act of walking, the maximum thermometer remaining in place for 15 or 20 minutes. From his observations he draws the conclusion that muscular exercise tends to raise the temperature. I copy one of his tables, the most interesting one, since it re- lates to the passage from the Grands-Mulets to Mont Blanc: August 18, 1870. 1:30 in the morning. At the Grands-Mulets, before rising 97.5°F. 3:30 in the morning. Ascent begun at 3 o'clock 97.7 5:00 in the morning. On the Grand-Plateau. Terrible weather 98.0 7:30 in the morning. I began to descend at 7 o'clock 98.5 8:30 in the morning. Arriving at the Grands-Mulets 98.5 9:15 in the morning. At the hotel in Chamounix, in bed 97.6 I should note, however, that the day before, when he reached the Grands-Mulets, his temperature suddenly dropped to 95.5°, and rose to 98.5° after a 10 minute rest. August 20, at Chamounix, in bed, Allbutt's temperature was 95.4°. Another English physiologist, C. Handfield Jones,128 attributed the sphygmographic records of M. Lortet to exhaustion from fa- tigue. The discussions between MM. Lortet and Forel again attracted the attention of physicians and physiologists to mountain sickness, especially in Switzerland. And so M. Dufour,129 in his turn, sug- gests in regard to this difficult subject a very noteworthy theory, which shows thorough acquaintance with the recent advances of science. 290 Historical In the session of the Diablerets section of the Swiss Alpine Club, on January 27, he expressed the idea That the somewhat undefined unhealthy state called mountain sick- ness results from the absence in the blood of the ternary elements which are used in combustion. (P. 72.) M. Dufour is especially struck by the contrast between travel- lers and aeronauts, since the latter are in good condition at eleva- tions which the former cannot reach without serious symptoms: If the mere rarefaction of the air were injurious to health, how much more seriously affected Glaisher and Coxwell should have been, who in 25 minutes rose from about sea level to the level of the summit of Mont Blanc! Besides, when aeronauts finally experience pathological symptoms, these symptoms do not at all resemble those of mountain sickness. M. Glaisher gives a description which resembles a paralysis of sensi- tivity and movement extending regularly from the extremities to the center. Is this paralysis produced by a stoppage or a slackening of the circulation, or is it a direct effect upon innervation? We cannot tell. The fact that M. Coxwell's hands were blue for a moment seems to support the first hypothesis, whereas the fact that M. Glaisher lost the use of the retina, while his mental powers were still intact, would rather support the second. At any rate, and this is the point which is important to us, the pathological symptoms come very late, and when they do come, they are not the symptoms of mountain sickness. We are therefore led to consider muscular work as the principal factor in the production of mountain sickness, and if the rarefaction of the air makes some contribution to it, it is through the combustion which the work requires. (P. 76.) M. Dufour thinks that inanition produced by work is the prin- cipal cause of mountain sickness. He says that he experienced the symptoms of it on the plain after great muscular efforts: M. Dufour experienced several symptoms of mountain sickness, including nausea, when he was mounting from the bottom of the mines of Freiberg in a shaft and by vertical ladders. He had walked in the mine for about three hours, and had eaten nothing; the distress attacked him while he was ascending, and was still 50 or 60 meters below the surface of the ground. In covering this short vertical dis- tance, he had to rest two or three times. Likewise in an ascent of Pilate, after too rapid a walk from Hergiswyl, he was seized by extreme prostration, throbbing in the neck, headache, and dyspnea. At that moment, feeling mechanically in the pocket of his coat, he found a morsel of bread which he put into his mouth. After taking five minutes to get enough saliva to moisten his bread, he swallowed it. A few minutes afterwards, the symptoms of distress disappeared as if by magic, and he was able to ascend very easily the remaining 100 or 200 meters. (P. 76.) Theories and Experiments 291 Then basing his conclusion on recent physiological data, he con- sidered that the work of ascent uses up the reserve of ternary materials contained in the blood and the tissues, and results in the muscular exhaustion. I shall quote this noteworthy passage verbatim: It is probable that during the first hours of the ascent, the muscu- lar work consumes the non-nitrogenous substances immediately avail- able either in the muscular substance or in the blood. What replacement can compensate for the effect of so great an expenditure? It can take place in only two ways: either the chylif- erous vessels bring into the circulatory stream new elements supplied by the digestion, or the organism absorbs and draws again into the circulation the elements of the subcutaneous adipose tissue. This last point is so certain that working hard and eating little is a means of getting thin that is well known to everybody. The first of these re- placements can be made quite quickly; the second, if we judge by the phenomena of absorption which we often witness, can take place only much more slowly. It is probable that the absorption of the adipose tissue to be used as a combustible in the work of ascent is a phenomenon too slow to compensate satisfactorily for the expenditure caused by the work of someone ascending without stopping. Therefore a moment must come whea, if the climber does not eat, the available combustible material keeps diminishing and can be only partly replaced by absorption. This effect will be produced most easily when after work of several hours the climber approaches a steep grade which he wishes to climb too quickly, so that there is a still greater disproportion between the work performed and the time used in performing it. (P. 77.) Therefore, according to M. Dufour, it is very easy to explain: a. The importance of rest, because during rest there is no ex- penditure whereas replacement continues. b. The fact that after rest, the quantity of work easily performed is obviously proportional to the duration of the rest; for the same reason as above. c. The fact that, to anyone who has mountain sickness, any new effort, such as stooping or using the arms, becomes painful. (See H.-B. de Saussure.) d. The fact that mountain sickness seems to attack plump persons more than thin persons, because the former produce, on an equal ascent, a much larger number of kilogram-meters of work. The fact that they have in the adipose tissue a deposit of combustible material is without importance here, for very thin persons always have a suffi- cient adipose membrane to supply the work of ascent as it generally appears. f. Finally, the fact that a means of avoiding mountain sickness is to eat often, that is, to furnish materials not by way of resorption, but by way of digestion and absorption. (P. 78.) 292 Historical Then he draws from his theory this logical conclusion: We are therefore led to seek a combustible food easy to digest and absorb, to avoid mountain sickness. M. Dufour thinks that sugar syrup or better, glucose syrup would fulfill these conditions. In fact, the fats, which are the best combusti- ble material, require a certain time for digestion and may not be digested in time to satisfy an immediate need; the feculae must be transformed into sugar, glucose syrup then would be the food which would reach the circulation most easily. (P. 78.) The discussion aroused by the important theory presented by M. Dufour brought a very interesting communication from M. Javelle,130 president of the Diablerets section of the Swiss Alpine Club. The narratives which it contains show, as we have already noted, that persons attacked by mountain sickness, even very seri- ously, often find that their illness disappears immediately when dangers appear or when a very intense application of mind be- comes necessary. They prove besides that these illnesses are much more frequent than is generally supposed, and make a satisfactory reply to cer- tain skeptics who did not hesitate to jeer at what they call the exaggerations of M. de Saussure. Let us note that M. Javelle has had great experience on high peaks, and that he has made nearly 200 ascents of 5000 to 15,000 feet, very often in the company of 10 to 20 young men: Mountain sickness very frequently appears in the medium region of the Alps, between 5000 and 10,000 feet, that is, at an elevation where the air is sufficient for the needs of respiration, and where one can hardly consider intoxication from excess carbonic acid as an explana- tion for it. At 14,000 or 15,000 feet, the illness experienced by even the sturdiest mountaineers differs in several characteristics. Mountain sickness affects particularly persons who are unaccus- tomed to the mountains, and especially those who lead a sedentary life. Those who are anemic rarely escape it. Novices who begin with a difficult ascent are very likely to pay tribute to it. (P. 136.) This illness appears especially on soft snow, turf, slopes covered with landslides where walking is difficult, in small valleys and on long slopes, in general, everywhere that walking is both tiresome and monotonous. It very rarely appears during the climbing of cliffs or on ridges, very rarely too on difficult or dangerous expeditions. An interesting conversation or merely a careful observation of the landscape often wards it off. M. Javelle has noted that young men who made the expeditions without interest or rivalry and merely to accompany their companions were most often affected by it. (P. 13.) Theories and Experiments 293 The editor of the Bulletin summarizes the discussions which arose about the etiology of mountain sickness among the members of the Swiss Alpine Club in this odd sentence: The principal factors are need of food, the intensity and rapidity of the work, and the mental characteristics. We cannot remove com- pletely from the list of causes the rarefaction of the air and intoxica- tion by carbonic acid. The question, which has a certain interest, therefore still offers some unknown quantities to be found. (P. 140.) Moreover, the following passage, taken from the celebrated physicist and daring mountain climber Tyndall, also gives inter- esting information on this subject: It is not a good idea to begin these ascents without having eaten and it is not good to eat heartily. One must eat a little here and there, as the need appears. But left to itself, the stomach inevitably falls ill, and the energy of the system is rapidly exhausted. If the illness brings on distaste for food, vomiting may ensue and the stomach be conquered. A little food is enough to restore it. The strongest guides and the sturdiest porters are sometimes reduced to this ex- tremity. "Sie mussen sich zwingen". The guides attribute these ca- prices of the stomach to the great elevation of the air. Perhaps that is one of the causes, but I am inclined to think that something is likewise due to movement,— the continuous action of the muscles on the diaphragm. The conditions under which the journey is made and those which have preceded it also deserve much attention. One sleeps little or not at all; the morning meal is taken at an unusual hour; and if the start is to be made from a cave or a hut instead of a hotel bed, there is a serious aggravation of bad conditions. It cannot be the slight difference in height between Mont Blanc and Monte Rosa that makes the effects of their ascents so different. It is because, for the first, one makes his coffee of the melted snow of the Grands-Mulets, and has a bare plank for his bed; whereas for the other, he enjoys the inn of the Riffel, very comfortable in comparison. Milk and a crust of bread are all I need to sustain my strength and ward off mountain sickness. (P. 304.) These very wise remarks have been made by many travellers. The degree of fatigue preceding the ascent is an element the im- portance of which is well known today. The same thing is true of the habit of walking and of living in the mountains. The fol- lowing observations of M. Durier 132 in this regard deserve our approval. We have told earlier how, by a strange coincidence, M. Durier and his companions, who suffered no ill effects from the decompression, ascended Mont Blanc just behind MM. Lortet and Marcet, whose symptoms we have given. M. Durier explains this difference in the following words: In general, the physiologists who have studied the effects of moun- tain sickness upon themselves tear themselves from work in their labo- 294 Historical ratory and rush to Chamounix; on the first favorable day, they attempt the ascent. Well! I think that they are making their experiment under conditions which are not very scientific. The ascent of Mont Blanc is, after all, very difficult. It requires previous exercise and training. These scholars are likely to confuse the effects of unusual fatigue which finds their muscles unprepared, with those of a rarefied atmosphere. (P. 63.) .... It is under these conditions that MM. Marcet of Geneva and Lortet of Lyons made their ascent .... We were in the fourth week of a journey on foot, during which, without resting even one day, we had crossed some of the highest passes of the Alps. (P. 66.) Finally M. Russell Killough,133 whose very astute replies to the skeptics who deny mountain sickness I have mentioned, is less for- tunate in regard to theoretical explanations. He revives, without the slightest proof to support him, either from experiments or rea- soning, the hypothesis of the injurious effect of snow: I am ready to agree that altitude is not exclusively the cause of these sufferings. I think, and others have thought before me, that snow is an important factor in the question, because as soon as one touches terra firma, he is relieved. Have we not all observed that on glaciers the air has a metallic taste, like water from melted snow, that it seems polluted, as if the ice and snow poisoned it with their emanations? Why in the tropics, where one walks on grass at an altitude of 18,000 feet, are nausea and the desire to sleep, this sort of somnambulism, felt only at much greater heights than in Europe? At any rate, whatever the cause may be, this peculiar sickness cannot be denied, and man cannot live at certain altitudes any more than in the depths of the ocean. (P. 244.) If we pass from the Alps to the Himalayas, we see modern travellers giving us in their narratives testimony that even in our days the sicknesses of great elevations are attributed by the natives to the influence of plants which are supposed to poison the air from a distance. Mistress Hervey 134 refers to it repeatedly: These extraordinary attacks on passes of great altitude are at- tributed by the natives to what they call Bischk-Ke-Hawa (Bischk, poison; Hawa, wind) or poisoned wind. They believe that the wind becomes poisoned because it blows over certain plants of the group of mosses, which grow abundantly on the high mountains of Tartary, and are found where vegetation ceases. From the summit of Bara Lacha to Yunnumscutchoo, I saw thousands of them. They have very small yellow flowers, and are of different species. A more scientific explanation of this peculiar illness attributes it to the great rarity of the air at these extreme altitudes. (Vol. I, p. 133.) We even see, in several parts of her narrative, and we have quoted some very strange ones in this connection, that she is not Theories and Experiments 295 always very sure of the superiority of ''the more scientific ex- planation". Henderson 135 also speaks of plants; only it is not a kind of moss, but an artemisia: Before reaching camp, many of our followers complained of head- ache, and I found several of the Thibetan shepherds lying by the road, in a state of complete prostration. When I asked them what was the matter, they placed one hand on their foreheads, and with the other tore up a piece of a strong-smelling artemisia, making signs that this plant was the cause of their sufferings. On several of the passes, this artemisia has an extremely powerful odor, and all the baggage, the horses and the men coming from Yarkand are tainted with it. Even mutton has this odor. Drew 1:;" does not limit himself to mentioning this prejudice and refuting it authoritatively, he looks at the question itself, and does not inquire why one is sick, which seems to him very simple, but how one can resist the dangerous effect of expanded air: In the valleys of Rupsku, water boils at about 187°' F., which corresponds to a barometric elevation of 17.8 inches; so that the quan- tity of air — and oxygen — drawn into our lungs by an ordinary inspira- tion is only 7/12 of the amount that enters at sea level. How do the Champas (tribes which occupy the high plains of Rupsku, to the south- east) compensate for this loss? I cannot tell exactly; I think, first, that there is less wear and tear on the tissues in their bodies than in the tribes which live in lower and warmer regions; they take less muscular exercise than the peoples of the surrounding lands; it is true that they are good walkers, but they think little of this quality and do not wish to carry burdens. Watching over flocks is not an occupation which causes the muscles to act vigorously. But that cannot explain everything; there must be some compensating habit which makes them capable of absorbing a large volume of this rarified air; probably, with- out realizing it, they breathe more deeply. In us, this oxygen compensation tends to take place by a simple and direct means. Respiration becomes more rapid and more deep; there is an effort to increase both the number of inspirations and the capacity of each of them. The intensity of this effect increases every time one mounts a little when one is already above the level where ordinary respiration is sufficient. (P. 290.) The natives commonly attribute these harmful effects of rarified air to plants which, in their opinion, have the power of poisoning the air. Some of the plants which grow at high altitudes exhale an odor when they are crushed, and it is to them that the discomforts are attributed. The onion, so much abused, which grows wild at great heights, is often blamed. But an easy reply to this error is that the effects are most marked at elevations where these plants, and all other vegetation have disappeared. (P. 292.) 296 Historical These ideas are far more definite and certain than those of Captain Burton 137 about the origin of mountain sickness: Some tried to explain our immunity to mountain sickness or the puna on the Grand-Pic, by the existence of a wind blowing violently and steadily from the east, which brought to our lungs the quantity of oxygen necessary for their consumption. I think, however, that this sickness must be, like seasickness, a disorder of the liver or the stom- ach, often aggravated by stimulants and by violent and sudden exer- cise. (Vol. II, p. 121.) The celebrated African traveller quotes seriously in this con- nection a passage from a work which I could not procure, which contains, I think, one of the most comical ideas ever expressed on this difficult subject: According to Dr. J. Hunt (Acclimatisation of Man) Europeans cannot live long at a great elevation in the northern hemisphere; the natives of the south can .... "This difference between the north and the south hemisphere, he says, is caused by the difference of the attrac- tion to the North Pole. In the northern hemisphere the ascent of a high mountain causes a rush of blood to the head; in the southern, it is attracted to the feet: and hence the cause of the discomforts ex- perienced in the ascent of a mountain in the first hemisphere." I shall end this long series of quotations by reporting almost entirely two very interesting accounts, which we owe to the pens of very distinguished physicians, and in which there is a discus- sion of the effects of altitudes insufficient to produce mountain sickness, but sufficient to cause physiological changes which have proved useful to therapeutics. The first is by Dr. Jaccoud,138 and is devoted to the study, from the medical standpoint, of the spa of Saint Moritz, in the Upper Engadine. The greatest variations of the barometer at the baths are in- cluded between 599 and 627 millimeters. The altitude of the vil- lage of Saint Moritz is 1855 meters above sea level. On the vast plateau of the Engadine the climate is much more clement than at corresponding elevations in the rest of Switzerland. In the adult who is in good health, the first effects of altitude are shown by an increase of appetite noticeable the first day, which keeps equal with a proportional increase of digestive and assimilative power .... The parallel superactivity of the digestive functions and of metab- olism is shown, on the one hand, by the ease and speed of digestion, in spite of the increase of the ingesta; on the other hand, by changes in proportion between the adipose tissue and the muscular tissue. . The first decreases considerably as a result of a prolonged sojourn in the Theories and Experiments 297 Upper Engadine, whereas the muscles gain a preponderant develop- ment shown by increase of strength and motor capacity .... The decrease of the atmospheric pressure causes the acceleration of the heart beats; in myself, I noted an increase varying from 12 to 18 in the number of radial pulsations; moreover, the circulation in general is considerably modified, in that there is a strong flow of blood to the periphery; the cutaneous capillaries are turgescent, and the tegu- ments take on a violet red color found in the upper mucous mem- branes, especially those of the mouth and tongue; if the sojourn con- tinues for several weeks, the predominance of the peripheral circu- lation produces a deeper pigmentation of the skin; as this phenomenon is more marked in regions usually exposed to the action of the sun, one might think that this is merely a pigmentation by solar irradia- tion; but the same modification occurs on parts protected by clothing, and its real cause is thereby clearly demonstrated. In a few cases, rarer than one would suppose a priori, instances of slight epistaxis also show the change in the distribution of the blood. The constant rush of blood to the periphery keeps the viscera in a state of relative anemia, which, in proportion to its degree, is re- vealed only by favorable phenomena; the cerebro-spinal functions are more active and easy, .the head is free and light, the locomotor power is increased, respiration is noticeably eased, although its mode is greatly changed, as we shall see in an instant. These organic changes awaken in the person who undergoes them the feeling of new strength, which he judges by comparison with his usual condition; he feels well and gay, he has a vim justified by the real increase of his capacity for physical work. (P. 31.) The rarefaction of the air at the altitude of Saint Moritz produces in the respiratory function two changes which are the point of de- parture of important modifications. The frequency of the respiration is increased, the average number of my inspirations in Paris, at rest, is 15 per minute; it is 19 to 20 in the Engadine; while it is more frequent, the respiration is deeper, or rather, more ample; the reason is that in this rarified medium a greater capacity and inspiratory ab- sorption are needed to maintain in the pulmonary apparatus the quan- tity of air necessary for the regular execution of the operations of hematosis and metabolism in a state of superactivity. The slight in- crease in the number of inspirations could not produce this result; it can come only from a greater pulmonary expansion, which puts to work certain regions of the lungs which I call lazy, because, under ordinary conditions, they take only a very slight part in the inspira- tory expansion; these regions are the upper parts of the organs. But since the atmospheric pressure is lowered, this more complete partici- pation of the lungs in the inspiratory act necessarily involves an in- crease in action of the muscular forces which control the expansion of the thorax; and this combination of subordinate conditions, all pro- duced by the change in pressure of the respirable medium, results finally in systematic and constant gymnastics of the respiratory appa- ratus, which are kept up without fatigue at the maximum of func- tional activity. And thus, by active intervention of the organs of respiration, there 298 Historical are produced effects analogous to those which they undergo passively under the influence of compressed air; in rarified air, the inspiratory absorption becomes complete by means of active use of muscular pow- ers; in compressed air, the increased inspiratory absorption is the result of an increased pressure, to which the lungs, and the lungs alone, yield passively. This comparison, which seems to me interesting, sufficiently establishes the superiority of the first condition, in regard to the de- velopment and regular exercise of the pulmonary functions. (P. 34.) And so increase in the number and amplitude of the respiratory movements, with the purpose of compensating for the oxygen defi- cit due to the decreased weight of the air, the acceleration of the heart beats, and the rush of blood to the periphery of the body are, in M. Jaccoud's opinion, the effects on the organism of a decompression of 15 to 16 centimeters. Dr. Armieux,139 of whom I still have to speak, examined care- fully the soldiers under his medical care at the thermal spa of Bareges (1270 meters) . He begins by calculating the decrease in the weight of the air sustained by a man's body at the elevation of Bareges; it is about 220 kilograms; "this decrease," he says, "is very perceptible; one is more agile and vigorous (p. 7)". Finally, at Bareges, considering the density of the air, there is a deficit in the quantity of oxygen admitted to the lungs of 22.56 grams per hour and 541.44 grams per day. But here is the really original part of the work of M. Armieux: May 4, 1867, at Toulouse, I measured the chests of 90 hospital attendants, who were to be sent to Bareges. The chest circumference, taken horizontally at the level of the nipples, gave me an average of 871 millimeters, at rest, and 905 millimeters in the greatest amplitude obtained by a deep inspiration. These men reached Bareges May 15, they did not take the thermal cure, and the subsequent observations showed only the effect of the hygienic medium. June 27, that is, after 43 days of residence, their chests measured again gave averages of 888 millimeters in circumference at rest and 917 millimeters in the maximum expansion; the increase of circum- ference then was on the average, in the first case, 17 millimeters, in the second 12 millimeters. September 17, after a sojourn of four months at Bareges, the same subjects, given a new measurement, furnished the following average results: 900 millimeters at rest and 930 millimeters in maximum ex- pansion; there was a new average increase of 12 or 13 millimeters over the measurements of the month of June, and a total progressive in- crease, after four months, of 25 millimeters in expansion, and 32.9 millimeters at rest. It is therefore indisputable that the chests of these soldiers in- Theories and Experiments 299 creased in capacity, in four months, in a rather large proportion, as a result of their removal to a place the altitude of which is 1100 meters higher than that in which they had formerly lived . . . . To get a more direct proof, in 1868, we made an experiment which confirmed the former one, taking care to get the exact weight of the subjects so as to compare their total material gain with the increase in volume of the chest. We also wished this time to keep an account of the changes made in the pulse rate and the respiratory movements by removal to high altitudes. We subjected fourteen hospital attendants to a close observation, before their departure for Bareges and after thirty-five days of resi- dence there. The following table gives the details and the averages of our observations: Toulouse Bareges May 7, 1868 1 June 18, 1868 Height Weight . 1 1 1 Weight 1 Age j meters kilos Chest |Pulse Res. kilos | Chest Pulse Res. 22 1.620 62.100 91c. 86 20 64.5 98 85 19 23 1.590 62 86 76 16 61 87 80 20 19 1.567 56 80 70 17 57 82 j 64 20 23 1.620 63.100 85 80 18 65 88 70 22 31 1.650 63 88 74 17 64 90 68 20 19 1.615 52 76 72 18 56.5 81 75 21 23 1.680 64 86 80 20 67 89 70 22 23 1.630 60 89 82 21 61 89 80 22 23 1.610 59.9 86 J 90 18 60 86 88 22 24 1.600 60 84 1 75 20 59.5 88 65 20 20 1.610 57 85 1 74 18 58 86 70 19 49 1.640 59.5 81 72 19 59.7 83 68 20 23 1.585 64 90 80 18 66.5 91 80 20 36 1.610 59 86 80 21 60 1 89 74 23 Totals _ 841.6 1191 |1091 |261 859.7 1227 |io: 290 Average 60.114 | 85.70|77.92 |18.64 61.4 87.64 74.07 20.70 Av. at Bareges 61.400 87.64j74.07 |20.70 | Av. at Toulouse Inc. at Bareges 60.114 ] 85.70|77.92 J18.64 1.286 | 1.94 — | 2.06 Dec. at Bareges — | — 3.85 | — 1 We see by this table that the increase in weight is, on the average, 1 kilogram and 286 grams, varying from 1 to 4 kilograms in 12 of these soldiers, and showing a slight decrease in two of them, whereas the increase in the volume of the chest is, on the average, nearly two centimeters, which is relatively greater; this increase went as high as 7 centimeters in the first subject; finally, it is general and exists even in those who lost weight, which is decisive. 300 Historical For the sake of completeness, I copy here a passage which concerns the composition of the gases of the blood, although it contains unexplainable mistakes, and although I understand nei- ther its purpose nor its results; but it is interesting to show by a very recent example how many unknown quantities and obscuri- ties these questions contain, even in the minds of the most learned physicians: Besides the phenomena which we have just reported, there are produced as a result of the decrease of atmospheric pressure an expan- sion and a greater tension of the gases contained in the blood vessels. The venous blood contains per liter: Oxygen 11 cubic centimeters Nitrogen 15 cubic centimeters Carbonic acid 55 cubic centimeters Total 81 cubic centimeters The arterial blood contains per liter: Oxygen 24 cubic centimeters Nitrogen 13 cubic centimeters Carbonic acid 64 cubic centimeters Total 101 cubic centimeters For M. Schoeuffele who studied the question at Bareges, these fig- ures become at the pressure of 65 centimeters: 94.780 for the venous blood and 119.640 for the arterial blood; the increase in volume of the intra-vascular gas would therefore be on the average 11.25% at the altitude of Bareges. M. Armieux ends his work with the following conclusions: The experiments which I have just reported show that persons who go to Bareges experience, as effects of the altitude: 1. A considerable increase of the thoracic capacity to compensate for the oxygen deficit; 2. An increase in weight, which shows greater metabolic activity; 3. An increase of respiratory movements; 4. A decrease in the pulse rate; 5. A lack of correlation between the two relations of the respira- tion and the circulation; 6. An expansion of the gases contained physiologically in the blood vessels, as a result of decreased atmospheric pressure; 7. A greater tendency toward diaphoresis for the same reason. This considerable increase of the thoracic capacity, observed by M. Armieux in soldiers subjected continuously to the influence of low barometric pressure recalls what was said long before by Theories and Experiments 301 d'Orbigny,140 in speaking of a Peruvian tribe, the Quichuas, who live in the lofty regions of the Cordillera: Their bodies are more bulky in the Quichuas than in the other nations of the mountains; we can describe them as characteristic. The Quichuas have very broad and square shoulders, their chests are ex- tremely capacious, very bulging, and longer than usual, which makes the trunk larger; the normal ratio of respective length of the trunk with the extremities does not seem to be the same in the Quichuas as in our European races, and differs equally from that of the other American branches. (Vol. I, p. 226.) And the celebrated traveller, struck at the same time by this thoracic amplitude, the habitat of this tribe, and its immunity to the soroche, tries to determine the anatomical fact and to connect it theoretically with the conditions of life of these Indians. Let us return to the causes which produce in the Quichuas the great volume we have observed: many researches have made us attribute it to the influence of the lofty regions in which they live and to the modifications resulting from the extreme expansion of the air. The plateaux on which they dwell are always included between the limits of 7500 to 15,000 feet, or from 2500 to 5000 meters above sea level; the air there is so rarified that a greater quantity is re- quired than at sea level for man to find the elements of life in it. Since the lungs need, because of the great volume necessary and their greater expansion during the inspiration, a larger cavity than in the lowlands, from infancy and during the whole period of growth, this cavity receives a great development, quite independent of that of the other parts. We wished to ascertain whether, as we should have assumed a priori, the lungs themselves had not undergone considerable modi- fications, as a result of their greater tension. Living in the city of La Paz, which is 3717 meters above sea level, and learning that at the hospital there were always Indians from very populous plateaux of still greater elevation (3900 to 4400 meters), we took advantage of the kindness of our compatriot M. Bernier, physician of this hospital; we asked him to permit us to make the autopsy of the cadavers of some of these Indians of the higher regions, and, as we expected, we found with him that the lungs had extraordinary dimensions, as the outer form of the chest indicated. (M. Burnier showed us, be- sides, that the lungs seemed to be divided into cells much more num- erous than usual. Since this fact seemed to us strange and hard to believe, we asked M. Burnier to repeat these observations on a larger number of subjects; and when, after a few years, we saw this well informed physician again, he confirmed it once more completely.) We noted that the cells are larger than those of the lungs which we had dissected in France; a condition which was necessary to increase the surface in contact with the ambient atmosphere. In summary, we dis- covered: 1. that the cells are more expanded; 2. that their expan- sion increases considerably the volume of the lungs; 3. that conse- 302 Historical quently the lungs need a larger cavity to contain them; 4. that there- fore the chest has a greater capacity than in the normal condition; 5. that this great development of the chest lengthens the trunk a little beyond the ordinary proportions, almost out of harmony with the length of the extremities, which have remained as they would have been, if the chest had retained its natural dimensions. (Vol. I, p. 267.) Thse anatomical observations are so interesting that the Society of Anthropology discussed them among the Ethnological and Medi- cal Questions Relating to Peru, and suggested in 1861 that travel- lers verify them. In a scholarly report, M. Gosse senior,141 states that "up to the present, the assertions of d'Orbigny have not been verified by any traveller" (p. 107). He even mentions a fact which would seem to prove that this is a racial characteristic independent of the environment, since: The descendants of the mountaineers settled in a colony by the Incas on the seashore near Cobija would have retained up to the pres- ent, as an effect of heredity, the special physical constitution, said to have been acquired in the atmosphere of the lofty plateaux. (P. 108.) The same, year, M. Jourdanet,142 speaking of the Indians of Mexico, said: The Indian, whom we may consider as positively acclimated, has a chest the amplitude of which exceeds the proportions which we should expect from his short stature. And so he performs work which might well surprise, us in any country .... His vast chest makes him com- fortable in the midst of this thin air. (P. 98.) On this point also he was contradicted by Coindet.143 Accord- ing to this observer, for a series of Frenchmen whose average height was 1.678 meters, the thoracic circumference on the level of the nipples was 92.450 centimeters, whereas in the Mexicans, in an average height of 1.620 meters, it fell to 89.048 centimeters. But the English traveller Forbes confirmed the observations of d'Orbigny and M. Jourdanet: M. D. Forbes, says M. Darwin,144 who carefully measured a great number of Aymaras, living at an altitude included between 10,000 and 15,000 feet, told me that they differ very greatly from the men of all other races he has seen in the circumference and the length of their bodies. Finally, in his last book, M. Jourdanet 145 gives specific data, saying: I have the abstract of a great number of observations which do not admit the least doubt. They justify me in stating that with an average height of 160 to 165 centimeters, the Indians of Anahuac have Theories and Experiments 303 a sternum 227 mm. long, with a thoracic circumference of 895 mm., measured immediately above the nipples. On the other hand, my researches permit me to state in a general way that to find the same chest dimensions in the Creoles, the height had to increase from 168 to 173 centimeters. (Vol. I, p. 317.) So the point is really not so much an unusually large thoracic capacity as a shorter height, or, to speak more exactly, lower limbs which are shorter in proportion to the height of the trunk. But let us return to the inquiries of Dr. Gosse. M. Gosse follows his shrewd observations on this interesting point by a questionnaire on mountain sickness, which I think it best to quote here verbatim: The study of the influence exerted by the rarefied air of high altitudes in the Peruvian Andes upon the physiological constitution of their inhabitants naturally leads us to the study of symptoms produced by this cause in persons foreign to the plateaux, who are exposed to it imprudently or too suddenly, and of the measures which are used to combat the symptoms or at least to moderate their effects. If the symptoms observed in our European Alps, to which the name of mountain sickness has been given, are limited in general to extreme breathlessness, accompanied by headache, throbbing of the carotids, palpitations, nausea, disturbance of the digestive functions, great lassitude and sometimes syncope, the symptoms appearing in the Andes of Peru, known by the names of soroche, mareo, or veta, reached such violence, they say, that they deserve the attention of physicians who are explorers, all the more because sufficient analysis has not yet been made, in this connection, of the mechanism of the action, usually combined, of the decrease of the oxygen in the air and of the atmos- pheric pressure, of the eventual drop in temperature caused by easier radiation of heat, of the absence of humidity, and especially of the unnatural strain on the muscles, and because, as explanation of the anomalies, there has been a tendency to suspect the existence in Peru of special unknown causes, which would not be found elsewhere. Observations carefully made and new records thoroughly verified would end doubts and reconcile opinions. With this purpose we are propounding the following questions: 1. What are the characteristic symptoms of the soroche of the Peruvian Andes, with reference to the nervous, circulatory, pulmonary, or muscular systems? 2. What is the normal sequence of these symptoms, in the com- monest cases, and which are the predominating ones? 3. Are there premonitory symptoms of the acute attack, and what are they? 4. Is a tendency to nasal, labial, pulmonary, ocular, cutaneous, etc., hemorrhages noted frequently at very great elevations? 5. Are a congested condition of the cornea and erythema of the face observed, in the absence of reflected light from the snow? 6. Does the skin take on a livid or cyanosed shade at an eleva- 304 Historical tion which cannot be less than 3800 meters, but which, in the latitude of Peru, must be the line of perpetual snow? If this phenomenon appears, is it only temporary during the ascent, or does it persist after the summit has been reached? 7. When the dwellers on the heights descend to the plains and toward sea level, do they experience a disturbance in their functions, and of what does this disturbance consist? 8. Is a mental disturbance corresponding to the physical disturb- ance, or discouragement, or irritability of temper often observed? 9. Are the symptoms of the soroche the same on the eastern and western slopes of the Andes, whatever the exposure of the places where they are observed? 10. Do they occur only at the line of eternal snow, as certain authors maintain, or do the Peruvian and Bolivian Andes furnish veri- fied exceptions to this rule? 11. Do strangers to the plateaux of the Andes experience the soroche when they reach high elevations on the Cordillera on horse- back? And when they feel the attacks, did muscular efforts usually precede the disturbance of the organs of circulation and respiration? 12. Do the effects of the soroche differ with age and sex? 13. Do they vary with idiosyncrasies, and what are the idiosyn- crasies which predispose to it or retard it? 14. What is the effect exerted upon its production or its symptoms by the seasons, the prevailing winds, or storms? 15. What is the effect of the cold in the places where the soroche appears? Specify the average temperature of these places and the absolute temperature at the time the symptoms appeared. 16. What is the effect of dryness or humidity? 17. Is it proved that the absolute altitude in the atmosphere is not enough to explain certain local anomalies? And if this is an actual fact, seek out the probable causes of these anomalies, either in the atmospheric conditions of the time or the locality, or in the telluric conditions, especially in the nature of emanations which may rise from the ground. Study in this connection the conformation of these lo- calities which might favor the continued presence of water and atmos- pheric humidity, their nearness to ore-bearing regions, which might exhale mineral, harmful, arsenical, or other vapors. Do not neglect occasional conditions in which individuals may be placed. 18. Does the acclimatization of strangers in relation to the soroche take place more or less quickly, and what are the conditions which favor or delay it? Does this acclimatization have a lasting or merely temporary effect? Do the negroes have more difficulty in becoming acclimatized than the whites? And if the opportunity offers, it would be interesting to make a series of experiments to ascertain the normal pulse rate of the inhabitants of the plateaux, Indians, negroes, and whites; taking care to repeat them on a great number of healthy per- sons of both sexes, adults of verified age, and to make these experi- ments at rest, standing and lying down, at a certain distance from mealtime, and to note the outer temperature of the season, hot or cold. 19. If the symptoms of the soroche appear in animals, what are their characteristics in the different animals and what are the condi- Theories and Experiments 305 tions which give rise to them? Especially what are the causes which give rise to the disease of mules known by the name of trembladera? Are the domestic llamas and those used as beasts of burden equally subject to this disease? 20. Is the mortality of certain animals (cats, for example), caused by their sojourn in very lofty places, an established fact or not? And if the fact is established, what are the symptoms which precede death, and what are the probable causes of this mortaltiy? 21. Are there means of awarding off the soroche, and if there are, what are they? Has anyone tried, for example, in Peru, as in Styria and the Tyrol, the ingestion of small doses of arsenic to prevent the fatigue of the ascent of mountains? Study particularly in this connec- tion the effects of the plant known as cuca or coca, either chewed or taken in an infusion, which they say has a remarkable prophylactic power. 22. What are the means employed with the greatest success in checking or lessening the symptoms produced by the soroche, either in man or in the animals? (P. 113-117.) As I said at the beginning of this first part of my work, I shall not discuss in this historical section any researches which rely upon the results of my own investigations or which oppose my conclusions. My discussion of them will naturally take place in the third part. And for this reason I shall say nothing of the book recently published by M. Jourdanet,140 in which he repeats, develops, and supports by new proofs taken from the study of altitudes over the whole earth the opinions suggested to him by observation of the diseases of Upper Mexico. I shall borrow from this immense work only the account of an important experiment in which appears the first attempt made to study chemically the degree of the anoxemia: I decided to devote myself to this work of analysis about the end of 1864. I found assistance— very worthy of special mention in this book — in the laboratory and the cooperation of M. Romuald Zamora, a Spanish gentleman, who studied the sciences in his hours of leisure. I analyzed the blood of three rabbits by means of carbonic oxide, fol- lowing the specifications given by M. Claude Bernard. I found an average of oxygen which was very low, but not enough to justify one in feeling authorized to make really legitimate general conclusions. I also felt hesitant because of a consideration which I thought exceed- ingly important; namely, that one could always ask himself whether these same animals would not have given this same quantity of oxygen at lower levels. In fact, differences in amount found in my previous analyses of blood prove that the proportion of this gas is an individual peculiarity, at least within certain limits. It seemed to me after that, that this interesting point cannot be indisputably decided without a double analysis of the blood of the same animal, drawn first at normal 306 Historical pressure, and second, at a more or less pronounced decompression. Therefore I again put off till a better time the realization of my wishes. (Vol. I, p. 181.) These wishes I had the good fortune to realize, thanks to the generous assistance of my learned colleague. And we shall see that I succeeded in proving how closely his anticipations agreed with the truth. But for this demonstration, I refer the reader to the second part of my book. In the third part he will find the detailed history of the latest aeronautic ascensions to great heights, and particularly of the one which had so fatal an end. We shall then specify definitely the causes of this disaster and draw from it the lessons it contains. Limiting ourselves to the subject of the present chapter, we shall say that the interpretations, given by the different scientific jour- nals and others, of the causes of the death of Sivel and Croce- Spinelli are merely those whose discussion fills the preceding pages. There is nothing new in them which deserves to be noted here, and all these ideas had already been given by authorities of greater weight. We shall except only the short discussion which arose on this subject within the Academy of Medicine. We see that, in the opinion of MM. Woillez, Mialhe, and Colin, the diminution of the weight sustained by the body again plays the principal part; in spite of the elementary principles of physics of which M. Giraud- Teulon, M. Gavarret and many others have already reminded them, they still harp on the theory of the Universal cupping-glass. But M. Colin adds to that a hypothesis which alone would deserve the honor of repetition, for it had been only very briefly suggested by a few former authors, and M. Maissiat did not go so far as to give it such importance. In his opinion, the escape of gases into the intestine and the expansion of these gases by the decrease in pressure played the chief part in the fatal ending. Here is the passage in full: M. Larrey: The ingenious experiments of M. Woillez and the new researches he has made on the spiroscope would no doubt lead him to the physiological study of respiratory phenomena at different alti- tudes, and then to the hygienic prophylaxis of the violent disturbances of this important function, under other influences. We should also decide upon therapeutic measures, when asphyxia, for example, is imminent and causes complex symptoms which rapidly become fatal, through sudden rarefaction of the air or through the progressive diminution of the air pressure. Finally, it would be desirable to determine and check the measures by which artificial respiration could Theories and Experiments 307 be established, for instance in the diving bell, comparable, in this respect, to the basket of the aerostat. The fatal disaster which has just startled the world of science and the two victims of which were buried this very day urges me to make this suggestion to the Academy, even if it is only a digression useful, perhaps, to the interesting communication of M. Woillez. M. Woillez: I cannot give an opinion here on so important a mat- ter; but it seems to me that it is not only a question of respiration; we must particularly take into consideration the decrease in the atmos- pheric pressure for which the oxygen they had taken along could give no help. M. Colin: Since the question of the balloon has been brought up, I should like to give my opinion of the causes of the death of the aeronauts. Certainly these causes are multiple, especially those con- nected with the decrease of pressure; some are already indicated by the conditions in which the aeronauts were. Two had lunched and they are dead; the other was fasting and he survived. The escape of gases into the digestive tract of the first two might have played a great part in the progress of asphyxia. We know that this escape is very great in ruminants following the eating of green fodder, and that it may, at ordinary pressure, produce sudden death by asphyxia by immobilizing the diaphragm. No doubt this escape is more limited in man: but it increases as a result of illness and indigestion, and then, since the expansion of the gases increases as the pressure decreases, the diaphragm is soon vigorously crowded upward; its movements become very limited and finally become impos- sible. We know that at a certain moment, when the traveller is climb- ing high mountains, he is seized by lassitude, his arms and legs are worn out; the muscles, irrigated by a blood which is imperfectly oxygenated, lose their energy. The diaphragm shares in this fatigue, and finally becomes inert, especially if it is crowded back by the expansion of the gases of the stomach. I know very well that aeronauts need to fortify themselves against becoming chilled, and that fasting does not warm them, but they can arrange their meals in such a way as to complete digestion before starting, and replace fermentable food by respiratory food, by liquids which stimulate and develop heat. Observations made on the victims and the survivor show clearly the chief cause of the symptoms. This cause is not, whatever M. Bert may say, the lack of oxygen, for in the experiments the animals do not die with the proportion of this gas which may be in the air at 7000 or 8000 meters. It is the decrease of pressure, as M. Woillez has just said, which produces the serious symptoms, the hemorrhages in the respiratory passages, the circulatory disturbances, etc. M. Blot: M. Colin's last words seem to me to contradict what he said at the beginning. So he explains death first by the compression of the diaphragm and the lungs under the influence of the expansion of the intestinal gases, and finally attributes it to the decrease in pressure. As to the comparison between the herbivores and man, it seems to me very debatable. 308 Historical M. Colin: I am surprised that M. Blot sees the slightest contra- diction in my words. I said that the symptoms and death in ascen- sions are due to several causes, among others the compression of the diaphragm by the gases of the digestive tract and the decrease of pressure on the tissues and the vessels resulting in pulmonary, nasal, and other hemorrhages. Each of these causes has a part in the effect; far from excluding each other, they are linked together. M. Mialhe: I agree with M. Woillez that the decrease of the atmospheric pressure was the principal cause of death, but I cannot accept the idea of M. Colin that one should not eat before making a balloon ascension. Man is not a ruminant, and things do not go on within him just as they do in the herbivores. M. Colin: What! Does man then have privileges in regard to diges- tion? Does the stomach function otherwise in the abdomen of man than in the abdomen of an animal? The dog which has eaten meat and bread has in his stomach much gas which one can measure by ligating the aesophagus and the pylorus. Why would not these same foods also produce gases in the stomach of man? Have not the diges- tive process and the fermentations uniform characteristics in species so closely related? I shall express myself later upon this question of the intestinal gases; but now, seeing" the importance which M. Colin seems to attribute to it, I cannot refrain from one remark: the desire of contradicting must be a very strong passion in some persons, since it has led a physiologist of this rank to say such strange things. The last document which I shall submit to my readers is perhaps still stranger. If there are some among them, as I fear, who think that, in giving the history of mountain sickness, I have displayed an excessive wealth of quotations and descriptions, they will, no doubt, pardon me for this imposition when they consider that in 1875, before the Geographical Society, before the Academy of Sciences itself, the very existence of mountain sickness was denied, a denial which depends upon the strangest of methods, or rather which is the very absence of scientific method, because it takes into account only the circumstances in which the travellers felt no symptoms during their ascents. The first communication from M. Virlet d'Aoust on this subject is dated May 19, 1875. The official Proceedings 148 of the Geograph- ical Society narrates it in the following words: M. Virlet d'Aoust, on the occasion of the recent disaster of the Zenith, made a communication about the effects of the rarefaction of the air in the region of lofty mountains. In an ascent of Popocatepetl, at an altitude of 4500 meters, he felt no other discomfort than a fatigue more pronounced than on the plains. There are numerous examples in the Andes of inhabited places at an altitude of 2000 and 3000 meters. Mexico City is at an elevation of 2300 meters. Theories and Experiments 309 A discussion took place in regard to the influence of atmospheric pressure on human life. MM. Antoine d'Abbadie, Maunoir, de Charencey, and de Puydt took part in it. The last mentioned for two years travelled through the valleys of the Andes, in Ecuador and Bolivia, living at altitudes of 4800 meters, always keeping his health and vigor. M. l'abbe Durand confirmed this statement, according to M. Stuebel, who made an ascent of Chimborazo two years ago. (P. 552.) We can see by the account of Stuebel's ascent which we have given into what an exaggeration M. l'abbe Durand has fallen. But without discussing this for the moment, it is interesting to repro- duce at greater length the arguments presented by M. Virlet d'Aoust and his learned colleagues, according to an authorized journal, the Explorateur:149 M. Virlet d'Aoust, on the occasion of the lamentable disaster to the Zenith, which cost the lives of two young scientists, MM. Croce- Spinelli and Sivel, recalled the circumstances of his ascent of Popoca- tepetl, in April 1853, with the purpose of emphasizing the considerable differences which exist between ascents of mountains and vertical bal- loon ascensions in the atmosphere. When one rises in the air by means of a balloon, says M. Virlet d'Aoust, he finds himself successively plunged in layers of air, if not of different compositions, at least of different densities, in which, how- ever, the carbonic acid must diminish in proportion because of its greater specific weight. This kind of ascension, moreover, is made too rapidly for the organs of human life to have time to undergo sufficient changes to make the successive differences in atmospheric pressure endurable. When one scales a mountain on foot, the layers of air have exactly the same composition as on the plain, for these layers, though becom- ing thinner, rise in currents from below up to the highest summits. The result is that any experiment which has for its sole purpose the determination of differences in the composition of the air at different heights should be carried out vertically in a balloon and not in a mountain ascent. The ascent of Popocatepetl (the smoking mountain) by M. Virlet d'Aoust involved numerous companions, and was, so to speak, an international expedition. The United States, England, Mexico, Ger- many, Belgium, Switzerland, Italy, and France were represented. Although the plain and the city of Mexico have an elevation of about 2300 meters above sea level, life there is very comfortable; public health is perfect and free from any endemic disease. The travellers halted at the foot of the cone at an elevation of more than 4000 meters; they had reached this spot on horseback without the least inconvenience and without feeling the slightest effect of the rarefac- tion of the air. The difficult part was the ascent of the cone, a regular sugar loaf, which had to be climbed on foot. That requires four hours of very difficult walking, although the descent is made in less than a half-hour. Neither M. Virlet dAoust nor his companions experienced 310 Historical any discomfort except that resulting from a somewhat accelerated respiration, and a little more heaviness in the limbs .... From these experiments M. Virlet d'Aoust has drawn the conclu- sion that the so-called mountain sickness is merely great fatigue re- sulting principally from heaviness due to the decrease of the layer of air which surrounds the traveller and which supports him in the lower regions .... M. d'Abbadie asked the author whether a distress manifested by dizziness and vomiting did not appear on lofty peaks. M. Virlet d'Aoust stated that he felt nothing of the sort nor did his travelling com- panions. M. de Puydt said that he had crossed the highest peaks of the Andes, from the equator to the sixth degree, north latitude; that he had reached altitudes of 4800 meters and that he had never felt any of these fatigues; and yet he had travelled more than 450 leagues in the Andes. M. l'abbe Durand supported this opinion, recalling the official ascent of the great volcanoes ordered by the government of Ecuador. Finally, M. Maunoir said that the effect of ascents, even in the mountains, must vary with the health conditions and the constitu- tion of the traveller. (P. 401.) M. Virlet d'Aoust130 returned to this subject in the session of July 7; he still followed the same strange method: M. Virlet dAoust, resuming the subject studied in a former session, that is, the effect of the rarefaction of the air in the higher regions of the atmosphere, reported an ascent of the volcano of Arequipa or Misti, the altitude of which is 5650 meters, during which the travellers were not at all inconvenienced (Reference to the Bulle- tin). (P. 107.) The Explorateur of July 15, 1875, is much more explicit:1,1 Mountain sickness. In support of what he had previously said, on the occasion of his ascents of Popocatepetl and Ixtaccihuatl, in refer- ence to the so-called mountain sickness, M. Virlet d'Aoust reported another ascent, that of the volcano Misti, more often designated by the name of the volcano of Arequipa, in Peru, which led to the same conclusions. Dr. J. T. Coates, of the United States, who made the ascent, left Arequipa September 22, and camped for the night at the foot of the mountain, situated 30 miles northeast of this city. The next day very early, accompanied by three guides and furnished with two aneroid barometers, he undertook the ascent. The little caravan could travel on horseback at first; but after an hour, since the grade became too steep and the difficulties kept increasing as they advanced, they had to continue on foot. After ten hours of difficult walking, at half-past six in the even- ing,, they finally reached the summit of the volcano, without having experienced hemorrhages, or difficulties in breathing, or nausea, or headaches, or any other of those painful sensations which, it is claimed, should be felt by persons who venture in the mountains to altitudes of more than 3000 meters .... Finally, M. Virlet d'Aoust thought he should mention another still Theories and Experiments 311 higher ascent which might have taken place in New Guinea. Several journals announced recently that the Englishman, Captain Lawson, had discovered in this huge isle of the ocean a mountain called Mount Hercules, which has an altitude of 10,929 meters above sea level, that is, 1262 meters more than Mount Everest, in the Himalayan chain, hitherto considered the highest point of the whole world. The Explorateur has suggested that the welcome to this alleged discovery should be given with certain reservations. At any rate, according to his story, when Captain Lawson attempted the ascent of Mount Hercules, he could ascend only to the height of 8435 meters, that is, an altitude almost equal to that reached by the balloon Zenith in its last and fatal ascension; but at this height, blood issued from his eyes and ears, and he nearly died as a result of the rarefaction of the air. This statement, like the discovery of a mountain claimed to be the highest in the world and yet so late in recognition, requires confirm- ation. (P. 65.) Nothing has confirmed this last account, which no one, unless he is exceedingly credulous, could believe. But I will not continue; the following chapter will contain the critical discussions. I Loc. cit., Chap IX— Sevilla, 1590. 'Novum organum, Book II, 11. Translation by Lorquet, p. 85. 3 Relation de divers phenomencs arrives dans le vuide, a dcs animaux qu on y avoit cnferm.es. — Collect, acad., foreign part, vol. I, p. 46-61>. 4 I do not know their exact date. Musschenbroeck lived from 1692 to 1761; the volume of the Collection academiquc in which they are included appeared in 1755. 5 Experience du Vuide— Histoire de I'Acad. dcs sciences de Paris, K6S; vol. I, p. 45.— Collect, acad., French part, vol. I, p. '23. .„..,«. i -ir 8 Boyle, R., Neiv Pncumatical experiments about Respiration. Plulos. Transact., vol. V, p 2011-2058, 1670.— Extracted and translated: Collect, acad., foreign part, Vol. VI, p. 23-59; 1761. 7 A new Experiment concerning an Effect of the varying Weight of the Atmosphere upon some Bodies in the Water.— Philosoph. Transact., VII, 1672; p. 5156. 8 Huyghens and Papin, Some Experiments touching Animals, made in the Air-pump.— Philosoph. Transact., X, p. 542-543.— Extracted and translated, Collect, acad., foreign part, vol. 9 To try the Effects of the Pncumatick Engine exhausted in Plants, Seeds, Eggs of Silk- worms. Philosoph. Transact., vol. II, p. 424-425; 1667. . in Sur la rarefaction et la condensation de Fair.— Hist, de I'Acad. des sc. de Paris, year 1705, p. 15; and Collect, acad., French part, vol. II, p. 181. II Sur la mort des animaux dans le vuide, Acad, des sc. de Bologne.—Coll. acad., foreign part, vol. X. p. 53; 1773. . . 12.S'»r la mort de quclques especes d'oiseaux et dc grenouilles dans un air, renferme. Acad, des sc. de. Bologne.— Collect. ' acad., foreign part, vol. X, p. 313-321. 13 Sur la cause de V extinction c la flamme et de la mort des animaux dans un air ferme. Soc. roy. des sc. de Turin, vol. II, years 1760-1761; p. 168.— Collect, acad., foreign part, vol. XIII. 14 Darwin. Experiments on Animal Fluids in the exhausted Receiver. — Philos. Trans., vol. LXIV, p. 344-349, 1774. 15 De Motu Animalium, Pars altera.— Rome. 1681. 16 I could not procure this book. But probably this solution is the one which Veratti quoted and which we have just mentioned. 17 hoc. cit.: Relation abregee, etc.. 1744. ^ Loc. cit.: Memoires philosophiques, 1787. 19 Elementa Physiologiae corporis hutnani. Lausonne, 1761. 20 De mcteoris aqueis, p. 40. I could not procure this work. 21 Rechcrchcs sur les Modifications dc V atmosphere, vol. II — Geneva, 1772. 23 Loc. cit. : Nouvelle description, etc., 1785 23 Discours en forme de dissertation sur I'etat actuel des montagnes des Pyrenees.— Paris, 1776. ** Voyage dons les Alpes— Geneva, 4 vol. in 4°; 1786 to 1796. 25 Essai de Physiologic positive appliquee specialcmcnt a la medicine pratique, vol. I,— Avignon, 1806. 28 Art. Air, Diet, des Sc. medi., vol. I, p. 24S; Paris, 1812. 27 Des effets de la pesanteur de Fair sur 1'homme considere dans I'etat de sante. — Theses dc Paris: 1813. . 28 Deuxicmc Memoir e sur la chaleur animal e ; 1813. Oeuvres de Legallois, avec dcs notes de M. Pariset, vol. II— Paris. 1830. 29 Description des Pyrenees, 2 vol.---Paris, 1813. 30 Memoirc concernant les effets de la pression atmospherique sur le corps humam, et ['application de la ventouse dans differents ordres de maladie— Paris, 1819. 312 Historical 3\Loc. cit.: Journal of a Tour, etc.; 1820. 32 Additional Observations on the Natural History and Physical Geography of the Hima- layah .Mountains, between the River-Beds of the Jumna and the Suite]. — The Edinburgh Journal of Science, conducted by D. Brewster, vol. II, p. 277-287, 1825. Read before the Royal Society of Edinburgh, December 10, 1824. 33Loc. cit.: The Ediub. Journal of Science, vol. I; 1824. 34 Loc. cit.: Account of Koonawur, etc. — London, 1841. 35 Loc. cit.: Narrative of a journey, etc.; vol. I. — London, 1840. 30 Loc. cit.: Asiatic Research, vol. XIV; 1822. 31 Loc. cit.: Nouveau Journal de mede.ine, vol. VII; 1.-20. . cit.: Bibl. univ., vol. XIV; 1820. 30 Loc. cit.: Bibl. univ., vol. XXIII; 1S23. 40 Observations sur la vitesse du pouls a differents degris de pression atmosph. — Journ. de Physiol, de Magendie, vol VI, p. 1-13; 1826. 41 On the Effects of removing Atmospheric Pressure from the fluids and solids of the human Body. Transactions of the Medico-Cliirurgical Society of Edinburgh, vol. Ill, p. 448-458; 1829. 42 Dictionnaire de Medecine, article Atmosphere, vol. IV; 1833. 43 Effects of Mountain Elevation upon the human Body.— London, Med. Gaz., vol. XIV, p. 207, 520; 1834. 44 Trait e de Physiologic, Tourdan translation, vol. VI; 1837. 45 Loc. cit.: Reise in Chile, etc.; 1836. * 46 Loc. cit.: Ann. de Chimie, Second series, vol. LVIII, 1835. 47 Sur la composition de I'air qui se trouve dans les pores de la neige. Ann. de Chim. et de Phys., Third series, vol. I, p. 351-360; 1841. 48 Loc. cit.: Lcttre a Delambre. Ann. du Museum; vol. II; 1805. 40 Loc. cit. : Ibid. 50 Loc. cit.: Ann. de Chimie, Second series; vol. LXIX; 1838. 51 The fact that atmospheric pressure is the real cause of the maintenance of articular adherences was discovered by the French physiologist Berard, something not generally known. Guerard, who bore witness to it, expressed himself as follows: "Long before the work of these physiologists was known in France, M. Berard, in a competition for the_ Central Board (about 1828 or 1S29), had had printed, according to the practice at that time, a series of propositions upon which the argument was based. One of these propo- sition was worded as follows: Atmospheric pressure can aid or hamper disjointing, according to circumstances. M. Berard quoted an experiment which he had devised, and which consisted of removing all the muscles which hold the thigh to the pelvis and of cutting the capsular liga- ment. When the leg was pulled, the adherence of the head of the femur to the cotyloid cavity under the effect of the weight was sufficient so that the body could be dragged on the ground without the two parts of the articulation separating." {Ann. d'hvg. publiquc ct de med. leg. Second series, vol. I, 1854, p. 304.) * What we really owe to the German physiologists is the mistaken application they have made of this truth to the theory of walking. 52 Rechcrches sur les effets physiologiqucs et therapeutiques de la compression ct de la rarefaction de I'air, taut sur le corps que sur les membrcs isoles. Ann. gen. de Med., Second series, vol. IX, p. 157-172: 1835. 53 De I Hemospasic.—Rccucil de Memoires sur les effets therapeutiques de cette mcthodc de traitemcnt. — Paris, 1850. * 54 Rapport sur un Memoire ayant pour litre: De la Condensation et de la Rarefaction de I' Air, apSries sur toutc I'habitude du corps on sur les membrcs seiilcmcut, consid recs sous leurs rapports therapeutiques. par M. Th. Junod, M. D.—Cpt. R. Acad, des Sc, vol. I, p 60- 65; 1835. 50 In fact, that is what Clanny himself says: "It is interesting to note that at the same time Sir James Murray of Dublin, Th. Junod of Strassburg, and I invented a similar apparatus, for the purpose of lessening the pressure of the atmosphere on the surface of the body, with- out anything having been published previously in any journal." {Researches of M. Junod into the physiological and therap. effects of compression and rarefaction. The Lancet, 1835-36; vol. II, p. 359.) • Clanny and Murray had invented only the great cupping-glass. — Apparatus for re- moving the Pressure of the Atmosphere from the Body or Limbs. The Lancet, 1831-36; vol. I. p. 804-805. 66 Junod, _ Traite theorique et pratique de I'hemospasie.— Paris, 1875. 57 Considerations sur les effets therapeutiques de I'hemospasie, d'aprcs les observations re- cueillics en Alqerie par T. Junod.— Paris, 1858. 68 Bibl. univ. de Geneve, Second series, vol. V, p. 151; 1836. 59 Ascension au Faulhorn. Revue medicate, 1841, vol. IV. 60 Loc. cit.: Influence, etc.— Revue medicale, 1842, vol. IV. 61 Loc. cit.: Peru, Reiscskizsen, etc.; 1S46. 62 Loc. cit.: Practical observations, etc.; vol. LVII, 1812. 63 Voyages au Perou et a Mexico, vol. I, I am borrowing this quotation from Flemeing, Ringuet translation; loc. cit., De V influence, etc.— Perigueux, 1869. rA Etudes ilc Physique animale.— Paris, 1843. 05 Betrachtung der Gcbirgsluft und der Lebenszueise dcr Gebirgsbewohner in Besua ihres F.iuflusses auf Bltttbereitung unii auf das Vorkommen gdvisser Kranhhcitsformen. Oesterr, Med. Jahrb., vol. XXIIL— Analyse in Schmidt's Jahrb.. vol. XXXIII, p. 298, 1842. 015 Notes sur les Causes de la lassitude et de lanhelation dans les ascensions sur les men- tagnes les plus elevecs.—Rev. Med., 1844, vol. Ill, p. 356-368. 67 Sur la Cause des plienomenes physiologiques que Von trouve quand on s'elifve d une certaine hauteur dans les montagnes.—Cpt. R. Ac. des Sc, vol. XX, p. 1501; 1845. 68 Physiologic des Atmens — Karlsruhe, 1645, p. 84-89. ™ Loc. cit., Mem. sur les phen. physio!.; 1845. 70 Allegemeine Zeitung Misccllcn: Erstcigung des ll'etterhorns, reproduit in extenso dans Dolfus-Ausset, loc. cit.. Materiaux, etc., vol. IV, p. 417-429. 71 Loc. cit.: Souvenirs, etc., vol. II, 1S50. Theories and Experiments 313 72 Esplorazioni Ji N.-M. Przevalski tiella Mongolia orientate e sulle falde N.-E del Tibet (187M873). Cosmos di Guido Cora, vol. II, p. 14-19, 164-175 and 261-277.— Turin, 1874. 73 Essai sur t'Emploi de lair comprime. — Paris-Lyons, 1850. 74 Observations tcndant a demontrer que, dans les ascensions sur les hautes montagnes, la lassitude et t'anhelation eprouv es par la plupart des exvloratcurs n'ont pas pour cause une insuffisance d'oxygene dans I' air respire. Cpt. R. Acad, des Sc.„ vol. XXXIII, p. 198; 1851. 75 Note sur les Effets de la diminution de la pression 'atmospherique sur les animaux. Cpt. R. Acad, des Sc, vol. XXXVII, p. 863; 1S53 76 On the Nature and Causes of the physiological phenomena comprised in the term "Mountain Sickness" more especially as experienced among the Higher Alps. — Assoc. Med. Journ., 1S53, p. 49 and 80. 77 Die Bergkrankheit, oder der Emfluss des Ersteigens grosser Hohen auf den thxenscheyi Organismus. — Leipzig, 1854; in octavo, 140 p. 78 Des Climats de montagne consideres an point de vue medical.— Arch des Sc. phys. et not. de Geneve, vol. XXXII, p. 265-306; 1856. 79 Lehrbuch der Physiologie des Menschen. Braunschweig, 1844. 80 Recherches de Pathologic comparce. Cass el. l€53. 81 Memoir e sur la pression atmospherique dans ses rapports avee I'organisme vivant. Cpt. R. Acad, des Sc, vol. XLIV, p. 233; 1857. ^Ueber den Einfluss, welchen der Wechsel des Luftdruckes auf das Blut ausubt. Mul- ler's Archiv.; 1857, p. 63-73. _ * 83 Du role des principaux elements du sang dans t'absorption on le degagement des gas de la respiration. Ann. des Sc. Natur. Fourth series; Zoo!., vol. VIII, p. 125; Kv~>7. 84 Ueber die im Blute entlialtenen Gaze : Sauerstiff, Stickstoff und Kohleusaiire. Poggen- do-rff's Annalen, 1S37; translated in Ann. des Sc. nal., Zool. Seco nd series, vol. VIII, p. 79; 1837. 85 For the development of this view see: Vierordt. Physiologie des Athmens — Karlsruhe. 1845. iG Traite de Physiologic.— Paris, First edition, vol. I, 1857; Third edition, vol. I, 1868. 87 De la chaleur produite par les Stres viyants, Paris, 1855. 83 Climats de montagne, etc., Second edition, 1858. 89 Bibl. univ. de Geneve, Fifth series, vol. II, p. 647, 1S5S. 90 Du froid thcrmometrique et de ses relations avec le froid physiologique dans les plaines et sur les montagnes.— Mem. de I Acad, des Se. de Montpellier, vol. IV, L859. 01 hoc. cit. De la phthisis, etc., 1862. 92 Les Altitudes de I'Amerique tropicale eomparccs an niveau des mers, au point de vue de la constitution medicate. — Paris, 1861. 93 De V Anemic des Altitudes et de I'Anemie en general, dans ses rapports apec hi pression de V atmosphere.— Paris, 1863. * 94 Le Mexique et I'Amerique tropicale: climat, hygiene et maladies.— Paris, 1S64. 05 Gazette hebd. de med et de chir., 1863, p. 777 rjaGaz. hebd. de med. et de chir., 1863. p. 778-781. 97 Gaz. hebd., 1863, S17-S21 . aiGaz. hebd., 1864, p. 33-37. "The average of the intra-pulmonarv air circulation tor Vierordt was exactly 6 liters, that is, equal to that observed by Coindet. 100 Gaz. hebd., 1864, p. 234, 265, 371. 450, 545, 579, 674. 101 Gaz. hebd., 1805, p. 145-151. 102 Traite elementaire de Physiologic, chap. IV, Section 138. 103 Gaz. hebd., 1865, p. 467-470. 104 This figure is relative to experiments made on Indians. (Gaz. hebd., 1864, p. 36.) 105 Recherches sur la quant d'ac carb. exhale par le poumon dans I'espdee humaine. Cpt. R. Acad. des. Sc. vol. XVI, p. 113, 1843. 106 Gazette hebdomadaire, 1865, p. 468. 107 De la Respiration sur les hauls plateaux de I'Anahuac.—Rec. de Mem. de med. milit,. Third series, vol. XIV, p. 512-516, isr.;. 103 Article Air from the Diction de Med. et de Chir. pratiques— Paris, 1864. 109 Die Travail dans I'air comprime. — Paris. 1863. 110 Considerations odncrales sur les maladies principals qui ont regne sur les chevaux et mulcts du corps expeditionuaire due Mexique pendant la periode de 1862 a 1863. — Journal de medecine veterinaire militairc, vol. Ill, March, April, May, 1865; vol. IV, June, July, August, 1865. 111 Article Altitudes from the Dictionnaire encyclopedique des Sciences medicales.—Faris, 1866. 112 Etude de quelques-unes des variations que {'altitude fait sentir a 1'air ambiant ct de rinftuence de ces variations sur I'homme. These de Paris 1866. 113 Influence de I'altitude des Heux sur les f auctions physiologiques — Paris, 1867. U4Kaufmann. Cpt. R. de VAcad. des Sciences, vol. LXV, p. 317, 1867. 115 Le Mexique considere au point de vue medico-chirurgical.—'Paris, vol. I, 1S67; vol. 11. 1868. 110 Article Atmosphere. Dictionn. encyclopedique des Sciences medicates.— Paris, 1867; p. 111-164. 117 De I Influence de la compression et de la rarefaction de 1'air sur les actcs mecamques de la respiration. Thierry-Mieg translation— Gaz. med. de Paris, 1868. 118 De ("Influence de In pression atmosph. ct de I'altitude sur la sante et les maladies de I'homme et des animaux. Ringuet translation.— Perigueux, 1S69. 119 Theses du Concours d' agre nation. — Paris, 1869. - . 120 Traite elementaire de physiologic, Book II. Chap. I, Section 244, Sixth edition; Paris, 1870. 121 Une Ascension au mont Blanc. Bibl. univ., Fourth series, vol. XXXI, p. 79-95, 1856. uzLoc. cit.: Bibl. univ.; 1865. 123 Loc. cit.: Deux ascensions, etc.; 1869. 314 Historical ni Observations sur la temperature du corps humain a differentes altitudes a I'etat du repos et pendant I'acte de i'ascension. Bibl. univ. de Geneve, Arch, des Sc. pliys. et nat.; Fifth series, vol. XXXVI, p. 247-289, 1S69. ^Experiences sur la temperature du corps humain dans I'acte de I ascension des mon- tagnes — Extract from Bulletin de la Societe medicate de la Suisse Romande, First series, Geneva and Bale, 1871; Second and Third series, 1874. 120 In his ascents M. Forel had not yet gone beyond la Cima di Jazzi (3818 meters). 127 The effect of exercise on the bodily temperature.— Journal of Anat. and Physiol., Second series, vol. VII, p. 160-119, November, 1872. 12S Observations on the Effects of Exercise on the Temperature and Circulation. Proceed, of the Roy. Soc, XXI, p. 374, 1872-73. 129 Sur le Mai des Montagues. — Bullet, de la Soc. med. de la Suisse Romande, 1874, p. 72-79. 130 Sur le Mai des montagnes. — Bull, de la Soc. med. ae la Suisse Romande. 1874, p. 136- 140. lj" Tvndall, Hours of Exercise in the Alps, Second edition.— London, 1871. "-Histoire du mont Blanc— Paris, 1873. 133 Loc. cit.: On mountains, etc., 1872. 134 Loc. cit. : The adventures, etc., 1853. 135 Loc. cit.: Lahore to Yarkand, etc., 1873. lmLoc. cit. The Jiiinnoo, etc., 1875. 137 Abeokuta — London; 2 vol., 1863. 13S La Station medicale de Saint-Moritz (Engadine). — Paris, 1S73. 139 Effets physiologiques du climat et des eaux de Bareges. — Mem. de VAcad. des. Sc. Inscr. et Belles Lettres de Toulouse, Seventh series, vol. IV, p. 214-231, 1S73. 140 L'hommc americain, 2 vol. — Paris, 1839. ^Instruction pour le Pcrou. Bull, de la Soc. d'Anthrop. de Pans, vol. II, p. 85-137.— Paris, 1861. ie Les altitudes de I'Am. trop.; Paris, 1861. 143 Gas. hebd.; 1.863, p. 779. 144 Descendance de I'homme, vol. I, p. 330. 145 Influence de la pression de I'air; Paris, 1875. 146 Influence de la pression de I'air sur la vie de I'homme, 2 vol. — Paris, 1875. 147 Bulletin de I'Academie de medecine. Seance du 20 avril 1875, Second series, vol. IV, p. 409-471. 148 Bull, de la Soc. de Geogr. Sixth series, Vol. IX, 1875. 149 First year, first volume. — Paris, 187a. 130 Bull, de la Soc. de Geog., Sixth series, vol. X. 151 First year, second volume.— Paris, 1875. Chapter IV SUMMARY AND CRITICISMS The time has come to summarize the long series of observa- tions, experiments, and theories, the details of which we have just related. After placing before the eyes of the reader nearly all that has been written about the effect of decreased atmospheric pressure, by the laborious but certain method of word for word quotations, we should now simplify his task by condensing all these varied assertions, often redundant and sometimes contradic- tory. We must, moreover, subject to careful examination the expla- nations suggested, opposed, or eclectically collected by travellers, physicians, physiologists, and physicists, who have considered in its various aspects this question, which is apparently so complex, but really so simple, as we shall show. In this part of my task I shall, of course, set aside the arguments drawn from my own experiments. It is by ideas previously known that I hope to prove that at the time when I began my researches, there existed in science no theory — I do not say demonstrated, for that is evident — which could sustain thorough criticism. Even the truth, when it was found, was mingled with so many errors or was so unfurn- ished with proofs that it could not force its clear evidence upon rebellious minds. Now anyone is right only when he can prove to everyone that he is right: "To keep on answering," Voltaire said, "is to prove that no answer has been given." The present chapter is naturally divided into three parts: the conditions under which mountain sickness appears, the summary of the symptoms which constitute it, the careful examination of the theories suggested to explain it. 1. Conditions Under Which Mountain Sickness Appears. The most general fact emerging from our study is that when 315 316 Historical men and animals ascend to great heights above sea level, they always finally experience a series of more or less serious symp- toms, the combination of which constitutes mountain sickness. The very existence of these symptoms, however, has been denied, as we have seen; but these denials, which are rash and unscientific generalizations upon a few isolated cases, do not merit our attention here. The first striking fact, when we examine the series of data which we have collected, is the difference in altitude at which the dangerous symptoms appear, depending upon whether we are dealing with mountain journeys or balloon ascensions. Whereas in the first case travellers often become ill at about 3000 meters, and almost never mount above a height of 5000 meters without serious suffering, Gay-Lussac, Barral and Bixio, and M. Glaisher felt only a few slight disturbances at 7000 meters. In a moment, we shall easily find the reason for this enormous difference. On earth as in the air, the severity of the symptoms keeps increasing with the altitude; but in its ascending progress, it follows a law of progression, not of proportion. Up to 3000 meters, a traveller who set out from the level of the valley, 1000 meters for example, will be warned of the decrease of pressure only by a slight increase in pulse and respiratory rates; from 3000 meters to 4000 meters, the symptoms increase considerably in intensity; above that, each ascent of a few hundred meters is marked by a progressively increasing aggravation of them, and a moment comes when it is harder to climb 50 meters than it was to ascend 500 meters at the beginning of the journey. It is not surprising, therefore, to see, as Captain Gerard reported, mountaineers of Koonawur, accustomed to observing sensations of this sort, esti- mate the altitude of the point which they have reached by the difficulty in breathing experienced there. The altitude at which the symptoms of mountain sickness appear varies considerably in the different regions of the earth. We have seen that in the Pyrenees serious symptoms appear only near the highest summits, that is, above 3000 meters and then they are very rare. At the same level in the Alps the accounts of trav- ellers begin to indicate some disturbances; they are rather customary between 3500 and 4000 meters; above that, their exis- tence constitutes a rule from which far fewer persons escape than the editors of the Alpine Clubs would have us believe. Etna, with its 3313 meters, is in this respect, as we have said, a limited moun- tain, as is the Peak of Teneriffe (3716 meters). In the Caucasus and the mountains of Armenia the level at which almost everyone Summary and Discussion 317 is severely attacked seems a little higher than in the Alps; on the volcanoes of the Pacific, which exceed 4000 meters, the sickness is hardly worse than on the Peak of Teneriffe; the same thing is true of the Kamerun Mountains, and on Kilimandjaro, New reached an altitude of about 5000 meters without serious distress; in North America, Fremont and his companions were ill at about 3500 meters; but in Mexico one must mount above 4500 meters, to expe- rience perceptible discomforts; they are not always very serious even on the summit of Popocatepetl (5420 meters). The long mountain chain of South America cannot be crossed at any point from Chile to Colombia without inflicting the terrible puna upon most of the travellers. But it seems that these sufferings do not appear at a completely uniform height; whereas on the passes of Santiago in Chile many are sick below 4000 meters, and almost all foreigners are severely attacked at La Paz (3720 meters), and even at Chuquisaca (2845 meters), and all at Cerro de Pasco (4350 meters), the ascent of the mountains near Quito causes almost no symptoms up to 5000 meters, and a thousand meters more present no unsurmountable difficulties from the physiological point of view. The immense mountains of central Asia may be compared to the Andes of Upper Peru from the standpoint of the line where mountain sickness appears. Passes less than 4500 meters high are crossed without serious sufferings; there are some more than 5500 meters high which are considerably frequented; several travellers have reached,' 6000 meters, and the Schlagintweit brothers ascended to the prodigious height of 6882 meters on the sides of Ibi-Gamin. These inequalities, from our standpoint, among the different mountainous regions of the earth, stand out among the multitude of facts which we have listed; but one can easily find numerous exceptions to these general rules. Indeed, and this is not the least interesting fact revealed to us by these multiple observations, we see that in the same region of the earth, in the same mountain chain, certain definite places are particularly feared by travellers and natives; and these places are not always the highest, far from it. This peculiarity is noted even in the ascent of a given moun- tain; for instance, the Couloir of Mont Blanc, where symptoms often appear which disappear on the summit. In a word, and these facts have been noted particularly in the Andes and the Himalayas, the intensity of the symptoms is not always in proportion to the altitude reached. This was the origin of strange hypotheses imag- ined by the natives, to which travellers too often gave credence; 318 Historical and thence came also the belief in metallic emanations, mephitic gases issuing from the ground, and fatal exhalations from different plants. But, barring these very interesting exceptions which we shall try to explain in another part of this work, the differences in aver- age height at which serious symptoms appear according to the parts of the world in which they are observed are in a remarkable agreement with differences in the altitude of the line of perpetual snow, when we consider them as a whole. The summary which we inserted earlier (see page 16) on this latter subject facilitates this comparison for the reader. But we must not go so far as to believe, as some travellers have done, that a direct relation, almost of cause and effect, exists between these two distinct orders of phenomena. Very evidently, no one has ever complained of mountain sickness in the polar regions, where the lowest hills are eternally covered with snow. But without having recourse to this reductio ad absurdum, we see that in our Alps it is almost always 500 meters at least above the line of melting where physi- ological disturbances appear with sufficient intensity to attract attention. The same thing is true upon the volcanoes of Ecuador and Mexico, the Rocky Mountains, and many other points. On the contrary, on the Bolivian Andes and still more on the Himalayas, the narratives previously published show us that travellers may be very sick when they are treading terra firma, and are still quite far from the zone of perpetual snow. But it is no less true to say that, in a general way, the higher the line of perpetual snow, the later will travellers in their ascent be threatened with the symp- toms which we have so often described. Besides these irregularities due to exterior circumstances, there are some which depend upon the idiosyncracies of the travellers who are subjected to the effect of decompression. Indeed, in the same region, on the same mountain, we see travellers sometimes complaining of severe sufferings, sometimes rejoicing or expressing surprise at having felt almost no distress. On the pass of Cumbre of Uspallata, most of those who are crossing the Andes are attacked by the puna; Samuel Haigh, Schmidtmeyer, and many others have testified to it: but we have seen that Miers, Brand, Strobel, etc. escaped it entirely. Whereas von Humboldt and Bonpland were very sick in their ascents of Chimborazo, M. Boussingault and Colonel Hall, who ascended higher than they, experienced only slight symptoms, and M. Jules Remy, who says that he reached the summit, states that he felt no symptom of ill- ness, On Popocatepetl, Bacon Gros and his six companions, and Summary and Discussion 319 later M. Laverriere, complained of real distress; MM. Turqui and Craveri, M. Virlet d'Aoust declare that they were completely- spared, while the Scientific Commission of Mexico was a little less favored. These differences are still more striking on less lofty moun- tains. Riche and Blavier, when attacked by hemoptysis, gave up climbing the summit of the Peak of Teneriffe, which von Hum- boldt, Leopold de Buch, Elie de Beaumont,1 and so many others reached without trouble. On Etna, Count de Forbin and A. de Sayve suffered greatly, whereas Spallanzani was unaffected, and Ferraro claimed to feel better than on the plain. The same thing is true of the Alps. In the hundreds of ascents of which its summit was the goal, Mont Blanc has given us the most contradictory results. De Saussure, Beaufoy, Clark and Sherwill, Hawes and Fellowes, Bravais, Martins and Lepileur, attest to violent distress, which they conquered only by prodigies of energy ;on the contrary, Clissold, Piachaud, and Albert Tissan- dier were hardly ill at all. I have heard "Alpinists" of repute state that they had experienced absolutely nothing unusual in this ascent which was formerly so much dreaded. By a striking contrast, Laborde, the brother of M. Lepileur, etc. were ill when they ascended merely to the Grand Saint Bernard (2490 meters) ; Spitaler and his companions relate the most painful details about their ascent to Venediger (3675 meters), when Desor and Gottlieb Studer affirm that they felt absolutely nothing when they ascended the Jungfrau (4170 meters) . In Armenia, Radde lay down exhaus- ted at 3700 meters, whereas daring travellers almost with impunity trod the summits of neighboring mountains of far greater height, Elbrouz (5620 meters), Kasbek (5030 meters), and Ararat (5155 meters). More than that, in 1868, Freshfield, Moore, and Tucker made the ascent of Kasbek without any suffering; in 1874, moun- taineers who were no less experienced, Gardiner, Grove, Walker, and Knubel suffered considerably on the same ascent. I shall not mention other examples. We need only refer to what we have said in the preceding chapters to find, among so many observations, examples of inequalities no less great noted in the Pyrenees, the Himalayas, and other mountainous regions. These differences are especially striking when they appear in travellers who, in apparently similar conditions of health, hygiene, and previous training, make the same ascent simultaneously. On Pichincha, Ulloa fell fainting; La Condamine felt no difficulty in breathing. While ascending Cotopaxi (5943 meters), one of Steubel's muleteers was so sick that he could not go beyond 5600 320 Historical meters; another felt absolutely nothing. On Mount Etna, de Gour- billon felt nothing, whereas his companion Wilson suffered greatly. In the ascent of the Finsteraarhorn (4275 meters), Hugi was in very good condition, as were his companions, except one of the sturdiest guides of the Oberland, who had vertigo and nausea. On the glacier of the Maladetta, Neergaard stopped, unable to continue an ascent which the celebrated geologist Cordier finished without any trouble. MM. Lortet and Durier ascended Mont Blanc on the same day; the accounts of their sensations are as dissimilar as possible. At 5300 meters, Croce-Spinelli in his balloon was seized with evident oppression; his travelling companions said that they experienced nothing. But that is not all; the same person, in conditions which seem to him identical, making the same ascent on two different occa- sions, does not always have the same sensations. On his first ascent of Buet, Canon Bourrit fell unconscious; the next year, he had no special experience. On the Breithorn (4100 meters), M. Lepileur, in 1875, felt no discomfort, whereas the following year he was seized there by an unconquerable drowsiness. There is a similar lack of agreement in the three ascents of Mont Blanc by M. Tyndall, and the two by M. Lortet. Observations made on the guides are still more conclusive. We must also note that while certain persons seem extremely sensitive to the effects of ascents, others without any complaint pass beyond the level where the great majority of travellers are attacked by the usual symptoms. We saw that Dr. Martin de Moussy had felt the puna at 1970 meters, whereas Jules Remy could ascend almost with impunity to the summit of Chimborazo (6420 meters). Victor Jacquemont seemed particularly immune in this respect, as we can see from the excerpts from his letters. Moreover, these facts are well known to all mountaineers; it is known that certain guides are unable to follow "their gentlemen" beyond a certain level, and travellers who were daring and tire- less on mountains of the second rank have had to renounce reaching the highest summits of the Alps. The numerous ascents, the narratives of which we have given, definitely differ then from one another in regard to mountain sick- ness, first, for reasons which seem to depend upon the mountain itself, and second, for reasons which depend upon the travellers; the latter may be constant or only transitory. The extremes of these differences may vary between 1500 meters (M. Javelle) and 6000 meters; that explains, without justifying them, the thought- less denials which we have so often recorded. Summary and Discussion 321 We should now apply ourselves particularly to the study of influences of a transitory nature, and by analyzing, in a more detailed manner, the narratives quoted find out whether it is possible to explain these differences by certain conditions of envir- onment, by circumstances in which the travellers are placed by chance, or by this combination of intrinsic conditions peculiar to each of us, some of which may be measured, others more or less unknown and designated by the general expressions of constitution and idiosyncracy. This is the place to investigate the effect of habit and acclimatization and to take into account the race to which the traveller belongs. In this last connection, the results observed seem quite contra- dictory: whereas d'Orbigny, Poeppig, Tschudi, de Saint-Cricq, Weddell, the Grandidier brothers, etc., note with astonishment the immunity of the Indians who run beside their mules without showing the least distress, we find, in von Humboldt's ascent of Chimborazo, a half-breed born in the lofty places suffering more than the Europeans; likewise the peons of Caldcleugh, Brand, and Steubel were sick when the travellers themselves felt almost no effects; and yet, in a general way, it is clear that in the Andes the Indians are much more resistant to the effects of mountain sickness than the Europeans are. I must quote in this connection a passage from an interesting letter written me by a French engineer, M. E. Roy, former assistant director of the School of Arts and Trades of Lima, who often visited the lofty regions of the Andes: The native Indian race is strong and vigorous; nature or the effect of a kind of atavism has endowed it with a powerful respiratory apparatus which permits it, probably by the respiration of a larger quantity of air, to find the oxygen equivalent necessary for its exis- tence and for the maintenance of a good constitution. The Indian of these high plateaux is thick-set, with an enormous torso and pelvis and relatively short legs; he is a walker of the first rank. Shod with his double woolen socks and his moccasins, he will walk 50 kilo- meters, without wincing, in his mountains and provided he has coca leaves to chew, he will make this distance in one stretch. For him and his llamas, a straight line is the shortest distance between two points: he does not try to wind around the valleys to go from one to another, he goes straight ahead, unless the mountain side is impassible; that shows you how necessary it is that he should breathe freely. Conversely, when these mountaineers go down to the seashore, they cannot perform any hard work, as they do in their mountains; many contract diseases of the lungs. At the school of which I was assistant director, many of the young men coming from these lofty regions had to return to their native air for this reason before finishing their studies, because the work of the shop was too hard for them. 322 Historical The opposite seems to be true in the narratives of travellers in central Asia. Fraser complains bitterly of his coolies. Accord- ing to Dr. Gerard (page 137), the inhabitants of Koonawur, born on the lofty plateaux, are as sick as the travellers. Johnston relates that whereas the natives who accompanied him on the peak of Tazigand breathed with the greatest difficulty, he and his English companions felt no ill effects (page 139) . Oliver Cheetam, Godwin Austen, and Henderson tell similar experiences. To the Schlagin- tweit brothers, the difference in races seems of little importance. Drew saw a native of Punjab sick at 11,000 feet (3300 meters). So Indians, even those born in mountainous regions, seem at least as sensitive as Europeans to the effects of ascents. The same is true in Africa in the ascents of the Kamarun Mountains and Kilimandjaro; likewise in Hawaii on Mauna Loa, the natives were attacked by mountain sickness before the European travellers, and more severely than they. But it should be stated at once that the natives and the Euro- peans were not, during these journeys, in identical conditions, either of clothing, or food, or exertion. If natives belonging to races which seem, according to the expression of Dr. Gerard, "born to live and die in inaccessible regions", are attacked by mountain sickness, the same thing should be true, for an even stronger reason, of the people of European races living in lofty places. All the accounts of Chapter I show, in fact, that the porters and the guides become ill as quickly and as seriously as the travellers, when the latter have already become used to exercise in the mountains. Sometimes even, the former become ill first; the account of Dolomieu (page 71) is quite charac- teristic. The slight advantage which they show, on the average, is rather quickly acquired by people of the plains whom wander- lust urges into the mountains. Another proof, and that not the least striking, of the slight importance of acclimatization in lofty places is drawn from the intensity with which the disease attacks domestic animals. All the accounts of travellers in the Andes and the Himalayas are rich in melancholy details of the pitiful condition of the mules or the horses which are carrying burdens; the latter often die; camels are no better off; the mules of de Saussure uttered plaintive cries on the glacier of Saint-Theodule; the wild cattle themselves, when they are hunted, often vomit blood, von Humboldt says, and we have seen what a sorry picture they made sometimes, according to de Castelnau, in bull fights. Dogs are also severely attacked, and have difficulty in running. Cats particularly seem to possess Summary and Discussion 323 excessive susceptibility, since, according to Poeppig and Tschudi, they cannot live above 4000 meters (pages 40, 46) . However, we must note that, in the opinion of Tschudi and Elliotson, animals born on the mountains are not as sick as the others. But it must be admitted that all of this relates to imported domestic animals. The' native species seem very comfortable at the greatest heights; only Captain Webb saw yaks attacked by the sickness (page 134); llamas seem completely immune, and in the free state graze at altitudes of more than 4000 meters. Since the time of Ulloa, everyone has been struck with astonishment at the sight of condors soaring habitually at 4000 or 5000 meters, and sometimes above 7000 meters; in the Himalayas, the lapwings and other sparrows live at altitudes of more than 5000 meters. Here we are dealing with one of the most interesting points of this birdseye view of the subject. The influence of habit or custom on mountain sickness is undeniable; but its conditions have been both exaggerated and poorly determined. On the testimony of d'Orbigny, Poeppig, Gay, Tschudi, and Guilbert, one can become quite accustomed to living in the lofty regions of the Andes, and the often unendurable distress which attacks the European in the early part of his sojourn gradually disappears. "In the streets", says Guilbert, "it is easy to distinguish the newcomers; every forty or fifty steps they stop for a few seconds" (page 54) . Analogous effects have been noted on our European mountains; a novice who, when newly arrived from the plains, is sick at a low altitude, can later make much higher ascents with impunity. But we must not think that this immunity is absolute; a fairly great change in level or peculiar circumstances may suddenly bring on the sickness that had disappeared; we shall find the proof of that in the accounts of M. Weddell, M. Pissis and d'Orbigny himself. In a word, the same thing is true of arrival in the mountains as of all sudden changes to which we may be subjected; the passage of a certain time' permits the reestablishment of the equilibrium which was shaken for an instant, and which slower transitions would have left unaltered. We shall try later to determine the nature and the importance of the conditions changed by the act of ascent; but even now we can assert the reality of habit or, as we usually say, acclimatization to lofty places. But here, as we cannot repeat too often, we are dealing only with the violent and sudden symptoms of mountain sickness, in a word; we have no intention of plunging into the delicate and com- plex study (in which the means of demonstration are the more 324 Historical numerous as they are less convincing) of real acclimatization, in lofty regions, of successive generations tending towards the formation of a race. With certain reservations, for it seems to be proved that certain persons cannot become accustomed to sojourn in lofty places, we simply state that a traveller who has been in the mountains for some time will feel no unusual sensations at a level where at first he was ill; that his descendants, if he founds a family there, will preserve his relative immunity; that the race thus formed will enjoy the same advantages, so that the traveller who is a new- comer will be surprised. But with the reservation already made that there is nothing absolute in this. We must also have an understanding in the matter of habit. Indeed, as we shall say in a moment, fatigue plays a great part in the intensity of mountain sickness. One of the consequences of prolonged exercise in the mountains is a lessened tendency to fatigue. The same thing is true of this special gymnastics as of all others; one finally contracts only the muscles, only the muscular bundles indispensable for the movement one seeks to make; one brings them only to the degree of contraction which is precisely necessary; in a word, one reduces the expenditure of energy to a minimum. Moreover, the muscles, and no doubt the nerves also, more frequently stimulated to action, from which a more active local circulation constantly removes the wastes, can suffice for a greater dynamic storage and expenditure, become, as we say, stronger, and, for the same work, give the sensation of fatigue in a much lessened degree. And therefore one fits himself for acclimatization on the heights by the simple gymnastic exercise of moderate ascents, with which the professional "Alpinists" always take care to preface their feats of lofty altitudes. For failure to comply with this rule, the most energetic often pay a forfeit. One of the members of the Austrian Alpine Club, very familiar with the lofty summits of the Alps, who boasted to me that he had felt no symptoms on Monte Rosa or Mont Blanc, confessed that he had been very ill one day because he had made an ascent of 2500 meters, coming from a sedentary life with no transition. That is one of the reasons why the moderate mountains of the valley of Chamounix, Buet and sometimes even Brevent (2525 meters) , cause illness in trav- ellers coming from Geneva; it is also this lack of training which explains the frequency of the symptoms of mountain sickness in the ascent of Mont Blanc, when that of Monte Rosa is much less feared in this regard; it is because the former ascent is often made Summary and Discussion 325 by novices or even by "mountaineers" who have experience, but who a few days before were living in the atmosphere of London or Paris, whereas usually no one attempts Monte Rosa without a series of preliminary exercises which have disciplined the loco- motor apparatus. Examples of the effect of fatigue are numerous in the very accounts which we have quoted. While listing the symptoms of mountain sickness, we must dwell on the fact of its aggravation by exercise, even the most moderate. Here, we should simply mention the cases in which it appears only under the influence of fatigue, and we may even say a passing fatigue, due to violent exercise. I myself have felt rather serious symptoms because I climbed a hill about a kilometer long at a quick step, on the road to the Grand Saint Bernard at an elevation not above 1500 meters. It is to the effect of fatigue, of burdens borne on the backs of men, that we should chiefly attri- bute the violent symptoms which sometimes attack the peons of the Andes and especially the coolies of the Himalayas Defore the European travellers are affected. The latter, moreover, usually allow themselves to be borne quietly along on the backs of horses, mules, or yaks. We have mentioned many cases in which the sickness attacked them sud- denly, as soon as they dismounted to walk beside their animals. If they are walking on difficult footing or on new snow into which the body sinks, the fatigue is increased and with it the intensity of the symptoms. If, as travellers usually do, we apply the word fatigue not only to the result of exaggerated muscular contractions but also to the effect of other exhausting causes, this factor of mountain sickness takes on still more importance. So insomnia and lack of rest and comfort are not to be neglected. On their second ascent of Mont Blanc, MM. Lortet and Marcet were much less ill than on the first; they had passed a good night at the Grands-Mulets. Most of the symptoms, when one is climbing this mountain, are partially caused by the fact that the resting place, the hut of the Grands-Mulets, is very poorly furnished; on the contrary, on Monte Rosa there is the inn of the Riffelberg, where one rests comfort- ably, and where one can stay several days at an elevation of 2570 meters. To fatigue and insomnia we must add insufficient or poor food. The guides are unanimous in urging one to eat little, but often and substantially. A bad condition of the stomach or the intes- tine infallibly brings on the symptoms long before the usual level. 326 Historical Guides have frequently become ill at a fairly low level, because they had been drunk the night before; peons who have bad habits suffer more from the puna than the others, says Caldcleugh (page 35). The following are the principal circumstances, variable and accidental, which may affect the intensity of mountain sickness: lack of acclimatization, lack of training, fatigue, insomnia, poor food, and temporary ill health. Different constitutions seem un- evenly affected. According to most of the travellers, according to A. Smith (page 44) , Tschudi (page 46) , Burmeister (page 52) , and Pissis (page 56), the plethoric and also the aged or very weak persons are especially affected. It is not rare to see persons appar- ently frail, but bilious or nervous, make with impunity ascents on which corpulent people fail. We may say that they have less weight to carry, which is important, especially when they are walking in the snow, into which they sink less; besides, their pulmonary surface is, like that of children, greater in proportion to their weight, but whatever the explanation is, the fact is com- monly observed. The state of ill health, for whatever cause, likewise predisposes one to be sick sooner. "When I was not well", said Al. Gerard, "I was sick at 13,000 feet, but in good health I felt no effects at 16,000 feet" (page 138). An effect of general nature is that of cold, which predisposes to mountain sickness. As we have seen, it usually appears in the region of perpetual snow, and in intertropical lands it recedes with the snow line to enormous heights. All travellers agree in declar- ing that when the icy wind of high places rises, it makes the symptoms unendurable, and may bring on death; this fact was first noted in the Andes by Acosta (page 25) . If then to the fatigue of walking and of burdens borne we add insufficient food, the privations of poverty, and clothing insuffi- cient to keep out the cold, we find united all the causes which may increase the intensity of mountain sickness. These causes, not to mention bad habits, combine to attack the unfortunate Indian coolies and also, though to a less degree, the peons of the Andes; that is enough to explain the violence with which they ordinarily suffer from the puna or the bies, to use their expressions. If now we refer to the differences mentioned at the beginning of this section among the different mountains in regard to the height at which the symptoms usually appear, we can explain them in part by the observations which have just been abstracted. If in' the tropics mountain sickness hardly ever appears below Summary and Discussion 327 4500 meters, whereas in our Alps it is not rare a thousand meters lower, temperature certainly has much to do with this considerable irregularity; as I remarked a moment ago, the zone of eternal snow is almost the same as that in which the symptoms appear. If the city of Cerro de Pasco is so much dreaded by all travellers, that is because its icy climate increases the severity of the symptoms caused by the altitude. Evidently it is to their position on the equator that the immense mountains which surround Quito owe i> part the relative immunity enjoyed by the persons who ascend them. At Quito, says Jameson,- the average temperature is about 14°; the thermometer fluctuates between 18° and 8°. But this element is not the only one. There is a great differ- ence, judging by what we said before, between a mountain situated on the shore of the ocean, like the Peak of Teneriffe (3715 meters) , for example, and another of the same height in the main range of our Alps, like Galenstock (3800 meters) . To make the ascent of the former, in fact, the traveller starts from sea level, and in one stretch covers a considerable vertical height; in the case of the second, the distance to be traversed is lessened by at least 1000 meters. In the latter case, the transition is infinitely slower. More- over, one cannot even approach the foot of the Alps without having had a sort of acclimatization with muscular training, in- stead of merely disembarking at the foot of the Peak or Etna. And so on these mountains of moderate height, in spite of the high temperature of their region, symptoms are still more fre- quent than on mountains of similar height in the Alps. For the same reason, in addition to their situation in the torrid zone, Chimborazo, Antisana, Cotopaxi, etc. cause only moderate symptoms; the city of Quito, which is at their feet, and from which one starts after a longer or shorter sojourn, is situated at an alti- tude of 2910 meters, so that there remains a vertical ascent of only 1950 meters to the summit of Pichincha; and so here we recall the irreverent comparison of Canon Bourrit (page 13) . The reader may convince himself, by reviewing the journeys across the Andes (pages 22-59) , that the symptoms are much more general and much more severe among travellers going from the Pacific to the Atlantic, than among those going in the opposite direction. In my opinion, the explanation of this apparent pecu- liarity lies partly in the fact that from the coast of Chile the ascent is extremely steep, whereas it is slow and progressive for the traveller going from the east to the west. The considerable height to which one must ascend in the Hima- layas before being attacked by mountain sickness may be due to 328 Historical the same cause. In the enormous range in which the Indus, the Bramapoutra, and the Ganges rise, one reaches the dangerous passes only after he has walked for a long time over hilly territory, the strata of which, rising higher and higher, gradually prepare him for the effects of the lofty heights. The transitions there are very slow; the dreaded symptoms should appear very late, and this actually happens. But of course this great effect must be reconciled with climatic conditions and other causes of variations which we have already noted. It seems to us that, except for a few cases which are still hard to interpret and upon which the discussion of theories sug- gested will cast some light, the strange irregularities which we mentioned at the beginning of this section can almost all be explained satisfactorily. 2. Symptoms of Mountain Sickness. Mountain sickness, the veta, puna, mareo, or soroche of the South Americans, the bis, tunk, dum, mundara, seran, or ais of the mountaineers of central Asia, the ikak of the natives of Borneo, is composed, at its maximum intensity, of a group of dangerous symptoms, which affect at the same time all the great physiologi- cal functions: innervation, locomotion, circulation, respiration, and digestion. We shall first summarize them in accordance with the preceding accounts, assigning them to each of these divisions of natural phenomena. Digestion. Exaggerated thirst, distaste not only for eating, but even for the sight and smell of food, lack of flavor in liquids, nausea, and vomiting have been noted by almost all travellers. One eats very little on lofty mountains; Martins and Bravais, with three guides, made a good meal on the rations for one man. As for violent symptoms, nothing is more striking than the descrip- tion given by Acosta: "After vomiting food, phlegm, and bile, one yellow and the other green, I even threw up blood" (page 24) . The modest euphemism of English travellers about "heavings of the diaphragm" and "distress in the stomach" give glimpses of the picture energetically drawn by the old Jesuit. In the narratives of the first chapter, we shall find it difficult to make a selection among the many descriptions. Sometimes the stomach becomes so sensitive that it cannot endure a spoonful of water (page 158) . Diarrhea has been noted, probably as a result of the spurts of bile injected into the intestine during the efforts to vomit. "My companions were exhausted with vomiting and defecating", Acosta Summary and Discussion 329 also says (page 24) . However we must say that in some cases it seems to be due simply to the cold, to wet feet, etc. The combination of these phenomena is always that which has most astonished and terrified the travellers; to these phenomena is due the old comparison which has given its significant name to mountain sickness, mareo. Secretions. Secretory disturbances are not very important; their relation of effect to cause with the act of ascent is far from demonstrated. If there is an exaggerated flow of perspiration, the violent exercise and the direct action of the rays of the sun are sufficient explanation for that. The decrease in urinary secretion may be the consequence of the same causes, but several travellers see in it the direct effect of lofty regions. Besides, no exact meas- urement has been taken, nor has any chemical analysis been made. Respiration. Respiration which is more frequent, shorter, then difficult, broken, and uneasy has been experienced and noted by everyone. Oppression is often accompanied by pains in the chest. This, along with exaggerated fatigue, is the first manifestation of mountain sickness. Animals are not immune. We have seen what importance has been attached to the increased respiratory rate by the theorists who have considered the question; we shall return to it in a moment. The observations of M. Lortet (page 111) have fixed the modi- fications in the respiratory rhythm caused by the altitude: the amplitude decreases if the number increases. Vivenot in his appa- ratuses has also noted this (page 280) . As to the consequences, in regard to respiration, of a permanent sojourn in lofty places, the data reported seem to contradict these results. To quote only the most recent authors, M. Jaccoud states that the number and the amplitude of the respirations increase on the Engadine (page 297) . Drew also finds "the respiration more rapid and more ample" (page 295) . M. Armieux reaches the same result in regard to number; moreover, he reports an increased respiratory capacity in the hospital attendants at Bareges. Every- one seems to agree on the question of frequency; but that of amplitude requires additional research. The same thing is true, for greater reason, if we take up the question of races (page 301). Circulation. The acceleration of the pulse, though it has not been noted by all travellers, like the digestive and respiratory disturbances, is no less constant. One can verify this, even though no feeling of discomfort attracts the attention. While I was making the very modest ascent of Nivolet (1558 meters) near Chambery (269 meters) , my pulse rate and that of all the other persons who 330 Historical composed our little caravan rose by 4 to 8; it was counted, of course, after a long rest. Lieutenant Wood only by chance noticed the extraordinary rapidity of his pulse, so that he thought he was feverish (page 143) . When the difference in level is very great, the acceleration becomes considerable. Moreover it is, as de Saussure said (page 85) , in proportion to the intensity of the distress experienced. The extraordinary rates of 130 and 140 are not very rare on lofty moun- tains: "My heart", says Mistress Hervey, "was going a railroad pace" (page 149) . Parrot tried to establish a sort of ratio, which might have served as a measure of the height, between his pulse rate and the altitude reached (page 122). The table published by Lortet (page 114) is very interesting in this regard; but such a regularity is far from being general. At great heights, the acceler- ation of the pulse becomes unendurable; it is accompanied by buzzing in the ears, throbbing in the carotids and temples, and more or less violent palpitations which become terrifying. This acceleration does not seem to be controlled by the use of digi- talis (page 151). This modification is not transitory; it continues through the whole sojourn in lofty places. It is regrettable that exact obser- vations on this point are extremely rare. So I think I should quote here those which were recently published by M. Mermod. M. Mermod" counted his own pulse rate repeatedly at the three stopping places of Erlangen (323 meters), Lausanne (614 meters), and Sainte-Croix (1090 meters); the sojourn in each ot these places lasted several months. These observations were made with meticulous care, and all necessary precautions were taken so that the causes of error might be less than the variations, evi- dently very slight, which the circulation might show under equally slight differences in altitude. The average of 900 observations made at Erlangen was 62.76 heart beats, that of 577 observations made at Lausanne was 66.68, and that of 333 observations at Sainte- Croix 68.87. The increase of the number with the altitude was noted at all hours of the day. M. Jaccoud (see page 297) also observed on the Engadine a per- sistent acceleration of his own pulse rate. I should, however, mention on the opposite side the observ- ations of Dr. Armieux (page 299) , who found an average decrease of 3.85 heart beats from Toulouse (200 meters) at Bareges (1270 meters) . The frequency does not show the only modification in the pulse. Its strength is greatly diminished, it becomes irregular, very Summary and Discussion 331 plainly dicrotic, and is progressively smaller and more easily de- pressed. The tracings made by M. Lortet during the ascent of Mont Blanc (see page 112) are very clear in this regard. The arterial tension decreases considerably. Other observers, on the contrary, have found the pulse full, strong, "vibrating," says Guilbert, "as in aortic insufficiency" (see page 54) . According to Junod, who experimented in closed vessels, it is full, depressible, frequent (page 229) . Without losing strength, says M. Lepileur, the pulse increases in rapidity considerably (page 236). The venous system displays no less striking phenomena; full- ness of the blood vessels, congestion of the skin, the lips, and the conjunctiva; face violet or reddish, swollen; lips blue and swollen. Then sometimes the picture suddenly changes completely; the face becomes pale; syncope seems imminent. Sometimes it actually appears, going as far as complete loss of consciousness. Upright posture is very likely to bring it on (see pages 79, 106) . The most terrifying, if not the most serious, of the circulatory disturbances is hemorrhage; it appears less frequently than is generally said; in order of frequency, we note first nasal and pul- monary hemorrhages, then hemorrhages from the eyes, the lips, the ears, and the intestines; finally, M. Martins experienced a slight hematuria. Mile. Dangeville found that her menstrual period was considerably advanced; but the violent exercise might explain that. These losses of blood have been observed in animals, especially horses and cattle. I mention in passing the important observation of Dr. Clark, who remarked that the blood coming from the nose was "darker than usual" (page 91). Locomotion. The heaviness of the lower limbs, the "blow on the knees", a fatigue which the efforts made do not explain, are among the first signs of mountain sickness. We have seen in numerous quotations that at a certain height it becomes impossible for the sturdiest walkers to take more than a few steps without stopping. And this is a matter of altitude, not of the ordinary difficulties of mountain journeys. "I made 34 miles on foot," says Captain Gerard, "through country which would be called moun- tainous by those who do not know the difficult parts of Koonawur, more easily and quickly than I could walk 12 miles in these lofty regions. When the altitude is more than 14,000 feet, every mile, even when the road is good, requires at least twice as much time as at the height of 7000 to 8000 feet" (see page 138) . 332 Historical It is not only walking that becomes painful. The slightest weight wearies the shoulders; a task, moderate in ordinary regions, cannot be carried out in the mountains without real sufferings, sometimes dangers. "We could not use our arms," said Dr. Gerard (page 136) , "to break off a piece of rock with a stroke of the ham* mer." Hamel says that "even talking tires one" (page 90) . And the Schlagintweit brothers, who make the same observation, add that "one heeds neither comfort nor danger" (page 155) . I have found convulsions mentioned only in the narratives of Mistress Hervey (page 147) and, in spite of the disrespect of the connection, in the horses whose story is reported by Liguistin (page 272) . But in both cases there is perhaps some other cause in addition to the effect of lofty places. Innervation. At the head of this category come the headaches, which are so violent and unendurable, compared to "an iron ring compressing the temples" (Guilbert), as if "the head were going to split in two" (Mrs. Hervey), of which travellers in the Himal- ayas complain in particular. The sensory modifications, and especially the mental depression, have been noticed much less than the preceding symptoms. How- ever, rather frequent mention is made of buzzing in the ears and a blunting of hearing and taste. The weakening of hearing is explained by the lessened intensity of noises transmitted by the thin air. Mention is more rarely made of sight, although we have quoted examples of travellers whose sight failed or who com- plained of dazzled or dimmed vision, etc. (see pages 94, 147) . Loss of consciousness, total swooning as a result of syncope, they say, is also mentioned. But only an unwilling report is given of what Captain Gerard frankly called "mental depression" (page 138), and Henderson called "great prostration of body and mind" (page 158). And yet when we read travellers' accounts carefully, we almost always find the manifest trace of it. Many disguise it under the name of drowsiness; there is no hesitancy about speaking openly of a desire to sleep which sometimes becomes unconquerable; but we do not admit so willingly that the senses are dulled, the intel- lect weakened, the energy lessened, that the mind like the body is invaded by extreme indolence, or, by a strange reaction, thrown into unhealthy exaggerations. Count de Forbin, however, declares (page 72) that he was "enfeebled, agitated by the terrors of a feverish brain. Weariness of the senses, exaltation of the imagination cast one into a state of near-delirium." Henderson also speaks, and de Saussure had Summary and Discussion 333 done the same long before him, of a great excitability of temper. On the other hand, de Saussure admits that he did not work with much zest on the summit of Mont Blanc. M. Lepileur goes further and relates (page 103) that he and his companions journeyed me- chanically, without thinking, so to speak, He attributes to this mental prostration the contradictions which he notes in the accounts of mountain climbers who preceded him. As for me, who have read hundreds of accounts of ascents, in the collections of Alpine clubs of all nations, I cannot help thinking that their mon- otony, their lack of real interest, the want of more than average thoughts which characterizes almost all of them, result largely from the unconscious state of mental depression of their authors, caused by the sojourn in lofty places. The average account of ascents to lower levels is infinitely more interesting, richer in out- side observations and evidences of intellectual activity; gymnastic feats and culinary preoccupations are much less in evidence in all cases. Aeronauts have noted similar facts, that is, slow depression leading to indifference and sleep: "The mental powers fail before the physical powers. First one loses memory and care. He forgets to give heed to the balloon; soon a slow and gentle sleep lulls all the members" (Robertson, page 183). In other cases, there is a strange excitement. Finally, at great heights, the aeronaut, even in the most complete physical calm, is suddenly struck by complete insensibility. That happens to Zambeccari and M. Glaisher. Such are the grievous symptoms produced by the influence of lofty places. At the beginning, a sensation of inexplicable fatigue, short respiration, rapid panting, violent and hasty palpitations; distaste for food; then, buzzing in the ears, respiratory distress, dizziness, vertigo, weakness constantly increasing, nausea, vomit- ing, drowsiness; finally, prostration, dimming of the vision, various hemorrhages, diarrhea, and loss of consciousness. Such is the as- cending series of symptoms, in proportion to the altitude reached. Among all the accounts which we have collected, which picture vividly all these distresses, in my opinion, there is none which is more vivid and complete than that of Tschudi, falling unconscious on the ground, in the icy Puna of Peru (see page 47) . Even death, an immediate death, may be the result of these serious symptoms. We have given some instances of this in the Andes (see pages 25, 33, 37, 43) and in the Himalayas (page 137). And it is not only men who may succumb; animals, cats, dogs, camels, mules and horses in particular, die still oftener. The intensity of these symptoms is considerably aggravated 334 Historical by walking, running, any expenditure of energy. We have had many examples of this: one of the best guides of the Oberland (page 94), whom a rather strenuous effort twice makes blind; the traveller Weddell, till then immune to the soroche, who is stricken after a rapid excursion (page 48) ; de la Touanne, falling on the ground almost unconscious, because he wished to go faster sud- denly (page 36) ; d'Orbigny, who, thinking himself acclimated, was compelled to stop every time he waltzed (page 38) ; Hedringer falling on the snow, because he wished to run to the summit of Mont Blanc (page 96) ; an inhabitant of the Alpine mountains, who, trying to outstrip his companions, rolls over "as if some one had shot him" (page 116). Travellers say that it is to the eagerness of the horses, which spring forward under the spur, that their fre- quent deaths are due, whereas the mules, patient and obstinate, survive because they refuse to quicken their pace. It is walking uphill which especially fatigues and exhausts. This fatal effect of muscular activity is felt at all altitudes. But in regions of moderate elevation rest is sufficient to dissipate its effects and restore complete calmness. And that is perhaps the most peculiar characteristic -of mountain sickness. To the uneasi- ness of the traveller, to his extreme fatigue, to his grievous dis- tress, there succeeds an unexpected comfort, as soon as he stops, sits down, or particularly lies down: his heart regains its rhyfhm, respiration becomes regular, a feeling of energy returns, all as if by enchantment; so that after a few minutes, astonished both by these unknown discomforts and this sudden cure, the inexpe- rienced traveller confidently resumes his climbing. But soon he is again attacked and conquered. On loftier mountains, rest, even rest in a horizontal position, even if it dissipates the most violent symptoms, does not, however, restore calmness. Palpitations, suffocations, trouble or prevent sleep. Sometimes a strange symptom appears; during the night, at dawn especially, sudden respiratory distress awakens the sleeper with a start (see pages 39, 54, 55, 132, 149, 155, 158, 160) . A few deep inspirations restore calmness; probably it is a consequence of this forgetting to breathe of which de Saussure had spoken (page 83) ; imminent asphyxia awakens the sleeper suddenly. Such is the series of symptoms which, in different degrees, at different altitudes, attack mountain climbers and aeronauts. It seems that there is no great difference, except in intensity, be- tween the symptoms observed in the different mountainous regions. Although the symptoms which we have described appear sooner in our Alps than in the Andes and the Himalayas, they Summary and Discussion 335 never reach there the dangerous severity which threatens the lives of travellers and their guides, even natives, in the other regions. That is because the height of Mont Blanc (4810 meters) is the maximum which one can reach in our Europe, and because one remains there only a few hours at the most. Conditions in the Himalayas are far different, because there one remains for a long time on plateaux at an altitude of more than 4000 meters, crossing almost every day passes which reach an elevation of 5000 to 5500 meters. A harmful influence whose dangerous effects many travellers have mentioned is that of the wind. "There blows in this place," says Acosta, whom I must constantly quote, "a little wind which is not too strong or violent. But it is so penetrating that men fall dead from it, almost without perceiving it" (page 25) . M. Lepileur also suffered from the wind to a much less dangerous degree (page 103). The Schlagintweit brothers also complain of it very bitterly (page 155) , and Henderson claims that it often kills travellers (page 159). Many narratives agree in stating that the symptoms are parti- cularly severe at points on the mountain where the air is renewed with greater difficulty. Should this irregularity be attributed to the heating of this air, expanded by the sun? Or to the tediousness of walking in these monotonous passages? The observations of M. Javelle and M. Forel tend to support this latter hypothesis. They state, in fact, that mountain sickness disappears in dangerous spots (page 289) and also as a result of attentive observation of the landscape or oneself (page 292) . It would not be very interesting to dwell on the medications used by the natives against the symptoms of mountain sickness. They generally agree in forbidding alcoholic beverages; in America, they praise bleeding, especially for animals. In the Andes protective powers are attributed to garlic or onion placed in the nostrils of the animals; in the Himalayas, acid and dried fruits are used. Almost everywhere it is recommended that one should eat little and often. M. Dufour declares that he dispelled an already violent attack of mountain sickness merely by eating a piece of bread (page 290). 3. Theoretical Explanations. We may divide into two great categories the hypotheses and the theories put forward to explain mountain sickness: some of them, by far the most interesting, try to settle the mechanical, physical, or chemical role of the diminished atmospheric pressure; 336 Historical the others, the most peculiar ones, seek the cause of the symptoms in something other than the fall of the barometer. We shall begin with the latter. Pestilential exhalations. The explanations which put forward pestilential exhalations, either from the ground or from toxic plants, must be given a moment of our time. They have their origin in the absolute ignorance of the native peoples about the very existence of an atmosphere. Therefore the Indians and the Tartars of the Himalayas, the Redskins of the Andes and their successors, almost as uncivilized as they, did not hesitate to attribute the symptoms which struck them and their domestic animals to some mysterious poisoning. In the Andes, the frequent presence of metallic ores and the evident effect of moun- tain sickness upon the unfortunate miners gave rise to the belief that there issued from buried metals, and particularly from anti- mony, "which plays," says Tschudi, "an important part in their physics and metallurgy," emanations dangerous to all those who passed over their veins. Hence the name soroche, which means both antimony and mountain sickness. In central Asia, the idea of exhalations from the earth also occurred to the people, especially towards China; we saw that Father Hue did not hesitate, with his usual credulity, to declare that the symptoms of Bourhan-Bota were due to carbonic acid from the ground (page 238) . Volcanic mountains, like Etna, the Peak of Teneriffe, the moun- tains of North America, because of deleterious vapors which rise from certain crevasses, have caused among travellers a much more pardonable confusion between the effect of the altitude and that of the mephitic gases; we have seen examples of it. All through the Himalayas, the mountaineers do not hesitate to attribute the distress from which they suffer to volatile poisons emanating from flowers or plants. Generally the narratives of the travellers limit themselves to these vague expressions; but when they are more exact, the strangest divergences appear. The Chinese author whom we quoted (page 129) gives rhubarb as the cause. When Fraser's coolies complain of the seran and blame the flowers which cover the ground, he looks around him and finds primroses, heather, and polyanthus (page 132) . For Mis- tress Hervey, whose distress we have narrated, it is a sort of moss, the boottee, which the natives show her as the cause of all her troubles (page 148) . They could not show Cheetam the dewaighas, the mysterious and toxic plant (page 153) . Henderson reports that they blamed artemisia (page 295) , and Drew, the onion (page 295) . Summary and Discussion 337 These hypotheses, natural product of the ignorance of the natives, have sometimes been accepted by European travellers. They served as an easy explanation of this curious fact that the intensity of the symptoms is not regularly proportional to the alti- tude, and that at certain points, sometimes of moderate elevation, almost everyone is sick. It is especially travellers in the Andes who believe in emanations from the ground. Some of them would say, like the peons of Brand: "There is much puna here" (page 36) . However, very few admit their credulity clearly; they are satis- fied with saying that there are "accompanying causes, which are unknown, and which act with the rarefaction of the air" (page 55) ; that "the atmospheric pressure is not included in the causes of the soroche, which should perhaps be attributed to emanations from the ground" (page 58) . Asiatic travellers have been more prudent. Hodgson alone allows one to glimpse a certain credulity (page 223) ; but all the others refuse to admit intoxication by plants; those who have deigned to take note of it declare formally that frequently the symptoms appear where there is no vegetation, not even moss: from Fraser to Mistress Hervey and Drew, they all agree on this point. To tell the truth, these hypotheses do not need any other refu- tation. Moreover, the identity of the morbid symptoms attributed now to antimony, now to vapors from the earth, elsewhere to emanations from undetermined plants, is enough to show that they have a single cause, which is closely connected with the ele- vation above sea level. Electricity. When. people do not know what else to say, they are very likely to invoke electricity as the cause. Dr. Govan did this (page 221) : "These phenomena," he says, "depend upon atmos- pheric circumstances, less general than the decrease in pressure, like the electric power which must be in a state of constant fluct- uation in the presence of such lofty conductors." For Heusinger (page 245) , electricity must act, for it is stronger and less often negative. But these authors were outdone by Dr. Cunningham, who declared that "in the northern hemisphere, the electricity attracts the blood to the head, and in the southern hemisphere, to the feet .... from which mountain sickness results, which explains why this illness is cured by the horizontal position" (page 225) . The strangest thing is that this strange doctrine has found votaries (page 296) . Lack of oxygen in the air. It is the unevenness of the effect of the altitude, according to the regions, which has suggested all these 338 Historical peculiar explanations. Truthworthy, even eminent men have not escaped this need of seeking elsewhere than in the effect of dimin- ished pressure the cause of the distress experienced. Certain persons believed that they had found this cause in a special weakening of the air or, to speak more exactly, in its diminished oxygen content. That was the opinion of von Hum- boldt (page 30), who said that he found only 20% of oxygen on Chimborazo, and attributed a great effect to this difference. M. Boussingault, struck by the fact that mountain sickness hardly ever occurs until perpetual snow has been reached, took up an old idea of de Saussure, who had maintained that the air released from the pores of the snow contains less oxygen than free air; he made an analysis which gave only 16% of oxygen, and then he attributed the suffocation which he had experienced to this foul air. freed by the action of the solar rays (page 227) . By this reckoning, one should experience mountain sickness on plains covered with snow, in a fine January sun. Other travellers (page 294), without other objection, accepted this hypothesis, which the celebrated chemist himself finally admitted was mistaken. Fatigue, cold. These are two causes frequently hailed, not as adjuvants, which would be correct, but as the principal or. even the sole cause. It is the warhorse of those who deny mountain sickness: "We can assert," says one of them, "that these are the same sensations experienced by ordinary travellers when they approach the summit of any mountain" (page 231). "What proves indisputably that these symptoms are due to fatigue," says Bouguer, "is that no one was ever affected by them when he was on horseback, or when he had once reached the summit, where the air, however, was still thinner" (page 208) . We must admit that at first glance and for slight symptoms confusion is possible. Hasty respiration, dyspnea, circulatory accel- eration, palpitations, even vertigo, and heaviness of the limbs are the result of any exercise which is somewhat tiring and prolonged. But we need only glance at the numerous data reported above to find in them the proof that there really is a special influence in lofty places: the symptoms appear, as we have seen, even during rest and sleep. Moreover, Acosta had very early refuted these errors (page 24), as did de Saussure (pages 213, 216). Yet it is still fatigue, though of a special type, which Rey invokes (page 232). M. Lepileur's ideas (page 237) are evi- dently of the same sort; this learned physician in his explanation of the fatigue gives overwhelming importance to "the congestion Summary and Discussion 339 of blood taking place in the muscles during their action." As to the other phenomena, they are the result of congestions of the lungs or the brain, caused by the constant repetition of efforts made during the act of climbing. Moreover, "the rarefaction of the air, making respiration more frequent and panting more rapid, necessarily hastens the rest of the ordinary effects of effort." But how does the rarefaction of the air make panting more rapid? That is what M. Lepileur does not tell us. Theories of M. Lortet and M. Dujour. Here now are two very important theories, which show a thorough knowledge of the most difficult questions of physiology. Their place is indicated here because they are, in a word, only a scientific form of the common charges against fatigue and cold. In the opinion of M. Lortet, the body temperature of man diminishes when he expends the enormous quantity of work nec- essary to raise the weight of his body to a great height. We have reported in full the data secured by Lortet (page 114) and the theoretical conclusions which he draws from them (page 286) . Un- fortunately, as MM. Forel (page 288) and Clifford-Allbutt (page 289) have shown, the very observations of the French physiologist were wrong: the temperature of the body always rises as a result of the act of ascent, as in the case of all violent gymnastics. Even referring to the figures of M. Lortet, who maintains that from Chamounix to the Grands-Mulets the temperature dropped 2°, and that at Chamounix the act of walking cooled the body 1.7°, serious symptoms should follow the slightest exercise at these elevations, where, however, mountain sickness has never been observed. Moreover, according to him, rest should restore the normal temperature almost instantaneously but it is far from dis- pelling all the symptoms. We must say, however, that M. Forel, never having had moun- tain sickness, could not take his temperature in this special condition; we might still say, until proved wrong, that he would find it lowered in this case. But even if it v/ere so, it would still have to be admitted that another element besides work must be involved, and that altitude is this element. We shall soon discuss the theories about insufficient oxygen- ation due to decreased pressure. If we introduced this new factor into Lortet's theory, we should be led to think that since the work of ascent requires an increased combustion, and since the propor- tion of oxygen is too small, heat would be transformed into motion, resulting in a drop of temperature and consequently, general dis- turbances. But this drop would have to be proved, and Lortet's 340 Historical observations are evidently tainted with causes of error which vitiate them as sources of proof: even the experiments of Legallois (page 218) , notable as they are, cannot be used in his favor, since they deal with confined air. The theory of M. Dufour (page 291) is also independent of the idea of altitude. In his opinion, mountain sickness is the conse- quence pure and simple of fatigue, which results from the exhaustion of the ternary materials stored in the muscles; and so he states that he experienced the symptoms even on the plain, after great fatigue. It cannot be merely the rarefaction of the air, he says, which makes one ill on the summit of Mont Blanc, be- cause aeronauts had to reach 7000 and 8000 meters to experience serious disturbances; moreover, these disturbances do not at all resemble those produced on the mountain. We leave to the reader the task of weighing the value of this last statement, and as for the comparison of mountain sickness to simple fatigue, we shall merely ask why it has never been made by tourists, who, not without great fatigue, walk all day in mountains less than 2000 meters high. At least they have never confused the lasting weariness which they experience in the eve- ning with the sudden "blow on the knees" which exhausts the limbs and disappears after a few minutes rest; nor have they confused the breathlessness and the acceleration of the pulse due to a la- borious or rapid walk with the dyspnea, the palpitations, and the total exhaustion which, at an elevation of 4000 meters, often halts the traveller after a few steps. There is, therefore, something be- sides the exhaustion of the ternary materials, and this something is the altitude reached, or, to speak more clearly, the diminished pressure. This objection is evidently applied to the ideas of Bou- guer, Lepileur, and Lortet, as well as to the theory of Dufour. We now come to the theories which involve the decrease in at- mospheric pressure. Laboratory experiments had shown that ani- mals placed under the bell of the pneumatic machine became ill, even died, when the pressure was lowered sufficiently, and the con- clusion had been drawn that the lowered air pressure on lofty mountains was probably the chief cause of the symptoms. But how does it act? Here the theories become numerous. Decrease of the iveight sustained by the body. One of the first which entered the minds of travellers may be summarized thus: At normal pressure, each square centimeter of our bodies sustains a weight of 1.03 kilograms, or, for the entire surface, a number which should be 18,000 kilograms for a man of average height. We do not feel this enormous weight which would crush us, the Summary and Discussion 341 authors say, thanks to the inner tension of the fluids of the body which counteract it; but if it diminishes, immediately this tension, which nothing now checks, will urge the fluids to the periphery, will fill the skin with blood, will swell it, will congest it, and by rupturing the blood vessels will cause hemorrhages: it will be the same as if the body were plunged into an immense cupping-glass. Now this is what happens when one rises in the air: at an eleva- tion of 3300 meters, 5000 kilograms will have been removed; at 5500 meters, half of the total weight, that is, 9000 kilograms. Why should one be surprised at the serious disturbances which occur then? This is the theory approved by the large majority of those who have considered the question, particularly, 'we must say, travellers and physicians. We find it suggested for the first time in a few words by Bouguer (page 209) . Haller develops it at length (page 210) ; it is true that, recalling a strange idea of Cigna (page 206) , he declared that there is a great difference between "air rarified by the removal of a part of it and that which is lighter because of the elevation. . . In the latter, although it has lost half its weight, respiration takes place without difficulty." That is no stranger, at any rate, than to see Bourrit maintain that at an equal elevation, "the air of the Alps is rarer than that of the Cordilleras" page 213) . De Saussure accepted completely the theory of the "relaxing of the vessels produced by the decrease of the compressing force of the air" (page 215) . It was this illustrious physicist who ex- pressed it most clearly. It was also accepted by Fodere (page 217), Halle and Nysten (page 217), Gondret (page 220), Dr. Gerard (page 222), Hipp. Cloquet (page 223), Burdach (page 225), Rey (page 231), Brachet (page 235), Lombard (page 243), Heusinger (page 245) , Foley (page 270) , Scoutetten (page 276) ; we mention only the chief advocates. We see that this theory has the support of the most eminent names. It is really painful to have to reject it by a sort of pre- liminary question, as absolutely contrary to the laws of elementary physics. But long before me, MM. Giraud-Teulon (page 246) and Gavarret (page 279) had called upon the principle of the incom- pressibility of liquids to combat this error. Valentin (page 244) had even calculated that the removal of a half-atmosphere would increase the volume of the body only about three hundred-thou- sandths. It is quite evident that all pressures or decompressions balance each other, immediately counteract each other, when they are applied to the whole body, since it is composed entirely of 342 Historical liquids and solids. If there is decreased pressure on the surface of the skin, on the outer wall of the blood vessels, the decrease is absolutely equal on their inner wall, and there is no change in the state of equilibrium. It is really strange that anyone could have thought seriously that by going to Cauterets he would be relieved of 2744 kilograms (page 276), and that Gay-Lussac should have felt 10,000 kilograms removed from his shoulders in a few minutes. If the liquids of the organism were really thus held by the outer pressure, a few centimeters decrease in pressure would produce the most terrible disturbances. It is the comparison with the cupping-glass which has caused the error: they forgot that in the cupping-glass it is the effect of the pressure on the rest of the body which causes the swelling, the congestion, and the local hemorrhages. Escape of the gases of the blood. The physicists, most of whom escaped the erroneous hypothesis which we have just discussed, were better inspired when they gave an important role to the escape of the gases of the blood, as an effect of the diminished pressure. Robert Boyle had been the first (page 201) to see that all the liquids of the body, blood, urine, bile, humors of the eye, release bubbles of gas, when they are placed in the vacuum. From it he drew the conclusion that in animals which die under these conditions, death may be, "besides the failure of respiration," the result of the formation of these bubbles, which "check or disturb the circulation in a thousand ways." He even thought that, at the time of slight variations of the barometer, it is "the spirituous or airy particles which, held in abundance in the blood as a whole, naturally expand the liquid, thus being able to distend the large vessels and change considerably the speed of the circulation of the blood in the capillaries and the veins." Borelli had the same idea and attributed to a sort of effer- vescence of the blood the symptoms which he had experienced on Mount Etna (page 207) ; but he soon gave up this idea (page 208) , to which, however, there rallied Musschenbroeck (page 198), author of a dissertation De aeris existentia in omnibus animalium humoribus, Veratti (page 204), Rostan (page 225), F. Hoppe, who made experiments upon animals to verify it (page 248), Guilbert (page 254) , and finally Gavarret (page 279) . The escape or the tendency to escape of the gases of the blood has been used especially to explain the circulatory acceleration and the hemorrhages. "When the outer pressure diminishes," says M. Gavarret, "these gases tend to escape from the blood, force the walls of the vessels from within outward and distend the pul- Summary and Discussion 343 monary and general capillaries, the walls of which, since they are thin and lack resistance, may be ruptured. Such is the mechanism of the production of hemorrhages." Indeed it seems settled, in spite of the objections of Ch. Darwin (page 207), John Davy (page 224), and M. Giraud-Teulon (page 246), that at a sufficiently low pressure, gases escape from the blood of living animals placed under the pneumatic bell; F. Hoppe did not even hesitate to conclude that the death of the animals under these conditions is due to this release of gases. But noth- ing in the experiments yet known proves that the escape takes place at pressures which coincide with mountain sickness, nor that the tendency to escape can bring on the disturbances for which it is blamed. No comparison can be made between an animal brought in a few minutes to a fatal decompression and a traveller who takes six hours to ascend vertically 2000 meters. If the gases were partial cause of the symptoms, aeronauts, who undergo enormous changes in pressure with great rapidity, would be the first to be stricken, and we know that that is not the case. Expansion of intestinal gases. The idea that the decrease of pressure must expand the intestinal gases is evidently not wrong from the standpoint of physics; but that is far from justifying the conclusion that this increase in volume is the cause or one of the causes of mountain sickness. However, Clissold (page 224) con- sidered that it must hamper respiration and circulation consider- ably. M. Lepileur (page 237) and Speer (page 241) also tend to attribute some effect to it; M. Maissiat is more positive: "The in- testinal gases, gaining volume, distend all, to the point of rupture" (page 234) . The learned physicist reasoned as if the intestine was a closed swimming bladder, and he forgot the double communica- tion with the exterior, which, in practice, permits no distention. The same thing is true of M. Colin, who sees a cause of death in "the forcing back of the diaphragm by the expansion of the gas" (page 307) . Loosening of the coxo-femoral articulation. It is under the patronage of the illustrious von Humboldt (page 228) that there appeared this odd explanation of the extreme fatigue and the heaviness of the lower limbs which appear in lofty ascents. It has since been accepted by many writers: Tschudi (page 232), Meyer-Ahrens (page 243), Lombard (page 252), and Guilbert (page 255) . It is undeniable, as B6rard (page 312) has shown, that the sur- face of the cotyloid cavity is sufficient to permit the atmospheric pressure to support the weight of the leg, when all the soft parts 344 Historical have been cut away. According to M. Jourdanet, the pressure thus exerted would be equivalent to about 23 kilograms. We have seen how this author proved, by calculations based on the surface of the cotyloid cavity, that at the time when the weariness of the lower limb appears, the atmospheric pressure is still capable of supporting a weight double that of this member (page 257) . Dr. Faraboeuf, at my request, consented to make precise meas- urements upon a human cadaver. Here are the results which he gave me: Man of forty-eight years, weighing 52.5 kilograms; height 1.65 meters, 0.85 meters in the lower limb; well proportioned, thin, but still apparently muscular. Diameter of the cotyloid cavity 51.5 mm. Surface 20.8 sq. cm. Weight of the atmosphere on this surface 21.4 k. Weight of the lower limb disarticulated in the fold of the buttock and the groin 6.3 k. Weight of the lower limb deprived of the muscles which are inserted into the pelvis 5. k. So the atmospheric pressure is capable by itself of supporting a weight four times greater than that of the lower limb deprived of the muscles which support themselves by their connection to the pelvis. We should therefore have to go to a fourth of an at- mosphere, that is, a pressure of 19 cm. to cancel the support fur- nished by the weight of the air. Evidently then the cause sug- gested by von Humboldt has no connection with the fatigue which appears on Mont Blanc at a pressure of 41 cm., at which point the atmosphere still represents 11.5 kilograms. Very certainly the effect of the pressure upon the firmness of the articulations has been exaggerated; setting aside this exaggera- tion, von Humboldt has not drawn the really logical conclusion from the principle which he thought correct. It is not a greater muscular fatigue which should occur, and it should not be limited to the muscles of the thigh; the danger for the traveller in regions where the atmospheric pressure is lessened is dislocations, and in all the articulations; but in spite of the unusual exertions which ascents entail, no such symptom has ever been noted. Other mechanical effects of decreased pressure. Borelli at- tributed the fatigue to the presence in the thorax of expanded air which "no longer aids," he says, "the effort of the muscles, com- pressing by its elasticity the air and blood vessels." It is not easy to see clearly what the learned physician-mathematician meant. But there is some truth in what we may suppose to have been his thought. If, in the phenomenon of effort, the chest walls, as M. J. Summary and Discussion 345 Cloquet 4 has shown, are immobilized in a certain state of expan- sion, because an equilibrium has been established between the pressure of the expiratory muscles and the elasticity of the intra- pulmonary gases which the closed glottis prevents from escaping, the original density of these gases should be important. If they are rarefied, the state of equilibrium will occur only with a stronger contraction, or a smaller expansion of the thorax, and this situation may be unfavorable to the phenomena of maximum ef- fort,. But the effect, in any case, should not be of great impor- tance. Musschenbroeck had given a very ingenious explanation of the death of animals in a vacuum. He had found their lungs "small, flabby, solid (page 198), specifically heavier than water," and he had considered that the death is the result of the stoppage of the circulation which this collapse should produce; the same fact was noted by the Dutch physiologists (page 202) , who interpreted it a little differently. But these explanations cannot, however, be applied to disturbances and death in an air which is much rare- fied but still far from a perfect vacuum. Cigna long ago com- mented that respiration should continue under these conditions, as long as "the air is dense enough to expand the lungs by its pressure"; but for that, it is sufficient "that this pressure should overcome the resistance offered by the contractile force of the lungs, for there is no thoracic air to increase this resistance, and this pressure hardly exceeds that of two inches of mercury" (page 207). It could not be better stated, and Cigna was replying in ad- vance, without knowing it, to those who would later give an im- portant part in mountain sickness to the tendency of the lungs to retract under a lessened density of the intra-pulmonary air. Their force, that is, their elasticity, is equal to only a few centimeters of mercury, as Cigna had said. Therefore only under a still lower pressure could the lungs separate from the thorax wall, making a vacuum in the pleura. The supposed effect is therefore abso- lutely nil. Pravaz fell into a similar error when he said that "in mountain air, respiration is mechanically restrained in its extent by the lack of elasticity in the atmosphere which presses the interior of the lungs" (page 239). His opinion is subject to the same objections. But at least it has some appearance of probability, whereas I can- not understand what made A. Vogt say that "the diminished at- mospheric pressure assists greatly in the expansion of the thoracic cavity, and thereby facilitates respiration" (page 237) . 346 Historical The learned physician of Lyons seems to me no better inspired when he ascribes to the diminished pressure the venous conges- tions, because "the return of the blood to the right cavities of the heart will be less active." His comparison of the heart to "a pump operating in a medium in which the air is greatly rarefied, and which could bring up water only from a much lessened depth" (page 239) is not at all valid; no one believes now in the active, sucking expansion of the heart. In conclusion, we shall quote a more accurate idea of the same author in regard to the recall of the venous blood by pulmonary expansion. One might think that the force of this recall should be decreased by the decrease in pressure. And yet, when we think it over, we see that there is no proof there: the return* of the blood of the large venous trunks towards the heart takes place because of the difference between the tension of the outer air and that of the air which enters the lungs and expands there, since, as we proved long ago,5 in no animal can the opening of the glot- tis suffice for the capacity of the respiratory pump. It would still have to be demonstrated that this difference, the negative pressure of the Germans, is less in rarefied air than in normal air, of which we are by no means sure, and which is not even probable. Excess of carbonic acid in the blood. We have reported with all the discussion it deserves the strange theory of M. Gavarret (page 275) , explaining mountain sickness by a real poisoning by carbonic acid. According to the learned professor, the act of as- cent would require such an increase of organic combustion that the carbonic acid which is the product of it could not be expelled quickly enough, in spite of the increase in the number of respira- tory movements and heart beats. The result would be a storing up which brings symptoms of poisoning; and also the improve- ment which immediately follows rest, during which the excess of gas is expelled. This theory was accepted by M. Leroy de Mericourt, M. Aug. Dumas, M. Scoutetten, M. Lortet (page 286), and many modern authors. I do not dwell upon the difference between the symptoms of mountain sickness and those of poisoning by carbonic acid. But it is quite evident that the theory of M. Gavarret is open to the same objection which we used in disproving the theories involving fatigue and the theory of M. Lortet. It is clear, in fact, that the quantity of carbonic acid which must be produced in raising the body 1000 meters, for example, is independent of the altitude; so Summary and Discussion 347 that there must be an excess of gas stored up, and consequently distress, just as much in ascending from Chamounix (1050 meters) to the Pierre-Pointue (2040 meters) as in ascending from the Grand-Plateau (3930 meters) to the summit of Mont Blanc (4810 meters) ; yet that has never been observed. Furthermore, even at sea level, a iask which is sufficiently energetic and prolonged should bring on the same result, and that is not the case. The necessary element, altitude, is not considered at all in this ex- planation. As to the fact advanced, it in itself is far from proved. There is no proof that the carbonic acid, the formation of which is in- creased during the labor of ascent, can really be stored up in the blood. According to M. Gavarret himself, when a man lifts him- self vertically 2000 meters, he forms 65 liters of carbonic acid, above the 22 liters which he produced per hour in his normal re- quirements. It will take him at least six hours to cover these 2000 meters. (MM. Lortet and Marcet took 8 hours to go from Cha- mounix (1050 meters) to the Grands-Mulets (3050 meters). We must then add 65 liters to the 132 liters formed during this time; in other words, the quantity of carbonic acid produced will have been increased by one third. Now it is very probable that the pul- monary excretion will have been sufficient to expel this small gaseous excess; the arterial blood, the nutritive blood, the impair- ing of which is so dangerous, is therefore probably not overladen with toxic gas. On the other hand, we know, from the experi- ments of M. CI. Bernard, that one can safely inject into the ve- nous system of an animal enormous quantities of carbonic acid, without producing symptoms, because of the rapidity and the en- ergy of the pulmonary exhalation. And so nothing proves that there is an excess of carbonic acid in the arterial blood; nothing proves that this excess, if it exists, is capable in its actual propor- tions of causing symptoms; at any rate, these symptoms should appear at any altitude whatsover, and consequently have no con- nection with mountain sickness. Theory of de Saussure and Martins. De Saussure noted, as we have reported (page 216), that, on the summit of Mont Blanc, "since the air had hardly more than half of its usual density, com- pensation had to be made for the lack of density by the frequency of inspirations. . . . That," he said later, "is the cause of the fatigue which one experiences at these great heights. For, while the respiration is accelerating, so also is the circulation." The former view, however, was incomplete, or, rather, incompletely expressed. 348 Historical De Saussure gave one to believe, in fact, that the respiratory ac- celeration could compensate lor the decreased density of the air. Now he certainly knew that that was not the case, and that on the summit of Mont Blanc neither the number nor the amplitude of the respirations doubled the pulmonary ventilation. This explanation was accepted by all the authors who followed de Saussure. Halle and Nysten (page 217), Courtois (page 218), Gondret (page 220), Clissold (page 223), von Humboldt (page 227) , Brachet (page 235) , Lepileur (page 236) , A. Vogt (page 237) , Pravaz (page 239), Marchal de Calvi (page 240), Meyer-Ahrens (page 243), Lombard (page 244), Longet (page 250), etc., repro- duced it in different forms. Some were satisfied with speaking, as de Saussure had done, in a rather vague manner of the insufficient quantity of air brought into the lungs at great heights; others, mak- ing more definite statements, declare that, since less oxygen reaches the lungs in a given time, less of it must be absorbed by the blood, and hence the symptoms; some, like Longet, deny this conclusion, affirming that "the person who dwells on the mountains .... compensates by more frequent inspirations, so that . . . the same quantity of oxygen can be absorbed in the same time" (page 250) . M. Martins criticized this evident mistake; he declared that there must be a lessened oxygenation of the blood resulting from this insufficient pulmonary circulation, and hence "a physiofogical cause of cold peculiar to high altitudes, and probably the principal among all those causes which bring on the symptoms known by the name of mountain sickness" (page 254) . But we have revealed the fundamental objection which Pay- erne (page 240) raised against the theory of de Saussure. In his opinion, there is quite enough oxygen in the air, even on the sum- mits of the highest mountains attained, to satisfy the needs of respiration and to meet the requirements of the combustions in- creased by the work of ascent. Lombard alone (page 251) seems to be affected by the cal- culations of Payerne; he makes no objection to them, and admits that "even at altitudes of 7000 meters, the atmosphere can furnish man with a quantity of oxygen sufficient to maintain respiration" (page 252). Nevertheless he drew the conclusion "that an in- sufficiently oxygenated blood reaches the different organs . . . This is the cause of a considerable part of the disturbances which occur in innervation and motility" (page 252) . In another part of this book, I shall discuss thoroughly the ob- jection of Payerne, and I shall show how much truth it contains. Summary and Discussion 349 But here I shall merely show that no one replied to it, and that consequently the theory of de Saussure, with the chemico-phys- iological commentaries with which it has been enriched, is now considerably damaged by it. If, even at 7000 meters, and without taking into account the respiratory acceleration, much more oxy- gen enters the lungs that is required by the organic combustions, why should not the blood take what it needs and what it can find there? And first, as a fact and not as a theory, is the blood really "less thoroughly oxygenated," as Brachet said? It is interesting to note that Hamel was the only one to suggest performing an experiment to "extract, on the summit of Mont Blanc, the blood of some ani- mal, and to see by its color whether it had been sufficiently de- carbonized in the lungs" (page 223). Yet we must confess that the purple tinge of the lips and the conjunctiva furnished some basis for the statements of those who maintained that oxygenation was incomplete: when one of Clark's guides had the nosebleed, "his blood seemed darker than usual" (page 91). Theory of M. Jourdanet. Some authors had glimpsed, as an explanation of this insufficiency of oxygenation, a cause other than the one which we have just been discussing. It was not merely the insufficient quantity of oxygen circulating in the lungs in a given time which they blamed; but, to borrow the actual words of Pravaz, "the lack of pressure which makes the solution of this gas in the blood less abundant" (page 239). This idea was clearly formulated only by Pravaz, in the passage which I have just quoted: no one adopted it afterwards. M, Gavarret opposed it energetically; the learned professor of the Faculte de Medecine of Paris declared "that the absorption of oxygen by the venous blood is not a purely physical fact, but that chemical forces play an important part in this fixation" (page 250). Moreover, if it were so, what would become of the people living at the dairy farm of Antisana, where the barometer stands at 47 centimeters, who would absorb "a weight of oxygen two thirds less than that con- sumed at sea level"? And Longet said a little later: "If the law of solutions applied, we should reach this conclusion, that the blood of those living in regions where the atmospheric pressure is hardly 0.380 meters would contain only half as much oxygen as the blood of those who live at sea level .... But, of course, the preceding law does not have an application here" (page 250) . But the point here was to find out what did happen to these dwellers in lofty places, and the reasoning of the learned profes- sors was a real vicious circle. Fortunately for them, the notable 350 Historical experiments of M. Fernet (page 249) , carried out meanwhile, ap- peared to justify them completely, seeming to show that the vol- umes of oxygen absorbed by the blood are almost independent of the barometric pressure. Everyone yielded then to these conclusions supported by ex- periments which give no opening for any objection of a purely physico-chemical type. M. Jourdanet alone (page 258) did not declare himself con- vinced. He remarked shrewdly that no matter how great was the affinity of the corpuscles for oxygen in the respiratory act, there was no doubt that in an air with low oxygen content, the solu- bility of this gas in the blood would be less. It cannot be other wise in rarefied air, and the blood there must take up a lessened, and possibly an insufficient, quantity of oxygen. Join to that the decrease due to the cause of which de Saussure had spoken and to which M. Jourdanet attributes considerable importance, and you will become convinced, he thought, that on the mountains the blood has a lower oxygen content than at sea level; and this de- crease in oxygen, although the number of blood corpuscles remains the same, produces the same dangerous effects as a decrease in the number of these corpuscles. Anoxemia is the pathological counterpart of anemia; thence comes this notable statement: "An ascent above 3000 meters is equivalent to a barometric disoxyge- nation of the blood, as a bleeding is a corpuscular disoxygenation" (page 261). When the symptoms are carried to the extreme, as happens on lofty mountains, the violent symptoms which we have described are the result of the irrigation of the organs by a blood containing too little oxygen, incapable of. stimulating and nourish- ing them. At lower altitudes, as on the Mexican plateau, the dif- ference in the oxygen content is not great enough to bring on dis- turbances serious enough to attract attention, in the usual condi- tions of life. But if some illness is contracted, it will immediately take on a character so peculiar that an experienced physician will at once recognize in his patient a real anemic. This is the general thesis which M. Jourdanet has ardently sustained since 1861; he has supported it in the successive works, which we have already reviewed, with an astonishing number of personal observations and quotations in agreement with them. To be sure, more or less definite statements had been made before his time, as we have seen, about insufficient absorption of oxygen, and even about blood incompletely oxygenated; but no one had connected the two causes which may produce a low oxy- gen content in the blood, or measured their importance, or shown Summary and Discussion 3d:. their prevalence; no one seemed even to have supposed that they could act at moderate altitudes, where no violent symptom attracts the attention of the traveller or the physician; no one had fol- lowed their consequences and shown their dangerous effect under pathological conditions; and finally, no one had tried to discover what part they play in the hygiene of peoples inhabiting lofty places, what effect they produce upon their character, their cus- toms, and their destiny. If it is true to say that the discovery belongs, not to the one who has found the truth, as if by chance, and who has carelessly ex- pressed it, but to him who, perceiving it in his turn, has felt its whole importance, has collected proofs to support it, has defended it against bitter attacks, even when they came from eminent au- thorities; who, in a word, has made a theory out of an isolated idea, it is to M. Jourdanet and not to de Saussure, Martins, Brachet, or Pravaz that we shall give the credit for having found the true ex- planation of the symptoms of decompression, as he already has the credit for having so clearly denned and described them by the name of anoxemia. However, we must note here again that the basis of the theory rested only on reasoning and deductions, very well connected, to be sure, but not sufficient to establish complete proof to minds ac- customed to the precision of scientific methods. It was necessary to make experimental proof of anoxemia and of its effect upon the production of the symptoms which appear in rarefied air. I had already said in 1869: "I cannot repeat too often that these are reasonings, likelihoods, probabilities at most. When shall we have the experimentation which will bring conviction? Who will do for the study of respiration, under decreased or increased pres- sure, what the King of Bavaria did when he furnished Pettenkofer with all the apparatus necessary for the study of the products of normal respiration?" G This appeal was heard. M. Jourdanet himself permitted me to subject to experimental test both his own theory and all those which deserved to be examined thus. The account of the experi- ments which I made with the help of the apparatuses which I had secured, thanks to him, will form the second part of this work. And now in completing this review of the opinions suggested to explain mountain sickness, I have only to remind the reader in summary that many of them could not withstand the critical ex- amination to which we subjected them; that others, whose ac- curacy is not very likely, are awaiting, for final judgment, experi- 352 Historical mental control; that still others, and among them the one which seems to us to have the firmest foundation, that of anoxemia, can bring conviction only by the aid of the supreme judge: experi- mentation. 1 Comptes rendus de V Academic des sciences, vol. XX, p. 1502; 1845. -Journey from Quito to Cayambe.—Joumel roy. geogr. Soc, vol. XXXI, p. 184-190, 1861. 3 Etude de I'Jnfluence dc I'altitude sur la frequence des battements du coeur. Bulletin de la Societe vaudoise des sciences naturelles, vol. XIII, p. 391-399, 1873. 1 De I'influence de I' effort sur les organes renfermes dans la cavite thoracique. — 'Paris. 1820. * 5 P. Bert, Lecons sur la physiologic de la respiration. Paris, 1870, p. 381-389. aLecons, etc., p. 129. I Title II INCREASED PRESSURE Nature offers no conditions where man and air-breathing living beings are subjected to the effect of a pressure greater than that exerted by the atmosphere at sea level.1 Only aquatic animals and plants endure pressures which may, in the depths of the ocean, be reckoned in hundreds of atmospheres. The quest for minerals, especially coal, has compelled many laborers to live at depths where the normal pressure of 760 mm. is increased by several centimeters of mercury. But the effect of this slight modification has never attracted the attention of observers, lost as it is, admitting that it is of some importance, in thd host of peculiar and unfavorable conditions under which miners live (dampness, darkness, confinement, deleterious gases, dusts, etc.) But since the sixteenth century, the progress of industry has caused men to work under pressures beyond four atmospheres. Diving bells, diving suits, and the caissons with compressed air invented by M. Triger have placed thousands of workmen in this modified medium. Serious symptoms have appeared, the number of which has terrified engineers and physicians. However, the latter, struck by the strange and often favorable changes which a stay in compressed air causes in certain patho- logical conditions, had the idea of regulating the use of this new therapeutic agent. Apparatuses have been installed, which have been of service in making interesting physiological observations and useful medical applications. In the following chapters, I shall report the data observed under the circumstances which I have just mentioned. A consider- able difference will be noted among them, if they are considered as a whole. Divers and laborers in caissons are subjected to 353 354 Historical pressures which are sometimes enormous; attention has been at- tracted only to symptoms appearing when these pressures were very high; and finally, these symptoms are, as we shall see, the result, not of the compression itself, but of sudden decompression. In medical apparatuses, on the contrary, the pressure used has always been low, less than double normal pressure; the physi- ological observations have been made on the phenomena produced by the compressed air itself, and no symptom could be charged to the decompression, which was always very gradual. I therefore had to divide into two chapters the report of such different data. A third is devoted to the account of the attempts made by various authors to explain the physiological changes and the more or less dangerous symptoms which attack the workmen. Finally, in the last chapter, I have summarized and discussed the data observed and the theories suggested, with the purpose of explaining them. 1 The small, almost uninhabited regions, where the ground is below sea-leve course, be excepted; the most important, certainly, is the valley of the Dead Sea. Chapter I HIGH PRESSURE 1. Diving bells. At the beginning of the sixteenth century Sturmius invented the diving bell, which was to render such great services. It was simply a bell heavily weighted, which, full of air, was allowed to sink vertically in the water until it touched the bottom. The water penetrated the apparatus to a height which increased with the depth of the immersion: at ten meters, there was under the bell, in volume, half air and half water; at twenty meters, two- thirds water and one third air, etc.; the workmen, who were ensconced up to that point on seats like shelves, got down from them to work under the worst conditions. The inventor considered the harmful effect which the air com- pressed by the descent might exert upon them; to prevent it, says Panthot,1 he advised that air should be taken along in bottles which would afterwards be broken under the bell. This procedure, which could not alter at all the tension of the air, was improved upon by Halley, with a purpose in greater har- mony with the laws of physics. The English physician planned to drive out the water which encroached upon the workman and to renew the air which had been made foul by his respiration; he 'did so by letting down under the bell small barrels full of air, which the diver received and opened at will; the warm and foul air escaped from the top of the bell by means of a valve. Halley even found the means of permitting a diver to leave the bell, keeping in communication with the compressed air contained in it by mean of a tube and a helmet covering the head. (Brize-Fradin, 2nd. S., pi. I.) . This was the first idea of the diving suit. Spalding made improvements of a purely mechanical type in Halley 's apparatus; these improvements did not prevent him from meeting death in his own apparatus in 1785. 355 356 Historical Brize-Fradin, from whose work 3 I have borrowed most of the preceding information, summarizes in the following words the disadvantages of the diving bell: 1. Keen and unendurable pain in the ear, due to the compression of the tympanic membrane; 2. Deterioration of the air by the breathing of the workmen, with asphyxia as the result; 3. Most physicists have found a third disadvantage; they believe that the elasticity of the air, acting in all directions and at all depths, compresses the blood vessels, and the arteries, and causes hemorrhages. We may oppose to this statement unvarying data and direct experiments; let us listen to M. Halley: "I myself was one of the five persons who dived to the depth of 18 meters, without being inconvenienced by it; we remained for an hour and a half; I could even have staid there longer, for there was nothing to prevent it." This testimony of M. Halley could be seconded by that of all the divers. The pressure of the air under water, at a depth of 18 meters, does not cause blood-spitting; if one dived deeper, of course, he would find the limit where the compressed air could not be breathed. (P. 171) And yet, adds Brize-Fradin: Noting the equal value of the water pressure and the compression of the air, it seems that the diver placed under the bell at a depth of 18 meters should be in a state of general collapse. (P. 173) The Court Councilor of the Emperor of Russia, whose fatal ascent of Mont Blanc we have already reported, Dr. Hamel,4 descended in a diving bell installed by Rennie in the port of Howth, near Dublin; the depth of the water was about 30 feet. He felt no other inconvenience than violent pains in his ears, "as if some one were forcibly inserting a stick," which he checked by swallowing his saliva. From that the idea came to Hamel "that the divers' bell might serve as a remedy in cases of deafness resulting from the obstruction of the Eustachian tube." In regard to the rest he merely says: I expected to experience some painful effect upon respiration, resulting from the pressure of the air increased by the weight of almost a whole atmosphere; and yet I did not feel the least incon- venience in this respect. The same year, Dr. Colladon B descended in the same bell and to the same depth. He is a little more explicit: We descended so silently that we did not perceive any movement of the bell; but as soon as it was immersed in the water, we felt in our ears and on our foreheads a sensation of pressure which kept Diving Bells and Suits 357 increasing for several minutes. However, I did not experience any pains in the ears; but my companion was in such pain that we had to stop the descent for a few minutes. To remedy this distress, the workmen advised us to swallow our saliva, after closing the nostrils and the mouth tightly, and to hold our breath for a few instants, so that, by this exercise, the inner air might act upon the Eustachian tube. My companion got little relief from this procedure. When we began to move again, he was in great pain, he was pale, his lips had lost their color, one would have thought him nauseated. His prostra- tion was due, no doubt, to the violence of the pain, added to a fear which he could not overcome. This experience produced the opposite effect upon me: I was in a state of excitement, as if I had drunk some alcoholic liquor, I had no pain, I merely experienced a strong pressure around my head, as if an iron ring had been fastened tightly about it. While I was talking with the workmen, I had some difficulty in hearing them; this difficulty in hearing became so great that for three or four minutes I did not hear them speaking; I did not even hear myself, although I was talking as loud as I could, and soon the noise caused by the violence of the current against the walls of the bell no longer reached my ear. (P. 6) .... At last we reached the bottom of the sea, where every disagree- able sensation ceased almost entirely .... We breathed very easily during our whole visit under water .... Our pulse rate showed no change ..... As we rose again, our sensations were very different from those we had experienced as we descended; it seemed to us as if our heads were becoming much larger; that all our bones were on the point of separating. This discomfort did not last long. (P. 8.) To these almost negative observations, Colladon adds two facts which are most interesting and which were the point of departure of important therapeutic applications: None of the workmen become deaf; it would rather seem that in certain cases, the effect of the bell on the ears might serve as a remedy for deafness. One of the workmen, who had habitually breathed with great difficulty, was completely cured shortly after undertaking work in the bell. (P. 14.) The diving bell today is completely abandoned. It has been replaced by caissons filled with compressed air by the Triger method. Interesting attempts have been made repeatedly to invent submarine boats in which men would live either in compressed air or in air at normal pressure. These attempts began in the seventeenth century; Father Mersenne, the friend of Descartes, did not scorn to apply himself to the subject; more recently R. Fulton in the port of Brest made attempts which perhaps should have been encouraged; then came Payerne, whpse submarine hydrostat operated with some success. In our own time, M. Villeroi, 358 Historical then Rear-Admiral Bourgeois invented cigar-boats which might be used in case of war. But since no observation of a physiological nature has been made with the help of these contrivances, and since I have no desire to write a history, no matter how short, of the industrial applications of compressed air, I now come without other transition to the numerous data relating to the digging of mine shafts and to the sinking of bridge piers by the Triger method. 2. Apparatuses Constructed by the Triger Method. It is, in fact, to M. Triger, a French engineer, that we owe the valuable invention of the use of air compressed to high pressures for boring mine shafts and sinking bridge piers. It was a question of working in the grant of Haye-Longue (Maine-et-Loire) coal- bearing strata covered with alluvial deposits over which flowed the waters of the Loire. It was impossible to drain off the water which seeped through and prevented them from extending the galleries: M. Triger conceived the simple but brilliant idea of driving it back and holding it by pumping compressed air in through the upper part of the shaft; protected by the drainage thus secured, workmen could stop the leaks by vaults of masonry. M. Trouessart, whose report on this wonderful discovery we shall quote later, comments that Denis Papin had already had an idea of this sort, in 1691, and he quotes the following passage, which is indeed very noteworthy: Fresh air could be injected constantly into the diving bell by- means of a strong leather bellows furnished with valves, by a tube passing under the bell and opening into its upper part. And so, since the bell would always remain empty and rest entirely on the ground, the bottom in this place would be almost dry and one could work there just as if he were out of the water, and I have no doubt that it would save much expense when construction must be carried on under water. Moreover, in case the leather bellows were not strong enough to compress the air as much as would be necessary at great depths, one could always meet this difficulty by using pumps to com- press the air. But from this idea to the complete invention of M. Triger is a long way; in 1839, he solved the problem from a practical stand- point, and listed the numerous applications which would later be made of it. The complete explanation of this invention is in a Memoir 8 presented to the Academy of Sciences in 1841. We naturally omit all details of the construction of the appara- Diving Bells and Suits 359 tuses and come to the mention of physiological phenomena, not much considered, as we shall see, by the celebrated engineer. An interesting fact appears at once; M. Triger wished to try upon himself the effect of compressed air. Now: At the moment when the manometer had hardly risen to the height of 40 inches (total pressure), there was a report, and we were struck with icy cold and plunged into the most complete darkness, because of the instantaneous formation of a thick mist: a windowpane of the apparatus had burst. This explosion had no other result that to cause us a great surprise. M. Triger next mentions, ascribing them quite accurately to their cause, the pains in the ears that accompany compression and decompression. Then he adds, and this is all his Memoir contains on the subject which interests us: At the pressure of three atmospheres, it is not possible to whistle in compressed air: but the power is lost only when one reaches this pressure. In compressed air, everyone talks through his nose, and this becomes increasingly noticeable with increase in pressure. The workmen have noticed that while they were climbing the ladders, they were less out of breath in compressed air than in free air. I shall end with a rather interesting observation, which I was in a position to note personally: namely, that a miner, named Floe, who had been deaf since the siege of Antwerp, invariably heard more distinctly in compressed air than any of his comrades. (P. 892.) Professor Trouessart,7 commissioned by the Industrial Society of Angers to investigate the practical results of the apparatus of M. Triger, gave an account of his researches in an interesting Memoir. There is very little mention of physiology in it; however, we do find in it a few observations which deserve to be reported here, particularly because they were the first made on man at pressures of 3 atmospheres above the normal atmosphere: It is with a certain apprehension, we admit, that one goes down for the first time into the apparatus to be subjected to a pressure of three atmospheres there. These 32,000 kilograms above the former pressure which you will have to endure are enough to terrify the stoutest shoulders. First comes the description of the pains in the ears, which are thoroughly studied and explained: A phenomenon which is more difficult to understand is that deaf persons not only hear better in compressed air than in free air, but that they hear better than persons whose ears are normal .... 360 Historical One of the strangest results is that one suddenly loses the power of whistling under the pressure of 2% to 3 atmospheres. The functions of nutrition, respiration and circulation do not seem perceptibly altered in compressed air. At the time of our first visit, we thought that we found an increase in the pulse rate of every one subjected to the experiment; but on our second visit, the result of a more accurate observation, made by a member with much experience in taking the pulse, was completely negative .... The respiration is neither slower nor faster. It seems that it is not more active and that the animal heat is not increased. The blood too gushes out under normal conditions. In a word, the most surprising thing is that there are very few changes in the vital functions. The workmen assert that they climb the ladder more easily and are less out of breath when they reach the top. This cannot result from the rather slight loss in their weight. Is it possible that they can hold their breath longer because of the greater density of the gas inhaled at each respiration? On the other hand, they maintain that they become much more tired when working in compressed air than in open air. We think that this is the result of the very great humidity of the atmosphere of the shafts, which hampers the insensible perspi- ration and promotes the more rapid secretion of sweat in those who have to exert their muscular powers in such a medium. Perhaps this humidity would also explain the somewhat severe pains in the ar- ticulations experienced by some workmen a few hours after leaving the shaft .... We may conclude that there is no serious danger in staying several consecutive hours for several successive days in air compressed to 3 atmospheres. Our author says nothing of the duration of the decompression; he seems, moreover, to pay more attention to "the passing from a low to a high pressure": he only says that they opened the cock gradually. In a second communication to the Academy of Sciences, M. Triger s repeats his former observations. He adds to them the following data: Everyone talks through his nose and loses the power to whistle at 3 atmospheres. To ascertain the effect of compressed air on a stringed instrument, I had a violin taken down into the shaft and it was found that at the above pressure the sound lost at least half of its intensity. Then comes the first suggestion of the rather serious symptoms of decompression: I should say here that two workmen, after passing 7 consecutive hours in compressed air, experienced rather keen pains in the arti- culations, half an hour after leaving the shaft. The first complained of a very sharp pain in his left arm, and the second experienced a similar pain in his knees and left shoulder; rubbing with spirits of Diving Bells and Suits 361 wine soon relieved this pain in both men; they kept on working the following days. In 1846, M. de la Gournerie,9 getting his idea, he said, from an apparatus suggested in 1778 and approved by the Academy of Sciences in 1779, used for the extraction of rocks in the channel of the port of Croisic a boat with a metal chamber open at the bottom, from which the water was expelled by compressed air. He submerged it only 3 or 4 meters; it is not surprising then that The workmen never found that the air pressure inconvenienced them. It merely gave them a slight discomfort in the ears for a few seconds. The pulse rate is not noticeably increased. (P. 308.) In the mines of Douchy (Nord) the method used by M. Triger on the banks of the Loire was first imitated. The difficulties were greater, because here it was not a matter of penetrating permeable sands with a sheet-iron tube 1.50 meters in diameter, but of digging a shaft 3 meters in diameter through limestone. We shall shortly quote the important Memoir which the physi- cians Pol and Watelle devoted to the study of the symptoms which attacked numerous workmen in this undertaking. The first ac- count of them was given by a report of the engineer Blavier,10 sent to examine this new invention. He first mentions the pains in the ears and the inability to whistle. A certain effort must be made in speaking: It seemed to us also that in the diatonic scale the voice lost a tone or a tone and a half in the upper notes without gaining in the lower ones. He found no difference in the pulse rate before entering the apparatus and while within it: If the effects of compressed air upon the animal organism do not appear during the whole time that one is subjected to it, at least during one shift of workmen, the same thing is not quite true if we try to consider subsequent effects .... Most of the workmen, although selected from the most robust and healthy, have frequently felt heaviness in the head or pains in the legs a few hours after leaving the caisson. Only one of them experienced complete paralysis of arms and legs for 12 hours. The superintendent of the mine assured us that the effects felt almost always coincided with some excess committed between shifts. (P. 361.) However, Blavier himself, after being subjected to the total pressure of 2.6 to 3 atmospheres, was attacked by a fairly severe symptom: 362' Historical The day after our visit of December 5, keen pains appeared in the left side, and we felt a rather severe painful discomfort for several days afterwards. Since a chill or some other cause not connected with the compressed air might have been acting, after we were quite free from these pains, December 28, we were anxious to try the experiment again, and when we left the shaft, we took the greatest precautions to protect ourself from any chill. In spite of these precautions, the next day, very noticeably at the same hour, that is, 20 hours after our exit from the medium of compressed air, we felt in the right side pains just like the former ones, which kept us numb for four or five days. (P. 362.) We now come to the important Memoir, the first written by physicians about these symptoms, in which MM. Pol and Watelle 1X recount the effects of compressed air upon the miners during the excavating at Avaleresse-la-Naville, at Lourches, in the grant of Douchy (Nord). The authors took care to warn the reader that since their notes were made without any intention of publication, they made their observations without plan, without program, and consequently without system. But they thought, and with good reason, that their work would nevertheless present some interest and some utility. During the exploitation, the total pressure rose to 4V4 atmos- pheres. The compression was made in a quarter of an hour, the decompression in a half -hour; 64 workmen took part in the work; they usually stayed four hours consecutively in the apparatus, twice a day. The authors described separately the physiological effects which they observed in themselves and the pathological effects experienced by the workmen: 1. Physiological effects: Pains in the tympanic membranes; slowing of the respiration and particularly a decrease in the amplitude of the thoracic expansion, which became hardly per- ceptible; slowing of the pulse, (from 70 to 55) ; increase of urinary secretion. The authors also mention a "muscular sensation of a resistance to be overcome, as if the unusual density of the ambient atmos- phere hindered movement; the inability to whistle, experienced above 3 atmospheres, is also attributed to an unexpected resistance, experienced by the muscles of the tongue in compressed air. On the return and during the decompression, they experienced a keen sensation of cold, a kind of panting; the pulse rose to 85. Pathological effects. Taking the observations as a whole, we Diving Bells and Suits 363 see that out of 64 men, 47 withstood the work fairly well; 25 had to be discharged; 2 died. Taking them in detail, we see that 14 felt slight symptoms, 16 more or less severe symptoms, sometimes even threatening life; 2 died. On the other hand, 2 benefited by a certain improvement. One (First category, obs. I) was asthmatic, and breathed better in the shaft; the other (Third category, obs. 3) chloro-anemic, having had frequent blood-spitting, found that his oppression /disappeared and his mucous membranes became redder: We see dawning, (MM. Pol and Watelle said in this connection) without concealing the difficulties of application, a new resource of palliative therapeutics in the treatment of most dyspneas. • The universal rule without exceptions was that the symptoms appeared at the time of decompression: The danger does not lie in entering a shaft containing compressed air; nor in remaining there a longer or shorter time; decompression alone is dangerous: pay only when leaving. Let us see now what these more or less serious symptoms are. They are, first, pains in the eardrum, more or less severe and lasting, and M. Pol states that they can be checked much more quickly by blowing one's nose than by going through the motion of swallowing. As for the other symptoms, as MM. Pol and Watelle had the good sense to give the complete observations, I think I cannot do better than to summarize each in a few words, following the order in which they presented them: First Category. Workmen on the Job from the Beginning. Observations. I. Asthmatic, breathes better in the shaft. On decompression, violent oppression with exaggerated circulatory re- action. Discharged. II. Went up to 4V2 atmospheres. Respiration hampered, decrease of appetite, indigestion, pains in the limbs. Stools dark. Lost much weight. III. Same effects. IV. Same. V. Did well up to 3 atmospheres. After that, dizziness, muscular pains, cramps or general numbness, vomiting of dark matter. All this on the return to open air. One day, an hour after leaving the shaft, having eaten, he com- plained of distress; when placed in bed, he lost consciousness. Pulse full and rapid, face congested, respiration short and stertorous; obscure sound everywhere, bronchial murmur, mucous rale; muscular reso- lution. Bled, purged, plastered. After four hours, return to conscious- ness. In three days, cured. Discharged. 364 Historical VI. Taken to 4V4 atmospheres without accident. One evening, after going to bed apparently well, at 11 o'clock seized by muscular pains accompanied by contractions like tetanus spasms. Skin cold, pulse small and slow, urine abundant and clear. Respi- ration uneasy; same results of auscultation as V. Baths at 32° so aggravated the pains that the patient could not remain in them. Friction, strong sudation, quiet. Recovered next day, back at work. VII. At a pressure of 3.3; cerebral disturbances, like intoxication with coma, hebetude, stuttering. Respiration accelerated, pulse rapid. Pupils dilated. Two similar attacks, cured one in nine days, the other in fifteen. Continuance of double vision and vertigo, with deafness oh one side. Discharged. VIII. Presented an excessive form of two common phenomena: 1. suppression of the functions of the skin and increase of the urinary secretion during the compression: 2. increased rapidity of the heart beats after decompression; his pulse rate rose from 58 to 130. IX to XVII. Nothing important to be noted. XVIII. Healthy and vigorous. Experienced repeatedly keen pains in the limbs and chest. Respiratory disturbances increasing with the pressure, as well as the muscular pains which were very acute. Was discharged. During the last days went down into the shaft without permission. Worked there without complaining; went out with his companions, washed himself like them, immediately fell unconscious and died in a quarter of an hour. Autopsy shows only obstruction of the lungs, congestion of the liver, the spleen and the kidneys; nothing in the brain except gritty congestion. XIX. Violent oppression with dullness on percussion and bronch- ophony; rapid pulse, cold skin, continual cough; clonic contractions of the limbs; more sensitive after five hours of treatment. Then, at another time, to these symptoms are added: dilation of the pupil, relaxing of the limbs, subdilerium, coma. Three bleedings in rapid succession; blood bright red on leaving the vein; cured. Dis- charged. XX. Same symptoms as VII. Also, remained deaf on one side, with vision much weakened. Discharged. XXI. One day, sight affected and double, hearing gone; respiration hampered, cough frequent, pulse hard and galloping. Blood red, recovered. XXIV and XXV. Nothing important. XXVI. Usual thoracic and cerebral symptoms; recovered after profuse sweatings. (P. 250 to 259.) Special Category of men who worked only one day and without preparation at 2.8 atmospheres. Nine men left the shaft without making any complaint. But shortly afterwards, eight experienced very severe muscular pains, which disappeared during the night, except in one, in whom they persisted several days. Diving Bells and Suits 365 Second Category. Workmen who worked only above 2.9 atmos- pheres. I. No effect. II. Only muscular pains in the left thigh, which yielded to cold water. III. IV. Nothing. V. Moderate muscular pains, but persisting from one shift to the next; recompression relieved them immediately. VI. Nothing. VII. 28 years old. Athletic. Pressure of 3.8 at the beginning. After 10 days, loss of consciousness, violent lockjaw. Rapid pulse. Reddish bleeding eight hours afterwards, purging, blisters. Two days after, consciousness suddenly returned: the patient opened his eyes, seemed to awaken from a dream, said a few aston- ished words. Recovers, but remains extremely deaf. Third Category. Workmen who began at 4.154 atmospheres. I, II. Nothing. III. Had previous hemoptysis. Improvement. IV, V, VI. Nothing, except rather severe muscular pains. VII. 40 years old. Very robust. Went down into the shaft only once. On coming out (decompression in twenty minutes) died almost immediately. Autopsy held 36 hours after death: generalized subcutaneous emphysema (existed before putrefaction began, the authors note) ; nothing in the meninges, in the brain, or the cerebellum; congestion of the lungs with generalized darkish tint (underlined by the authors) ; blood fluid and dark in the heart; liver, spleen, and kidneys congested. VIII. Nothing. IX. Moderate muscular pains. X. At his first trial, very severe muscular pains, persisting for several days. Discharged. XI. Same. XII to XIX. Nothing, except insignificant muscular pains. How- ever, they sustained the pressure of 4y4 atmospheres for three months. XX. At his first trial, too rapid decompression. A few minutes after his leaving the lock-chamber, looked like a corpse: face pallid, icy cold, eyes dull, pupils enormously dilated, respiration uneasy; on listening to the heart, heard only a vague quivering; pulse impercep- tible; perception gone; involuntary urination; dark vomit; complete loss of muscular power. Warm bath, blankets, friction. After a half-hour, the pulse begins to be perceptible, the respiration is deeper, a little warmth appears in the body; the patient stammers disconnected words. During the night, hardly has warmth been reestablished when acute pains appear in the muscles; keen pains in the head, blindness and deafness; wretched pulse, 50. 366 Historical Evident improvement two days afterwards; the patient sees vaguely. Vision remains weak and pupils are abnormally dilated. XXI. At his first trial, too rapid decompression. Severe muscular pains persisting for six days. XXII. At his first trial, too rapid decompression. Loss of con- sciousness, resolution of limbs; respiration embarrassed, pulse full, hard, 130. Bleeding blood red, blistering; after four hours, consciousness returns. During the night, cramps and muscular pains of terrible violence. Survives, but with great weakness of vision and extreme deafness. (P. 265-275.) I shall now quote the description of the complication whicch attacked M. Pol himself, because it contains the account of a very strange symptom, upon the importance of which we shall dwell later. The pressure undergone had been 3.48 atmospheres: At 11 o'clock, he reached his lodging; he felt keen pains in his left arm and shoulder; the walls of the thorax were also painful. It seemed to him that emphysema existed in these regions .... About midnight, he had a few chills, followed by vomiting. He took a cup of tea and went to sleep; soon abundant sweat broke out. The next day, he was in his usual condition. (P. 250.) In summary, the symptoms noted, at the time of decompression, are as follows: Respiratory difficulties, which may go as far as anxiety; Acceleration and hardness of the pulse; Muscular pains which are often very severe: "none of the effects of decompression appeared so general; sole symptom in many cases, it is the initial symptom in almost all .... It is the first and the largest link in a chain which includes successively, by ascending order of severity and descending order of frequency, non-permanent or clonic spasm, resolution, and finally sideration" (P. 227) ; Cerebral symptoms, dullness of intellect, loss of sensitivity and consciousness, coma. Deafness, blindness, very often permanent; Finally, sudden death. The reading of the observations abstracted above shows what a variety of form and intensity is presented by the symptoms, even for the same pressures, in different individuals, and sometimes in the same individual. MM. Pol and Watelle noted that young men from 18 to 26 resisted much better than mature men; out of the 25 who were discharged, 19 were more than 40 years old, and 5 were more than 30; the other was 28 years old. Diving Bells and Suits 367 These symptoms are attributed by the physicians of Douchy exclusively to pulmonary, hepatic, renal, or cerebral congestions. In the special chapter devoted to the enumeration of theoretical explanations, we shall see what theories of these pathological phenomena were given by MM. Pol and Watelle. I have wished to review at length their important Memoir, the first study of high pressures to appear, not only because of the numerous interesting observations reported in it, but also because truths of great importance are clearly revealed by it: 1. "Compression, up to 4%, atmospheres, is not dangerous in itself; it is endured very well and infinitely better than a rare- faction which is proportionately much less." Only the return to normal pressure is dangerous; its danger is proportional both to the amount of the compression and the speed of the decom- pression: the decompression must therefore be very gradual; 2. In compressed air, the venous blood becomes bright red. This effect lasts a short time after return to normal pressure; 3. We are "justified in hoping" that a sure and prompt means of relief would be to recompress immediately, then decompress very carefully; 4. Chlorotic or anemic persons and those who have respiratory difficulty will be benefited by a stay in air compressed to a variable degree. During the work at Douchy, an explosion occurred at a time when the total pressure was 3.20 atmospheres. It was the subject of a report by M. Comte,12 chief engineer of the mines. Eight men were in the apparatus at the time; four were crushed to death; two others, after beginning to climb the ladder to leave the cylin- der, let go of it, without anyone ever being able to find out why or how; a seventh workman felt no ill effects; the eighth, who was overtaken by the water, also managed to escape. In regard to him, M. Comte suggests a strange and interesting hypothesis, interesting because it shows how easily the best minds go astray in these questions: Perhaps he found some help in rising above the water .... in the specific lightness given him by the compressed air with which certain parts of his body were still more or less filled. (P. 130.) The new method quickly became general. Other shafts were sunk, and data similar to those reported by MM. Pol and Watelle were observed. That happened, for instance, according to the report of Bouhy 13 in the mine of Strepy-Bracquegnies (Belgium) : 368 Historical At Strepy-Bracquegnies, all the laborers, except one, who worked in air compressed to 3.70 atmospheres, and from 4 to 5 hours conse- utively, were attacked, after leaving the apparatus, by more or less acute pains .... These pains, the seat of which was chiefly in the articulations, such as the knees, the shoulders, and the joints of the arms, appeared in certain persons so severely that they sometimes went more than forty-eight hours without being able to sleep .... It was noted that some laborers who had had rather severe attacks and who had gone down to work were completely relieved of pain as soon as they were in compressed air, but that the pains came on again some time after they had left the apparatus. Besides these effects, the author again mentions unpleasant sting- ing over the whole surface of the body and especially on the ex- tremities. But compressed air is used chiefly on the foundation of bridge piers, and it is under these conditions that hundreds of workmen are exposed to its effects every year. It is therefore of interest for us to explain briefly the mode of application of the Triger method in this particular case. Figure 6 will permit us to be very brief in our explanations; it is a cross-section which we borrow from the memoir of Dr. Foley, which will be reviewed later. A cast-iron tube MM composed of concentric rings fastened together by bolts m, and ending at the bottom of a widened cham- ber or "crinoline," is let down upon the bed of the river in the spot which the bridge pier is to occupy. It is topped at its upper end by a room with 3 compartments; the one in the middle, F, is in constant communication with the cast-iron tube; a blowing machine, through a tube G, constantly pumps into it air which is sufficiently compressed to drive all the water out of the cast-iron cylinder, and escape constantly bubbling all around; the bottom then becomes dry, as happens in a glass tube into which a child blows after immersing it in water. Under these conditions, the workman who is coming to work opens the door of one of the lateral chambers, E, and closes it behind him, and by a cock communicating with the central cham- ber F, equalizes the pressure of the air about him with that of the air in the cylinder. When this has been done, he easily opens the inner door, hitherto held shut by the pressure, and goes down to the bottom of the shaft by a ladder. There he works and fills with the earth which he digs out buckets which are hauled up and emptied outside. Does he wish to leave? He goes to the other lateral chamber C in which the air has remained under pressure, goes in, closes the door, and by a cock communicating with the Diving Bells and Suits 369 exterior allows the excess of compressed air to escape. He can then easily open the outer door and leave the apparatus. Fig. 6— (borrowed from the thesis of M. Foley). Diagram representing the construction of a bridge pier by caissons with compressed air. As the work progresses and the excavation becomes deeper, the cast-iron tube sinks of its own weight and that of the masonry nn in which it is loaded; then more cast-iron rings are superposed 370 Historical until the digging is finished; then there is nothing more to do but fill the whole cylinder with masonry and the pier is finished. It is by this method, which is so simple and yet which is much more complicated in practice than the preceding description seems to indicate, that a great many bridges have, been constructed since 1851. The idea of this application of his system of drainage to the foundation of bridge piers belongs to M. Triger 14 himself. But this idea was not put into execution until 1851, by an English engineer Hughes, in the construction of the Rochester bridge over the Medway in the county of Kent. An engineer of French descent, Brunei, constructed by this system the bridge of Chepstow, over the Wye (1849-1851) and that of Saltash (1854-1859) ; for the latter, the maximum depth reached was 26.68 meters below high water. Only in connection with this one did a fatal accident occur; a man died on leaving the cylinder in which he had remained a very short time. I could not get detailed information on these facts, however. In 1856, M. Cezanne 15 was charged with the construction of a bridge at Szegedin (Hungary), to permit the Austrian railroad from the south-east to cross the Theiss, a tributary of the Danube. He used the system of caissons with compressed air. The work of excavating was "stopped at about 20 meters below high water, so as not to expose the men to the pressure of 3 atmospheres, beyond which work is very difficult." (P. 355) A special section of the memoir of my regretted colleague is devoted to the study of the physiological effects of compressed air: There are three phases to be distinguished: the entrance, the stay, and the exit. When the cock admitting the air is opened, the ears are immediately attacked by a violent buzzing accompanied by pains the intensity of which varies with the individuals .... The stay at the bottom of the caisson, in a pressure of three atmospheres, may be prolonged for several hours without ill conse- quences; the tone of the voice is somewhat impaired, and the respiration hastened as if by rapid walking; if a cigarette is waved about, it burns with a flame; candles burn rapidly, but with smoky flame The time of exit, though not very painful for the great majority of individuals, is the most dangerous for the workmen .... Sometimes there is an issue of blood from the nose and the throat; some persons experience violent, but brief neuralgia; others have headaches and toothaches for several days Laborers who usually work in the caissons look ill; however, they resist the ill effects very well. (P. 369.) Diving Bells and Suits 371 December 12, 1859, there was an explosion at a bridge pier at Bordeaux, and consequent instantaneous decompression; seven of the laborers working there felt no ill effects. Two were killed, but by purely mechanical causes. M. P. Regnauld,1" who gave a report of the work, does not say at what pressure this accident took place, but we conclude from his Memoir that the caisson at that time had certainly been sunk more than 12.90 meters, (p. 82) In 1859, the bridge of Kaffre-Azzyat was built over the Nile: the piers were excavated to a depth of 26 meters below the water. Five Arabs died from the effects of the pressure: one in the cage, as he was leaving, but before he had reached the open air; the pressure was 36 English pounds per square inch.17 The others felt ill in the caisson and died during the decompression; the pressure then was more than 30 pounds. Blood issued from their mouths, noses, and ears. The Memoir of Babington and Cuthbert,1* from which I have borrowed the preceding data, is particularly devoted to the medi- cal study of symptoms observed during the laying of the founda- tion of the bridge of Londonderry, in October, 1861. The depth reached was 75 feet below water level: The pressure sustained by the laborers was, at the maximum, 43 pounds per square inch, in all. They suffered from pains in the ears, headaches, pains in the legs, nosebleeds, and general distress. These symptoms increased greatly when the cocks were opened wide and the change in pressure was therefore too rapid .... These symptoms appeared first when the men entered the compressed air; but they were much worse when the change was made from the caissons to the open air: serious, even fatal, symptoms appeared then. I am copying in abridged form the six observations of the au- thors: I. October 3, 1861. Man 28 years old, who had worked four hours under a pressure of 23 pounds; when he came out, he fell unconscious. Cold and livid; total insensibility, facial paralysis on the right side; strabismus of the right eye; pupils almost motionless; pulse 150, small and irregular; heart sounds hardly perceptible; respirations very irregular, 24 to 44 per minute; inspiration abrupt, expiration pro- longed. Bleeding: blood dark, viscous and sticky .... Died 24 hours after leaving the cylinder. II. Case absolutely similar, occurred at the same time .... Died also in 24 hours. III. 23 years old. When we visited him, he was completely pros- trated, but was conscious, and complained of pains in his legs and thighs. Unable to walk, hands and feet cold and without sensation. 372 Historical Was seated with his feet in the fire, so that several of his toes were burned without his feeling the heat. He had not become sick immediately, and as he had had pains in his legs for days before, he had not called the doctor until several hours after leaving the cylinder. Two days afterwards he was cured except for his burns. IV. Similar case. Hemoptysis. Cured. V. 18 years old, October 3. Four hours under pressure; fell unconscious while being decompressed .... In a semi-comatose state, responded when stimulated and fell back into unconsciousness. The symptoms of coma passed in 18 hours; he was then totally paralyzed from the fourth rib. Retention of urine, loss of sensation, and other symptoms of diseases of the cervical medullary region. Died in the hospital 162 days afterwards; never regained sensi- bility or movement. VI. 30 years old. Identical symptoms; except that the paralysis began only with the eighth dorsal vertebra. Lived 30 days. Many other cases of slight paralysis, muscular pains, and other nervous affections were also observed. Unfortunately no autopsy could be made. We shall see later the explanation which the two English physi- cians gave of these data. In 1859, a work of the greatest importance, the bed of the piers of the bridge from Strassburg to Kehl, was carried out with the use of compressed air. Two interesting Memoirs, one more 'par- ticularly pathological, the other more physiological, reported to us the sensations felt, the phenomena observed, and the symptoms which appeared. The first in date is that of Dr. Francois; 19 we shall discuss that one first. The author begins by describing briefly the apparatuses used in the construction of the bridge. One shift lasted four hours, and there were eight hours of rest between shifts. The total pressure rose to 3V2 atmospheres. According to the rules, the decompres- sion should have taken from 6 to 8 minutes up to 2 atmospheres; from 12 to 15 minutes up to 3 atmospheres; but the carelessness of the laborers almost always prevented strict carrying out of this rule. Physiological effects. Easier, less frequent respiration; greater expansion of the chest, "which explains itself;" circulation accel- erated during the compression, then slowing at the time of the return to open air; perceptible loss of weight, even in the work- men who had no pains. The author does not give much time to these data, and says that they will be discussed in the work of M. Bucquoy which we shall review presently. Diving Bells and Suits 373 Pathological effects. These are first earaches and inflammations of the ear, after which the hearing often remains much impaired. Then pains in the muscles or the joints: there were 133 cases of this sort. They disappeared after a few days. Sometimes there was a rather evident local swelling, but without crepitation. In one of the cases, the left breast of one of the workmen suddenly swelled so as "to resemble the well-formed breast of a woman;" this painful swelling quickly yielded to the application of cupping- glasses with scarification. (P. 307.) In another case, the patient was left unable to use his left leg. M. Francois also mentions as frequent the itching of the skin, fleas, as the workmen call it; it yields, he says, to washing with cool water. He explains, by congestions about the lungs, the heart, the liver, and the spleen, some rather vague symptoms, in which suffocations, palpitations, etc. are involved; one of the patients, who was, more- over, subject to hemoptysis, died a few months afterwards. Finally, the violent headache and the loss of consciousness are attributed to a cerebral congestion; these congestions began only after a quarter or a half an hour. In one of these cases, the work- man, who left the caissons (3 atmospheres) without experiencing anything but a very uncomfortable prickling over the whole body, walked to the citadel with a nimble step; when he reached there, he fell as if struck by lightning: repeated bleedings, purgings, etc.; he recovered, except for a considerable weakness of the lower limbs for a rather long time. This brings us to the description of some functional lesions of the spinal cord: retention of the urine, violent pains in the limbs, and, for one patient, paraplegia persisting on the left side; the pressure was 3 atmospheres. Let us finally say that slight nasal and even pulmonary hemorr- hages have sometimes been noted. I mention only for the record a work of M. Willemin,20 which is only a simple report of that of M. Francois, all of whose conclu- sions the author seems to accept, for he does not give any attention to the theoretical explanations. The thesis of M. Bucquoy LM is, on the contrary, an original work of real importance. His observations, as I have said, were made at the time of the construction of the bridge of Kehl. At the beginning of his exposition we find a bit of information from which we shall perhaps later derive some profit, namely, that the air in the caissons in which the laborers were working 374 Historical contained on the average (six analyses at different periods) 2.37% of carbonic acid. Reaching the study of the physiological phenomena, M. Bucquoy first describes the pains in the ears. In regard to the circulation, he gives the following table: Number Pulse Pulse of in the during the different periods Increase Observations open air of the compression 10 77.85 While the air was entering 100.05 22.20 9 77.08 After a quarter hour stay 90.12 13.04 7 75.39 After 25 minutes 86.80 11.41 28 76.05 After a half-hour 81.57 5.32 11 76.59 After 1 hour 83.58 6.99 3 76.50 After 2 hours 83.30 7.00 So, in compressed air, the pulse rate is higher than in open air, and that is true for all degrees of pressure and especially up to 2Vz atmospheres. M. Bucquoy, who states here that he disagrees with the authors who observed the patients, adds: I have, nevertheless, one observation which seems to confirm what M. Pravaz says as to the sedative effect of compressed air. One of my friends, M. Ritter, who went down into the caissons with me in spite of a very high fever, found that his pulse fell from 95 to 75 after an hour's stay. (P. 24.) The respiratory capacity also increases, as Pravaz had already said (see the following chapter) ; the following summarizing table gives the average measurement of this modification: Number of Time Respiratory capacity Observations when they were made in cubic centimeters 103 10 minutes before entering the lockchamber 2950 103 After a halfhour stay in compressed air 3224 103 A quarterhour after return to open air 3075 10 After three quarters of an hour 3004 10 After 2 hours 3000 10 After 10 hours 2980 10 After 15 hours 2950 So the increase, which is constant, and which, as other tables show, keeps growing up to 2 atmospheres, persists for a fairly long time after the decompression. So M. Bucquoy adds with reason: Showing that this effect is not passing, that it does not cease with the compression, my experiments make us anticipate the efficacy of treatments of compressed air for patients whose vital capacity is too small. (P. 29.) Diving Bells and Suits 375 In regard to the general phenomena of metabolism, M. Bucquoy, after analysing all works preceding his and showing their contra- dictions, at least apparent, declares that he: Is inclined to believe that in compressed air the respiratory com- bustions increase; but the bases on which they have tried to establish this idea lack solidity, and the question must be re-examined. Dr. Foley 2L> has written an odd pamphlet on our subject, which is often quoted and praised. He had observed the symptoms of the caisson-workers at the time of the construction of the bridge of Argenteuil over the Seine in 1861; the maximum pressure had not gone above 3V2 atmospheres. I shall begin by quoting a few of the most characteristic passages in which M. Foley describes and at the same time explains the phenomena experienced in com- pressed air: In the caissons all sounds have a metallic tone which shakes your brain; and when one speaks, he makes the base of his skull vibrate as a trumpet would do. Let us explain these phenomena. By flattening all of our mucous membrane which is exposed to the air, the compressed air makes" our pharyngo-laryngial and bucco-nasal cavities larger and more sonorous through the bones. Moreover, for the vibration, it gives to the edges of the larynx, the tongue, the lips, the soft palate, and even the nostrils, tensions which are greater in proportion to the increase in its density. We must therefore not be surprised that all these organs raise the pitch of the sounds which they produce .... Because of the weakness of our lips, we all lose the power to whistle in compressed air. Some persons feel that taste and the sense of smell are weakened or entirely lost in compressed air. The flattening of the mucous membrane which is exposed to the air, which makes impossible any hemorrhage of the respiratory tracts and cures suddenly (though not without pain) coryza and hoarseness, explains all these data perfectly. How could a withered, shrivelled organ collect any savors? Our skin is more substantial than our mucous membrane; in spite of that the caissons affect it. Its papillae, like those of the nose and tongue, become less sensitive, and many workmen, whose hands, how- ever, are very callous, find their sense of touch less sure in compressed air ... . In this same medium, our pulse soon becomes filiform and even imperceptible. The venous pressure soon fails, our circulation flags, but our tissues do not become livid; the contrary is more likely to take place. That is because the great tension of the air, favoring the combin- ation of the oxygen with the blood, as with all the other combustibles, makes it so rich that it comes out of our veins as ruddy as out of our arteries. What loss of color would be possible with such a liquid? 376 Historical In compressed air, our pulmonary capacity increases, and the movements of our ribs lessen. The excessive pressure which dissolves the oxygen in our finest vasculo-sanguine ramifications makes the action of the thorax unnecessary, and for this reason, our coordinating nervous center reduces it to its minimum of amplitude. Economy of strength and time, such is the law which the human spirit follows in the numerous combinations which it makes to keep us in harmony with the world, even when it is a matter of our vegetative life. The laborers, when they are working in the caissons, feel fatigue less than in the open air, and do not become so breathless. Hunger seizes them quickly; they sweat a great deal and yet are never thirsty. This is the reason for all these phenomena, which are contra- dictory only in appearance. The absence of thirst, in spite of enormous loss by sweat, is the result of the great quantity of water which the compressed air holds in solution and forces into the organism. The sweat is due to the assistance which our outer tegument never refuses to the lungs, especially in a warm atmosphere, when it is a matter of throwing off much of the muscular materials broken down by work. Hunger results from the enormous consumption of our various tissues by the excess of oxygen which penetrates them and by the more energetic contractions of some of them. The lessened breathlessness is caused by the circulatory slacken- ing which brings back (towards the lungs, the liver, and the spleen) only a very little venous blood, since there is hardly any, to tell the truth. Finally, the absence of fatigue results precisely from the richness of this same nourishing liquid, which unceasingly repairs our muscles at the same time that their own contractions destroy them. In compressed air, our secretions are modified; those of the lungs and the skin increase considerably. Those of the alimentary canal, the kidneys and the liver, their converse in many circumstances, do not change, or rather, generally diminish. (P. 12 and 13.) When leaving the compressed air, when no illness is to follow, one immediately has a feeling of comfort. It seems as if one breathes as if in spite of himself, that one's chest is full of air, and that one is lighter. That is because there is no longer the heavy weight upon you. (P. 17.) Such are the effects produced by the passing action of com- pressed air. According to M. Foley, the workmen who are frequently subjected to it experience phenomena of another sort: Any too long period of work within the caisson is divided into two stages: one of benefit, the other of organic loss .... As long as the first lasts, the caisson worker has an increased appetite, leaves his work without fatigue, and returns to the open air more alert, more lively, and more eager than usual. He feels stronger and boasts of it with reason, for then the richness of his blood profits him. Diving Bells and Suits 377 As soon as the second begins, the contrary takes place. The work- man loses appetite, and, more and more, reaches his work as he leaves it, melancholy and tired. His skin becomes flabby, loses color, be- comes almost clay-colored. The conjunctiva takes on a wine-colored hue. His gaze is dull. His face and body grow thin. Indecision, dis- taste for movement, stupor almost, appear in all his motions, and gradually the time comes when, outside the caisson, he seems to have lost strength; when the normal atmosphere is no longer sufficient to aerate his blood. In the compressed air, all these painful symptoms disappear; unfortunately they reappear as soon as he goes out, and more and more quickly too. Soon even the excess pressure fails to revive him. He is then on the point of being able to regain the strength he loses, every time he works, only by the intervention of morbid phenomena. (P. 18.) So much for the purely physiological phenomena. As for the symptoms, the fleas, or excruciating itching of the skin, hardly ever begin to appear before the pressure of 2.5 atmospheres; be- yond 3 atmospheres, "everyone has them;" the muscular swellings (sheep) are frequent at about 3 atmospheres, as are the "synovial swellings;" but the joints themselves are attacked only later and more rarely. The muscle symptoms affect particularly those which have been tired by repeated contractions. The number of days during which the laborers have worked in the caissons seems to M. Foley a very important consideration; under an almost equal pressure, the symptoms would become more and more frequent and severe the longer one worked. No fatal ending or paralysis, however, has been observed at Argenteuil. The most serious symptoms are muscular pains, which, judging by the details of the observations, seem to have been of extreme violence. M. Foley disagrees with all the other authors on two main points, which are of the highest practical importance. According to him, in the first place, when the workmen prolong their stay in the caissons beyond 12 hours, they come out without harm: that results, he says, from the fact that "the nervososanguine reaction is general" (p. 49) ; but this so-called explanation is of little im- portance. In the second place, curiously enough, he considers that the speed of the decompression is of little importance. One minute per atmosphere of compression seems to him long enough: For pressures above 3V2 atmospheres (decompression in 2 min- utes 30 seconds), would it be necessary to follow the same progres- sion? I do not think so; two and a half minutes are a long while in an icy lock-chamber. (P. 56.) 378 Historical If one is to use these high pressures, M. Foley advises that the men be decompressed in "three minutes." Furthermore, he is so far from the idea that a rapid decompression can be dangerous, and so persuaded that it is merely a matter of chilling, that he summarizes his thought by this precept: If the thick and icy mist which is sure to appear seems too pene- trating to you, make haste! (P. 53.) Constructing foundations by the use of compressed air was used in 1862 on the viaduct over the Scorff, at Lorient, and in 1864, on the bridge over which the railroad of Napoleon-Vendee crosses the Loire at Nantes. The chief engineer Croizette-Desnoyers,23 who gives the most minute details about the construction and the operation of the apparatuses set up by the Gouin Company, does not mention the condition of the workmen; he is satisfied with admitting that "at great depths, the system of laying foundations by the use of compressed air may injure the health of the work- men." (P. 392) And yet serious accidents had occurred at the bridge over the Scorff. The list of sick workmen, drawn up by Dr. Nail, contains 16 names; the accidents, all due to the compressed air, include: 1 case of deafness, 6 cases of pains in the joints, 1 of muscular pains, 6 cerebral congestions, 2 deaths. The two deaths were not simultaneous. The first occurred March 17, 1862; the workman died "of asphyxia on leaving the caisson;" the second, June 3, in another pier; the medical note says: "died after four hours of cerebral congestion and asphyxia." I could get no details about either the symptoms which pre- ceded death or the results of the autopsies, if there were any, or even the pressure reached. I know only that the decompression was made regularly in 10 seconds and that the maximum exca- vation for the first pier was 18 meters, for the second only 12 meters. There were, therefore, 8042 shifts of workmen, among whom there were only 16 accidents serious enough to be noted. Other workmen who were in the lock-chamber with the two victims experienced no symptoms. This double disaster was the cause of a court summons against the company officials, accused of homicide by carelessness; they were acquitted by the court of Lorient (September 30, 1862) and by the court of Rennes (December 11, 1862). The preambles of of the judgment and the decree are very interesting, because they Diving Bells and Suits 379 reveal the vague ideas of the doctors about the real cause of the accidents, and these uncertainties inspired the acquittals given: Another accident, followed by another court instance, took place at the bridge over the Scorff. M. Gallois, civil engineer, an agent of the company, who went down into the caissons May 12, 1862, on his return to open air was attacked by symptoms of paralysis "as a result of cerebro-spinal congestions, spells of dizzi- ness, and nervous shocks," so that he had to be sent to a watering- place; he died two years afterwards. His request for damages was refused by the tribunal of the Seine (August 18, 1861); the Orleans company produced an opinion of M. Dufaure, which reveals, like the legal documents which I mentioned a moment ago, the uncertainties of medical science. The celebrated lawyer combats the opinion of Pol and Watelle about the necessity of making the decompression very slowly with that of M. Foley. The tribunal gave no decision as to the scientific question, but declared that Gallois had not received an order to go down into the caisson, and that consequently the company could not be held responsible. Here is the condition in which Dr. Hermel,"4 a homeopathic physician living in Paris, found M. Gallois, who had him called in consultation a few days after the accident: May 21, 1862, we were called in Paris in the case of M. Gallois, a civil engineer, aged 24. We found the patient suffering from incom- plete paralysis of the lower limbs, permitting him neither to stand upright nor to walk without support; he could advance only in a very awkward manner, placing both hands on all the surrounding objects; the movements of his limbs were irregular, jerky, trembling; he dragged his feet; if he tried to stand upright, a violent trembling immediately shook his legs and forced him to sit down. After three or four steps, the same convulsive trembling stopped him, because it kept increasing and would have made him fall. Over his whole body cutaneous sensitivity was exaggerated, it was hyperesthesia, the skin was the seat of an annoying pruritus, without any trace of an erup- tion. The movements of the tongue were so difficult that the patient could not pronounce all the words distinctly. Both memory and ideas were confused. As a result of the suffocation, a frequent cough tired him when he talked and produced a profuse expectoration of mucus with the appearance of the white of an egg. Auscultation of the chest and percussion showed that the lungs, though permeable to air in their whole extent during deep inspirations, did not possess their full elasticity; one could hear, especially on the left side, the expansion of the pulmonary vesicles beginning and stopping suddenly before the movement of inspiration was finished. This expansion of the pulmonary vesicles was therefore incomplete, which hampered normal respiration. The abdominal functions were interrupted; the 380 Historical constipation could be overcome only by enemas; there was paralysis of the rectum. The bladder was also paralyzed; urination could take place only by use of the catheter. He had lost appetite, and the cough often caused vomiting. Knowing the perfectly regular life of this young man, we asked him about the date and the mode of onset of this disease. He told us that while he was employed at the railroad works at Lorient, he had gone down into a caisson under a pressure of three atmospheres (including the outer pressure), where he had remained three hours to check the progress of the work in the foundation of a pier. Three or four minutes after his exit, he felt an icy cold, sudden and penetrating, as a result of the enormous rarefaction of the air in proportion to the inner pressure. When he tried to wash his hands, he perceived that movements of the arms were impossible, he could not put his hands into the tub because he could not lift them higher than his waist. Taken home by two men who supported him under the arms and placed his feet on the steps he had to descend, he went to bed; after four or five hours he wished to get up, but he was completely paral- yzed. An energetic treatment was given him and made him able to come to Paris after a fashion. On the tenth day he was in the condition which we described above. For ten days we gave belladonna (twelfth) and bryonia, which checked the cough a little. June 2, we began to apply every other day the rheophores of an electro-galvanic machine over the hypogastrium, to overcome the paralysis of the bladder. After the third treatment, he began to urinate without the catheter, but the next day, he was forced to have recourse to it again. After the fourth treatment, he urinated voluntarily only during the day. After the fifth, the urine resumed its natural course. The constipation persisted. We electrified the walls of the abdomen and the anus. Defecation, although some- times difficult, was reestablished about the eighth treatment. After the tenth treatment, the abdominal organs had gained strength and activity, especially on the left. The right leg was still dragging, and in certain positions it was still affected by convulsive trembling; he could not have stood up on one leg; he used a cane in walking. In July, he went to the baths of Balaruc, from which he returned August 1. His condition was improved, but there was still a faltering in the right leg. The cough persisted, although not so bad; respiration was still incomplete. Soundness of speech, ideas, and memory was reestablished. He no longer experienced pruritus or hyperesthesia of the skin. Six more applications of electricity caused a great im- provement in the movements; he could walk without support. Today, January 12, that is, after eight months of treatment, he has at times tiring fits of coughing; his respiration is almost normal, he becomes breathless if he walks too far or too quickly. He walks without support, but there is still stiffness in the right leg, and we cannot say when he will be completely cured. (Vol. XVII, p. 198-200.) Also in 1862, a bridge was constructed over the Adour, in Bayonne, in the construction of which the pressure had to be Diving Bells and Suits 381 raised to more than 4 atmospheres. The civil engineer who super- vised the work, M. Counord, twenty years old, who up to that time had felt no symptom, on December 31, a few minutes after leaving the lock-chamber, in which the decompression had been made in 4 or 5 minutes, was attacked by vertigo, dizziness, and complete loss of consciousness. The pressure was 4 atmospheres, the length of the stay in compressed air was one hour; the day before, he had remained in the caisson for two hours. Three hours afterwards, when he regained consciousness, he was completely paralyzed in both sensation and movement in the lower limbs, with loss of sensation in the arms. The detailed observation of the beginning of this strange case was given by Dr. Limousin,25 of Bergerac, who does not hesitate to attribute the symptoms to a hemorrhage of the spinal cord: I called upon M. C, who had been brought from Bayonne to Bergerac, on January 12, 1863: complete paralysis of the lower limbs, involuntary excretion of the feces! and urine, normal sensitivity everywhere, a little exaggerated in the lower limbs; if they were" struck suddenly, or touched with a cold body, a sudden extension was produced. Intelligence normal. In the epigastrium and the hypo- chondria, pains which were checked by the application of morphine on the bare skin. Up to January 20, two doses of cathartic were given; nothing new appeared except very painful convulsive movements of the abdomen. January 28. Excruciating pains appeared yesterday in the belly; it is flaccid, pressure does not change it. The patient's condition is terrible: constant moaning, voice faint, cold sweat, face cadaverous, pulse imperceptible, 48. Dry cuppings, enemas with laudanum have no effect. I then prescribed 20 centigrams of extract of opium in four pills, one every hour. On January 29, with the second pill, the pains stopped; the patient fell into a profound sleep; he awoke quite free from pain. In the first few days, a small erosion had formed on the sacrum, today there was a huge scab; the buttocks, and the lumbar region were dull red; the patient could lie only on his back. February 20. The sore on the sacrum, sprinkled with gray cinchona bark, has shrunk to the size of a 5 franc piece; it is pink and granu- lated; painful contractions have yielded to the application of metallic armatures. Movements can be made by the paralyzed limbs; they are executed more freely on the right side; on the contrary, sensitivity is very dull on the right, and keener on the left side in the same parts; there are formications over the whole body; one day sight was entirely gone for a few instants; erections, rare at first, have become more frequent. Finally defecation and urination are voluntary. It is hard to find a better example of medullary apoplexy: sudden attack, lesions of contractability, sensation, a special sense, and the eye; reflex movements caused by the slightest stimulus; great lowering of the vitality of the tissues, manifested by the rapid mortification of 382 Historical the regions sustaining the weight of the body; finally, erections not accompanied by any stimulus of the genital impulse. There was never any considerable sensitivity along the spine. The improvement did not make very rapid progress. In May, 1870, M. Counord took several steps without support; he still had very unusual reflex movements when his lower limbs were pinched; the sensitivity of the left leg was much diminished. I saw him again in May, 1876; he could climb one flight of stairs with great difficulty and with the aid of an arm; formications in the upper limbs seemed to indicate a morbid action in the upper regions of the spinal cord; the functions of urination and defecation had become normal again. A few days later, a terrible accident, in which three men died, saddened the Bayonne works; the caisson had burst, as happened at Douchy, and later at Chalonnes. The suggestion 26 was made that the death of the workmen had been caused by the decom- pression; that is probably a mistake, as is shown by the following extract . from a letter written me by the engineer Bayssellance, who was kind enough to make a little investigation of the matter, at my request: The pier, being deeply imbedded in the sand, measured in all more than 30 meters from base to the water level. The inner pressure, therefore, was about 4Vi atmospheres. The upper surface, not being constructed with a view to such a high pressure, buckled perceptibly: this buckling caused a deformation of the cast-iron cylinder of the equilibrium chamber. One of the bolts having yielded to the uneven tension, a shock was produced which made the whole upper part of the equilibrium chamber fly to pieces. The decompression in this small portion of the apparatus was therefore sudden; in the interior of the pier, the capacity of which was 200 to 300 cubic meters, it must have been more gradual, and brought a violent current of air upwards from below, bringing with it the planks and the sand of the resting stages. According to the foreman, the results were quite different from what was reported. No man was killed by the change of pressure. Since the wet sand from the bottom was no longer restrained, it rose rapidly, reached and passed over one of the men who was climb- ing the ladder; he was found seventeen days afterwards when the caisson was being cleared out, clinging to the ladder rungs in the position of climbing. Another was carried away by the air current and found himself at the top without really knowing what had hap- pened to him. Two others who were on the intermediary stages were carried up and crowded against the under side of the floor of the equilibrium chamber, and were almost suffocated, with their mouths full of sand; they were taken to the hospital, and died the next day, I think. Finally, five men who were in the equilibrium chamber itself Diving Bells and Suits 383 were covered with sand, which even penetrated the skin, and remained for a few moments as if stupefied, but none of them was seriously ill. This result does not agree with what had been told me; but M. Wolff was on his rounds at the moment of the accident; and M. Counord was ill; it seems more certain to trust the version of a witness though it is almost the opposite. Moreover, this man was present at a similar accident, at the time of the construction of the bridge of Bordeaux; there too, no death was caused by the sudden decom- pression; two men only were killed by fragments of iron. But if a sudden decompression of more than three atmospheres was not fatal, this change, though moderated by a stay of 4 or 5 minutes in the equilibrium chamber, was none the less dangerous in the long run. According to M. Counord, 90% of the workmen were ill, all attacked by violent pains in the joints, oppression, disturbance of vision, etc. The foreman whom I saw was attacked three times, and suffered greatly, but never more than a day. One morning, out of eleven men who were leaving, nine were seized with pains after a few moments. Certainly it is not impossible that the decompression had some- thing to do with the death of the two workmen who were buried in the wet sand; but that is not proved. The strangest thing in this observation is to see men experiencing almost no symptom after an instantaneous decompression from at least 4 atmospheres. In 1865, there was a similar foundation under the Louet, at Chalonnes (Maine-et-Loire) , for the bridge of the line from Angers to Niort. A catastrophe as yet unexplained killed two workmen: February 20, 1865, when pier number 2 had reached bed rock, at a depth of 14 meters below the low-water mark, when everything seemed finished, when the work-chamber was already filled with concrete, and when the caisson, like a chimney, was also filled up to a depth of 5 meters, suddenly a violent explosion occurred and half of the metal roof of the equilibrium chamber " was hurled about 30 meters away. Two laborers, who were in the work-room, were crushed. No explanation for this terrible accident has yet been found. (Lectures on Bridges by M. Morandiere) It is probable that in this case, for some unknown reason, the tension of the compressed air had risen far above that required by the depth reached; the force of the explosion proves that. I am endebted to Dr. Gallard for some interesting details about this distressing accident: The death of the two workmen (this learned colleague writes me) was almost instantaneous, like a thunderbolt for one of them, a little slower for the second, who still breathed for a few seconds, but had already lost consciousness. The autopsy (made by M. Gallard under bad conditions, after exhumation and previous autopsy by the physician of Chalonnes) 384 Historical showed numerous patches of interlobar and vesicular emphysema on the lungs of the two victims. There were besides numerous ecchy- moses in spots under the pleura and the pericardium .... I seem to remember that the blood .... contained a few bubbles of gas .... The notes of the autopsy were lost by the physician of Angers to whom I had dictated them. Should we attribute the death to the decompression? It is hard to decide, in view of an unsatisfactory autopsy and especially the fact which we reported above in discussing the bridge of Bayonne. M. Triger was disturbed by the accidents caused by the appli- cation of his method, and sent to the Minister of Public Works a Memoir on this subject, which was submitted to the examination of MM. Combes, Hennezel, and Feline-Romany. The report 2S of these engineers, after briefly reviewing the works carried out by the Compagnie du Midi over the Tech, at Bordeaux and Bayonne; by the Compagnie de l'Ouest at Argen- teuil, at Elbeuf and at Orival over the Seine, at Briollay over the Loire; by the Compagnie d'Orleans over the Scorff at Lorient, over the Louet at Chalonnes, and over the Loire at Nantes, states that: The accidents to which laborers working in compressed air are exposed rarely endanger their lives, cause only rather short inter- ruptions of work, and, especially, are very few, compared to the number of men passing through the lock-chambers in each job. The diseases caused by these accidents can be prevented by the use of the means specified in the course of this report. These means are the use of woolen garments in the lock- chamber and a decompression for which no uniform rule could be given: There is no rule to be observed other than the one which common sense indicates, namely, not to open the cock too quickly, for com- pression as well as for decompression, so as to give the organism time to place itself in equilibrium with the medium in which it is immersed. M. Triger requires that the decompression last 7 minutes, and states that then the symptoms disappear completely. It seems to us that this time should vary with the constitution of the workman. (P. 125.) The excavation of the shaft of a coal mine at Trazegnies, in Belgium, at about this same time, was the subject of a very inter- esting work by M. Barella.29 The total maximum pressure was 3V2 atmospheres. The decom- pression was made in about 20 minutes. According to M. Barella, in addition to pains in the ears one experiences: Diving Bells and Suits 385 Dryness of the pharynx, a considerable decrease of the urinary secretion, a sensation of respiratory improvement, for it seemed to me that I had never breathed so freely, and so easily. As for the pulse, we did not obtain a very definite result; how- ever, in most of our workmen, it seemed to us that the rate had de- creased by a few beats. (P. 598.) The symptoms observed were: 1. In seven workmen, epistaxis, not serious; 2. In eleven workmen, pains in the thoracic and abdominal members, sometimes crushing, lancinating, excruciating. 3. Severe itching on the legs, unaccompanied by pain, a very fre- quent symptom. (P. 605.) M. Barella calls attention to the fact that none of these symp- toms occurred during the stay in compressed air; they were ob- served only when the workmen were leaving the apparatuses. Moreover, they began to appear only above 2.8 atmospheres. M. Barella says that the little wounds which the laborers inflicted on themselves while at work did not bleed, "which is explained by the pressure on the cutaneous teguments." A student at the School of Mines of Liege, who went down into the shaft April 15, experienced' on his exit very serious symp- toms, which he describes himself in the following words: During the decompression, I felt a discomfort which I attributed to the cold. After I had come out, when I wished to raise my right arm, I could not make it reach a definite point without making the effort two or three times. My sight was affected, and I saw my arm moving much as one perceives objects after he has whirled about several times. The paralysis grew worse and it became impossible for me to move my arm which hung inert, I could not even make motions with my hand. The phenomenon was rather like that of an arm which has gone to sleep. It appeared progressively and in the same manner in my right leg. They placed me on a bed, for I could not walk, I sank down. They rubbed me. I was dazzled and my eyes refused to serve me at all. I saw only at long intervals, and for a second at the most, then everything disappeared to reappear only after a few moments in the same way. My eyes were dull and glassy, they told me, and perceived only a white, vaporous light. I recovered the use first of my leg, then of my arm; the instants during which I could see grew closer together, and I saw distinctly for longer periods. Finally no symptom was left except a violent headache and the usual signs of a fit of indigestion. I threw up my food. My headache disappeared in the open air, and I went home, having nothing but fatigue to remind me of my former experiences. 386 Historical The friend who accompanied me, who had eaten the same meal as I, had no unusual sensation. (P. 612.) Among the conclusions of M. Barella, we shall quote two: 1. It is best not to go beyond a pressure of three and a half atmospheres above normal pressure. 2. We may take as a standard of the duration of the decom- pression 10 minutes per atmosphere. The others have only a purely medical interest: lymphatism, heart ailments, etc. In America, the first bridge constructed by compressed air was over the Great Peedee River, for the railroad from Wilmington to Columbia and Augusta. I have found in my reading no information about this work from the point of view which interests us here. In 1869, a truly gigantic work was undertaken at Saint Louis (United States). A bridge with two piers was built over the Mississippi. On the east pier, the depth reached was 33.70 meters below the usual water mark; it was a depth without precedent in the applications of the method, which was to be increased by the occasional floods of the river. The total pressure rose to 4.45 at- mospheres. The total number of workmen employed there was 352; about 30 were seriously affected: 12 of these died. Here is an extract from the report made by the chief engineer of the work, M. Eads:30 When the depth of 60 feet was reached, some of the workmen were affected by muscular paralysis of the lower limbs. It was rarely painful, and went away in two or three days. As the caisson sank deeper, the paralysis went away more slowly. In some cases, the arms were affected, and more rarely the' sphincters and the intestines. The patients also had much pain in the joints when the symptoms were very severe. Nine tenths of the patients felt no pain and got well very quickly. The duration of the stay in the air chamber was gradually short- ened from 4 hours to 3, to 2, and finally to 1 hour. The use of galvanic plates or rings seemed, in the opinion of the director of construction and the workmen, to give a remarkable immunity against attacks. Finally, they all had them. They were made of alternate rings of zinc and silver, and placed on the chest, the arms, the elbows, the waist, and under the soles of the feet. The acidity of the perspi- ration was sufficient to establish a galvanic current, and the opinion of those with the greatest experience in these matters was quite favorable to this remedy. Captain Eads is strongly inclined to believe it to be valuable The engineers of the port, who very often visited the caisson, have never been ill. Physicians have differed greatly about the cause of the symptoms. Diving Bells and Suits 387 Some maintained that a slower return to normal pressure would have been less dangerous; others blamed too rapid compression for all the trouble. The fact that the workmen employed to operate the doors were never affected, although during the two hours of their work they were very frequently in extreme and alternating conditions of pres- sure — one moment at normal pressure, and 5 minutes afterwards sustaining a weight of 50 pounds per square inch of the surface of their bodies — would seem to prove that these two theories are wrong, and makes us believe that the real cause of danger lies in the long duration of the stay in this air where the body endures so great a pressure, and not in the rapid changes to which it is exposed The transitions lasted from 3 to 4 minutes Considering that thousands of persons, even delicate ladies, had visited the air chambers for a short time without harm, after the caisson had reached bed rock too, and that no serious symptom attacked the workmen after the reduction of the working time to 1 hour, M. Eads concluded that the real cause lay in the prolonged labor .... Too long a stay was invariably followed by paralysis. Dr. Jaminet, physician at the job, after staying one day for 2% hours when the depth was 90 feet, was severely affected after returning home. Dr. Bauer,"1 surgeon at the City Hospital, to which were taken the 25 workmen affected during the laying of the foundation of the Saint Louis bridge, presenting what he calls "Bridge cases," gave some interesting information about the symptoms observed in these patients: Respiration becomes more laborious, and the pulse more rapid at the beginning of the compression, which passes off rather quickly in persons who are in good health. The voice takes on a nasal tone which it retains even after leaving the compressed air. When they leave, all the workmen are very pale and extremely weary, even to the point of stretching out on the ground. In others, one sees involuntary, choreic muscular contractions with bleeding from the nose and lungs. In serious cases, there is paralysis in different degrees, from slight paresis to a complete loss of movement and sensation. Very often, urination is rendered difficult or wholly impossible, so that the urine must be drawn with a catheter: it is often bloody. Respiration is not affected; fever rarely appears and then it brings on a fatal ending. Death occurs in a state of coma, with delirium, hiccuping, stertorous respiration, and muscular cramps; the pupils are dilated towards the end Among the patients observed, only a few were cured in the course of the first week; others remained under treatment for a month; four died. In the paralytics, there are found congestions of the cerebral and medullary meninges, edema of the arachnoid, softenings of the brain and the spinal cord without definite localization. In one case, the softening covered the anterior horns and lateral column the whole 338 Historical length of the spinal cord. Baumgarten found in this focus abundant cells of the neuroglia attacked by fatty degeneration. The same facts were told by the chief engineer of bridges and highways, Malezieux,32 in his fine report on the public works of the United States of America in 1870. He copies verbatim (p. 91-93) the passage from the report of the engineer Eads which we quoted above. M. Malezieux has also given details about the foundation of the bridge which was to connect New York to Brooklyn. At the time of his visit, they were only at the beginning of this work. But the plans were gigantic; the foundation caisson was 52.46 meters long by 31.11 meters wide, that is, more than 16 ares in area. In the second Memoir,33 M. Malezieux gives the depth actually reached. The Brooklyn pier had a foundation 15 meters deep; the New York pier, 24 meters. For the latter, steam-heating was installed in each of the air- locks, so as to prevent the chill produced by the sudden escape of the compressed air (p. 385.) As to the physiological effects, M. Malezieux states: That he has little to add to what he reported previously about the Saint Louis bridge. M. Roebling (that is the engineer and con- structor), however, notes this fact, that the action of the lungs is changed involuntarily in compressed air; the number of times one breathes in a given time is reduced 30 to 50 per cent; which would indicate that the organism reacts against the introduction of oxygen in a proportion two or three times greater than in normal atmosphere. The natural conclusion to be drawn from this observation is the one which M. Eads had made at Saint Louis; to shorten the duration of work in compressed air as the pressure increases. (P. 395.) I shall quote in conclusion some information which I owe to the kindness of the managers of a great industrial company, which does a great deal of work on the foundations of bridges with the use of compressed air. These documents refer to works executed very recently outside France; a discretion the motives of which everyone will understand prevents me from giving more definitely the details of date and place. First, here are general specifications about the manner in which the works were carried on, and which resulted in the accidents; these specifications come from the superintendent of the job him- self: 1. At a depth of 20 to 22 meters, the shifts still lasted 8 hours, and our men were not too tired, none of them felt any ill effects from the pressure, they were merely inconvenienced by the evil odor of the mud and by the hot air, which, however, we took care to Diving Bells and Suits 389 renew frequently through the hoisting-shaft; under this pressure of two atmospheres, the workmen underwent decompression in 4 or 5 minutes. 2. From 22 to 25 meters, the shifts lasted 4 hours; under this pressure, the men began to feel rather severe symptoms; the decom- pression took 10 minutes, the opening of the discharge cock was only 25 millimeters, then afterwards 18 millimeters. 3. From 25 to 28 meters, the workmen relieved each other every 3 hours, and were decompressed by means of a cock, the opening of which was reduced to 10 mm.; it took 16 to 17 minutes, and it was while working under this pressure, that our men were most fatigued; very often it happened that 4 out of 7 were affected by the pressure in their legs, heads, and stomachs; in others, the decompression caused paralysis of the bladder or of vision; some of these workmen expe- rienced horrible sufferings for two or three days and then three or four days of convalescence before being able to go back to work; these were the ones most seriously affected; as for those who had lighter attacks, they also experienced great pain for twenty-four hours and then 1 or 2 days of inability to work. (July 22, 1875) As a sequel to my letter of the 22nd, I wish you to know that in the last four days we have had only two workmen affected by the pressure; only slightly, but enough to keep them from working; we still have in the hospital 2 workmen seriously affected by the pressure since the 21st on coming off duty at 6 o'clock in the evening; they are paralyzed in the lower parts of their bodies, and their urine must be drawn by the catheter. The decompression lasts on the average 18 minutes; the shifts work 3 hours. (July 28) To continue my letter of the 28th of this month, I wish to inform you that a man named R, one of the two working in the excavation who were hospitalized as a result of the pressure, died today at half past twelve. The second workman is out of danger, the doctors think; he has recovered except that his legs are paralyzed, and they hope that this trouble will soon clear up. The doctors claim that the death of R. is due to the pressure, which probably affected the spinal cord; this man had worked before in excavations with compressed air, but had never gone beyond 2.1 or 2.2 atmospheres. (July 30.) The first of the two workmen who were seriously affected and whom we have just discussed returned to his home; we have had no further information about him. As to the said R., his autopsy was performed. It resulted in noteworthy findings which Dr. L. describes in a letter addressed i the company, and a translation of which follows: r After opening the spinal canal, I found that at the height of the thoracic vertebrae the spinal cord was very soft; for some inches it was transformed into a soft, flowing mass, yellowish gray in color, which above and below merged into the healthy part. 390 Historical The cord in general was much congested, as was the brain, but I saw nothing else abnormal, there or in the other organs. 3. Diving Suits. As we said when we began this chapter, the diving bell has been entirely abandoned for the diving suit, an apparatus which is infinitely simpler and less costly, and which allows each man to work by himself with a certain liberty. I have no intention of going back to the origin of this invention although it is very recent; the French word itself scaphandre (o-Ka'/'os, boat, avSpos, man) dates from the end of the last century, and was given to a simple life preserver. It is only during the last fifty years that Siebe of London, then M. Cabirol, and finally MM. Rouquayrol and Denayrouze have made a practical apparatus of it, easy to use in fishing for oysters, coral, pearls and sponges, in saving sunken objects, in cleaning and inspecting the hulls of ships, etc. However, I cannot keep from mentioning a strange invention of Borelli, which had some connection with the diving suit and is interesting in the history of the theories of respiration; I borrow the description of this apparatus, very poorly planned because it did not provide for renewing the air for the diver, from Brize- Fradin who quotes it without telling where the celebrated doctor- mathematician described his apparatus. He expresses himself in these words: Borelli, inventor of the machine called diver's bladder, prefers it, for some reason or other, to Halley's bell. It is a globe of brass or copper about two feet in diameter, placed over the head of the diver; it is fastened to -a goat-skin garment made to fit the diver. In this globe are the tubes by which the circulation of the air is maintained; at his side the diver carries an air-pump, by means of which he can make himself heavier or lighter, as fishes do, compressing or expand- ing their air-bladder: in this way he thinks he can meet all the objec- tions made in regard to other machines, and especially the objection in regard to lack of air, since the air which has been breathed is, according to him, deprived of its harmful qualities by circulation in the tubes. (P. 44.) Let us recall that in Halley's diving bell a man could take several steps outside the bell and continue to breathe by means of a sort of helmet and a tube which ended in the air of the bell; he was therefore almost in the conditions of the modern diving suit. The principal part of the present apparatus (Fig. 7) consists of a heavy metal helmet, with glass portholes, which the diver places over his head; a tube which communicates with a compressing Diving Bells and Suits 391 pump placed on the bank or on the deck of the boat furnishes him compressed air which escapes through orifices contrived for this purpose. The pressure to which the air breathed by the diver is Fig. 7 — Diver equipped with the Denayrouze regulator, complete suit. subjected is therefore practically equal to that which the water exerts on the rest of his body. This condition absolutely must be met, as we shall see in the following part of this work, and very 392 Historical serious symptoms must have been the result, under certain circum- stances, of forgetting this fundamental rule. It is scrupulously observed in the apparatus of MM. Rouquayrol Fig. 8— Diver equipped with the Denayrouze regulator, helmet removed. and Denayrouze. The diver dressed in their suit does not breathe directly the air furnished him by the pump; on his back there is a metal reservoir in which the compressed air is constantly Diving Bells and Suits 393 stored up and from which, thanks to a very ingenious mechanism, it escapes only to meet the needs of the diver at the pressure absolutely necessary at the depth reached. When the reservoir is full, the diver can detach the tube which leads to the pump, and move about freely for a certain time. He can even, for work of short duration, remove the helmet and take in his mouth the tube which comes from the regulator (Fig. 8) . To return to the surface, the divers sometimes climb a rope ladder, and sometimes are hoisted on board by means of a rope fastened to the belt. In both cases, they hardly ever take more than one or two minutes to return to normal pressure. The diving-suits are now used very frequently in all our sea- ports; but the depths reached are generally rather shallow and do not exceed 20 meters. They are also used considerably in the seas of the Archipelago for sponge-fishing. There, the depths reached are as much as 40 meters; I even have it from M. Denayrouze that divers have reached 48 meters; in that case the total pressure was therefore 5.8 atmospheres. According to M. Leroy de Mericourt, divers with suits in the employ of English companies have ventured to the depth of 54 meters, the pressure therefore being 6.4 atmospheres. It is not with impunity that such pressures have been endured, or to speak more exactly, it is not with impunity that divers have risen from such depths in a few minutes to the surface of the water. Many accidents have been reported, a large number of which have ended in death. Their frequency and their severity are such that the accounts telling us of them seem to scorn and omit whatever does not amount to paralysis or death. However, the financial returns are so great that the use of suits keeps increasing every year. They were introduced only about twelve years ago in the Archipelago, where their appearance caused regular riots in 1866; and in 1867, about a score of machines were operating in sponge-fishing. I have been told that today there are more than three hundred of them,— and that the deaths have risen to about thirty per year! The first document which informs us of these strange and dangerous accidents we owe to M. Leroy de Mericourt,34 and bears the date of 1869. This article is based, the author says, on infor- mation contained in an unpublished memoir of M. Auble, agent of the Society for sponge fishing by means of the Rouquayrol and Denayrouze diving apparatuses: During the 1867 cruise, no serious accident occurred among the men who were equipped with this apparatus for fishing. But in the 394 Historical same season, out of 24 men who used 12 suits of English manufacture, 10 died. The lack of doctors at the fishing places and the difficulty of get- ting information from the fishermen of the Archipelago, who are of a very distrustful nature, did not allow us to determine, as would have been desirable, the nature of the symptoms which preceded the death of the 10 men we have just mentioned. We could learn only that three of them died suddenly as they were leaving their subma- rine work, and that others had languished from one to three months, paralyzed in their lower limbs and bladders. Because of the existence of paraplegia in the 7 divers who lived for a time, we may assume, up to a certain point, that this symptom must also have been present in the 3 who died rapidly. What are the injuries which caused the death of these unfortunate fishermen during the cruise of 1867, and how can we explain the mechanism of their production? The lack of medical observations and especially of autopsies requires that we express an opinion on this subject only with considerable reserve. Paraplegia, it is true, is a symptom so characteristic and apparent that one does not need to be a physician to observe it. In one of the victims, a very daring young Greek diver, there was such a distention of the bladder that the father, in the hope of relieving this unfortunate young man, tried to catheterize him; he caused disturbances which were followed by a peritonitis which was soon fatal. We shall see in Chapter III the explanation which M. Leroy de Mericourt suggests for these symptoms, which he attributes to medullary hemorrhages. The rest of the note is devoted to very accurate remarks about the superiority of the Denayrouze apparatus and the necessity of a slow decompression: Whereas the group of divers among whom the symptoms appeared reached the considerable depths of 45 to 54 meters and consequently endured pressures varying from 5V2 to 6.4 atmospheres, M. Denay- rouse with a prudence which does him honor, had given the order not to go beyond 35 meters, not to stay more than 2V2 hours, per diver and per day, and finally to come up very slowly, taking one mmute for each meter of depth. Moreover, the apparatus used offers greater safety than the diving suit: the air is given out in proportion to the needs of respiration, and at a pressure mathematically equal to that of the ambient medium. But it was not possible to make the Greeks observe these strict precautions. The decompression to which M. Denayouze had as- signed a duration of 15 minutes began to be made in one or two minutes again. The symptoms reappeared also. A private letter from M. Denayrouze, dated July 9, 1872, gives me the following information on this point: Diving Bells and Suits 395 For 6 months, I have had about a hundred men diving at depths varying from 30 to 40 meters. 200 other foreign divers were working under my supervision under the same conditions. All these men were breathing air at the pressure of the ambient medium, about 4 or 5 atmospheres. Five men died at these pressures, a great many others were attacked by different affections, the most frequent of which were paralyses of the lower limbs and the bladder, deafness, and finally anemia. The men subjected to sudden decompressions were really more affected by the symptoms than the others. Those who died never expired at the bottom of the water, they came up complaining of inward pains, particularly of the heart, lay down in their boat, and died after a few hours. July 19, 1872, a young doctor who in 1868 had made a cruise on board a boat bound for sponge fishing on the coast of Turkey, Alphonse Gal,35 sustained before the Faculty of Montpellier a very interesting thesis on the data which he had observed. In the first part of his work, he discusses the modifications in the physiological functions caused by a stay in compressed air. Naturally I am reporting only the part of the observations which come from his experience. Speaking first of respiration, he says: It is impossible to use a spirometer in a diving suit; and it is rather difficult to appraise sensations of the type that we were studying. However, at pressures varying from 15 to 25 meters, I observed myself from the point of view of respiratory movements and I think that the expansion is less than in the normal state. No doubt the pulmonary capacity, which M. Bucquoy calls the vital capacity, increases, in the inspirations in which the lungs are called upon for their full strength; no doubt when one is making an experiment and tries to produce the fullest expansion, the results are better in the compressed air; no doubt also the patient subjected to the air treatment and quickly experiencing a sensation of well-being "due to the greater efficiency of hematosis, instinctively takes deeper inspirations; but the diver, subjected to a pressure of 2, 3 and 4 atmospheres, does not feel the necessity of increasing his pulmonary expansion, and like Foley, I believe in the action of the nervous centers in moderating the extent of the inspiration, since this extent has become useless because of the greater quantity of oxygen brought in contact with the capillaries of the pulmonary plexus in a volume which merely equals the normal volume. And so in summary, for forced respirations the pulmonary capacity increases with the atmospheric pressure; but for ordinary inspirations, especially in a healthy man, this rule no longer holds, for one is more likely to observe — at least I think I noted it, especially at pressures of 2 to 3 atmospheres — a decrease in the pulmonary amplitude (P. 17). In regard to the number of respiratory movements: 396 Historical For my part, I have been able to make a rather large number of observations on this point; when a diver was on the bottom a short distance from the boat, and when the sea was calm, I clearly saw the bubbles of air from each respiration coming to the surface. As one could see in the description of the regulating air bag, the diver with the Denayrouze suit breathes through his mouth air contained in a reservoir, and he expires also through the mouth. The air thus ex- pired escapes through a valve which closes immediately after the expiration. The time separating two respiratory acts can therefore be measured in this way, and during this time the diver is under the normal conditions of work and does not know that he is being observed. I have thus been able to note individual differences, but within very narrow limits. The minimum number of respirations was 12; the maximum 30; but we should not think that the average is the number halfway between these two numbers. Taking all the obser- vations I have made, the average is 18, but it is too high and cannot give the normal number of inspirations in compressed air. In fact, every time I observed in a diver a respiratory rate higher than 20, I am sure that this respiratory acceleration resulted from a chance cause (emotion, muscular effort, rapid walking, etc.). In many cases, after following the respiration of the diver for a few minutes, I saw it dropping little by little and finally getting below 20. In summary, the physiological modifications of the respiratory apparatus affect the extent and the rhythm of the movements. Let us add to what we have said on this subject that respiration is always very easy in compressed air. In this we agree with all who have carried on experiments under good conditions of ventilation. Under the water, whatever the depth, one breathes easily and freely (P. 19) . We have seen in divers that the respiratory movements increase in number as the men ascended the ladder and were consequently decompressed. A great part of this acceleration must no doubt be attributed to the very act of decompression, for the ascent is extremely easy for the divers; and because of the air contained in their suit, which expands as the ascent continues, they need rather to hold themselves down than to make efforts to ascend. But however great is the pressure undergone, this acceleration of the respiratory move- ments never goes as far as panting (P. 21.) Let us turn to the circulation: In diving suits, only inexact observations can be made in this regard; the pulse is very hard to take and there is no way of meas- uring exactly the time occupied in the observation. Nevertheless I tried to find the rhythm of my circulation, and I think that its rate never dropped. We may say, without trying to explain it, that in compressed air, at pressures used by sponge divers, the circulatory rhythm does not seem altered. This is not true of the amplitude of the pulsations; in this all experimenters, except Junod alone, agree. They all admit that in compressed air the pulse becomes filiform and sometimes impercep- tible .... Diving Bells and Suits 397 Evidently the superficial capillaries and the arteries which are nearest the skin are more subject to the effect of the outer pressure and their caliber lessens. If one goes into compressed air with a part of the mucous membrane or the outer tegument congested, the congestion quickly disappears. In the diving suit, in spite of rubber rings which clasp the wrists tightly, the hands are pallid. But al- though the quantity of blood in the periphery is diminished, the organs which by their position are less directly subjected to the action of the compressed air have a more abundant circulation. Since the lungs - are under the same conditions as the skin, they must receive less blood than in the normal state. (P. 22-23) If one returns from a higher pressure to normal pressure, the pulse rate accelerates, the pulse which was filiform regains its full- ness, and if the difference in pressures was considerable, slight hem- orrhages are sometimes observed. The agreement of authors on this question is perfect. We were not able to follow the changes in the circulation during the act of decompression, but we noted by a great number of observations that at the moment of reaching the deck the pulse rate of the divers was almost always more than 80 per minute. Out of 240 observations we found it to be: Below 80 heartbeats 11 times From 80 to 90 heartbeats 103 times From 90 to 100 heartbeats 124 times From 100 to 109 heartbeats 2 times Half an hour afterwards, 203 times the pulse had returned to nearly normal; 3 times it had fallen definitely below, and 34 tirnes it was still between 75 and 80. Here, as in regard to respiration, we cannot attribute the accel- eration of the rhythm to the act of ascent. As we have said, mus- cular fatigue is almost absent because of the expansion of the air in the suit and the slowness with which the diver ascends. (P. 24.) The secretions furnish him with the following observations: All authors, except MM. Foley and Frangois, note a greater secre- tion of urine; I think that this opinion is correct. The divers whom I have observed could not remain more than an hour and a half sub- jected to a pressure of 20 meters of water without feeling the need of urinating; sometimes they even urinated in their suits. The increase of the salivary secretion was noted only by MM. Eugene Bertin and Junod; as for me, I cannot form an opinion on this matter; in all the French divers and in myself the salivary secretion was more abund- ant than in the normal state; but the presence in the mouth of a rubber apparatus intended to admit air accounts satisfactorily for this phe- nomenon. After this series of purely physiological observations, M. Gal reaches the study of dangers of high pressures. He divides the diseases which one may attribute to the effect of compressed air 398 Historical into two categories: diseases which begin suddenly, which never occur while the diver is in the compressed air, and which are the result of the decompression; and diseases with an insidious begin- ning, which must be directly connected with the action of the compressed air. Diseases with a sudden beginning. In the first rank M. Gal places the "fleas": This disorder disappears without any treatment and ends when a hypersecretion of perspiration occurs. (Foley, p. 33) Is it then because our divers were always covered with sweat when they reached the deck that I have never had the opportunity to observe it? That seems to me more than probable. (P. 33.) Then come the muscular pains, the attacks of arthritis: Among all these disorders, I have seen only extremely acute pains appearing suddenly, soon after the exit from the compressed air; affecting particularly the parts of the body in which muscular effort was longest exerted, generally the left deltoid in divers; almost always a little swelling in the part affected, but with no redness. These pains never lasted more than two days, and generally they disappeared after a few hours. All the divers, except two named Thepot and Paugarn, expe- rienced them repeatedly. I have not listed any observations on this subject, because these disorders, which were always slight, showed me nothing abnormal, either in their course or in their ending. Rubbing with soothing balm or application of a poultice with laudanum always dispelled them. Then pains and inflammation of the ears, of which M. Gal mentions some examples, and gastric disturbances, the cause of which lies perhaps in the nervous centers. A case of hemorrhage was observed, which offers this rare circumstance of having begun during the compression: December 15, a man by the name of Feroc, 28 years old, a diver trained to the use of the suit, went down to a depth of 14 to 15 meters, stayed at the bottom three quarters of an hour and came up with a nosebleed which began while he was subjected to the pressure. His face was slightly flushed, his pulse was 70. He told me that it was the third noseblood he had had, and that it always began on the bottom. Like the former ones, it stopped without treatment. January 12, this same diver went down again for the first time since December 15, to a depth of 20 meters. Another hemorrhage under the same conditions; only the pulse was 90 a quarter of an hour after he came up, and an hour afterwards it was 70, weak and easily depressed. At the same time, an acute headache. Stimulating friction; rest. The next day he was quite well. (P. 41) In regard to serious symptoms, M. Gal observed only one para- Diving Bells and Suits 399 plegia, which, strangely enough, began only twenty-four hours after the decompression. Here is the complete observation: Quidelleur, 28 years old, given to drink. January 18, 1869, descent to a depth of 28 meters. After staying on the bottom for an hour, he came up deaf in one ear; it was his first symptom, he had no pain, and merely noticed a buzzing, accompanied by deafness in the left ear. January 19, he went to a depth of 16 meters, finished his shift of an hour and a half, and told me when he came up that his deafness disappeared at the bottom. January 20, he went down to a depth of 28 meters. That day, while four divers were in the sea, and among them Quidelleur, the ship made a complete turn around its anchor, and this accident resulted in rolling around the ship's chain the four air tubes and the four signal cords of the divers. There was a moment of confusion, during which the signals could no longer be felt; and when Quidelleur reached the deck, he com- plained that at three different times he was raised from the bottom to a depth of about 10 meters, and each time he fell back suddenly, with great injury to his ears. In all, he remained for one hour at an actual pressure of 3.8 atmospheres; and he complained only of pains in his ears, especially the left one. I had him rubbed with dry flannel, as was always done after a descent of more than 20 meters, and I noticed nothing abnormal about him. On January 21, diving was interrupted all day, and Quidelleur like the other sailors worked at different jobs on board. In the evening at 5 o'clock, he came to take me on shore, and I noticed that he did not look well; when I inquired about it, he assured me that he had no pain except a little in his left ear. One hour afterwards, I was sent for; he was complaining of violent pains, without a definite loca- tion, extending over his whole body. I had great difficulty in making him talk, but his attitude showed me that the chief pain was in the abdomen. The patient was doubled over, all his members were bent against the front of his body. The pains were so great as to make him weep; he finally told me that the pain was as great as if some- one were tearing open his belly and his chest. I noted no swelling and no redness of the skin. His pulse was 70; it was greatly depres- sed. The rather hasty respiration was jerky .... At eleven o'clock in the morning (January 22), I was told that the patient was complaining again of not being able to urinate; I noted the presence of liquid in the bladder, and warned by this symptom, I tested for a lessening of sensitivity and motility. Both were weak in the lower limbs, without being entirely gone. The penis was in a semi-erection. The introduction of a catheter into the bladder gave a half-liter of urine. It flowed slowly; muscular contraction was not present; the bladder was paralyzed. The pulse was quite normal, the pains of the day before were gone, the respiration was good. Friction on the spinal column and on the lower limbs with opodeldoc balm. Elder tea. 400 Historical January 23. The patient, less stiff, tried to rise, but his legs could not support him, although when he was in the hammock, he could move them as on the day before; lessened sensitivity. Pulse 70, easily depressed. Respiration normal, no pains; the hearing which on the day before was rather weak on the left, had returned to normal. I had plasters put on the lower limbs and along the spinal column. Elder tea. Catheterisms in the morning. Soup. In the evening, the paralysis had gone; the patient urinated easily. Nothing new in his condition; he had not defecated since the day of the accident, that is, January 20. January 24. Legs in the same condition; pulse and respiration normal. No movement of the bowels. The patient wished to eat .... January 27. Slight improvement, movements of the lower limbs a little easier, although there was not much strength .... From that day to January 30, the improvement progressed very slowly; then suddenly, February 1, the patient came up on deck and one could hardly tell by his gait that his lower limbs were paralyzed. During the following days, the improvement was maintained; the rectum alone was still paralyzed. There were no results unless enemas were used. The patient was very intractable as long as his illness lasted; I could testify that he was of a very weak character, and that he was easily prostrated by pain. I wanted to purge him the very first day; but in spite of all my persuasion, he would not consent. Up to February 5, he did not defecate and suffered greatly from his constipation. I administered to him, without his knowing it, 80 centigrams of calomel in some milk; this purge brought on an evacuation which was the signal for his complete recovery. From that day, the rectum resumed its normal functions, and the health of this diver was excellent. M. Gal gives three more observations of the same sort, the details of which he gathered himself, although he did not see the patients at the time of the accident. In the first case, death occur- red as a result of the doctor's ignorance: August 5, 1869, a man named Nicolas Theodoros was seized by paralysis of the lower limbs. This diver had been fishing on the shores of Crete since the beginning of May, that is, for three months. He was a man of great height and at the same time of an enormous corpulence, due chiefly to the very considerable development of adipose tissue. August 5, he was fishing near Sitia, and for a week he had been working in depths of twenty fathoms and more, that is, 30 to 35 meters. No serious symptom, no pain, gave him any warning, when August 5, a quarter of an hour after coming up from a depth of 37 meters, he was seized by complete paralysis of the lower limbs. I learned from the Greeks who were diving from the same boat that he had remained on the bottom more than a half-hour, that he Diving Bells and Suits 401 had been hoisted up, according to the bad habit of the Greeks, and that consequently the decompression had been very rapid. He had taken off his diving clothes and was going to rest on the deck of his caique, when the illness began gradually by general dis- comfort, and soon he perceived that he could no longer move his legs, and that they were completely without sensation. Unfortunately, at that time I was in Kanea, that is, more than a hundred miles from the place where this unhappy diver was. His boat went to the nearest point where they hoped to get help; that was at Sitia. There was there only an Italian physician completely ignor- ant of the symptoms which may appear in divers. Finding no fever and no pain, he did not know what could be the cause of the illness and remained completely inactive. The death certificate which he gave to the comrades of the diver simply said that he died: From intestinal strangulation and constipation. Although these words indicate that he had recognized the inabil- ity of the diver to urinate and defecate, he did not heed the first indication, did not catheterize the patient, and merely gave him a cathartic; he did not even do that until the eighth day of the illness, the day before he died. To the paralysis, which had been painless at the beginning, soon were added the ordinary symptoms of paralysis of the bladder and the rectum, when the former is not emptied and the bowels are not kept open. When I reached Sitia, August 16, the patient had been dead for two days, after terrible sufferings located in the abdomen and accom- panied by a considerable increase in the volume of that part of the body. The information given me by his comrades was quite recent, and I am convinced that Theodoros succumbed to the paraplegia only from want of care. It will be seen by the observations which I shall give that when the paralysis reaches only the lower limbs, cure is quite frequent, or at least if the paralysis persists, the patients do not die, or at least die only after several months. (P. 48.) In the other two cases, the paraplegia was half cured: At Symi I saw two divers, Foti Kazi Foti and Yanni, who, during the cruise of 1867, were both completely paralyzed in the lower part of their bodies. Both of them returned immediately to Symi, where they were attended by a doctor who had had his medical course at Paris, M. Migliorati. I had an opportunity to talk with him; unfortunately, he was very ill, in the last stages of pulmonary tuberculosis, and he could give me only a little information. The two divers remained three months without being able to use their lower limbs; little by little, however, it became possible for them to make some movements; the paralysis of the bladder and the rectum disappeared first. M. Migliorati exhausted all the resources of thera- peutics on them: friction, blisters, cupping-glasses with scarification, tincture of nux vomica rubbed in or given internally, etc. However, he did not try cauterization or faradization: When I saw them, I noted that the paralytic lesion of the lower 402 Historical limbs still persisted; they had been ill for more than a year. However they were able to walk, provided that they used two sticks, but they did not need crutches. It was evident that it was difficult to them to lift their feet, and they did so only as much as was absolutely necessary. I tested the sensitivity and found a marked weakening on both sides of tactile sensitivity, sensitivity to heat and cold, and sensitivity to pain. All the other mechanisms and all the other functions were normal. I observed, however, a little anemia in Yanni, but it had no connection with the paralysis; in 1868, he had had obstinate intermittent fevers, from which he had recovered only a short time before I saw him. The muscles of the lower limbs were not manifestly atrophied. These two men continued to use the diving suit. They resumed their work, one in the month of October, 1868, the other in the month of May, 1869, and they found that walking was easier in the water than in the open air. In the month of January, 1870, their condition was unchanged. (P. 50.) Next comes a series of 9 observations, in which 2 divers died very quickly, one after twenty-four hours, the other after three months, from the sequelae of paraplegia. The last five recovered more or less completely. I reproduce in full these observations, which are very brief: I. June 23, 1868, at Navarin, Jorgieos Koutchouraki, who had gone down to a depth of 40 to 45 meters, remained on the bottom for a quarter of an hour. According to the custom of Greek divers, he had himself hoisted up after this time; he reached the deck of the boat in perfect health; a few minutes afterwards, he complained of dizziness, and fell upon the deck. Loss of speech and intelligence; face red; sudden death. II. July 10, 1868, in the Greek Archipelago, Manolis Couloumaris, went down to a depth of 25 fathoms, that is, about 40 meters, and remained on the bottom about three-quarters of an hour. He then gave the signal agreed upon and was hoisted up. He had been on deck about a quarter of an hour, and, according to his comrades, he was squeezing out the sponges which he had brought up, when he was suddenly attacked by severe pains, and almost immediately by com- plete loss of consciousness. He rapidly succumbed. III. June 15, 1869, on the coast of Bengasi, a man by the name of Joannis Xippas went down 20 fathoms, that is, 30 to 35 meters. This diver had gone down five days in succession, and several times each day, in depths always more than 30 meters, and until that time had felt no symptoms, except a little pain in his left arm. June 15, he had gone down for the second time when the attack came. Coming up after a stay of more than a half-hour, at first he did not seem ill, and went down to the deck of his caique to rest. Only an hour after- wards one of his comrades, going down to him, found him uncon- Diving Bells and Suits 403 scious, his face red, his limbs completely inert and covered with cold sweat. They tried to warm him, but could not succeed. They set sail for Alexandria, where they hoped to find help; but death came after 24 hours. The patient had remained all this time absolutely motionless. He had not defecated or urinated. Those present at his death stated that shortly before he died, he gave certain signs of consciousness and pain; but the paralysis of his limbs re- mained complete. IV. July 1, 1869, on the coast of Rhodes, a man named Nicolas Roditis, who had been diving in a suit for about three months, came up from a depth of 35 to 40 meters. After a half-hour, he was seized by severe pains in the epigastric region, and at the same time per- ceived that he could no longer stand up. They took him to Rhodes, where he first consulted a quack, who had him put in an oven. He was not relieved, as one may well imagine; the pains in his stomach persisted; the paralysis of the lower part of his body was complete, and affected the legs, thighs, bladder, and rectum. To the pains of the epigastric region was added the tension of the belly; for three days he had not urinated or defecated, and then an Italian physician was summoned, who catheterized him at once and then tried to cure his paraplegia. They gave him various remedies and had him rubbed; but it was impossible to find out exactly what treatment was given him. One month after the accident, he came to Calymnos, where Dr. Pelicanos attended him. At that time, he was completely paralyzed in the whole lower half of his body, both in motility and sensitivity. The bladder and the rectum shared in this paralysis. Moreover, he had on the back and lower part of the trunk a large sore 14 by 15 centimeters. All the soft parts were ulcerated and the sacrum was bared. At the level of the two great trochanters, there were also two sores; one had destroyed the skin; in the other, the bone was -bared. Scab on the right calcaneum. Scab on the lower and outer part of the fifth left metatarsal and on the sole of the same foot. Excruciating pains in the region of the stomach; persistent con- stipation. The patient was very anemic. He was first given syrup of lactate of iron, cinchona bark, old wine of Cyprus, and a diet as nourishing as possible. The sores were washed with a decoction of camomile and cinchona; they were dressed with aromatic wine. From time to time a cathartic with castor oil or jalap powder. No improvement; the sores grew larger; a fever of the daily inter- mittent type, growing worse every evening, appeared. It was evi- dently hectic fever. Appetite was almost wanting, the general condition grew worse; a gangrenous sore spread over the prepuce, and finally the patient succumbed in marasmus three months after his accident. The paralysis of the bladder had disappeared one month before; but there had been no improvement in the motility and sensitivity of the lower limbs. V. In the early part of September, 1868, a man named Nicolas Kardachi, on the coast of Bengazi, was seized by paralysis of the 404 Historical lower limbs, the bladder, and the rectum. He showed complete paral- ysis of movement, hyperesthesia of the skin, and severe pains from the region of the kidneys to the ends of the toes. The disturbance had appeared very shortly after he had come up to the deck of his caique. He was taken as quickly as possible to Calymnos, where he arrived five days after the beginning of his illness. He had not urinated or defecated; the bladder, which was much distended, caused him acute pain. Catheterization, the use of cathartics, and the application of a large blister to the spine in the region of the loins were the first measures used by Dr. Pelicanos. The patient was wholly free from fever; his appetite was good; the regimen was tonic from the first. The blister in the lumbar region was renewed, and motility re- turned little by little, at the same time as normal sensitivity. The paralysis of the bladder was the first to yield, and after a month and a half the patient could walk a little, dragging his feet. First he was given frictions along the spinal column with tincture of nux vomica, and then with the following liniment: Olive oil 250 grams Essence of turpentine 30 grams Camphor 4 grams Tincture of cantharides 4 grams Liquid ammonia 20 grams Dr. Pelicanos is well satisfied with the use of this last remedy; motility returned little by little, and at the end of three months the patient was perfectly cured. VI. September, 1868. The history of this patient, named Nomikas Sissois, is exactly the same as that of the preceding one. Like him, he was attacked while fishing at Bengazi, at the end of the fishing season, in depths of 35 to 45 meters; he was slower in going to Calymnos, and the disease lasted longer, although he could walk, dragging him- self about, at the end of a month. The treatment was the same, the duration of the disease six months; and in January, 1870, that is, fifteen months after the begin- ning, there was only a slight hesitation in his gait. They tried with him an injection into the bladder of a dilute solution of sulphate of strychnine; but this measure did not give satisfactory results. VII. In the month of August, 1869, on the coast of Crete, a man named Philippe Karantoni was paralyzed in his lower limbs after diving to a depth of 35 to 40 meters. The bladder and the rectum were not affected. They used as treatment only the stimulating liniment already indicated, and he was cured in two weeks. VIII. In the month of September, 1869, in the Greek Archipelago, a man named Georges Ervloia was paralyzed in the whole lower part of his body; the bladder and the rectum were affected; the patient also had violent pains all through his body. He reached Calymnos the day after the beginning of his illness. Catheterization, a cathartic, and the use of the stimulating lini- ment brought a complete cure in twenty days. Diving Bells and Suits 405 IX. In the month of September, 1869, a man named Georgios Baboris was diving at Candia; he was slightly affected by paralysis. Treated at Megalo-Castro, he was very soon on his feet and only a slight weakness of his lower limbs remained. After this interesting enumeration, M. Gal adds: What we have just shown by these observations, the frequency of functional lesions of the spinal cord, appeared also in the ten divers who died in 1867. Only three died suddenly; the other seven dragged on a longer or shorter time. The latter were all paraplegic. I had another purpose in listing these observations, that is, to show tiiat with precautions one can lessen the number of accidents considerably. So in 1867, there were in Greece 12 diving suits manned by 24 divers; there were ten deaths. The Greeks went down to depths of more than 45 meters, had themselves hoisted up rapidly when they wished to come up, and made a considerable number of dives during the day. In 1868, there were at least ten suits at Calymnos alone. They used 30 divers; there were two deaths, and two cases of paraplegia ending in recovery. In 1869, more than 15 suits, using more than 45 divers. Three deaths and three cases of paraplegia. I could get these statistics only for the island of Calymnos; but one can see how much the number and the severity of the accidents diminished. The precaution of taking three divers for each suit, to lessen the daily work of each one, and a little greater care in regard to the depth were enough to bring about this result. A little book published in Greek by M. Denayrouze and distributed liberally among the divers has no doubt had its share in bringing about this improve- ment. (P. 56.) And now we come to the second category of diseases obser- ved among the divers. M. Gal calls them by the name of Diseases with gradual beginning; according to him, they are the multiple manifestations (emaciation, loss of strength) of a peculiar anemia: Like Foley, we attribute the emaciation to the effect of the com- pressed air and what we have noted many times, that after several days of work, all the divers without exception showed evident symp- toms of anemia, and a much more definite susceptibility to attacks of the diseases with a sudden beginning. It was then that almost all experienced more or less keen muscular pains, and that prudence required us to make them take a restorative rest. (P. 57.) I owe to Dr. Sampadarios of Egina a series of interesting and unpublished observations which I copy without omitting anything; I am glad to be able to thank him here for his interesting com- munications: Observation I. During the summer of 1866, they called me to attend one L. This man had for some time been diving in a suit in 406 Historical sponge fishing; he was forty years old. The day before, after he had come up from the bottom, he had fallen into a state of coma; when I saw him, he was in his last moments, his face puffed up and bluish, as if he were dying of asphyxia. Observation II. In 1867, I observed another patient; he had gone down three times in one day to fish, he said; the third time, he had felt an oppression in his chest at the bottom of the sea, and he had hardly had time to give the signal to be raised. When he was in the boat, he had fallen into a state of coma, quite insensible, from which he had recovered after three hours. He then had dyspnea, complete paralysis of the lower limbs and the bladder, constipation, incomplete paralysis (paresis) of the upper limbs, on one side especially. The dyspnea had soon disappeared; they were forced to empty the bladder with a catheter. The progress of the patient had been followed for a month, there was an improvement, then they lost sight of him. Observation III. N. B., attended by another colleague; for some months he had had a paralysis of the lower limbs and the bladder, with constipation; the urine was always drawn with a catheter. There was only a slight flexion of the coxofemoral articulation and that of the knee; more or less advanced paralysis of sensitivity. When the patient had been drawn up from the bottom, he remained for several hours in a state of coma; when he had recovered from this, he had dyspnea and his members were paralyzed. Observation IV. N. A., a sturdy young man, aged 25, in good health till now; for some time he had been connected with a company of sponge fishermen, and he was diving in a suit. I had been sum- moned to attend him July 20, 1870, and he told me that two days before, he had worked too long, because he had stayed, he said, for five hours on the bottom, collecting sponges, and consequently he had had a sort of fainting fit. However he had gone down again to work; but after working a half -hour, he felt ill, gave the signal to be drawn up, and was pulled up very quickly, as usual, when there is a sign of danger; the diving suit was also taken off him very quickly, and after that, he fell into a state of insensibility. He had felt a numbness of the limbs and dizziness, and his mouth foamed, he said. They had not called a doctor, because the divers had had such symptoms several times, and had recovered after several hours through the use of frictions and revulsives on the extremities. He too had recovered from this comatose state after five hours, after he had vomited several times; but for twenty-four hours he was dizzy whenever he opened his eyes; the lower limbs and the bladder were paralyzed. At the beginning there was also a sort of paresis of the upper limbs, which quickly disappeared, but the complete retention of the urine persisted, and that is why they called me on the third day. I found the bladder rising as far as the navel; there was consti- pation and the lower limbs were paralyzed; on the right side there was complete paralysis of movement and sensitivity; on the left, sensi- tivity was partly present with weak flexion of the coxofemoral articulation; there was no other disturbance, no pain in the spinal column. We emptied the bladder with the catheter; the next day a purge with castor oil gave evacuations. We continued to catheterize the Diving Bells and Suits 407 patient; finally, after twenty-one days, the patient could urinate with- out assistance. We should note that after the eighth catheterism a very severe attack of intermittent fever came on, for which we gave quinine, and which did not recur. The paralysis of the limbs yielded also to stimulating frictions, and on the fortieth day the patient could walk with crutches. We gave him extract of nux vomica, pains appeared along the limbs, but no improvement resulted. Not knowing the nature of the illness, we gave a symptomatic treatment; we gave iodide of potassium intern- ally. October 24. The lower limbs were still weak, especially on the left, where we noted at the same time, in the leg and the foot, lack of sensitivity to pain and touch, and a moderate sensation of cold. On the right, where at the beginning there was complete paralysis of sensation and movement, the insensibility persisted only on the outer part of the back of the foot. The active movements were carried out well, except a weakness on the left at the tibio-tarsal articulation, especially in flexion. The passive movements were natural. Examination by electricity (induction apparatus) found at the right the electrical contractility lessened in the muscles which depend upon the peroneal nerve. On the left, not only these, but also the tibial muscles showed lessened electrical contractility. The other muscles reacted well, like those of the belly. We continued to faradize the skin and the muscles of the limbs and the belly. There was an improvement. For two hours after the faradization the patient felt that his movements were free, as if he were quite well. November 28. Lack of sensitivity to pain, touch and cold on the left halfway along the thigh, even half of the penis, on the right only lack of sensitivity to pain and touch on the foot; weakness of the limbs, however, extension of the foot on the right was very incom- plete. If the patient closed his eyes, he tottered and began to fall. Lack of coordination or irregularity of movements during walking, involuntary, convulsive contractions, through reflex action of the lower limbs, for example, from the bite of a flea on the buttocks or the loins. Sometimes retention of the urine, at other times, incontin- ence. We applied two cauteries on the spinal column, and gave him internally iodide of potassium. December 10. Improvement, he wants to go away. After my publications on this subject, in 1871, in the month of September, Dr. Cotsonopoulos, of Nauplia in Morea, published an observation, followed by an autopsy in the Greek Journal Asclepios (Esculapius), in which my observations are also published. I will make a translation of it for you. D. N, aged 30, a sailor in good health, strong, who had been working for a year with the English diving suit, was taken to the hospital of Nauplia on May 2. Six days before he had been working on the shore of the Argolic gulf, at a depth of 30 meters on a muddy bottom. When he was drawn up, he felt a pain in the loins and great numbness in the lower limbs, movement of which after an hour was wholly impossible. His companions rubbed him and cauterized his penis. 408 Historical A physician bled him before he entered the hospital and several times placed on his loins cupping-glasses, a blister sprinkled with strychnine, and cauteries with the cautery already there. When he entered the hospital, the paraplegia was complete; no movement of the lower limbs; no contraction even by electricity, they said; loss of sensitivity, even electrical sensitivity. The upper third of the thigh a little sensitive; the patient sometimes had spontaneously a burning sensation in the legs; paralysis of the bladder, sluggishness of the ali- mentary canal, the belly swollen: the bladder was emptied twice a day. Pressure on the spinal column was not painful. A painful erythema existed in the sacral region, that was the beginning of the gangrene of decubitus, which developed later. No fever. In the pres- ence of such symptoms which came on suddenly with pain in fne loins, a hemorrhage in the spinal column was assumed, and orders were given again for cupping-glasses and leeches on the anus, cath- artics, and vinegar enemas, since the cathartics were not effective. There was a slight improvement: sensitivity increased a little on the upper part of the thighs, but soon the disease made progress; a cystitis developed with gangrene of decubitus, fever, chills, incon- tinence with retention, involuntary evacuations; finally, on account of the progress of the gangrene, the sacrum was wholly bared. During the last days of the sickness sores appeared on the heels. Death occurred on the fortieth day from the beginning of the sickness. The patient had preserved his mental faculties intact up to the end. Autopsy. There was some difficulty in getting the permission of the relatives for the autopsy. Dr. Jeanopoulos was present. The dorsal canal was opened and blood was found in quantity, half-coagulated, reddish-black, between the dura mater and the canal of the bone and extending from the first lumbar vertebra to the end of the meningeal sac. The outer surface of the dura mater, which was wet with blood, was reddish black and infiltrated with extravasated blood. Its inner surface after being sectioned was found to be whitish and slightly bloodshot. In the lower part of the subarachnoid cavity there also existed an effusion of dark red blood, half-coagulated in a fairly large quantity around the nerves forming the cauda equina. Having made incisions in different parts of the spinal cord, we found that a large part of the lumbar portion and the upper third of the thoracic portion had undergone the white softening to a considerable degree, because hardly was the pia mater cut or torn when the substance of the marrow flowed out, so to speak. The other parts of the marrow, even those which were situated between the softened parts, had the natural consistency; no congestion in either the marrow or the pia mater. Since the relatives of the patient had arrived, no examination was made of the other cavities; only the hypogastrium was opened for an examination of the bladder, the walls of which were much hyper- trophied. Such are the observations published in our country up to the present concerning this question. If we analyze these different data, we see that death occurred in two manners: either immediately or by lesion of the spinal cord. Diving Bells and Suits 409 When the nature of this disease has been determined, we shall know whether there are two different causes which produce these two kinds of morbid manifestations, or whether they are different degrees of one affection. I shall merely remark that if one tried to explain these symptoms solely by the change in the atmospheric pressure, that would not be enough; because very certainly the disturbance of health began at the bottom of the sea. The fisherman felt ill and gave the signal to be hauled up. M. Cotsonopoulos mentions a case in which the diver was hauled up almost dead, and died after a few movements. The patient whom I attended also told me of a similar accident. I am not sure whether death came to my patient in the same way (obser- vation I). These people say that they are sick when they work at a great depth for four or five hours, when there are wind and waves (and perhaps the pressure of the machine cannot be regulated then), and finally when they are too tired. It must be noted that when the diver gives the signal that he is ill, haste is made to draw him up very quickly, and to the first disturbance perhaps that of sudden decompression is added. When they go down to a depth greater than 30 meters, they cannot work there very long; the deeper they go, the shorter a time do they remain. Moreover, sometimes the pressure of the machine is not strong or regular enough, and the diver feels the column of water beginning to press the suit around his hands and feet; then he makes the signal agreed upon and air is sent him. It seems that they were working in our country, at least at first, with the English suit. As for the persistent paraplegia, we see that it is a remnant of a disturbance which acted upon the whole organism (observations 2, 4), but which, not having caused death, leaves material disturbance only in the spinal cord, because we cannot accept the idea that this affection of the marrow alone caused death or that general state observed at the beginning. But what is the nature of this affection? M. Le Roy de Mericourt thinks that capillary hemorrhages occur in the spinal cord during the deebmpression. In our patient, (observation 4), we saw at the beginning a paraplegia, a complete failure of the functions of the spinal cord; a very great improvement occurred after a few days, and later we had the syndrome of myelitis. The seat of the affection must be in the thoracic portion, since the bladder and the rectum were more or less paralyzed, for when the lumbar region is affected, there is merely paralysis of the lower extremities. The autopsy of the other patient showed us diffused softening of the spinal cord and a hemorrhage. But it is the softening of the cord, which did indeed affect the thoracic portion, which can explain the symptoms of paralysis of the bladder and the rectum, and not the hemorrhage which affected the lumbar portion. As for us, we think that the ecchymoses of the membranes are related to the gangrene of the sacrum. Let us say in addition that our patient had felt no pain, and pain would have been produced in case of hemorr- hage of the membranes of the cord. But how is this inflammation of the cord produced? Is it by cap- 410 Historical illary hemorrhages? Is it by expansion of the capillaries by gases and, as a consequence, by faulty metabolism (softening)? Microscopic examinations in men and animals may settle this question. Samsoun (Turkey in Asia), June 6, 1875. - 1 quote this opinion of Panthot frcm Brize-Fradin, p. 31. 3 La Chimie pncumatique apptiquee aux travaux sous I'eau Paris, 1SOS _ 4 Lettre au professeur Pictct sur la clothe du plongeur. Btbl. univ. de Geneve, Vol. Alii. j 230-234 1820 5 Relation d'nne descentc en mer dans la cloche du plongeur. Paris, 1826. 6 Triger, Memoir e sur un appareil a air comprime, pour le percement des pints de mine et autrcs travaux, sons les caux et dans les sables submerges: Compt. rendus Acad, des sciences. ■'Rapport sur' les puhs a air comprime de M. Triger. Bull, de la Soc. indust. d' Angers et du depart, de Maine-et-Loire, 1845. 8 Lettre a M. Arago. Comptes rendus de I' Academic des sciences, Vol. XX, p. 445-44y; IMS. 9 Memoir e sur V extraction des roches de la passe d'entree du port du Croisic. Ann. des ponts et chaussees, 184S, First semester, p. 261-315. 10 Rapport sur le precede suivi, a Douchy, pour traverser des nappes d eau considerables. Ann. des mines, Fourth series, Vol. IX, p. 349-364; 1846. , u Mcmoirc sur les effets de la compression de 'air apphquee au creusement des pints a houille. Ann. d' hygiene publique et de medicine legale. Second series, Vol. I, p, 241-279: 18o4. Memoir written at the end of the year 1S47, and presented to the Societe de Douchy shortly 12 Rapport sur V explosion d'un cylindre a air comprime sur I'avaleresse No. 7, situee dans la concession de Douchy (Nord). Ann. des mines, Fourth series, Vol. II, p. 121-148, 1847. _ 13 Creusement a travers les sables motivants d'un puits de la mine de Strepy-bracquegnies. Ann. des trav. publ. de Belgique, Vol. VII, 1848; quoted by Barella, p. 621 14 Lettre a M. Arago. Comptes rendus de V Academic des sciences, Vol. XX, p. 445. 1S4&. ^Notice sur le pont de la Theiss et sur les fondatiens tubulaircs. Annales des ponts et chaussees, 1859, First semester, p. 334-3S2. 16 Memoire sur la construction du pont metallique sur la Garonne, a Bordeaux. Ann. aes ponts et chaussees, 1867, Second semester, p. 27-145. 17 One atmosphere corresponds to 15 pounds per square inch. 15 Paralysis caused bv working under compressed air in sinking the Foundations of London- derry New Bridge. The Dublin quart, journal of medical science, Vol. XXXVI, p. 312-318, 1SG3. 19 Des effets de I'air comprime sur les ouvriers travaillant dans les caissons servant de base auv piles du pont du grand Rhin. Ann. d'hyg. publ. et de med. leg., 1860, Second series, Vol. XIV, p. 289-319. . , , „ ., , c, „ 20 Remarques sur I'emploi de Van comprime dans les travaux dart. Gaz. med. de Stras- bourg, 1860, p. 179. 21 De I'air comprime. These de Strasbourg, 1861. 22 Du travail dans I'air comprime. Paris, 1863. 23 Memoire sur I'etablisscment des travaux dans les terrains vaseux de Bretagne. Ann. des Ponts et Chaussees, 1864. First semester, p. 275-396. ; 24 Symptoms produced by the use of caissons in underground and undersea works. Art Medical, Vol. XVI, p. 428-452, 1862; Vol. XVII, p. 27-48. 105-124, and 194-213. 1863 23 Action de I'air compnmes apoplexie de la moelle epimcrc. Union medicate de la Uironde. 1863, p. 269-270. ,,. - vv 26 Soc. des Sc phys, et nat. de Bordeaux, year 1874-1875. Minutes of the sessions, p. XX. 27 Weighing nearly 500 kil., says the report of the engineer Dubreil. ™ Ann. des Ponts et Chaussees, 1867, Second semester, p. 116-131. . 29 Du travail dans I'air comprime. Observations recueillies a Trazcgnies. lors de I enfonce- ment d'un nouveau puits houiller. Bull. acad. de med. de Belgique, Third series, Vol. II, p. 3» The' effects of compressed air on the human body. The Med. Times and Gazette, Vol. II. 31 Pathological effects upon the brain and spinal cord of men exposed to the action of a largely increased atmospheric pressure. St. Louis Med. and Surg, journ.. May, 18.0. Extract in Canstatt's Tahr., Vol. I, p. 178. 1870. . 32Travai:v publics des Etats-l'nis d'Amcrique en 1.^73. 1 avis, is,.). 33 Fondations a I'air comprime. Ann. des Ponts et Chaussees, 1S74. First semester, p. 329- 402 34 Considerations sur I'hygiene des pecheurs d'eponges- Ann. d'hygiene publique et de medecine legale, Second series. Vol. XXXI, p. 274-'2>6. 1><1!>. 35 Des dangers du travail dans I'air comprime et des moyens de les preventr. theses de Montpellier, 1872. Chapter II LOW PRESSURES The pressures discussed in this chapter have never reached one atmosphere above normal pressure. Workmen employed on the foundations of bridge piers, and divers in suits are evidently also subjected frequently to these moderate pressures; but since they do not experience any distress there (except pains in the ears at the beginning) and since they come from them with no ill effects, the attention of engineers or physicians has almost never been at- tracted to the phenomena which they might have observed under these conditions. The case is quite different for the low pressures which physi- cians use frequently today for therapeutic purposes. Here, on the contrary, delicate observations, of a purely physiological order, have been accumulated, and a study has been made of the effect of slightly compressed air with the same care and following the same method as that of any medicinal substance: that is, on man in good health at first, then in different pathological cases. To three French physicians, Junod of Paris, Tabarie of Mont- pellier, and Pravaz of Lyons, is due the honor of having introduced into therapeutics an agent the efficiency of which is noted every day by practitioners and the use of which will become, we are safe to state, more and more frequent. I do not wish to take sides in the quarrel which has arisen among them on the subject of priority of invention; as far as I can judge, it belongs to M. Junod; at least it is he who first had publications on this subject. Today, the apparatuses intended for treatment by compressed air are fairly numerous. Establishments are now found: in France, two in Paris, others in Lyons, Montpellier, and Nice; in Germany, at Hanover, Stuttgart, Wiesbaden, Johannisberg, Reichenhall, and Ems; in Denmark, at Altona; in Sweden, at Stockholm; in Scot- 411 412 Historical Fig. 9— The aerotherapeutic establishment of Dr. Carlo Fornanini, at Milan. Horizontal cylinder containing two chambers; the front wall of the chamber at the right has been removed. land, at Ben Rhydding; in England, at London; in Italy, at Milan. Figure 9 represents the apparatus which Dr. Fornanini has in- stalled in the last-mentioned city. The various directors of these establishments have different opinions as to the pressure which should be used or rather as to the degree at which they should begin. There are some who ap- prove of high pressures, 30 centimeters at least; in Paris, M. Leval- Piquechef prefers to begin very moderately, 10 centimeters at the most. It is not for me to discuss these different points in practice; nor shall I give any time to the therapeutic applications of the method, limiting myself to saying once for all that its efficacy has been considered very great in emphysematous asthma, chronic bronchitis, chloro-anemia, and passive hemorrhage; it seems to be both tonic and sedative, to use the language of the School.1 (of Medicine) Before listing the evidence collected by physiologists and phy- sicians, I think I should report, acccording to Jaeger,2 the account of a catastrophe which made a great stir at the time, and in which workmen and physicians maintained that compressed air increased Medical Apparatuses 413 the sufferings of the victims, a point which is far from being proved, in my opinion. February 28, 1812, at 11 o'clock in the morning a gallery of the coal mine of Beaujeu, near Leodium, was overrun by water; there were 127 workmen at a depth of 270 meters. Ninety of them were cut off at the end of a gallery, in compressed air "capable of hold- ing water at 64 feet in a metallic tube, so that its density was double that of the atmosphere." They remained in this critical position for 7 days; only 70 survived: As it was impossible for these unfortunate men to communicate with the rest of the gallery, they remained confined in a narrow space, deprived of air and everything. But their foreman Coffin and his son showed heroic courage .... It was not possible to reach them before the seventh day. So, for seven days and as many nights, they were deprived of light and food, and exhausted by constant work. They suffered incredibly from hunger and thirst; respiration was difficult, and the candles went out for lack of air. They felt suffocating heat; their skin was dry and burning. They said that the enormous pressure of the air was very painful to them .... Some became mad, and the others had to aid them and protect themselves against them .... In my opinion, the amazing density of the air was the cause of these phenomena. There is no doubt that the air produced more heat by its condensation, for, we know, condensation can produce fire .... And therefore the processes of combustion were so accelerated in the lungs that the sensation of heat can be explained. (P. 98.) The first publication relating to symptoms experienced by men placed in compressed air was made by M. Junod.3 He reports his observations in the following words: When we increase by one half the natural pressure of the atmos- phere on the body of the man placed in the receiver, this is what we observe: 1. The membrane of the eardrum, pushed back towards the inner ear, becomes the seat of a rather unpleasant pressure. However, this sensation disappears as equilibrium is reestablished. 2. The respiratory movements go on with new ease, the capacity of the lungs for air seems to increase, the aspirations are deep and less frequent; after 15 minutes, one feels an agreeable warmth within the thorax, one would say that the pulmonary areolae, which for a long time had not known contact with the air, are expanding to receive it again, and the whole system with each inspiration drinks in increased life and strength. 3. Increase of the density of the air seem to modify the circulation considerably; the pulse has a tendency to become rapid; it is full and not easily depressed; the caliber of the superficial venous vessels 414 Historical lessens and may even be entirely obliterated; so that the blood, on its return towards the heart, follows the deep veins. If the caliber of the superficial vessels increases or diminishes because of the tension of the atmospheric elasticity, the same thing must be true in the pul- monary organs, which are under the same conditions in this respect; the inevitable result of this must be that when the pressure of the air is increased, the quantity of venous blood contained in the lungs must decrease; no doubt that is why a much greater quantity of air can be inhaled at each inspiration than at normal atmospheric pressure. If the increasing density of the air lessens the caliber of the venous vessels, the necessary result must be that the blood flows in greater quantity in the arterial system, and towards the principal nervous centers, especially in the brain, which is protected from the direct pressure of the atmosphere by the resistance of the bony case in which it is contained. So the functions of the brain are activated, the imagination is lively, thoughts have a peculiar charm, and in some persons symptoms of intoxication are evident. This increase of inner- vation acts also upon the muscular system; movements are easier and more assured. 4. The functions of the alimentary canal are expedited: thirst is wanting; 5. The salivary and renal glands secrete their fluids abundantly. (P. 159.) The report made by Magendie on the work of M. Junod, from which we quoted earlier (page 229) the part relating to the effect of decrease in atmospheric pressure, says nothing new on the sub- ject, about either symptoms or theories. It was not until 1838 that Tabarie 4 published his researches, which, he said then, nevertheless dated back to a considerably earlier period. His note ^hows that he had planned a series of very complex problems, since the processes which he had used included: 1. General compression of the air over the whole body; 2. Local compression over the limbs; 3. Local rarefaction over the limbs. 4. Alternate and local compression and rarefaction or oscillation on the limbs; 5. Rarefaction over the whole body except the head; 6. Use of alternate compressions and rarefactions over the whole body except the mouth, resulting in an artificial and complete respir- ation to be used in cases of asphyxia. The rest of his note contains only a very short summary of applications of these different methods. It contains nothing definite either in regard to physiological phenomena or relating to the theoretical ideas he formed about the action of compressed air. Medical Apparatuses 415 But in a later work 5 he is a little more explicit in the description of the phenomena. The effect of compressed air, he says, is marked by two chief points: 1. Compressed air acts upon the circulation by slackening it; and while it lessens the number of heartbeats, it regularizes their rhythm. These phenomena, which are hardly noticeable in a normal state of health and under the effect of short or incomplete experiments, become very marked in case of inflammatory or feverish diseases, provided that the experimental conditions are properly fulfilled and sufficiently maintained .... 2. Compressed air does not affect general heat production as air with higher oxygen content would do; for far from stimulating this function, as has been supposed through analogy, it moderates it, and in certain cases even depresses it. This fact, which I stated with some hesitancy in 1838, has been proved since then by new evidence. Not only does the use of the compressed air treatment develop no unusual heat within the thorax, but, on the contrary, it tends to produce a general sensation of cold, even when the temperature within the apparatuses is higher than that outside; and in some subjects in whom this chilly feeling is more marked, we note that it increases with the length and the degree of compression of the treatment. Better results are obtained at moderate pressures (% of an atmos- phere) than at higher degrees (% of an atmosphere). However, Tabarie's note contains no theoretical explanation. The first attempts of Pravaz to apply compressed air treatments to therapeutics date back to 1836. In 1837,6 he began to publish the result of his observations. He summarized his previous notes and memoirs in the work which we are taking as our guide.7 His apparatus measured 9 cubic meters. The pressure used was generally from 30 cm. to 35cm. Pravaz describes as follows the phe- nomena displayed by the subjects of his experiments: In most of the subjects of good constitution and in a healthy state, the arterial circulation does not show great modifications, no doubt because the respiration which was sufficient for hematosis under ordinary pressure keeps about the same rhythm in compressed air; but this is not true when there is a morbid acceleration of the pulse; then it drops considerably, except in a few exceptional cases which will be discussed later. The congestion of the capillaries of the skin and the mucous membranes is evidently decreased by the increase in pressure exerted upon the periphery of the body. This effect becomes very apparent upon the surface to which a vesicant is applied or the conjunctiva, when the latter is red and inflamed. The stimulation of the digestive organs, noted by MM. Colladon and Junod, is not always limited to producing a simple increase of 416 Historical appetite; sometimes this stimulation, after a certain time, reaches the point of causing a real bulimia, which forces one to discontinue or make less frequent the use of the compressed air treatment. Among the secretions the increase of which has been mentioned by the authors whom I have just quoted, that of the urine displays, in quantity and nature, changes which seemed to me most remarkable; and that would naturally result from the greater activity brought to the metabolism of the tissues by a greater absorption of oxygen. The feeling of easier, deeper respiration is not experienced in the same degree by all subjects placed in compressed air. Those who usually breathe deeply hardly notice it, but the same thing is not true of patients or valetudinarians attacked by a more or less pronounced dyspnea, either on account of an affection of the thoracic organs, or on account of a state of venous plethora; in general they experience a sensation of extraordinary well-being which would persuade them that they are cured, if it continued after the treatment. (P. 112.) Another doctor of Lyons, Milliet,8 who had founded the estab- lishment at Nice, a few years afterwards published observations which partly agree with those of Pravaz: One of the most remarkable phenomena produced by increase in pressure of the air breathed is the considerable slackening of the circulation caused in most of the subjects. The circulatory rhythm drops 10, 15, and even 45 heartbeats .... In a woman 74 years old, suffering from a subacute catarrhal affection, the pulse, which had risen to 120, fell to 60 and remained there. (P. 13.) .... In compressed air, the movements of inspiration slacken; they are repeated with less frequency in a given time to maintain regular pulmonary nutrition. (P. 15.) However the new method of treatment had made progress; ap- paratuses had been installed at Stockholm, by Dr. Sandahl,9 who in 1862 reported the physiological phenomena which he had observed. After indicating, discussing in detail, and explaining the usual pains in the ears, Sandahl comes to the respiratory and circulatory phenomena: In 1454 observations, dealing with 75 persons, the respiratory movements were slowed in 1362 cases, including 64 persons; in only 11 persons, who took in all 102 treatments, was respiration more rapid than before .... In general, we find that the decrease in the number of respiratory movements not only comes during the treatment, but also lasts after the treatment .... The heartbeats also become slower .... So the pulse in the treatment where the air was compressed a half-atmosphere, dropped 9.94 beats on the average. Medical Apparatuses 417 Similar observations were made at Nice. Tutschek 10 declares that the effect of compressed air is shown by: 1. Enlargement of the pulmonary alveoli; 2. decrease of the num- ber of respirations; 3. slackening of the arterial circulation; 4. accel- eration of the venous and capillary circulation; 5. stimulation of organic expenditures and of assimilation, evidenced by greater excre- tion of carbonic acid and urea, and by hunger reaching the point of gluttony; 6. greater stimulation of the nervous system by a blood richer in oxygen, evidenced by activity of mind and a sensation of lightness of movement. He does not give the pressure used. Everything leads us to think, moreover, that this summary of symptoms is merely bor- rowed from former authors; Tutschek made observations on only 3 healthy persons and 6 sick ones. In the former, the number of respirations decreased by 3 to 5 and that of the heartbeats by 0 to 10; the changes were greater in the invalids. In Germany, Dr. G. Lange, physician at the spa of Johannisberg, had installed in this establishment an apparatus for the use of com- pressed air. In collaboration with Rudolph von Vivenot, he there made numerous observations which we shall discuss, and published a memoir, translated into French by M. Thierry-Mieg, about the results of his practice. The interesting extracts from this memoir will be better placed in the chapter devoted to the study of theoreti- cal explanations. I shall quote here only the summary which he gives of the phenomena observed in persons subjected to the action of com- pressed air: Slackening of the respiration and the circulation; very probably, greater absorption of oxygen by the skin and the lungs; increase of exhalation of carbonic acid; decrease of cutaneous transpiration and pulmonary exhalation; increase of the urinary secretion, which elimin- ates more uric acid and less phosphate; improvement in hematosis and nutrition; increase in the energy of the muscular apparatus and in the vital capacity of the lungs. (P. 33.) In 1860 von Vivenot began the series of his publications on the physiological and therapeutic effect of compressed air. His numer- ous notes and memoirs 1X led him to write a lengthy work,12 which appeared in 1868; it is by far the most important work which has been published on this subject. The larger part of his researches were made at the baths of Johannisberg. Since the altitude was fairly great, the average barometric pressure was only -741.17 mm.; as the compression used rose to 318.07 mm., the total pressure was 1060.24 mm. This pres- 418 Historical sure was reached in the apparatus in 20 minutes; it stood there for 1 hour; 40 minutes were used for the return to normal pressure. Respiration. The most important of Vivenot's memoirs is the one which he devoted to the study of the changes in the mechan- ical and chemical reactions of respiration. Since in his long work he added to it only details of observation of moderate interest, I cannot do better than to reproduce the principal passages of the original work, published in 1865; it is a sort of analysis of Vivenot by Vivenot himself. We shall, however, limit ourselves here to reporting the obser- vations relating to changes in the respiratory rhythm and the pul- monary capacity; the chemical part, since it is much more closely connected with questions of theory, will be better placed in the following chapter: If we examine a person first under normal pressure, then under compressed air, we may detect, by percussion, auscultation, and pal- pation, changes in the size and location of different organs, corre- sponding to the new conditions of pressure. If we have noted, under normal pressure, the position of the diaphragm and the upper limit of the liver corresponding to as deep an inspiration and expiration as possible, as well as the boundaries of the dullness of the heart, we find, in both cases, the diaphragm and the liver situated lower under com- pressed air; the drop is from 1V2 to 2 centimeters under an increase of pressure of 3/7 of an atmosphere; the dullness of the heart has become less extensive and has taken another form (that of a sickle, the con- vexity of which is turned towards the sternum). At the same time, the cardiac impulse seems less vigorous to a palpating finger, and the ear in auscultation finds the heart-sounds weaker, as if they were further away. There is sometimes produced in compressed air a me- chanical expansion of the lungs, as a result of which the diaphragm and the liver are pushed down, while the anterior lobe of the left lung places itself above the corresponding half of the heart. For this reason the dullness of the heart diminishes, its form is changed, and the impulse and sounds of this organ seem weakened. The increase in capacity of the lungs, shown by these facts, is demonstrated in another manner. In compressed air, the spirometer shows us a rather considerable increase of the respiratory capacity. The average of a great number of experiments, made during a stay of an hour and a half under the pressure of 1 and 3/7 atmospheres, gave in me an increase of 108.07 cubic centimeters, in Dr. G. Lange 133.3, in Dr. Mittermaier (after a single experiment) 121.0 and in M. H. .y 99.2. Now since my pulmonary capacity on the average is 3425 cubic centimeters, that of Dr. Lange 3950 cc, that of Dr. Mittermaier 4159 cc, and that of M. H. .y 2910 cc, it follows that the increase in lung capacity was in me 1/31.7, in Dr. Lange 1/29.7, in Dr. Mittermaier 1/35.4 and in M. H. .y 1/29.3. We see that these results do not differ perceptibly from each Medical Apparatuses 419 other and they indicate an average increase of pulmonary capacity equal to 1/31.5 of the volume of the lungs, or 3.3%. As the maxi- mum of this increase, I found in myself 254 cc, in Dr. Lange 200 cc, in M. H. .y 223 cc, in M. R. 270 cc. and even 500; 686 in a patient with emphysema, M. G., whose average respiratory capacity was 2268 cc, that is, about 2/9 to 2/7 of the total respiratory capacity. The effect obtained, as we see, is doubled; on the one hand, we have in the same volume more atmospheric air, and on the other hand, our enlarged lungs are capable of receiving a greater volume of this compressed air. If then my average respiratory capacity is 3425 cc. under normal pressure, the same volume of compressed air at 1.37 atmospheres would represent by itself 4893 cc. of normal air. And as, under increased pressure, my lungs inspire an average of 108.1 cc more, which is equivalent to 154.5 cc. of normal air which I inspire, then 3425 + 108.1 cc. = 3533.1 cc of compressed air, it fol- lows that the volume of air drawn in by the deepest inspiration under the effect of compression is equal to 5047.5 cc. of air at normal pressure .... Experimentation has proved that after a stay of 2 hours in com- pressed air, the pulmonary capacity, even under normal pressure, does not return to its original volume, but retains an increase which, in me, rose on the average to 50.53 cc, at the maximum to 183 cc; in M. H. .y on the average to 57.6 cc, at the maximum to 124 cc. It next gave this interesting and astonishing result that the sub- sequent effect is not a passing effect, but that it is partly permanent, so that as a result of the use of compressed air for two hours every day, one enters the pneumatic apparatus with a pulmonary capacity which, naturally disregarding physiological variations, every day exceeds what it was the day before by 20 to 30 cc. For instance, from April 30 to September 19 inclusive, that is, in 143 days, after 122 treatments with compressed air taken during this time, my pul- monary capacity under normal pressure had risen successively from 3051 to 3794 cc (under compressed air even to 3981 cc), a figure which it had already attained August 12 after 91 air treatments, and at which it remained almost constantly. The vital capacity of the lungs therefore in me in three and a half months had made a progres- sive increase of 743 cc, that is, nearly a quarter of its original volume (24%). A similar result was observed in other persons. In M. H. .y, the respiratory capacity had risen after 11 days use of compressed air from 2900 cc. to 3085 cc; in M. de K., in 4 days, from 3252 cc. to 3664 cc; in M. G., a patient with emphysema, in 17 days, from 2202 cc. to 2550 cc; the respiratory capacity of the latter had even reached 2836 cc. in compressed air. A suspension, even for several days, showed no retrogressive effect, and three weeks after my last stay in compressed air, the spirometer showed that my respiratory capacity had remained at 3800 cc. Like- wise percussion, by Professor Duchek, revealed after 3 weeks that the forcing downward of the diaphragm and the liver for 2 centi- meters and the decrease of the dullness of the heart, matters dis- cussed above, were maintained. 420 Historical It is quite evident that such changes in the pulmonary capacity must have some effect upon the sum total of the respiratory func- tions, and particularly upon the number, the depth, and the rhythm of the respirations. The number first: In my first experiments published several years ago, I had al- ready found the number of inspirations diminished; my long present series of experiments has confirmed this result, as being constant, one may almost say. The decrease in the number of inspirations varies with the individual. On the average, it increases proportionately with the original number of respirations; in general, it is 3, 2, 1, to Vz respirations per minute. As a maximum, I have observed in two patients with emphysema, whose inspirations rose to 33 per minute, a decrease which was respectively 16 and 11 inspirations. Upon the return to normal pressure, the number of inspirations increases again a little, but without reaching its original figure. In that also, the effect of the compressed air is not merely temporary, but has a somewhat permanent quality. This is more evident when we consider the frequency of the respiration in a longer series of observations. Then we note that the respiration is always less -fre- quent the day after than on the day before. As it undergoes a new decrease as a result of each new treatment with compressed air, the result is this certain and constant fact that the continued use of com- pressed air lessens the frequency of the respiratory movements every day, up to a certain limit. My own respiration, after three months of daily use of com- pressed air for two hours every day, had fallen from 20-16 per min- ute to 4.5 under normal pressure, and even to 3.4 in compressed air. When it had reached this degree of slackening, it remained stationary during the subsequent experiments (still slackening a little under the influence of pressure) and even now, while I am writing these lines, although 5 months have passed since then, my respira- tion does not exceed the noteworthy figure of 5.4 inspirations per minute. The same result, though less remarkable, because the series of experiments was shorter, was noted in observations made on other people. In M. H. .y, the number of inspirations had fallen in 12 days successively from 21 to 16 and in compressed air to 13 per minute. In Dr. Lange, after 4 treatments taken in 11 days (in spite of interrup- tions of several days) from 19 to 16, and in compressed air from 14 to 6; in M. G., an emphysematous patient, after 14 treatments taken in 19 days, from 20.5 to 15.5; in Dr. D., also emphysematous, from 33, on the second day, to 18, and in 5 days to 10.4. It is during the first days that the respiratory frequency lessens most noticeably and most promptly; later, the decrease becomes slower and the differences less great. If we compare the result obtained as to the frequency of the respiration with the result given us by the spirometer, it will be dif- ficult not to observe that there is between the two a well-founded relation, that the frequency of the inspirations is inversely propor- Medical Apparatuses 421 tional to their amplitude, so that while this amplitude increases, the frequency of the respiration diminishes. The increases of the capacity of the lungs, under the effect of compressed air, is the cause of the slackening of the -respiration; or, in other words, the slackening of the respiration is an inevitable consequence of the increase of the pul- monary capacity, because the inspiration and expiration of a greater volume of air necessarily require more time. Then the depth: We could imagine three different methods as possible. A com- pensation might be established between the frequency and the depth of the inspirations by the fact that the amplitude of the respiration could be less than under normal pressure, since a greater quantity of air enters in the same volume, and the frequency of the respiration could nevertheless be reduced also; or, in the second place, the com- pensation could be established, for the same reasons, by less numerous inspirations, keeping the same amplitude. Finally, in the third place, there might be, in spite of the supplying of a greater quantity of air, as a consequence of the compression, a slowing down and an increase in depth of the inspirations. This last condition appeared a priori most probable if we took into account the increase in amplitude of the respiration, as we had observed it, and it should occur particularly in persons whose pulmonary capacity had been pathologically reduced. To settle these questions, I used an apparatus constructed for the purpose, which could be attached around the thorax, and followed its movements of inspiration and expiration, the increase of the cir- cumference of the thorax being indicated in millimeters by the sep- aration of two movable needles. This greater or smaller increase in the thoracic circumference served to measure the greater or smaller depth of the inspirations. In each of the thirty-nine experiments made with this thoracometer, the depth and the number of the in- spirations were noted for fifteen consecutive minutes, long enough for the effect of the will or a slight error of observation to be negli- gible. The experiments were always made comparatively in atmos- pheric air and in compressed air; and as the frequency of my inspira- tions was then from 7.67 to 4.40 per minute, from 115 to 66 observa- tions were needed in each experiment, making a total of about 3000 numbers concerning the mobility of the thorax. The measurement made as explained above justifies the state- ment that in me, on the first day of the experiment, the thoracic expansion, that is, the increase of the thoracic circumference produced by an ordinary inspiration was 12.39 mm. at normal pressure, and at the beginning of the maximum pressure 15.68; after an hour of this same pressure 17.22; and at the end, under normal pressure 18.14, whereas the frequency of the inspirations had dropped from 7.67 to 6.07, 5.80, and even 5.60; there had been produced therefore under the influence of the compressed air a progressive decrease of frequency at the same time as a progressive increase in the depth of the inspirations, which continued even after ordinary pressure had been restored. The next day, the thoracic expansion under normal pressure was 14.92; the third day, 17.84; the fifth day, 18.98; a fort- 422 Historical night later it had risen to 21.86, while the number of inspirations un- der atmospheric pressure had dropped respectively from 7.67 to 7.07, 6.40, 6.53, and 5.00 per minute, and the respiratory capacity on the contrary had risen from 3350 cc. to 3400, 3474, 3498, and 3644. The experiments made on MM. de K. . . and Dr. M. . . gave the same result. In the latter, the frequency of the inspirations had fallen during a single experiment in compressed air from 7.6 to 6.5 per minute, whereas his thoracic expansion had risen from 19.28 to 23.02 mm., and his respiratory capacity had likewise risen from 4159 to 4280 cc. This result proves that under the influence of compressed air the depth of the inspirations as well as the capacity of the lungs increase, whereas the frequency of the inspirations diminishes in in- verse proportion. The expansibility of the thorax, as it has been investigated up to the present, is only that which corresponds to an ordinary inspira- tion, not modified by the will, and as it is produced as an effect of the prolonged influence of the compressed air. However, the modifications already noted suggest also a change in the conditions of the voluntary inspirations, and this change is to be verified by the increase of the total circumference and of the volun- tary expansion of the thorax before and after the prolonged action of the compressed air. If the capacity of the lungs had really been in- creased, the last measurements should indicate an increase in the circumference of the thorax, not only during the greatest expirations, but also during the deepest inspirations; and if by a prolonged stay in compressed air the ease of a habitually more vigorous respiration had been gained, the maximum expansibility of the thorax should also have increased. This result is also verified by the figures. My thoracic circumference, which on April 30 after the deepest inspira- tion had been 85 centimeters, was 86.5 on September 1; and after the strongest expiration, it was 77 cm. on April 30, and 78 cm. on Septem- ber 1; so that my pulmonary expansion was 8 centimeters on April 30, and 8.5 cm. on September 1. The general increase of the lung capacity, as it was indicated by the spirometer, and the increase of the vertical diameter of the lungs, as it was determined by percussion, receive an additional demonstra- tion by the increase of the thoracic circumference. Finally, the proportions of the respiratory periods: The inspiration is made more easily, being favored by the increase of pressure, by the extensibility of the pulmonary tissue, and by the compressibility of the intestines, whereas more force is needed for the expiration so as to contract the lungs which are more distended and to expel the greater quantity of air expired. That is why the expiration is made with more difficulty and more slowly than in the normal state. While under atmospheric pressure the duration of the inspiration is to that of the expiration almost as 4:3, this ratio be- comes in compressed air almost as 4:6, 4:7, and even 4:8 and 4:11. However the resistance to the expiration finds partial compensa- tion in the more powerful contraction of the abdominal muscles Medical Apparatuses 423 which the compression supports in their action. Through the effect of this contraction, the first half of the expiration is made quickly and energetically; but the second half is made so slowly and so im- perceptibly that there is a sort of pause between the inspiration and the expiration. This pause which should in any case be added to the expiration and the length of which has been, according to my ob- servations, from two to six seconds, is increasingly longer as the in- spirations are fewer. Vivenot has tried to express these different modifications of the respiratory rhythm by the following graph (Fig. 9) , which I borrow from his long work (p. 251), and in which the solid line indicates the normal respirations, and the dotted line the respiration under compressed air, the whole during fifty-some seconds. Circulation. The memoir published by Vivenot in 1865 in the archives of Virchow contains detailed information about the modi- fications in his pulse under the influence of compression. These explanations are accompanied by numerous graphs obtained by means of the sphygmograph of M. Marey; I reproduce here the most characteristic: A rapid glance at the curves shown below reveals that under the influence of compressed air they undergo considerable modifica- tions in their original forms; closer attention shows that all parts of Fig. 9— (bis). the curve are so essentially changed that their analysis requires care- ful dissection of separate segments of the curve. We see that in all the curves without exception, under the in- fluence of compressed air, the height of the curve decreases. The line of ascent, more or less abrupt originally, becomes more oblique; the apex seems more rounded, and because of the lessening of the amplitude, the line of descent, still less abrupt, finally is bent into the form of a wave which is more or less convex on the right. Because of the decrease in the height of the curve, the angle formed by the intersection of the ascending line and the descending line of the pulsa- tion inscribed and which under normal atmospheric pressure measures about 45° is considerably blunted; and also, because of the more oblique direction of the line of ascent, the apex of the top of the 424 Historical curve is further prolonged backward ... so that the curve as a whole assumes the form of the segment of a sphere. The changes which we have just described are proportional to the strength of the air pressure and to the duration of the stay in compressed air and consequently are more marked and more pro- nounced as the air pressure is carried higher and the stay in the ap- Fig. 10 paratus is lengthened. We find then that the indications produced after twenty minutes of maximum pressure, that is, the visible ob- liquity of the line of ascent, the shortening of the wave, the rounded flattening of the top, and the transformation of the wavy line of descent into a straight line or a simple convex line, after an hour and a half, that is, after an hour of exposure to the constant maxi- mum pressure, take on a still more evident character, so that the tracing of the pulse finally presents, so to speak, only a straight line. Fig. 11 In these four figures letter a indicates the sphygmographic tracing obtained under normal pressure; b is the tracing while the pressure is rising in the apparatus; c, during the period of constant compression; d, after return to normal pressure. Fig. 11, ai was taken while the pressure was increasing; Ci while it was decreasing. Upon return to normal atmospheric pressure, immediately after the treatment, the curve resumes its original form, or only partially returns to it, or, somewhat frequently, the change when it has once begun in the blood curve undergoes a downward movement. Figure 9 expresses all these different phases. Medical Apparatuses 425 In no case did I find this change in the curve lasting, but this effect, agreeing with. the results which we obtained for the pulse rate, in favorable cases is prolonged for a few hours. Curve d, in Figure 12, furnishes an example of a curve rising and regaining its original form, not immediately, but twenty minutes after the return to nor- mal pressure. Fig. 12 To establish the truth of the assertion which we have already accepted, that the vestige, remaining after the treatment, of an effect upon the tracing has already disappeared after several hours, one may use curves obtained upon myself May 26, a day on which I had had two experimental treatments in compressed air. If we com- pare the curve obtained on that day before the first treatment, at eight o'clock in the morning (Fig. 12, a) with the corresponding Fig. 13 curve of the second treatment, that is, taken at half-past two in the afternoon (Fig. 13, a), one can note no essential difference between these two pulse tracings. After this period of four hours and a half there is no perceptible sign of the effect still noticeable at ten o'clock on curve b of Figure 13; still less should we expect to find the persist- ence of this effect from one day to another. Now, to grasp the value of the differences so far found, we should picture the different elements of the curves as the expression of these changes. The irregularity in the ascending line which coincides witn the systole of the heart is produced by the blood wave expelled by the contraction of the heart, and this wave, tending to spread in all direc- tions, partly urges on the blood current and partly exerts an excentric pressure upon the walls of the vessels which it stretches. The ascend- ing part of the curve (line of ascent) therefore corresponds to the arterial diastole. The more easily the blood flows in the capillaries, 426 Historical the more quickly does it move in the arteries, and the more easily does the heart contract, since the blood pressure representing the resistance opposed to the systole of the heart becomes weaker. It is well known that every muscle contracts so much the more easily and quickly, in proportion as the execution of this movement requires less expenditure of energy. Consequently, in such a case, the arterial expansion will take place in so much less time; and if the time from the rise of the blood pressure to its maximum increase is very short, that will be expressed in the steepness of the ascending line of the curve; and if the period of time is so short that it cannot be measured, then the line of ascent will appear completely vertical, as is almost always the case in the normal state. When, on the contrary, on the tracings made in compressed air we observe that the line of ascent is becoming oblique, we conclude that the resistance opposed to the blood wave produced by the systole of the heart has increased at the same time that the flow of blobd is checked in the capillaries; that consequently the systole of the heart is less rapid, that the blood wave reaches the arteries slowly, and that consequently also the dilatation of the arteries does not take place suddenly, but progressively. The apex of the curve which we do not wish to consider as a mathematical point, but as the convergence of the ascending and descending lines, shows us the moment when the artery, having reached the maximum of its dilatation by the blood distending it, resists by means of its own contractility the pressure of the blood which acts upon it, and by its contraction exerts a new impulse on the blood. If the resistance which the blood wave meets in the arterial trunks at a distance from the heart decreases a little, then the flow of the blood in the direction of the current, from the heart to the periphery, becomes easy and rapid, and the pressure of the blood in the arteries decreases rapidly, and the arteries can contract rapidly. The more marked this tendency is, the more acute the apex of the tracing appears, as we can see, for example, in the normal pulse. The contrary takes place in compressed air, and the original acute angle changes, as we have seen, into a more or less obtuse angle, and even into an arch, which takes place, if, on account of the con- siderable obliquity of the line of ascent, the highest vertical point intersects the middle of the curve. Consequently the increase of resistance already expressed in the ascending part of the curve, by its obliquity under the influence of the compressed air, is communicated or transmitted also to the apex of the curve (p. 557-560) .... The descending wave of the curve of the pulse, which corresponds to the diastole of the heart, shows us the decrease of the blood pressure in the arteries, coinciding with the closing of the semilunar valves, and with the simultaneous flow from the large arteries into the capillaries, that is, the arteries gaining the victory in their struggle against the pressure of the blood, and by means of their elasticity, through the transformation of their expansive energy into active energy, contracting to the minimum limit of their caliber. The vary- Medical Apparatuses 427 ing appearance of the line of descent, according as it bends, becomes straight, or oblique, or convex, or falls perpendicularly, shows us how much more or less easily the blood passes through the capillaries. The tracings of the pulse taken at normal atmospheric pressure, be- fore entering the compressed air (tracings I - XVII of Vivenot) show this more or less accentuated characteristic oscillation which the finger detects only in the most pronounced cases, which is called dicrotism, and which consists of two or, more often, three oscillations of the wave. (P. 562) Whereas we have found polycrotism as a more or less marked peculiarity of the normal pulse at ordinary pressure, it appears from our curves that the compression of the air causes the polycrotism to disappear and transforms the wavy line of descent into an almost straight line or one which is more or less convex. So we find the proof of a congestion of blood in the vessels and of a hindrance of the capillary circulation, in the descending line of the curve as well as in its ascending part and its apex. Whereas, as Marey has shown and has proved by an example in a tracing made in a case of heart disease (Fig. 86 of Marey), the dicrotism is proportionately greater as the wave expelled by the ventricle is smaller in proportion to the caliber of the artery, we con- firm, for our part, this proposition in regard to the dicrotism, be- cause, as it appears from the preceding discussion, the arteries, which are compressed by the outer pressure and therefore convey very little blood, are nevertheless very full of blood in proportion to their les- sened caliber. Upon return to normal pressure, at once the original figure of the line of descent reappears, and the simply convex line resumes its previous polycrotism, or rather the form which has been produced per- sists for a time, one or two hours, and then yields and gradually re- gains its original appearance (See above, Fig. 9). In our analysis of the pulse tracings we have hitherto omitted one circumstance, that is, the somewhat important change in the amplitude of the curve under the influence of compressed air. For the sake of clarity, we have delayed analysis of it until we reached the subject of the energy of the pulse, better named the size of the pulse, which refers to the vertical height of the blood wave, that is, the maximum height, and which, according to Marey, is pro- portional to the energy of the pulsation. As we have concluded from the agreement in the tracing of the curves which we have collected for far, the amplitude of the pulse is lessened by the stay in com- pressed air, and often loses from 4/5 to 5/6 of its original height, so that the whole series of pulsations traced is often changed into a line in which the separate waves are hardly perceptible. This decrease of amplitude is proportional to the compression of the air and to the length of the stay in the compressed air, and so the minimum amplitude is noted particularly at the end of the stay in the compressed air; it happens by exception that after the return to normal pressure the amplitude remains stationary, and returns to the normal state after a long stay under ordinary pressure. It is also exceptional to see the amplitude, after reaching its minimum, 428 Historical begin to rise gradually during the period of constant maximum pressure, without reaching its original height, however. Moreover, the changes which the pulse undergoes here are ex- plained by and are perceptible to the touch, because in most cases the pulse which is normal before the entrance into the pneumatic ap- paratus is almost imperceptible to the touch of the finger in com- pressed air; it is really the pulsus debilis. We should note in regard to this last point that the changes of the pulse described above in a pulsus longus, such as we have seen appear in the pneumatic apparatus, and Which are observed in normal air pressure in certain morbid processes, such as aneurisms and embolisms, give a deceptive sensation to the finger, so that even when the vertical height of the pulse remains identical, as Marey observed (p. 243), the pulse will ap- pear stronger in proportion as the blood wave is more gradual, which is expressed by the rise and fall of the blood pressure in the vessels; but since in our case, in compressed air, the decrease of the strength of the pulse indicated by touch is also confirmed by the decrease in vertical height of the tracing, the decrease of the strength of the pulse in itself must be considered certain. We should now have to show the cause of this decrease of the strength of the pulse in compressed air, as it appears from our re- searches; we might well think first of the weakening of the action of the heart itself, and of the occasional circumstance of the decrease of the strength of the pulse in compressed air, a weakening which perhaps is caused by the rise in resistance, which the increase of the atmospheric pressure, compressing the whole of the peripheral vessels, produces in the arterial system; in support of this hypothesis we might mention data which I reported under other circumstances and in another place; in fact, inspection and palpation of the heart show its weaker impulse; auscultation of the heart gives an identical result, and the sound appears further away, so to speak. However, these data in no way show and prove that a change has taken place in the strength of the heart impulse, for, on the one hand, we find it extremely difficult to get an almost certain and demonstrated proof of the changed intensity of the contraction of the heart, and, on the other hand, the weakening of the heart impulse and of the heart sounds, noted by sight, hand, and ear during the stay in compressed air, can be only apparent; and, as I have already shown in the dissertation mentioned above, can be only a simple effect of a displacement of the heart, caused by the compression of the air and connected with the increase of the capacity of the lungs and the pass- ing of the anterior layer of the left lung in front of the heart. (P. 564- 567). So far we have discussed only the form of the isolated wave, with- out taking into account the combination of the successive waves, and yet this complex phenomenon requires some explanations. Let us draw a line from the beginning to the end at the base of the wave or across its apex; we shall then have what Marey called a line of the whole (gemeinsame linie), which may give us some in- formation about certain changes in the pressure of the blood and in the distention of the vessels. This line which, as we have said, varies Medical Apparatuses 429 according to certain changes in the attitude of the body, may display a total or partial change in its form and in its direction. The first case appears following a change of long duration in the blood pressure and in the distention of the vessel, and is evidenced by a consider- able modification of the whole line in reference to the original form of the pulse, whereas a frequent change in blood pressure and vascu- lar distension, such as takes place, for example, under the influence of an irregular respiration, finds expression in the more or less marked and more or less frequent incurvations in a series of rises and drops of the pulse line. Now since this line, according to Marey, indicates that an obstacle to the blood flow increases the distension in the arterial system at some point, we had to investigate whether that took place in compressed air because of the compression of the super- ficial vessels, and whether the obstacle or the difficulty recognized by us in the arterial circulation by the change in the line of ascent also produced a change in our line of the whole, and found its ex- pression in its rise (oblique ascent of the whole line) in compressed air. After preparing the instrument for this purpose, according to the rules established in our preceding experiments made with the use of the sphygmograph, and arranging things in such a way that the reg- istering stylus should be placed just in the middle of the band of paper, at an equal distance from the upper and the lower edge, and after releasing the clockwork, I thus made in the open air a tracing of the pulse in the exact middle of the paper; but I did not have the same success with operations in compressed air. Although the in- strument had not been lifted, and no change had been made in the attitude of the arm or the position of the instrument, the registering stylus under the influence of the compressed air moved from its original situation and rose; it even rose so high that it passed above the upper edge of the paper band, and it had to be lowered, by a slight movement of the hand, to the level of the paper so that a tracing could be obtained. By this experiment we demonstrated: for the radial artery a general rise of the blood tension and of the vascular distention independent of that which can be observed in an isolated pulsation. As far as concerns the influence of the respiratory movements shown by the arched incurvations of the pulse line, it is slight and imperceptible enough to go unnoticed by superficial observation. It is very apparent only when one takes deep inspirations and when there is a difficulty in respiration. In consequence of changes produced in the size of the thorax by the inspirations and expirations on the one hand, and, on the other, as a result of the rising and falling of the diaphragm, which alternately contracts and enlarges the abdominal cavity and Ihe thoracic cavity, and of the consequent change in distention of the abdomen, a stronger pressure is produced alternately in the thoracic aorta and the abdominal aorta; the result is a variable distention in these vessels which is then communicated to the remote arteries. And so, as I have shown elsewhere, under the influence of com- pressed air, we observe a slackening of the frequency of the respira- 430 Historical, tion which, maintained by the daily repetition of this same influence of the pressure of the air, increases from day to day to a certain figure; moreover, the respiration is easier in compressed air; it be- comes calmer and more complete; and thus certain respiratory dis- turbances are quieted. So whereas in the open air the influence of •the respiration was shown in the curve of the pulse, in compressed air this influence should be weakened,, that is, the curves and arches of the line of the pulse should, under this influence, lose frequency Fig. 14 and intensity, as, moreover, we can see in Figure 14, which, made May 1 on an emphysematous patient aged 44, in a at normal pressure shows noticeable variations in the curves expressing the pulsations, which show great difficulty in respiration, whereas, under the in- fluence of compressed air in b, the intensity of the curve has fallen so considerably that the pulse line almost becomes horizontal, and that at the same time there is a greater number of pulsations for one respiration than in a, and by this change the abatement of the previous respiratory difficulty is indicated. The existence of this change in the respiratory curve under the influence of compressed air may be considered the rule, and we rarely find the opposite state. (P. 578-580.) As to the number of pulsations, Vivenot summarizes in the fol- lowing words 423 observations made upon himself: In the morning between 6 and 7 o'clock, when I awoke, my pulse rate was 65.22. After I had breakfasted in bed, this number rose to its maximum, 81.20; at the time of entering the pneumatic apparatus it was only 79.03. Under the influence of compressed air, it fell to between 75.43 and 71.66; on return to normal pressure it was still 72.41, and in the course of the day my pulse did not rise to the figure given before my entering the apparatus. This decrease in the pulse rate in compressed air was noted 375 times in my 423 observations; 18 times there was no change; 30 times, an increase in the pulse rate. (P. 532). Vivenot observed that the congestion of the vessels of the con- junctiva disappeared wholly or partially through compression. The examination of the retina in a person who had been given atropine also showed him that the vessels of the eye are emptied of blood in compressed air. Besides, he made five direct observations upon a tame white Medical Apparatuses 431 rabbit in regard to changes in the circulation in the ears and the conjunctiva. I copy the details which he gave on this subject, because they do not seem to me to justify the conclusions which he drew from them and which were accepted on his authority. I. (a). Normal pressure: The rabbit quiet and free. The ears erect, swollen with blood. The vessels of the conjunctiva congested. The iris and particularly the pupil very red. (b). During the increase of pressure: Vessels of the conjunctiva thinner and paler. Loss of. color in the iris and the pupil. (c). During the constant maximum pressure: By transparency, the vessels of the ears empty of blood; the largest are hardly visible; shortly after, the ear is quite pale and limp and the vessels have completely disappeared, (d). During the decrease of pressure: The ear and the conjunctiva remain pale. (e). Under normal pressure, immediately after treatment: After the treatment, even an hour after, the ears are empty of blood, pale and limp. II. (a). The vessels- of the ears are moderately congested. (b). At the beginning, a greater congestion of the arteries and the veins of the ear; later the iris first grows pale and then loses its color. (c). The ears remain pale; the iris is darker; the pupil redder. III. (a). The vessels of the ears are moderately congested; the iris and the pupil are a beautiful red. (b). Swelling of the vessels and particularly of the veins of the ears, the largest of which are dilated. (c). At the beginning, no change noticeable in the color of the iris and the pupil. The vessels of the ear alternately grow pale suddenly and fill up again; however, some time afterward, they are definitely pale and remain empty of blood, (d). The ears are still pale and limp. (e). Some hours after the treatment, the ears are still quite empty of blood, pale, and limp. IV. (a). Long before the treatment, the ears are rather empty of blood. (b). The vessels of the ears are alternately congested and pale; finally they remain pale. (c). Because of the darkness in the apparatus, the color of the pupil cannot be observed. (d). The ears still pale. (e). The pupil seems to become dark red. The ears are well filled with blood. V. (a). The conjunctiva congested at isolated places. The vessels of the ear moderately congested. (b). The congestion of the conjunctiva and the vessels of the ear partly disappears. 432 Historical (c). Vessels of the ear and the conjunctiva obliterated; the ears pale; sometimes congested in an instant. Because of the increas- ing darkness, the color of the pupil and that of the iris cannot be de- termined. (d). The ear and the conjunctiva remain pale; finally, no vessel can be perceived. (P. 587). So, Vivenot concluded, under the influence of compressed air the blood diminishes in the vessels of the periphery of the body. After the details which I have just reported about the changes in the two great physiological functions of respiration and circula- tion, changes which are at the same time the most important and the easiest to verify, I think it will be sufficient to reproduce the summary which Vivenot himself gives of all his observations. Unfortunately, the statement of the data in it is so thoroughly mingled with the theoretical ideas which the author conceived to explain them that it would be impossible to separate them from each other; but the difficulties resulting from this confusion will be settled in reading the following chapter. Summary of the Physiological Phenomena. 1. Impressions in the ear. 2. The change in the tone of the voice, the tones rise in pitch; the difficulty in pronunciation, the impossibility of whistling, some- times slight stammering. 3. Smell, taste, and touch' lose their keenness. 4. The negative pressure in the inspiration and the positive pressure in the expiration increase. 5. The convexity of the abdomen decreases because of the compression of the intestinal gases. 6. For the same reason, the diaphragm and the base of the lungs fall. 7. The lung, during inspiration as well as during expiration, comes around in front of the heart. 8. Thence comes the decrease of the cardiac impulse upon pal- pation and the faintness of its sounds upon auscultation. 9. The pulmonary vital capacity increases. At 3/7 of com- pression, it is increased in a half-hour by 73.40 cc. on the average, and in 1V2 hours by 105.27 cc, that is, 3.30% of their original dimensions. 10. On return to normal pressure, the increase in pulmonary capacity decreases, but the lungs do not regain exactly their orig- inal volume. 11. Repeated treatments bring every day an increase of the pulmonary capacity; more at the beginning than at the end. After 3V2 months of air treatments my pulmonary vital capacity had be- come greater by 743 cc, that is, increased one quarter without any loss of the contractile power of the lungs. Medical Apparatuses 433 12. The changed activity of the diaphragm and the thorax per- sists after the end of the experiments. 13. These increases do not take place solely in extreme respira- tions; they are observed in the regular respiration, and the diaphragm then is also lower than in the normal state. 14. The respiration becomes less frequent. The number of the movements decreases by 1 to 4 per minute. This effect continues a little while after the return to normal air. 15. 16, 17, 18. These sections repeat for frequency what was said about depth in 10 to 13. 19. The inspiration is faster, the expiration slower; the first part of the latter is rather short, but the second becomes so slow that there seems to be a pause. 20. The proportion of carbonic acid contained in the expired air increases; a respiration with 3/7 of an atmosphere above the normal contains on the average 22.26% more carbonic acid than at normal pressure. 21. This increase therefore is not in exact proportion to that of the pulmonary capacity, which is 3.3%. 22. It takes place not only in exaggerated respiratory move- ments but also in quiet respiration. 23. Upon comparing this increase of carbonic acid with the de- crease of respiratory frequency, we see that there is definitely a greater quantity of carbonic acid given off and consequently of oxygen absorbed. 24. The result of this is that after a series of treatments in com- pressed air, the venous blood appears brighter, the temperature of the body increases (from 0.1° to 0.4°), the muscular energy is greater, hunger appears, and, in spite of a larger amount of food, the weight of the body lessens through emaciation; however, if the pressure is not too great and if one eats a great deal, one may, on the contrary, grow fat. 25. The pulse rate drops by 4 to 7 per minute; this decrease is still more marked when there was an abnormal acceleration. 26. On return to open air, the pulse resumes its normal rhythm. 27. However, when the frequency of the pulse was due to some respiratory difficulty, a permanent drop may be the result of treat- ment by compressed air. 28. The decrease of the frequency of the pulse seems to be the result of the purely mechanical action of the compressed air; the increased pressure on the surface of the boody increases the re- sistances met by the blood waves sent out by the systole of the heart; the systole then becomes more difficult, with the result of a decrease in the number of pulsations. 29. The curve of the radial pulse undergoes changes in form; its height lessens, the line of ascent is less steep, more oblique, the apex more rounded, the line of descent loses its wavy form and be- comes straight or slightly convex. There is therefore a shrinkage of the vessels, and consequently of the quantity of blood which they contain, an increase in resistance to the systole of the heart, and a greater difficulty in the capillary circulation. 434 Historical 30. On return to normal air, the tracing gradually regains its original form. 31. The radial pulse seems changed to the touch; it becomes small, filiform, almost imperceptible. 32-33. These sections relate to an experiment which will be re- ported in the following chapter. 34. The action of the heart in compressed air is not stronger; but we do not know whether it diminishes, although that is probable. 35. The sphygmographic curve, while the pressure is increasing, is above that obtained in normal air. There is, therefore, in this phase an increase in the total pressure of the blood, at least in the radial artery. 36. Experiments made on animals, on the pressure of the blood in the carotid artery, by means of the hemo-dynamometer gave no result. It is probable that when the air pressure has become constant, a new degree of equilibrium is reached, the action of the heart which has become less strong brings a decrease in the aortic system. 37. The decrease in caliber of the vessels of the conjunctiva, of the retina ,and of the ears of rabbits, the loss of color in the pupil and the iris of white rabbits, the pallor of workmen who labor in compressed air, directly prove the ebbing of the blood from the periphery towards the center. 38. Thence come the decrease, of the intra-ocular pressure, the contraction of the pupil, the lessened sensation of the pulse in the ear and the jaw, the decrease of the redness in the membrane of the tympanum, the improvement in cases of erysipelas, and finally the decrease in size of scrofulous strumae. 39. A manometer placed in the jugular vein showed that the venous pressure diminishes in compressed air. (Vivenot did not make any experiments on this; he depends upon an experiment of Panum, which he himself finds unsatisfactory and poorly carried out. (P. 414). No direct experiments have been made in regard to the effect of compressed air upon the venous and lymphatic systems. But it is certain that it can only be stimulating; moreover, the negative pressure, which is increased, acts also on the heart and the large vessels. 40. The temperature in the armpit increases while the air is being compressed, it reaches its maximum with the compression. Dur- ing the stage of constant pressure, there is also an increase of rectal temperature. 41. It is shown by our experiments that a part of the blood is driven back from the periphery of the body; the organism has there- fore at its disposal a quantity of blood which must rush to the organs which are more deeply situated, such as the brain, the spinal cord, the muscles, the alimentary canal, the liver, the spleen, the kidneys, and the uterus. Thence result, for the brain, the heaviness of the head, the slight deafness, and the yawning; for the alimentary canal, the hunger and the increased rectal temperature; for the muscles, the increase of muscular energy and of the axillary temperature; for the Medical Apparatuses 435 kidneys, the greater quantity of urine. Those complex symptoms, in which the outer cold also has some influence, act only within physi- ological limits. 42. That is why the compression of the air causes no serious dis- turbance in the circulation of the blood, even when it is carried to 4% atmospheres. 43. The same thing cannot be said of the stage of decompression, which, when.it is too sudden, causes annoying and even very danger- ous disturbances in the distribution of the blood. 44. The stay in compressed air is therefore less dangerous than the return to open air, which causes congestions, hemorrhages, pains and particularly disturbances of equilibrium of different sorts in the circulatory system, which, by the development of gas in the blood, may even cause a stoppage of the circulation and consequently a sudden death. 45. The means to be used in the case of these symptoms is a rapid return to compressed air. (Zur Kenntniss, etc. P. 489-495.) The series of Vivenot's works attracted the attention of physi- ologists and physicians to the interesting symptoms which he was the first to note or which he described with more accuracy than the preceding authors. The publications followed each other rapidly. Freud 13 noted a considerable increase in his pulmonary capacity. After 30 air treatments, it had risen from 3100 cc. to 3600 cc; this increase still persisted 5V2 months later. There were only four respirations per minute. Elsasser,14 who did his research in the apparatus of Gmelin, at Stuttgart, summarized the observations of his predecessors and his own in regard to the respiratory rhythm in the following statements: 1. The total value of the respiratory movements in a given time is diminished . . . . ; 2. The decrease affects partly the frequency, and partly the amplitude of the movements; the more nearly the frequency approaches the normal, the less deep the respirations are; if they are very rare, they become deeper; 3. In very deep inspirations, a greater quantity of air enters the lungs than at normal pressure. (P. 26.) Moreover, his memoir seems to be only a sort of summary of the former works of Vivenot. It is especially devoted to thera- peutics. But in the front rank of the authors who, after Vivenot, con- sidered these questions, we must mention Professor Panum. The work of the Danish scientist is exclusively of a physiological nature.15 We shall give it an important place in the following 436 Historical chapter; here, we shall mention only observations relating to the physico-mechanical phenomena of circulation and respiration. Respiration. The first phenomenon discussed is the enlarge- ment of the pulmonary cavity in compressed air: Respiration is always deeper than at normal pressure. This effect often lasts for 24 hours or more and increases with the repetition of the air treatments. In one person whose inspiration, under normal pressure, amounted to 400 to 700 cc. (an average of 480 cc), the first treatment of 35 cm. raised it from 650 to 800 cc. (average 750 cc); the second took it on the average to 900 cc. The frequency of the movements had fallen from 13 - 14.5 to 11.5 per minute. (P. 153) Here, moreover, is a table which expresses the modifications shown by respiration in normal air and in compressed air, follow- ing different voluntary rhythms of respiration: COMPRESSED AIR NORMAL PRESSURE Quantity of Number Quantity of Number air in each of air in each of respiratory respira- respiratory respira- movement. tory movement. tory In cubic move- In cubic move- centimeters. ments. centimeters. ments. Quiet respiration 631.8 13.5 563.5 14.2 Quiet respiration 745.6 10.8 679.5 11.9 Deep and strong respiration 1326.4 8.4 1314.6 . 9.9 Respirations as deep and as rapid as possible 2301.6 6.4 1846.7 12.7 Respirations as slow and creating as little circu- lation of air as possible __ 1216.4 4.2 930.3 5.8 As for the respiratory rhythm properly so-called, Panum states that "the relative duration of the inspiration and the expiration is similar in compressed air and at normal pressure." And in sup- port of this statement, which contradicts what we previously re- ported on the authority of Vivenot, he gives a tracing of respiratory movements directly recorded. Circulation. Panum reports the observations of Vivenot and Sandhal, and admits the slowing down of the pulse. He tried to make experiments on two dogs to study the modifications of the manometric pressure of the heart; but they gave no result. The decrease of the blood flow in the capillaries is proved, Medical Apparatuses 437 according to him, by the fact that a toothache disappeared in compressed air. However, observations on the conjunctiva and the ears of rabbits showed nothing definite; besides, he says, there are too many causes of complications. But what is the immediate cause of these modifications in the circulatory acts? The decrease of the pulse and of the tension must be due to an effect on the heart action. Is this effect the result of respiratory- changes? Does it depend on the pressure exerted on the muscles and the ganglia of the heart? Or on some other circumstance? I do not venture to give an authoritative opinion. The work of G. von Liebig 1G contains the account of the experi- ments made at Reichenhall in the apparatuses of the Mack brothers. The average pressure at Reichenhall is 72 to 73 centimeters; in the apparatuses it varied from 100 to 130 centimeters. G. Liebig first observed, as did so many others, that respiration slackened in compressed air. In Kramer, one of the persons whom he observed, it fell from 10 to 7 per minute, and remained at this figure under normal pressure: but in the other, Mack, one of the proprietors of the establishment, who was accustomed to com- pressed air, the difference was only from 4.3 to 4.1. The respiratory amplitude was also modified in the first subject. It rose from 0.819 liters to 1.073 liters, and remained at 1.068 liters. But in the second, the change was only from 1.437 liters to 1.489 liters and we may consider it as non-existent. Mayer ,7 made similar observations on a lady affected with dropsy and on himself: He noted the usual phenomena. But (contrary to Vivenot) he found a constant slackening of the pulse, which he explains by in- creased circulatory resistances (increased pressure on the heart and the vessels); the respiration was also slowed down. The vital capacity of the lungs increased in a perceptible manner which seemed to be persistent. The increased combustion raised the temperature in the patient from 37.3° to 37.7°. The work of Marc 18 is more interesting, although it deals only with an observation which Dr. Stachelhausen, who had been suf- fering from hemoptysis and emphysematous asthma for four years, made upon himself. After treatment for a month, a considerable improvement was made; but I have no intention of dwelling on pathological details. The most striking detail of the observation is the marked change caused in the number of heart beats and of respiratory movements; I have summarized the author's figures in the following table: 438 Historical JUNE T23|24|25|26|27I28I29130 (Out of apparatus |80|78|76I80|80|72|80|80 Pulse I I I I II I I (In apparatus |64|60|60|68|68|68|75|74 I I I I I I I I Respiratory (Out of apparatus ^|24|24|20|20|20|17|18|18 Movements (In apparatus |12|12|13|12|13|13|12|12 JULY >| 3| 4| 5| 6| 7| 8| 9]10|11|12|13|14|15|16|17|18|19|20121 7<5170|76|76|7 I I I I 18 18 18|18|16 riTi )|80|80176|80|80|80 S0|7S76]80] 75|68|66|75|80|72|7e I II I I I I I I I 16|l4|15|14|16|16|16|14|14|16|14|14|14|14|14|14 12|12|14ll2i|12|12|12in|10|12|ll|12.|ll|12|ll|ll|12|12|l2|lO|10 So two things are to be noted: first, the sudden decrease of the number of heart beats and of respiratory movements by the effect of compressed air; the decrease in the number of the latter, even in the open air, as long as the treatments were being given, where- as the pulse rate did not change. The pulmonary capacity measured on the spirometer was in- creased 550 cc. June 22, before the beginning of the treatments 1450 cubic cent. June 29, during the treatments 1600 cubic cent. July 8, during the treatments _ 1800 cubic cent. July 15, during the treatments r 1900 cubic cent. July 21, during the treatments F 2000 cubic cent. It is regrettable that Marc specified neither the degree of the air compression nor the length of time his patient stayed in the apparatus. 1 Here is a list of the chief works published on the therapeutic use of compressed air. I did not include those which I am quoting and analyzing in the present and the following chapter. This list shows the astonishing variety of ailments in which the new treatment has been Pravaz, Mem. sur V emploi du bain d'air comprime dans le traitement des affections tuber- culeuses, des hemorrhagic capillaircs et des surdites catarrhales. Acad, de Med. de Paris, Dec. 6, 1837. Cpt. R. Acad, des Sciences, Vol. VII, p. 283, 1838. Id., De I'influence de la respiration sur la sante et la vigueur de I'howme. Lyon, 1842. Id., Memoire sur V emploi de la compression au moyen de I'air condense dans les hydarth- roses, et sur la possibility de reduire certaines luxations spontanees de la hanche. Lyon, 1843. Dubreuil, Bains d air comprime. Marseille, 1848. # . De la Prade, Rapport sur le memoire relatif aux bains d'air comprime, in Essai sur I emploi medical de I'air comprime, par Pravaz. Lyon, 1850. Poyser, On the treatment of chronic and other diseases by baths of compressed air. Asso- ciation Med. Journal, September 9, 1853. . . Devay, Du bain d'air comprime dans les affections graves des organes respiratoires. Gazette hebd.. 1853. Schtitz, Brief liche Mittheilungen aus Nizza. Deutsche Klinik, February, 18o7._ Bottini, Dell' aria compressa come agente tcrapeutico. Gaza. med. italiana, Stati Sardi. 185i. A. Simpson, Compressed air as a therapeutic agent. Edinburgh, 1857. Haughton, On the use of the compressed air baths. Dublin, Hosp. Gaz.. 1S58. Pravaz fils, Des effets physiologiques et des applications therapeutiques de I'air comprime. Lyon, 1859. , Gindrod, The compressed air-bath, a therapeutical agent in various affections of the respira- tory organs and other diseases. London, 1860. Lippert (in Nizza), Ueber Paris nach Nizza, medicinishe Reiscskizze. Deutsche Klinik. October, 1861. Trier, Om Bode i fortoettet luft. Copenhagen, 1863. G. Lange, Der pneumatische apparat. Vienna Med., Wochenschift, August, 1863. Levinstein, Beobachtungen iiber die Einivirkung der verdichtcten Luft bei Krankheiten der Respirations-und Circulations-Organ e. Berl. W ochenschrift, 1864. _ . Freud, Der pneumatische apparat. Wirkung und Anwendung der comprimirten Luft tn verschiedenen Krankheiten. Vienna, 1864. Fischer, Errichtung eines Luft compression Apparates zu Hannover. 1864. _ Josephson, Die therapeutische Auzvendung der comprimirten Luft. Deutsche Klinik, 1864. Levinstein. Grundzuge zur practischen Otiartie mit Berucksichtigung der neucsten thera- peutischen Technik, etc. Berlin, 1865. Smoler, Die Anwendung der comprimirten Luft in Krankheiten der Gehororganes, Osterr. Zeists. f. pract. Heilkunde. Vienna, 1865. Storch, Jagttagelser over Virkningen af comprimirct Luft ved behandhngen af Brysttidelser. meddelte fra Rasmussens medico-pneumatiskc Austalt. Hospitals-Tidende VIII. Aarg. Copen- hagen, 1865. Medical Apparatuses 439 Sandahl, Nyare undcrsdkningar och iakttagelscr rorandc de fysiotogiska och tcrapentiska verkningarne of bad i fbrtdtad luft. Hygiea. Stockholm. 1865. Id., Bertittelse om den mcdiko-pncnmatiska anstaltens verksamhet i Stockholm under aren 1863 och, 1864. Stockholm. 1865. , Freud, Vortrag iiber der pneumatisch Apparat, ilnd seme liirkungcn vn I icnna Doctoral colleg. Zeitsch f. pract. Heilk., 1865. . ,. Bertin (Emile). Analyse de trois brochures sur I'air comprime. Montpellier medical. 1866. Kryszka, £> 8.8; CO 9.4. The lethal air contained O* 8.3; CO 9.8. CO CO + O. = 18.1 ; = 0.78. O XXI. Bell of 7 liters. Begun at 2:51. At 2:55, pressure is 30.3 cm. The bird, which has been struggling a good deal, is quite sick, and has difficulty in stand- ing up. Cocks closed. At 5:25, very sick. Dies at 7:20. It therefore lived 4 hours 25 minutes in a quantity of air corresponding to 2.79 liters, or 1 hour 34 minutes per liter. At 7:30, its temperature is only 25°; no rigor; at 7:40, found stiff. Lethal air: O 8.2; CO* 10.1. COs CO2 + O2 = 18.3 ; = 0.79. O XXII. Bell of 5 liters. Begun at 2:47. Struggles a great deal. At 2:51, the pressure is only 26.1 cm. The bird is very sick and crouched against the rim of the bell. Dies at 2:53. At 3:10 is very stiff. Its temperature is 34.7°. Lived 6 minutes. No air sample taken. XXIII. Bell of 5 liters. Begun at 3:20. Struggles a great deal. At 3:24, the pressure is 30.3 cm.; the bird does not seem sick; cocks closed. At 5:25, very sick. The time of death was not noted. Lethal air: O 8.3; CO' 10.3. CO CO- + O = 18.6; = 0.81. O XXIV. Bell of 2.5 liters. Begun at 2:51. At 2:59, the pressure is 30.5 cm. Struggled a great deal, vomits, but does not fall. Cocks closed. About 3:05, a little struggling. Dies at 4:30. At 4:50, temperature 27°; pronounced rigor. Lived 1 hour 31 min- utes in the bell the capacity of which corresponds to 1 liter. Lethal air: O- 10; CO 10.4. CO* CO= + O* = 20.4; = 0.95. O The average of the four experiments in which the air was ana- lyzed is for the pressure of 30.5 cm.: O2 8.7; CO2 10.1. Experiments XXV to XXVIII, simultaneous, made with the same purpose as the preceding ones. June 8. Temperature 20.5°; pressure 76 cm. House sparrows. Death in Closed Vessels 519 XXV. Bell of 11.5 liters. Begun at 3:45. At 3:53, the pressure is 24.2 cm. Struggled; some- what sick; lying down, yawns frequently; cock closed. At 4:15, gets up on its feet; at 6 o'clock, in fair condition; at 7:30, somewhat sick; found dead at 9:30. Therefore lived about 5 hours in a bell the capacity of which represents 3.66 liters; or about 1 hour 22 minutes per liter. Lethal air: O 13.7; CO* 5.4. CO, CO, + O, = 19.1 ; = 0.75. O, XXVI. Bell of 7 liters. Begun at 4 o'clock. At 4: 10, pressure of 24.2 cm. Struggled a great deal; has convulsions and seems near death. Cocks closed. At 4:15, gets up on its feet; at 4:30, very lively, struggles a good deal at 5 o'clock, becomes sick; at 6 o'clock, drowsy; at 6:20, dies after violent convulsive struggling. Lived 2 hours 10 minutes, in a quantity of air corresponding to 2.22 liters; or 58 minutes per liter. At 6:32, rectal temperature 30.3°, is not quite stiff; at 6:45, stiff, temperature 26.5°. Lethal air: O, 12.6; CO, 7.0. CO, CO, + O, = 19.6; = 0.84. O, XXVII. Bell of 5 liters. Begun at 4:15. At 4:21, reached a pressure of 24.2 cm.; struggled at first, then grew calm at a pressure drop of about 42 cm. as the pre- ceding ones did; did not fall. Cocks closed. At 4:22, staggers, vomits, crouches down; but soon gets up and seems fairly well. At 5:30, very sick; at 6:10, dies. Lived 1 hour 50 minutes in a bell the capacity of which corresponds to 1.55 liters of air; or 1 hour 10 minutes per liter. At 6:21, stiff; temperature 27.2°. Lethal air: O, 11.6; CO, 7.8. CO, CO, + O, = 19.4; = 0.84. 0* XXVIII. Bell of 2.5 liters. Begun at 4:16. At 4:26, the pressure is 24.2 cm. Struggled, but does not seem in danger. Dies at 5:30; lived 1 hour 4 minutes in a quantity of air corre- sponding to 0.79 liters; or 1 hour 21 minutes per liter. At 5:50, found stiff; temperature 27.5°. Lethal air O, 12.6; CO, 5.9. CO, CO, + O, = 18.5; = 0.71. O, Average of the four experiments: O, 12.6; CO, 6.5. 520 Experiments Experiments XXIX to XXXII, simultaneous. June 10. Tempera- ture 21°; pressure 75.5 cm. House sparrows. XXIX. Bell of 11.5 liters. Begun at 2 o'clock. Struggles a great deal; at 2:08, a pressure drop of 40 cm.; grows calm for a moment, then struggles again. At 2:12, the pressure drop is 47 cm.; no longer moves; a little out of breath. At 2:16, drop of 55 cm.; more out of breath, vomits. At 2:17, the pres- sure is only 17.5 cm. Cocks closed. The bird is breathing with great difficulty, and remains lying down. It dies with convulsions at 2:20, that is, after 3 minutes. The air hardly contains traces of carbonic acid. XXX. Bell of 11.5 liters. Begun at 2:45; struggles a good deal. At 2:50, the pressure is decreased 42 cm.; the bird grows calm; at 2:53, a decrease of 44 cm.; staggers, vomits, but begins to struggle again. At 2:56, a decrease of 52 cm.; suffers greatly. At 3:05, a decrease of 56 cm.; falls and seems about to die. A little air is admitted until the decrease is only 49 cm. At 3:08, since the bird seems to have recovered fairly well, the decompression is resumed; at 3:11, a decrease of 58 cm.; convulsive struggling, death imminent; we return to a decrease of 49 cm. At 3:16, fairly well recovered; at 3:18, a decrease of 56.5 cm.; not too sick. Cocks closed. At 3:35, the bird vomits; at 3:55, as it is not too sick, the decom- pression is carried to 57.5 cm.; that is, an actual pressure of 18 cm.; it immediately becomes uneasy, but death does not occur until 4:30. Therefore it lived 1 hour 4 minutes in a quantity of air represen- ting 2.70 liters; or 23 minutes per liter. Lethal air: Cb 17.7; CO2 2.8. CO CO-» + 0= = 20.3; = 0.87. O XXXI. Bell of 1.9 liters. Begun at 3:35. At 3:45, the pressure is 41.3 cm. Cocks closed. Dead at 5:23; at 5:30, rectal temperature 28°. Lived 1 hour 45 minutes in a bell corresponding to 1.03 liters; or 1 hour 40 minutes per liter. Lethal air: O2 6.5; CO 12.9. CO CO + O2 = 19.4; = 0.89. o= XXXII. Bell of 1.5 liters. Begun at 3:35. At 3:45, a pressure of 48.5 cm. Closed. Dead at 5:10. At 5:20, temperature 24.8°. Lived 1 hour 25 min- utes; the capacity corresponded to 0.92 liters, or 1 hour 32 minutes per liter. Lethal air: O 5.2; CO-* 14.1. CO* CO* + Os = 19.3; = 0.89. Oa Death in Closed Vessels 521 Experiments XXXIII -XXXIV, simultaneous. June 14. Tempera- ture 22°; pressure 76.5 cm. House sparrows. XXXIII. Bell of 3.2 liters. Begun at 4:16; moderate agitation. At 4:21, pressure decrease of 43 cm.; vomits, is tired; at 4:22, pressure is 23 cm.; very sick. Cocks closed. At 4:26, still on its side; rises later. Dies at 5:20. At 5:31, tem- perature 32°, not stiff. At 5:40, 30.7°. Lethal air: O2 11.2; CO* 7.6. CO, CO* + O2 = 18.8; == 0.78. O2 XXXIV. Bell of 2.8 liters. Begun at 4:19; moderate agitation. At 4:25, pressure of 25 cm.; vomits. Cocks closed. Not so sick as the preceding bird. At 4:27, pressure dropped to 24.5 cm.; panting hard. At 5:27, dies with convulsions. At 5:40, the temperature is 31.6°; at 5:52, it is 29.4°. Lived 1 hour 2 minutes in the equivalent of 0.9 liter of air; or 1 hour 7 minutes per liter. Lethal air: O2 11.3; CO2 8.1. CO2 CO2 + 02 = 19.4; = 0.84. O2 Experiments XXXV - XXXVI, simultaneous. July 26. Temperature 22°; pressure 76 cm. House sparrows. XXXV. Bell of 2.25 liters. Brought in a few minutes to a pressure of 55 cm. Cocks closed at 1:45. Dead at 3:25. Therefore lived 1 hour 40 minutes in a bell the capacity of which represented 1.6 liters at normal pressure; or 1 hour 3 minutes per liter. At 3:33, rectal temperature 28°. Lethal air O2 4.6; CO2 13.4. CO' CO2 + O2 = 18.0; = 0.81. O2 XXXVI. Bell of 3.2 liters. Brought to a pressure of 47 cm. Cocks closed at 2 o'clock. Dead at 3:53. Lived 1 hour 53 minutes in a capacity equivalent to 2 liters; or 57 minutes per liter. At 4 o'clock, rectal temperature 27°. Lethal air: O2 5.5; CO-' 12.4. CO2 CO.- + 02 = 17.9; = 0.80. O2 Experiment XXXVII. March 18. Pressure 76 cm. House sparrow, placed at 1:45 under a bell of 3.2 liters. The pres- sure is lowered to 38 cm. Dead at 3:15. A few spots in the cranial 522 Experiments diploe, in the occipital region. Lived 1 hour 30 minutes in the equiva- lent of 1.6 liters of air, or 56 minutes per liter. Lethal air: O 8.2; CO? 11.6. CO. CO + O* = 19.8; == 0.91. O2 I have purposely given in the preceding pages an account of a great number of experiments so as to show what is indefinitely variable in the phenomena and at the same time what stands out as general in this variety, which defies both deceptive averages and sham precision of decimals. Certainly, when a sparrow dies under a bell at a certain pressure, the air of this bell has a com- position which the best methods of modern chemistry could per- haps permit us to determine to about one ten-thousandth. But what would be the use of this precision when our experiments show us that another sparrow exactly like the first, placed in apparently identical conditions, dies with a composition of ambient air which may differ from the first by 4 or 5 tenths of oxygen or carbonic acid, or even more? It is evidently better to multiply experiments to try to find the explanation of these differences and to adhere to convenient methods of analysis which permit one to work rapidly. But the height of absurdity — and this, unfortunately, is found rather frequently in German work — is to claim to give to these other methods an appearance of precision which they do not pos- sess, carrying calculations to the second and third decimal and even resorting to a table of logarithms to get more decimals. This charlatanism of decimals which leads one to claim exactness for the thousandths in a number which is wrong beyond the units, is an illusion which must be avoided. Let us make our criticism specific by applying it to the present case. Let us imagine, in a tube graduated to tenths of cubic centi- meters, inverted over the mercury bowl, our usual gaseous mixture of nitrogen, oxygen, and carbonic acid. To avoid taking account in the first determination of a convex mercurial meniscus and in the other two of a concave aqueous meniscus, I first introduce into the tube some drops of pure water, and try to determine the level. Now admitting that the greatest precautions have been taken, it is impossible to estimate the height of the liquid column with a closer approximation than five hundredths. Let us suppose that I have found that it is between 25.3 cc. and 25.4 cc; but I cannot be sure whether it is 25.32 cc. or 25.37 cc, for example. I now add the potash, shake it vigorously and repeatedly, and again plunge the tube into the mercury to bring it to its original temperature. Death in Closed Vessels 523 Again I make a supposition: the present level will be, let us say, between 20.2 cc. and 20.3 cc. and I must choose between 20.23 cc. and 20.28 cc. According to whether I take my meniscus level higher or lower — and we know how difficult the estimate is for a colorless liquid, without mentioning the fact that the meniscus of pure water in a tube which is necessarily rather dirty is not the same as the meniscus of a potash solution which wets the glass perfectly, — there will have disappeared in an average quantity of 25.35 cc. either 5.04 cc. or 5.14 cc. of carbonic acid, which gives for the percentage composition in the first case 19.88 cc. per 100 (25.35 : 100 = 5.04 cc. : x = 19.88) ; and in the second case, 20.27 cc. per 100 (25.35 : 100 = 5.14 cc. : x = 20.27) . That is, without taking into account the cause of error due to the operation itself, which here involves the second decimal, my analysis, though made as well as possible by the volumetric method, exposes me to an error which in this present , case may equal 0.39 cc. In other words, the first decimal can and must be con- stantly vitiated in the necessary speed of the analyses. It is with this consideration that we must examine all the results of our analyses; and therefore no one will reproach me for having prudently stopped at this figure which indicates exactly the degree of precision which one can expect from this volumetric method of analysis, any more than for not having used other methods, when the experimental differences, over which we have no control, are at least of the same order, as I said above. With these reservations, let us examine the results of the ex- periments which, in order to shorten tiresome reading, I have grouped in a summarizing table, arranging them in the order of the pressures. If we examine Column 8, which gives the proportion of oxygen remaining in the air which has become irrespirable, we see that the numbers which it contains increase proportionately as the pressure diminishes. This rule, however, has apparent exceptions, as the table shows. But if we consider the results given by the analyses of air which has become incapable of supporting life made at the same pressure, we see that the exceptions mentioned are of the same order as the differences which separated the re- sults of these analyses. Thus at normal pressure, the proportion of oxygen remaining varied between 3.0 and 4.2 per cent; similarly at 24.2 cm., it varies between 11.6 and 13.7 per cent. The general tendency of the phenomenon is shown still more clearly in the curve represented by O, Figure 17. Here the pres- 524 Experiments sures are measured on the axis of the abscissae, in increasing order, and the quantities of oxygen are represented on that of the ordi- nates. We shall see presently that this curve, if we set aside the Fig. 17— Composition of confined air which has become lethal at pressures below 1 atmosphere. O. Proportions of oxygen remaining. CO2. Proportions of carbonic acid. CO'-f-O. Sum of oxygen consumed and carbonic acid formed. little irregularities of which we have spoken, takes a precise geo- metric form, which is exactly a branch of a hyperbola. The proportion of carbonic acid produced naturally follows an opposite course, as is shown by curve C02, which represents its modifications. Therefore, the weaker the pressure, the less the confined air needs to be altered in its chemical composition to become irre- spirable. At very low pressures it becomes irrespirable even though perfectly pure, for a reason which we shall give presently. But the general fact which we have just mentioned is enough to show that the carbonic acid given off in the confined space plays no part in the death, since its proportion decreases progressively Death in Closed Vessels 525 Table I Q.CD CJ O •o CD o <" 3 °-^T3 (D 02 ■^ > UoJ c o 2 v 3^1 g Si 3 O Si Cfl 02*26 of lethal air d + d" u Oo |h.m. h.m. co2 O, 1 1 I 15 76 1 115 1 5 3.0 14.8 1 3.0 17.8 0.82 2 II 15 | 76 1 1.9 | 1 55 | 0 57 4.2 14.6 | 4.2 18.8 0.87 3 VI 16 75 2.5 | 3 23 1 20 3.5 14.6 3.5 18.1 0.84 4 III 24 75 1.3 | 3 45 2*50 3.3 16.0 3.3 19.3 0.86 5 VII 16 55 3.2 | 4 31 1 57 4.5 14.4 3.2 18.2 0.84 6 XXXV 22 55 2.2-1 1 40 1 03 4.6 13.4 3.3 18.0 0.81 7 XXXII 21 48.5 1.5 1 1 25 1 32 5.2 14.1 3.3 19.3 0.89 8 XXXVI 22 47 | 3.2 | 1 53 0 57 5.5 12.4 3.4 17.9 0.80 9 XXXI 21 41.3 | 1.9 | 1 45 | 1 45 6.5 12.9 3.5 | 19.4 0.89 10 XXXVII — 38 I 3.2 I 1 30 1 0 56 8.2 11.6 4.1 19.8 0.91 11 XIII 17 | 37 | 2.5 | 1 45 | 1 27 7.2 11.5 3.5 18.7 0.84 12 VIII 16 | 36.4 | 5 | 3 00 | 1 15 — 13 XII 16 1 34.3 4.6 | 2 34 | 1 21 8.2 10.8 3.7 19.0 0.85 14 XX 20 | 30.8 11.5 | 6 53 | 1 28 8.3 9.8 3.4 18.1 0.78 15 XXIV 20 ] 30.5 2.5 1 31 | 1 31 10.0 10.4 4.0 | 20.4 0.95 16 XXIII 20 | 30.3 5 1 8.3 10.3 3.3 | 18.6 0.81 17 XXI 20 | 30.3 7 4 25 | 1 34 8.2 10.1 3.2 18.3 0.79 18 V 15 j 29 3.2 9.3 11.2 3.5 20.5 0.96 19 XIV 17 | 28.3 3.2 1 30 | 1 15 7.9 10.3 3.0 18.2 0.79 20 XVIII 19 | 27.8 3.2 2 00 | 1 44 8.5 10.9 3.1 19.4 0.88 21 XXII 20 | 26.1 5 0 06 | — 22 XXIV 22 | 25 2.8 1 02 1 07 11.3 8.1 3.6 19.4 0.84 23 XI 16 | 24.5 3.2 0 38 0 38 12.8 6.2 4.1 19.0 0.76 24 XXV 20 | 24.2 11.5 5 00 1 22 13.7 5.4 4.3 | 19.1 0.75 25 XXVI 20 | 24.2 7 2 10 0 58 12.6 7.0 4.0 19.6 0.84 26 XXVII 20 | 24.2 5 1 50 1 10 11.6 7.8 3.6 19.4 0.84 27 XXVIII 20 24.2 | 2.5 1 04 1 21 12.6 5.9 4.0 18.5 0.71 28 IV 15 23 | 5 1 35 1 08 10.3 7.5 3.1 17.8 0.70 29 XXXIII 22 23 3.2 | 11.2 7.6 3.4 | 18.8 0.78 30 XV 17 21.5 4.6 | 1 40 1 17 11.8 7.0 3.3 | 18.8 0.77 431 XVII 19 20.8 4.6 I 0 02 — 32 X 19 20 2.2 0 02 — 33 XVI 19 1 19.7 I 5 1 45 | 1 20 12.9 7.0 3.3 19.9 0.87 34 XXX 21 18 11.5 1 04 | 0*25 17.7 2.8 4.2 20.3 0.87 35 XXIX 21 17.5 11.5 0 03 | — | 36 IX 16 17.4 11.5 0.11 | 1 avg | lhr. | 16 min. 19.6 0.6 | 4.5 | 20.2 | |avg| I | 3.5 | sxcept exper iments marked with an as'te risk to minimum amounts. Furthermore, direct experiments, in which this acid was largely absorbed by a solution of potash as rapidly as it was formed, have shown that the composition of the lethal air, from the point of view of its oxygen content, was not changed at all. It is this content, or rather this lack of oxygen which is the cause of death, and which we must consider carefully. 526 Experiments It really seems very difficult at first glance to attribute death to a lack of oxygen in experiments where 12, 15, or 17 per cent of it remained in the air. But this difficulty disappears after suffi- cient reflection. Indeed, we know that when a bird dies at normal pressure in confined air, this death is due (for the most part, at least; we shall give a longer explanation later) to a lack of oxygen, or to speak more exactly, to the too weak proportion, and more exactly still, to the too weak tension of this gas in the ambient atmosphere. This tension can be expressed at normal pressure precisely by the figure which indicates the percentage. One may say, for example, that at one atmosphere the tension of the oxygen of ordinary air is 20.9; and likewise that the tension of the oxygen of confined air which has become lethal varies somewhere between 3 and 4 per cent. According to this, the tension of oxygen at a pressure lower than one atmosphere will evidently be represented by a number obtained by multiplying the percentage by the proportion of this pressure to normal pressure, both expressed for greater simplicity in centimeters of mercury. Thus the pressure of the oxygen of ordinary air at 30 cm. of pressure will be represented by the 30 number 20.9 x — = 8.2. 76 Applying now this simple calculation, whose formula is 02xP -, to all the figures listed in our table, we reach the results 76 given in Column 10. We see that at whatever pressure our birds were placed, their death came when the pressure of the oxygen was lowered to values varying between 3.0 and 4.3, which are precisely the values with which air becomes irrespirable at normal pressure. The table shows that, even at very low pressures, we find figures (numbers 28, 30, and 33) which indicate the most com- plete exhaustion and the weakest tension, when we have taken sufficient precautions, to which we shall refer in a moment. The differences between the results of the analyses at different pressures are exactly of the same order as those which separate the results obtained at the same pressure. This stands out in the most striking manner in the graph in Figure 18, which expresses the results in Column 10. Thus at the same pressure of 24 cm., Death in Closed Vessels 527 there are deviations as great as those of the whole tracing, as the little crosses show. These are differences which experiments made in apparently identical conditions always display. T3 0> as o ^ J3 CO +j o '■J3 -£ S1 .2 £ 8 ►> "3 ca CO Summing up, we arrive at this very simple statement: In con- fined air, at pressures less than one atmosphere, the death of spar- 528 Experiments rows occurs when the tension of the oxygen, measured by the method that has just been specified, is represented by a number varying between 3 and 4, which we can call k. If we refer now to line O of Figure 17, we see that each of its points corresponds to the equation — = k, therefore xy = 76k. 76 Now k having a value which varies from 3 to 4.3, taking 3.6 as an average, for the point which corresponds to 41 cm. of pressure, for 41 x 6.5 example, the equation will be = 3.6. In other words, it is 76 the equation of a hyperbola having for asymptotes the axis of the x's and a parallel to the axis of the y's at the zero of pressures, or, to use an exact expression, of an equilateral hyperbola. These facts show us under a new aspect the action of the diminu- tion of pressure upon the organism. They tend to show that it consists principally of diminishing the exterior tension of the oxygen, and, consequently, of placing the animal in conditions similar to those which would be given it by respiration at normal pressure in a medium containing less oxygen than the air. We could even state already that no other important element is in- volved, since at pressures from 20 cm. to 25 cm. we find again in the table the figures 3.1 or 3.3, which indicate an exhaustion as great as at normal pressure. Continuing this reasoning, we can determine the lower limit of pressure which it will not be possible to pass without killing the animals (we are still speaking of sparrows) . It will be given by x x the formula 20.9 x — = 3 and 20.9 x — = 4.3, since 3 and 4.3 are 76 76 the extreme numbers given us by the experiments reported above. 4.3 cm. x 76 We reach thus the equation x = = 15.6 cm. for the 20.9 highest figure, and for the lowest, x = 10.9 cm. But it is clear that, to reach such low pressures, we must take the greatest precautions, and slowly accustom the animal to this asphyxia of a new kind. A sudden change surprising it with too great an oxygen consumption would kill it, and that very thing Death in Closed Vessels 529 happened (numbers 21, 31, and 32 of the table) at pressures of 20 and even 26 centimeters. We must not forget that the birds which die in containers of confined air die very slowly, grow cold, and therefore can live a long time with a very slight consumption of oxygen. Claude Bernard- showed with admirable sagacity the difference existing between a vigorous and a weakened animal from this point of view. It was with the purpose of reaching the lowest possible point, by going slowly, that the following experiments were made. Experiment XXXVIII. March 30. House sparrow. Bell-jar of 50 liters. Entered at 2 o'clock. Current of air maintained by the steam pump. At 2:04, 51 cm. of pressure; at 2:05, 39 cm.; at 2:06, 33 cm.; uneasy, panting a little. At 2:07, 25 cm.; falls with its beak forward, panting, does not get up again. Pressure rises to 28 cm.; the bird does not stir; pressure falls suddenly to 24 cm. (2:09 o'clock), and the bird hops about staggering and falls immediately. At 2:11, 22 cm., same condition; at 2:13, 16 cm.; violent convulsion; pressure restored to 20 cm.; at 2:25, still 20 cm.; pressure lowered again; at 2:27, only 17 cm.; and at 2:30, only 16.5 cm. At 2:32, the mercury suddenly goes to 8 cm.; convulsions and death. Rectal temperature is 32°. Experiment XXXIX. Same day, same apparatus. Entered at 2:40. In one minute brought to 22 cm.; falls on its side and does not get up. At 2:43, 20 cm.; at 2:45, 17 cm.; at 2:54, 16 cm.; at 3:15, 15.5 cm. In the intervals, the pressure was lowered two or three times suddenly to 10 cm., and raised immediately. The bird remained motionless, bristling, breathing with difficulty. Taken out at 3:15, is very cold. Recovers very well after a quarter of an hour and survives. At 4:30, has a normal temperature. Experiment XL. January 2. House sparrow, vigorous. Barometric pressure 753 mm.; bell-jar of 4.5 liters. Decompression begun, with air flowing through chamber, at 2:35. At 2:55, the pressure under the bell-jar is only 58 cm.; the bird is calm. At 3:05, pressure, 48 cm.; at 3:15, 40 cm.; at 3:25, 30 cm.; at 3:35, 23 cm.; the bird is crouched on its tarsi. At 3:45, pressure, 17 cm.; the bird is lying on its side, , but does not appear very sick. From 3:50 to 3:55 the pressure is lowered to 15 cm.; from 3:55 to 4 o'clock, to 14 cm.; from 4 o'clock to 4:05 to 11 cm.; from 4:05 to 4:10, to 10 cm.; the bird is on its side but fairly quiet. Air is admitted suddenly; the bird gets up on its feet immediately; its rectal temperature is 28°. It is warmed by the stove, and gets up on the perch in its cage. But it dies during the night. Here are sparrows with which we proceeded slowly enough to bring on weakness and chill, and which underwent diminutions of 530 Experiments pressure quite comparable to those which the preceding calcula- tions indicated. It is a matter of care and patience. If now we examine Column 11 of Table I, we find numbers representing the result of the addition of the carbonic acid pro- duced and the oxygen remaining at the moment of death. They are represented by the line C02 + 02 in Figure 17. We see that these different numbers vary between 17.8 and 20.5: the general average is 18.9. And so we find at all diminutions of pressure the fact observed by earlier authors, which caused them to make such strange hypotheses on the nature of asphyxia in closed vessels, that is, the diminution of the elasticity of the air, or, in other words, the disappearance of a certain quantity of oxygen which is not recovered in the carbonic acid given off. Furthermore, — and this is very evident on the graph — this amount keeps increasing when the pressure diminishes; above one half atmosphere, it is on the average 18.7, and below, it is 19.2. So, at very low pressures, there is given off a greater proportion of carbonic acid in comparison to that of the oxygen absorbed. In studying the gases of the blood under diminished pressure, we shall easily understand this phenomenon. That is not all: a careful inspection of Column 11 shows us another interesting fact. If we group on one side all the cases in which the number indicated in Column 10 is between 3 and 3.5, and on the other all those in which this number is above 3.5, we shall find that for the first series the average is 18.6, while for the second it rises to 19.5. That means that the greater the exhaustion of oxygen, the greater has been the quantity of this gas not recovered in the carbonic acid exhaled. Hence we can draw the conclusion that in asphyxia in closed vessels, whatever the pressure may be, towards the end of the animal's life, the oxygen, which it continues to absorb in very small quantities, remains in the tissues under some form or other, without giving rise to carbonic acid. This conclusion is corroborated also by the examination of Column 12 of the table, containing for each experiment the ratio between the carbonic acid produced and the oxygen consumed. We see that these numbers are in a general way proportionately smaller as the pressures become lower. In the first eleven experi- ments (above a half-atmosphere) the average is 0.85, and for the others only 0.80. We conclude then that at very low pressures the proportion of oxygen that is absorbed without producing carbonic acid is greater than at more moderate pressures. I tried to ascertain whether some relation existed between the Death in Closed Vessels 531 numbers contained in Columns 5, 7, and 10, which express different important elements of our experiments. To grasp these relation- ships, I drew three graphs in which the experiments are arranged Fig. 19 — Relations between oxygen tension (graph A), duration of life (B) and actual capacity of the vessels (C) in death in closed vessels under decreased pressure. 532 Experiments according to their numbers in Column 1 of Table I on the axis of the abscissae, so that pressures decrease from left to right. To each of these experiments correspond three values plotted on the vertical ordinate; the first, A, expresses the final tension of the confined air (Column 10) ; the second, B, the duration of life (Column 7) : this duration is calculated by reducing the volume of the rarefied air to 76 cm. and seeing how long the birds lived for each liter of air: the third, C, represents the volume of rarefied air reduced to the pressure of 76 cm. of mercury and permits us to compare the true quantities of air that the birds had at their disposal. We do not see very clear relations between the line A which expresses the oxygen tension at the end of the experiment and line B which expresses the duration of the lives of the birds. We con- clude from comparing the two graphs that the greater or less exhaustion of air (A) is by no means in constant relation to the length of life (B), since a very short duration may coincide with considerable exhaustion (Experiment 8) or inversely (Experiment 15). However, if we take the average of the duration of life cor- responding to very low oxygen tensions (below 3.5, Column 10) , we have the figure of 1 hour and 11 minutes; whereas in making the same calculations for higher oxygen tensions we find 1 hour and 23 minutes (the general average being, Column 7, 1 hour 16 minutes). And so in a general way, the longer the animal lives, the more it exhausts the air, very naturally. Inquiring next into the duration of life in its relation to the capacity of the bell-jars in which the animals died, and setting aside the wholly exceptional cases like those of Experiments 16, 21, 31, 32, and even 35 and 36, we see that at first glance graph C, which expresses these varied volumes, has nothing in common with graph B. A very considerable capacity may coincide with a moderate duration of life (Experiments 13 and 24) or inversely (Experiment 9) . But if, as in the preceding case, we consider capacities corresponding to longer than average durations of life (1 hour 16 minutes), we find that their average volume is 2 liters, while for the more rapid deaths the volume is only 1.5 liters. Generally speaking, then, life is longer when the capacity of the vessels is greater (the whole evidently related to the unit of volume and the unit of pressure). Thus we confirm, unmodified by the influence of the diminution of pressure, a law which was earlier formulated by M. Claude Bernard, who, however, mentions numerous exceptions; the prin- Death in Closed Vessels 533 cipal ones are due to the calmness or the agitation of the animal enclosed, which uses up more or less quickly the quantity of air left at its disposal. We now have to compare graphs A and C, that is, the capacity of the vessels with the exhaustion of oxygen. Here again the curves have little agreement. We even find strongly opposed results, as in that of Experiment 19, in which maximum exhaustion corre- sponds to a small vessel, and that of Experiment 24, where in a very large vessel there was little exhaustion compared to Experi- ments 14 and 16, which give opposite results. But if we take an average, we see that numbers less than 3.5 (graph A) correspond to an average of 1.8 liters, while those that are greater correspond to 1.6 liters. There is then some advantage in vessels of large capacity, another conclusion agreeing with those of Claude Bernard. But the differences are very slight, and when we examine these numerous results, we can understand the apparent contradictions of investigators. Therefore, whatever point of view we take, we find that the re- sults of the experiments under diminished pressure agree with all that we know about asphyxia in closed vessels. We are then more and more led to see in the rarefaction of the air only a physical process which leads to the same end as the impoverishment of oxygen, a chemical process. The following data also corroborate this view. We know that at very low temperatures and under normal pressure animals exhaust much less the oxygen of the air in which they are confined than they do at an average temperature. Is the same thing true for death in closed vessels at low pressure7 The following experiments give the answer to this question. Experiments XLI to XLIII, simultaneous. December 12. Pressure 77 cm. The temperature of the laboratory is +6°. After the sparrows had been placed under the bell-jars, the latter were packed in snow, and the temperature dropped to about + 2°. XLI. Bell-jar of 2.25 liters. Entered at 2:40. Pressure brought to 54 cm., and the cold lowers it to 52 cm. The bird is found dead at 4 o'clock. Lethal air: O 8.3; CO,' 11.4. CO. CO. + 0* - 19.7; = 0.90. O. XLII. Bell- jar of 3.2 liters. Entered at 2:50. Pressure brought to 44 cm. by vacuum and cold. At 4 o'clock is breathing with great difficulty; at 4: 15, dead. Lived 1 534 Experiments hour 20 minutes in a quantity of air corresponding to 2 liters, at normal pressure, that is, 40 minutes per liter. At 4:35, rectal tempera- ture 18°. Lethal air: O. 7.6; CO. 12.0. CO. CO. +C = 19.6; = 0.90. O. XLIII. Bell- jar of 5 liters. Entered at 3 o'clock. Pressure brought to 27.5 cm. Living at 5:35. Found dead at 5:05. Lethal air: O. 10.4; CO. 8.8. CO. CO. + Os = 19.2; = 0.83. O. Experiment XLIV. December 13. Outside temperature -\-6°. Pres- sure 77 cm. Sparrow placed under bell-jar of 3.2 liters, at 2:45. Pressure brought to 30.5 cm. including the following action of the cold. The bell- jar is surrounded by a mixture of ice and salt. At 3:35, still living; at 3:45, dead. Lived about 55 minutes in an equivalent of 1.28 liters of air, that is, 43 minutes per liter. The temperature of the bell-jar is then — 5°. Rectal temperature of the bird + 16°. Lethal air: O. 11; CO. 8.8. CO. CO. + 0. 3= 19.8; = 0.89. O. Experiments XLV to XLVI, simultaneous. December 14. Temper- ature + 6°. Pressure 76.5 cm. House sparrows. XLV. Bell-jar of 3.2 liters. Placed under bell-jar at 12:50, total reduction of pressure 29.5 cm. The bell-jar is surrounded with ice and salt. The interior ther- mometer registers + 1° at 1 o'clock; at 1:20, it is — 2°; at 1:35, — 4°; at 2:05, —4°. At 2:05, the bird is still alive; dead at 2:10. Lived 1 hour 20 min- utes in the equivalent of 1.24 liters of air, that is, 1 hour 4 minutes per liter. At 2: 17, rectal temperature 15°. Lethal air: O. 10.3; CO. 7.4. CO. CO. + O. = 17.7; = 0.70. O. XLVI. Bell-jar of 3.2 liters. Entered at 2:42. Pressure brought to 29.5 cm. No cooling mixture. The interior temperature of the bell-jar at 3:05 is +8.5°, and at the time of death, +6.5°. At 4:15, very sick; at 4:25, dead. Lived 1 hour Death in Closed Vessels 535 40 minutes in the equivalent of 1.24 liters of air; that is, 1 hour 20 minutes per liter. At 4:30, rectal temperature is 19°. Lethal air: CX 9.2; CO 9.2. CO CO + O = 18.4; = 0.79. O Table II 1 ■i 3 4 5 6 7 8 9 v f "a! > — 0 Composition of X O u 0 81 Om lethal air O O often already = 3.6. 76 540 Experiments The general conclusion from all this is that all disturbances, symptoms, and death, which occur in consequence of diminution of pressure, are due entirely to asphyxia; an animal subjected to an increasing diminution of pressure is like an animal which smothers in closed vessels in ordinary air, with the unimportant reservation, as we shall see later, of the action of the carbonic acid produced. When an animal in a closed vessel is subjected rapidly to a certain decompression, and allowed to die, as in the preceding experiments, the gradual depletion of the oxygen of the air in which it is con- fined acts exactly as if one continued in a pure air to diminish the barometric pressure around it. Oxygen tension is everything; barometric pressure in itself does nothing or almost nothing. I shall stress these facts and the conclusions to be drawn from them in another chapter, and I shall also indicate elsewhere the practical results which may be deduced from them. I shall not now dwell upon the exterior phenomena displayed by the sparrows subjected to the lowering of pressure. This study, generalized and supported by precise observations made on animals of different species, will be taken up in a special chapter. I shall merely mention today three principal facts: 1, the increase in number of respirations; 2, the drop in temperature; 3, the convul- sions which precede death, and which will give us an opportunity to judge the theory which attributes the convulsions to the action of excess carbonic acid in the blood. I shall now give the results of experiments made on birds other than sparrows. Experiments LII to LV, simultaneous. July 2. Temperature 20°; pressure 76 cm. Owls (Stria; psilodactyla, Lin.) LII. Young, weighing 125 grams. Bell-jar of 2.25 liters. Entered at 3:07; left at normal pressure. Seemed affected at about 3:50, dies at 5 o'clock, with 3.8 cm. dim- inution of pressure due to absorption. Dead after 1 hour 20 minutes of distress. After 15 minutes, the rectal temperature is 31.3°; no rigidity. Lethal air: O 3.3; CO 13.4. CO. CO. + O. = 16.7; 0.76. O; LIII. Like the foregoing. Bell-jar of 7 liters. Began at 3:15. At 3:20, pressure has been lowered 22 cm., some- what uneasy. At 3:22, pressure has been lowered 41 cm., the bird is calm; at 3:25, staggers; cocks closed. Actual pressure 27.7 cm. Death in Closed Vessels 541 Soon closes its eyes and seems to sleep. Dies at 4:30, after 1 hour of uneasiness. Ten minutes after death, rectal temperature is 35.0°; after 25 minutes, it is 33.8°: no rigidity. Lethal air: O 13.4; CO 6.4. CO, CO + O = 19.8; = 0.87. O Oxygen tension = 4.8. LIV. Similar. Bell-jar of 7.5 liters. Began at 3:18; at 3:20, decompression of 33 cm., no uneasiness; at 3:27, 51 cm. of decompression, vomits; at 3:28, actual pressure 22 cm. Cock closed. At 3:32, falls and seems about to die; a little air admitted and the pressure rises to 32 cm.; the bird gets up. Same procedure repeated twice. At 3:58, pressure is 23.5 cm., the bird has half risen; cocks closed. At 4:10, pressure lowered to 22.5 cm. Dead at 4:35, without con- vulsions, after about 1 hour 10 minutes of respiratory embarrassment. After 20 minutes, the rectal temperature is 30.2°; after 30 minutes, 29.7°: no rigidity. Lethal air: O 17.1; CO 3.3. CO. CO. + O = 20.4; .= 0.87. Oxygen tension = 5.0. O2 LV. Owl five years old, weighing 170 grams. Bell-jar of 11.5 liters. Began at 3:08; considerable agitation, which lasts until 3:13, when the pressure has been lowered 36 cm., the bird then grows calm. At 3:16, pressure has been lowered 44 cm., vomits twice. At 3:21, 48 cm., at 3:26, 57 cm., that is, approximately 19 cm. of actual pressure. Falls and is about to die; pressure raised to 28 cm., the bird gets up after a few minutes. Same procedure repeated twice, but each time the bird is evidently less affected. At 4:03, pressure is 20.2 cm.: bird falls; cocks closed. At 4:10, lowered to 19 cm., bird is still prostrate, beak forward. Dead at 4:45, without convulsions, after about 1 hour 20 minutes of respiratory embarrassment. Twenty-two minutes after death, rectal temperature 30.2°; after 30 minutes, 29.6°: no rigidity. Lethal air: O 17.6; CO. 2.6. CO CO= + 0 = 20.2: =0.79. Oxygen tension = 4.4. ' O2 We see that our rule is verified, in spite of an irregularity greater than usual, presented by the experiments made at normal pressure. The value of the oxygen tension in the lethal air was, in fact: at 76 cm., 3.3; at 27.7 cm., 4.8; at 22.5 cm., 5; at 19 cm., 4.4. 542 Experiments These last barometric pressures are very low, and quite evidently the transitions had not been careful enough. Experiment LVI. August 3, hawk (Falco tinnunculus, Lin.). Pres- sure 75.5 cm. Bell-jar of 13.5 liters. Began at 3:25; current of air. The decompression at 3:30 is 8 cm.; at 3:35, 16 cm.; at 3:45, 30 cm.; at 3:50, 40 cm.; at 3:53, 50 cm.; that is, actual pressure about 25.5 cm. Bird vomits and falls; pressure raised to 31.5 cm., then slowly lowered to 25.5 cm.; the bird, which had recovered a little, falls again, seems about to die, and the pres- sure has to be raised to 27.5 cm. At 4:05, pressure is 25 cm.; at 4:10, 24.5 cm.; at 4:15, 21.5 cm.; the bird vomits, staggers, and reels, but seems to recover a little, while remaining weak. At 4: 17, the pressure is only 20 cm.; at 4:20, 19.5 cm. Cocks are closed, and the bird dies at 4:32. Lived about 40 minutes with respiratory embarrassment. Eight minutes after death, rectal temperature was 37.4°. The air, as one might expect, is hardly altered; C^ 20.0; CO 0.8. Oxygen tension = 5.1. The interesting point of this last experiment is that a bird of prey, zoological neighbor of the vultures and the condors which mount to prodigious heights, was at least as sensitive to the lower- ing of pressure as a simple sparrow. B. Experiments on Mammals. These have been rather few, since the principal point of the question had been settled by the experiments on sparrows. They have shown me, as a general fact, that mammals can be brought to pressures considerably lower than birds. One might have con- jectured as much anyway, since mammals deplete the oxygen of the confined air more than birds do. (See my Lessons on the Physiology of Respiration, page 510.) They are, besides, more pliable, so to speak, that is, easier to reduce to the state of cold-blooded animals, enduring then as the latter do, extremely low pressures (See later) ; this is especially true of rodents. A remarkable example of this fact (Exp. LVII) was shown by a guinea pig, which, having been placed for four hours in a current of air (temperature 15°) , continued to live under a pressure constantly lower than 20 cm., which was repeatedly lowered to 11 cm. for four or five minutes. It is true that after this time the unfortunate animal remained motionless, almost uncon- scious, with a rectal temperature of 20°, and that it died several hours after the experiment. In another case (Exp. LVIII) , a guinea pig was brought to and maintained at a pressure of 12 cm. for about a quarter of an hour, Death in Closed Vessels 543 by a gradual lowering of the pressure lasting an hour and a half The animal was then very weak, and its rectal temperature was only 25°; but three minutes after the animal was restored to nor- mal pressure, the temperature rose to 31°, and the guinea pig could already get up on its feet. This animal survived. CATS. Experiments LIX to LXIII, simultaneous. July 11; pres- sure 75 cm. Cats from a month to a month and a half old. LIX. Cat weighing 280 grams. Bell- jar of 3.2 liters. Entered at 3:15; normal pressure; died at 4:35, without convulsions. 280 grams lived 1 hour 20 minutes in 2.920 liters of air, which gives per liter and per kilogram 80 m. 280 x = 7.7 m. 2.92 1000 Lethal air: O* 4.4; CO-' 13.4. CO CO^ + O-" = 17.8; = 0.81. Oxygen tension = 4.4. LX. Weight 380 grams. Bell-jar of 7 liters. Began at 3:20; at 3:25, the pressure is 51.2 cm.; cocks closed; died at 4:45. 380 grams lived 1 hour 20 minutes in 6.62 liters of air at a pres- sure of 51.2 cm.; reducing to 76 cm. of pressure and to 1000 grams, we get the value. 80 m. 380 80 m x 380 x 76 x = = 7.1 m. 6.62 x 51.2 1000 6.62 x 51.2 x 1000 76 Lethal air: O? 7.2; CO^ 11.4. COs CO- + 0? = 18.6; = 0.81. Oxygen tension = 4.9. O LXI. Weight 460 grams. Bell-jar of 13.5 liters. Began at 3:25; at 3:44, pressure is 21.8 cm. The animal is very sick, 250 respirations per minute. At 4 o'clock, violent convulsive movements, falls back, and dies at 4: 13. 460 grams lived 29 minutes in 13.04 liters of air at 21.8 cm., which gives 3 minutes per liter at 76 cm. and per 1000 grams. Lethal air: O* 15.5; CO* 5.1. CO2 CO2 + 02 = 20.6; = 0.94. Oxygen tension = 4.4. O2 544 Experiments LXII. Weight 665 grams. Bell-jar of 15.5 liters. Began at 3:22; at 3:40, the pressure is 27 cm.; vomits, defecates. At 3:48, pressure is only 16 cm.; very uneasy. Cocks closed. Dies at 3:53, without convulsions. Duration of life, per kilogram and per liter, 1 minute. Lethal air: O* 19.0; CO* 1.0. O* x P = 4. LXIII. Weight 485 grams. Bell-jar of 15.5 liters. Pressure reduced in 15 minutes to 16 cm. Lying down, panting; dies in 20 minutes. Duration of life, per kilogram and per liter, 3 minutes. Experiment LXIV. August 4. Cat weighing 2.57 kilos; bell-jar of 21.5 liters. Began at 4:10. At 4:22, the actual pressure is 29.5 cm. Cocks closed; the animal does not seem in much pain. At 4:37, violent struggles and cries. At 4:45, convulsions, with quivering of the cutaneous muscles. Dead at 4:47. Duration of life, per kilo and per liter, 8.7 minutes. Lethal air: O* 10.3; CO 9.6. CO* CO* + O* = 19.9; =0.90. Oxygen tension = 4. O* The value of the oxygen tension in these experiments was: at 76 cm., 4.4; at 51.2 cm., 4.9; at 29.5 cm., 4; at 21.8 cm., 4.4; at 16 cm., 4. If now we find the duration of life taking as base a liter of air and reducing the calculation to one kilogram of body weight, the result is: at 76 cm., the duration of life was 7.7 minutes; at 5.12 cm., 7.1 minutes; at 29.5 cm., 8.7 minutes; at 27 cm., 3 minutes; at 16 cm., 3 minutes. We must not forget that the cat at 29.5 cm. was very different from the others, and being much bigger, should consume less oxygen in a given time, and consequently live longer in a given space. I thought it would be interesting to experiment on new-born animals, which resist asphyxia much longer than adults, as is known. However, I could not go noticeably farther with them in decompression than with adults. Kittens born two days before, brought rapidly to 8 to 12 centimeters of pressure, died in seven or eight minutes. Here are the results of experiments in which the air was analyzed. Experiments LXV to LXVIII, simultaneous. July 4; pressure 76 cm. Kittens born July 1, weighing an average of 125 grams. LXV. Bell-jar of 675 cc, subtracting displacement of animal, 550 cc. Entered at 2:42; brought rapidly to a pressure of 58 cm. At 3:40 seems dead, but does not really die until 4:35. Lethal air: O* 3.0; CO* 17.1. Death in Closed Vessels 545 CO* CO -j- O2 = 20.1; = 0.95. Oxygen tension = 2.2. O2 LXVI. Bell- jar of 2.5 liters. Entered at 3 o'clock; at 3:06, pressure is 25.5 cm.; cocks closed; dies at 5:40. Lethal air: O* 7.1; CO2 13.5. CO2 CO + 02 = 20.6; = 0.98. Oxygen tension = 2.4. O2 LXVII. Bell-jar of 3.2 liters. Entered at 2:54. At 3 o'clock, pressure 20.5 cm.; mews. Cocks closed. Dies at 7:15. Lethal air: Oa 8.5; CO* 12.0. CO2 CO* + 0* = 20.5; = 0.97. Oxygen tension = 2.2. O2 LXVIII. Bell- jar of 5 liters. Entered at 2:38; at 2:48, pressure is 22 cm.; cat still walks and mews; at 2:53, pressure is 16.2 cm.; animal is lying flat. Cocks closed. At 3:08, pressure lowered to 13.4 cm. Dead at 7:35. Lethal air: O* 13; CO2 7. CO2 CO^ + O- = 20.0; = 0.98. Oxygen tension = 2.2. O2 O, x P The ratio is maintained here with remarkable regu- 76 larity at 2.2, a number about half that given by adult cats. Already, in my Lessons (page 510), I had found that, while adult cats leave on the average 5.3 per cent of oxygen in confined air, when they die at normal pressure, new-born kittens left only 3.0 per cent. For adult rats, the average was 2.0 per cent, and for a new-born rat, 0.75 per cent. If now we make the calculations necessary to find the duration of life of these new-born kittens, reduced to a liter of air at 76 cm. and to a kilogram of body weight, as we did for the adults, we find that this duration is: at 58 cm., 33 minutes; at 25.5 cm., 24 minutes; at 20.5 cm., 37 minutes; at 13.4 cm., 32 minutes. We see that the duration of life was obviously the same at very low pressures as at average pressures. Moreover, comparing these figures with those obtained from the study of adult cats, we see 546 Experiments that the duration of life of the new-born kittens was about four times greater. These two facts agree with what is known about the vital resistance of new-born animals. Finally, it is interesting to note that the ratio between the oxygen consumed and the carbonic acid produced was considerably higher in the new-born than in the adults: its average, in fact, is 0.97, while for adults it is only 0.86. DOGS. Experiment LXIX. March 11. Dog weighing 4.3 kilos. Bell- jar of 31 liters. Entered at 1:40 at a pressure of 43 cm. Uneasy; lies down at 2 o'clock; found dead at 2:20. Air at 2 o'clock: O2 5.5; CO2 16.1. Air after death, O 5.4; CO 16.7. Oxygen tension = 3.0. RABBITS. Experiment LXX. March 15. Rabbit. Bell-jar of 11.5 liters. Entered at 2:28. Left at normal pressure. At 3:50, standing, panting; at 3:55, struggles; at 4 o'clock, falls; at 4:30, last breath, without convulsions. Fifteen minutes after, its rectal temperature is 34°. Lethal air: O2 3.7; CO2 15.2. CO2 C02 + ©2=18.9; = 0.96. Oxygen tension = 3.7. O2 Experiment LXXI. March 16. Rabbit weighing 1.900 kilos. Bell- jar of 20.75 liters. Began at 2:05; at 2:25, the pressure is only 41 cm. Cocks closed. At 2:55, uneasiness; at 3:20, great uneasiness; at 3:35, falls; at 3:50, dead without convulsions; 5 minutes after, the rectal temperature is 35.3°. Lived 1 hour 25 minutes in 18.85 liters of air at 41 cm., which gives, per liter and per kilogram, a duration of 16 minutes. Lethal air: O2 5.9; CO2 13.3. CO* CO2 + O2 = 19.2; = 0.81. Oxygen tension = 3.2. O2 Experiment LXXII. March 14. Pressure 76.6 cm.; temperature 13°. Rabbit weighing 1.340 kilos. Bell-jar of 31 liters. At 2:27, began the current of air; the manometer rises slowly; at 2:58 pressure lowered 41 cm.; up to that point the animal remained perfectly quiet. At 3:02, pressure lowered 50 cm.; rabbit becomes uneasy; the inlet cock is closed, and pumping continued. At 3:07, the pressure is only 15.6 cm.; the animal lies down. At 3:12, it is 16 cm. Dead at 3:20. Lethal air: O2 19; CO2 1.6. CO.- CO2 + O2 = 20.6; = 0.84. Oxygen tension = 4.0. O2 Death in Closed Vessels 547 Experiment LXXIII. March 15. Rabbit weighing 1.650 kilos. Bell-jar of 20.75 liters. Began at 3:48. At 4:05, the pressure is 29 cm. Cocks closed. The animal dies at 6:42; ten minutes after, its temperature is 32°. Nothing can be said about its duration of life, because a little air entered during the experiment. Lethal air: Oa 11.0; CO, 9.0. CO, CO* +0=20; =0.90. Oxygen tension = 4.2. O, The value of the ratio O x P in these four experiments is: at 76 normal pressure, 3.7; at 41cm., 3.2; at 29 cm., 4.2; at 16cm., 4.0. GUINEA PIGS. Experiments LXXIV-LXXV, simultaneous. Aug- ust 5. LXX7V. Weight 420 grams. Bell- jar of 3.2 liters. Entered at 3:45, at normal pressure. Dead at 5:05, after uneasiness, sudden leaps, etc. . . . Never remained quiet. A quarter of an hour later, its rectal temperature is 37°. 420 grams lived 1 hour 20 minutes in 2.78 liters of air, that is, 12 minutes per liter and per 1000 grams. Lethal air: O* 2.3; CO, 16.4. CO, CO- + Os = 18.7; = 0.88. Oxygen tension = 2.3. 02 LXXV. Weight 470 grams. Bell-jar of 5 liters. Began at 3:55, and brought in 2 minutes to 46.5 cm. of actual pressure. Remains perfectly quiet. At 5:17, convulsive trembling. Dies at 5:20; 17 minutes after, the rectal temperature is 34°. 470 grams lived 1 hour 24 minutes in 4.53 liters at 46.5 cm., repre- senting at 76 cm., 2.10 liters. Therefore 1000 grams lived 14 minutes per liter. Lethal air: O, 3.5; CO, 16.0. CO, CO, + O, = 19.5; = 0.92. Oxygen tension = 2.1. O, Experiments LXXVI — LXXVII, simultaneous. June 23. LXXV7. Weight 580 grams. Bell of 13 liters. Began at 1:45. Reduced to a pressure of 16 cm. with current of air at 2:45. Dead at 3:10; 27 minutes after, its rectal temperature is 31.5°. Lived 1 hour 12 minutes in a volume of air corresponding to 2.6 liters at 76 cm., that is, 16 minutes per 1000 grams per liter. 548 Experiments Lethal air: O. 14.5; CO 9.8. CO. CO- + Oa = 24.3; = 1.51. Oxygen tension = 3.0. O* LXXVII. Weight 490 grams. Bell- jar of 10 liters. Began at 1:45. Brought to a pressure of 12 cm. at 2:45. Dies at 3 o'clock; 17 minutes after, temperature is 33.3°. Lived 15 minutes in 1.5 liters of air at 76 cm.; that is, 4.9 minutes per liter and per 1000 grams. Lethal air: O. 14.5; CO? 16.0. CO. CO, + 0, = 24.3; =1.51. Oxygen tension = 2.1. O. Experiment LXXVIII. Weight 485 grams. Bell-jar of 13.5 liters, pressure 76 cm. Began at 3:24; no uneasiness. At 3:30, pressure lowered 50 cm.: staggers, then recovers; respiratory rate 100, walks a little. At 3:34, pressure lowered 56 cm.; respiratory rate 135; at 3:35, pressure low- ered 58.5, lies down on its belly. At 3:40, actual pressure 13.6 cm.; respiratory rate 80, violent, painful. Cocks closed. 3:45, still lying down, pupils dilated; 3:46, little convulsive shud- ders; 3:47, fallen on its side; convulsive movements; rigidity; belly enormously swollen. 3:49, dies, having lived 9 minutes. After 13 minutes, rectal temperature is 34.6°: after 36 minutes, 31.8°; after 1 hour 16 minutes, 28.4°, and rigidity begins; after 2 hours 11 minutes, 25.4°; slight rigidity. Lethal air: O. 19.1; CO. 2.3. CO. CO. + O. = 21.4; = 1.27. Oxygen tension = 3.4. O. Experiments LXXIX-LXXXI, simultaneous. May 28. Pressure 76.3 cm. LXXIX. Weight 620 grams. Bell-jar of 16 liters. Began at 2:32; at 2:35, pressure lowered 41.3 cm., that is, 35 cm. of actual pressure; cocks closed. At 4:50, falls on its side; at 5:30, dies; 30 minutes after, its rectal temperature is 28°. 620 grams lived 2 hours 55 minutes in 4.44 liters of air at 76 cm. Which gives 24 minutes per, 1000 grams and per liter of air at 76 cm. Lethal air: O. 4.9; CO. 17.2. CO, CO. + 0. = 22.1; =1.07. Oxygen tension = 2.2. O, LXXX. Weight 520 grams. Bell-jar of 13.5 liters. Began at 2:37. At 2:44, pressure 27.8 cm.; cocks closed. At 4:10, fallen on its belly; at 4:55, on its side; dead at 5:05; 15 minutes after, its rectal temperature is 28°. Death in Closed Vessels 549 520 grams lived 2 hours 20 minutes in 4.76 liters of air at 76 cm.; which makes 17 minutes, per 1000 grams and per liter of air at 76 cm. Lethal air: O* 5.4; CO2 15.7. CO2 CO, _|_ 02 = 21.1 ; =1.01. Oxygen tension = 2.2. O2 LXXXI. Weight 620 grams. Bell- jar of 19 liters. Began at 2:40; at 2:49 the pressure is 19.5 cm.; the animal stag- gers. Cocks closed. At 2:55, falls; at 3:20, a little better; at 4:15, still making efforts to rise; at 5:10, convulsive jerks; dies at 5:30; 20 minutes after, the rectal temperature is 23°. Lived 2 hours 40 minutes in 4.71 liters of air; which gives 21 minutes, per 1000 grams and per liter at normal pressure. Lethal air: O* 8.1; CO2 15.6. CO2 CO + 02 = 23.7; = 1.21. Oxygen tension = 2.0. O2 The value of the oxygen tension in these different experiments was: At normal pressure, 2.3; at 46.5 cm., 2.1; at 41.3 cm., 2.2; at 27.8 cm., 2.0; at 19.5 cm., 2.0; at 16 cm., 3.0; at 13.6 cm., 3.4; at 12 cm., 3.0. It will be noted that at very low pressures the sum C02 + 02 was: 21.1; 21.4; 22.1; 22.1; 23.7; and 24.3, that is, higher than the original proportion of oxygen. The excess is due, no doubt, to the carbonic acid contained in the intestines of these rodents, whose bellies balloon out at the beginning of very low pressures, and which probably then let escape a part of their expanded gases. As to the duration of life, reducing it to 1000 grams of body weight, it was, per liter, : at normal pressure, 12 minutes; at 46.5 cm., 14 minutes; at 41.3 cm., 24 minutes; at 27.8 cm., 17 minutes; at 19.5 cm., 21 minutes; at 16 cm., 16 minutes; at 13.6 cm. and at 12 cm., death came much more rapidly. We find here a regularity not displayed by the birds, which were extremely variable in their behavior under the bell-jars. The two extremes 12 and 24 are explained by the incessant movement or the complete calm of the experimental animals. If we compare these numbers with those furnished us by the other mammals, we see that they are about double those given by adult cats/about equal those of rabbits, and much lower than those of new-born kittens. Let us say in conclusion that for sparrows, whose ordinary weight is about 30 grams, making the same calcula- 550 Experiments Table IV 1 2 3 4 5 6 7 8 9 10 01 ■3« | g ,i, o £J2 § > | to 81" 6 1 LII Strix psilo- gm. c. lit. h.m. m. | 02 CO, dactyla 125 76 2.25 1 53 6.2 3.3 13.4 3.3 LIII Id. 125 27.5 7 1 10 3.4 13.4 6.4 4.8 LIV Id. 125 22.5 7.5 37 2.1 17.1 3.3 5.0 LV Id. 170 19 11.5 35 2.1 17.6 2.6 4.4 LVI Falco Tin- nunculus 19.5 13.5 12 20 0.8 5.1 av3.4| 1 av.4.5 MAMMALS | 1 LIX LX LXIV LXII LXI LXIII Cat 1 mo. old Id. Adult cat_ | Cat 1 mo. | old I Id Id 280 380 2570 460 665 485 76 51 29.5 21.8 16 16 3.2 7 21.5 13.5 15.5 15.5 LXV LXVI LXVII LXVIII Cats 3 days old Id Id. Id. 125 I 125 | 125 | 125 | 58 25.5 20.5 | 13.5 | 10.5 2.5 3.2 5 1 20 1 20 25 29 05 20 7.7 7.1 8.7 4.4 7.2 10.3 13.4 I 4.4 11.4 I 4.9 9.6 | 4 3 15.5 5.1 — I 19 I 1 3 av. 5.9 1 55 2 35 4 15 4 30 33 24 37 32 av.31| 4.4 4 av. 4.4 0.3 7.1 8.5 13 17.1 13.5 12 7 | 2.2 | 2.4 | 2.2 | 2.2 | av.2.2 LXIX | Dog 4.3K. | 43 1 31 5.4 I | 3.0 LXX | Rabbit . LXXI | Id LXXIII | Id. _-__. LXXII | Id. ___. I | 11.5 I 20.7 I 20.7 I 31 I 2 1 25 13 16 3.7 5.9 11 19 15.2 13.3 9 1.6 3.7 3.2 4.2 4.0 av.3.8 LXXIV | Guinea pig LXXX LXXIX I LXXX | LXXXI | LXXVI | LXX VIII | Id. LXX VII | Id. I Id. Id. Id. Id. Id. 420 76 470 46.5 620 35 520 28 620 19.5 580 16 485 13.5 490 12 3.2 5 16 13.5 19 13 13.5 10 20 20 55 20 40 12 9 15 Av. 17.3 2.3 3.5 4.9 5.4 8.1 14.5 19.1 19 16.4 16 17.2 15.7 15.6 9.8 2.3 3.1 2.3 2.1 2.2 2.0 2.0 3.0 | 3.4 | 3.0 | av.2.5 Death in Closed Vessels 551 tions, we should find an average of about two minutes per kilogram and per liter. Now, if we refer to the celebrated and classic work of Regnault and Reiset on respiration, we shall find analogous results, that is, the greater consumption of oxygen in a given time by carnivores than by herbivores, by birds than by mammals, by small animals than by large ones, etc. All the data which have just been given are summarized in Table IV. I add, in conclusion, the account of an experiment (Exper. LXXXII) made on a hedgehog July 6, with the purpose of trying to put this animal into a state of hibernation by keeping it for a certain time at very low pressure. But we could not, without imminent danger, pass below a pressure of 18 cm.; at 26 cm., the animal uncurled and vomited. After two hours, during which the pressure varied between 28 cm. and 18 cm., we removed the ani- mal, which recovered rapidly and survived. This hedgehog there- fore behaved like a cat or any other animal not endowed with the remarkable power of hibernation. C. Experiments on cold-blooded animals. I made only a few experiments on cold-blooded animals. Frogs, so useful for other researches, often manifest a strange unevenness in duration of life, composition of lethal air, etc., when they are allowed to die in closed vessels, even at normal pressure. However, here is a series of simultaneous experiments, in which, by taking great precautions and choosing my subjects with great care, I suc- ceeded in getting an interesting result: Experiments LXXXIII-LXXXVII, simultaneous. June 15, at 3 o'clock; temperature 22°. LXXXIII. Normal pressure, vessel of 275 cc; dies at 5 o'clock in the evening, June 17. Lethal air: O 2.7. LXXXIV. Pressure of 20 cm.; vessel of 1.350 liters, representing 355 cc. at normal pressure; it dies June 16 at 2 o'clock. Lethal air: O- 8.4. Oxygen tension = 2.2. LXXXV. Pressure of 14 cm.; vessel of 1.9 liters, representing 350 cc. at normal pressure, dies June 16 at 2:50. Lethal air: O 15.3. Oxygen tension = 2.8. LXXXVI. Pressure of 10 cm.; vessel of 2.2 liters, representing 290 cc. at normal pressure; lived 4 hours. Lethal air: O? 18.5. Oxygen tension = 2.4. LXXXVII. Pressure of 5.5 cm.; vessel of 2.8 liters, representing 200 cc; lived 2 hours. Lethal air: Oa 18.6. Oxygen tension = 1.3. 552 Experiments Finally I report the results of an experiment made on an insect, the poplar beetle (Chrysomelida) : Experiment LXXXVIII. August 3, 4 o'clock in the evening; temperature 24°. 10 grams of beetles entered: A. In a bell- jar of 60 cc. at normal pressure. B. In a bell-jar of 800 cc. at a pressure of 9 cm. C. In a bell-jar of 1.5 liters at a pressure of 4 cm. On August 4, at noon, the insects are motionless and seem dead; the air of the bell- jars no longer has a trace of oxygen; there as 18 to 20 per cent of CO--. The insects return to life about an hour after- wards. 3. Conclusions. The results which the data given in the present subchapter have brought us can be summarized in the following conclusion: In a closed vessel, at pressures below one atmosphere, death occurs when the tension 0.2 x P of the oxygen of the air is reduced to a certain value which is constant for each species, or at least varies within narrow limits around an average (4.4 for adult cats; 3.6 for sparrows; 2.5 for guinea pigs; 2.2 for newborn kittens) . This average remains the same, whatever the initial composition of the air used; but for super-oxygenated air the carbonic acid must be absorbed as it is produced. Subchapter II PRESSURES ABOVE ONE ATMOSPHERE 1. Experimental Set-up. After studying the composition of confined air which had be- come irrespirable under pressures less than one atmosphere, it was quite natural to find out what would happen if one used higher pressures. We have seen that, the weaker the pressure, the greater is the proportion of oxygen remaining in the lethal air, or, in other words, the less the air is exhausted. Would this law hold good at higher pressures? Would there come a moment when a sparrow would exhaust the oxygen of the air under pressure, as the beetles of which I gave an account above did at weaker pressures? Apply- ing the law and taking as an average of the exhaustion in oxygen at normal pressure the figure 3.6, at 3.6 atmospheres we should find only 1 per cent of oxygen in the air which had become lethal by Death in Closed Vessels 553 confinement, at 7.2 atmospheres only 0.5 per cent, and so on. We shall see how far this hypothesis is from the truth. In the experiments which I shall report, I used sparrows almost exclusively. Their small size allowed me to use glass apparatuses whose advantages are evident, but whose dangers, when highly compressed air is used, are no less evident. In fact, glass has this serious disadvantage, that one is never sure that an apparatus which withstood a certain pressure at a certain moment, will be able to withstand it again. Furthermore, under the influence of atmospheric changes, the metallic pieces in which it must be held expand or contract in lengthy experiments, following a law dif- ferent from that of the glass, which is thus subjected to pulls in opposite directions which threaten its solidity and may even crack it without the application of any pressure, since these glasses are very thick. At any rate, thanks to the precautions we used, the accidents which occurred never had serious consequences. One of the apparatuses which I used most frequently and which allows me to compress air up to 25 atmospheres, consists of a glass cylinder, of a capacity of 650 cc. and a thickness of 18 millimeters, protected by a large-mesh jacket. This reservoir is topped with a bronze part, which exactly fits its orifice, or rather fits another fixed bjonze plate which is fastened to the stand on which the reservoir rests by four steel columns which pass through both the fixed part and the movable part. These two parts are solidly held by four movable nuts which screw on the steel columns. All of this is plainly visible in Figure 20. A Bourdon manometer, which indicates the pressure of the air in the reservoir, is fixed on the immovable plate. A screw cock with a very small opening at the right of the cylinder permits one to take a sample of this air whenever he wishes. To do so, one fits to this cock a rubber tube which dips into a mercury basin below a graduated tube; if then this cock is opened carefully, the com- pressed air escapes from the apparatus and enters the graduated tube; I always took care, of course, to let out a certain quantity before taking what I intended to analyze. The air is compressed in the reservoir by means of a small force- pump; I had this pump enclosed in a metal jacket through which a constant stream of water passes; the operation of it is then less painful and — which is more important — no hot air is pumped to the animal. I can thus reach a pressure of 25 atmospheres in about 20 minutes. Finally, a large cock fastened to the movable part topping the cylinder opens or closes the apparatus hermetically. 554 Experiments It establishes or cuts off communication with the pump, and, when the tube surmounting it is taken away, permits sudden decom- pression of the air in the reservoir, when necessary. OJ cd £ a rC £ a w o 1 £ cd A! u o Cd a T3 0) o CJ £ tt) s >> ">> o c cd co a 3 Cfl m CJ t-t a o N cu cm 43 M >> M cd X 2 PQ O o a tH m £ Cfl cu 3 3 h1 a a cd H cd £ M cd O o U o a cd cd i H 1 0) -0 Efl o> 3 H o CO 00 CO a w cd "Sib >> X o CD o cu a £ o CJ CJ H a cd (5 a £ 'h c 3 CO X! o a cu 0> 51 tH o 'QJO '0J3 c "5 0) 43 o CM c 0) u O u 3 01 £ U > In the experiments in which I simply compressed the air, the bag pictured in the figure was not present, of course, and the suc- tion of the pump was directly outside. Death in Closed Vessels 555 I used even more often an apparatus made in a similar manner, whose reservoir was a simple receiver of a Seltzer water generator. I could take this only to 10 atmospheres; but the rounded form of the apparatus gave the animals more liberty. Finally, I used a mercury bottle, mounted like the glass cylinder, The extreme solidity of this instrument would have allowed me to carry the pressure to 40 atmospheres without difficulty. Its capac- ity of 3 liters also has great advantages; the only inconvenience is that of not being able to see what is going on inside. 2. Experiments. A. Compression with Ordinary Air. I now come to the experiments. I shall list them, as I have done hitherto, in the order in which they were performed. What I said at the beginning of this sub-chapter indicates sufficiently why I began with a pressure of 3.75 atmospheres. The apparatus which I used in this first series is a Seltzer water receiver, of a total capacity of 1060 cc. Experiment LXXXIX. July 18; temperature 26°. House sparrow, young. In 10 minutes the sparrow is taken to 3.75 atmospheres; it does not seem affected; but, an accident making the pressure fall sud- denly, it bristles up and hides its head under its wing. The increase of the pressure to its original level restores its healthy appearance. Cocks closed at 2 o'clock. At 2:20, sick; at 3:10, very sick; at 5:20, seems to be dying; at 6:30, the same. At 10 o'clock in the eve- ning, thinking it dead, I withdrew air so that the pressure fell to 2 atmospheres; it was breathing then, and I left it until 10:30. Taken out then, it was still living, with a rectal temperature of 28° (the same temperature as that of the receiver) ; it died during the night. The air which I took at 10 o'clock, and which probably would have changed but little afterwards, contained: CCb 7.2; O2 11.1. Experiment XC. July 19; temperature 25°. House sparrow, young. In 10 minutes, taken to 7 atmospheres; closed the cock at 2: 10. At 4:45 very sick, eyes closed. At 10 o'clock in the evening, found dead. I made the decompression rapidly and on examining the jugular vein, I found the blood red and frothy like foam. The lethal air contained CO2 3.7; O 16.2. Experiment XCI. July 20; temperature 21.5. House sparrow, young. Taken rapidly to 2V2 atmospheres. Closed cocks at 5:30. Sick at 5:55; seemed dead at 9:45. I took out an air sample and opened the apparatus. Taking the bird in my hand, I perceived that it was still breath- ing a little, and was still a little sensitive. The rectal temperature was 23.5°, probably equal to that of the receiver. I cut its head off; it had very energetic reflex movements. The bird therefore lived 556 Experiments about 4V2 hours, in a quantity of air corresponding to 2.650 liters at normal pressure. The blood was very red in the left heart; less dark than in the ordinary condition in the right jugular; no free gases in the blood. Lethal air: CO* 11.2; O. 8.5. Experiment XCII. July 21; house sparrow, young. Put in a pres- sure of 5 atmospheres at 10 o'clock in the morning; found dead at 1 o'clock. Lethal air: CO. 6.0; O 14.2. Experiment XCIII. July 24; temperature 21°. House sparrow. Placed in a pressure of 1V2 atmospheres at 5:10. Died at 8:45. Rectal temperature 25.5°; venous blood fairly red; no free gases. Lived 3 hours 35 minutes in 1.580 liters of air, at normal pressure. Lethal air: CCb 15.2; O* 2.6. Experiment XCIV. July 25; temperature 23°. House sparrow, rather old. At 4:35 taken to 2 atmospheres. Found dead at 7:45. Lethal air: CCh 13.7; O? 5.0. Experiment XCV. July 26; temperature 23°. House sparrow. At 1:25, taken to 5 atmospheres. Died at 4:15. Rectal temperature 23°; blood and tissues red; the heart was still beating after removal. Lived 2 hours 50 minutes in the equivalent of 5.300 liters of air. Lethal air: CO 5.1; O* 13.4. Experiment XCV I. August 4. House sparrow. At 4:35 taken to 6 atmospheres. At 5:30, very sick; found dead at 9:30. Venous blood red; gas in the right heart and the jugulars, but not in the left heart. Lethal air: CO2 4.2; O 16.0. Experiment XCVII. August 11. House sparrow. At 2:55, placed at IV2 atmospheres. Very sick at 5:30. Found dead at 9 o'clock; venous blood, dark. Lethal air: CO* 15.4; O2 2.5. Experiment XCVIII. August 17. Yellow-hammer (Emberiza cit- rinella, Lin.). At 4:45, at 1 and % atmospheres. Sick at 6 o'clock; found dead at 8 o'clock; venous blood dark; no gases. Lethal air: CO2 12.9; O* 4.9. Experiment XCIX. August 19; 22°. Linnet (Fringilla cannabina, Lin.). Taken to 8.8 atmospheres. Closed the cock at 2:50; at 3:45, dis- tressed, made efforts to vomit. At 4:45, fell on its side, respirations grew slower and weaker; no convulsions. At 6 o'clock a quivering in one foot, then extension: it was the last movement. Rectal temperature 25.5°. The venous blood was very red, with- out gas; the heart was still beating, auricles and ventricles. Lived 3 hours and 10 minutes in 9.330 liters of air at normal pressure. Lethal air: CO* 2.8; O* 17.4. Death in Closed Vessels 557 Experiment C. August 19; temperature 22°. Linnet. At 6:20, taken to 95 centimeters pressure; at 9:55, found dead. Venous blood dark, without gas. Lethal air: CO* 13.3; O* 3.7. Experiment CI. August 20; mountain sparrow. Placed at llA atmospheres. Lethal air: CO= 14.3; O* 3.4. The results of these experiments are grouped in the increasing order of pressures in the following table. Table V 1 2 3 4 5 • 6 7 8 9 10 n 01 CI o Compo- -M o >». 0 o a sition of ~i c o +-> •2 lethal air 6 h 9 3 c o C > X d X 6 °u w£ £ < P P.Q.Z o CO; O, u d u u |o c i y4 26.1 13.3 3.6 15.6 4.2|16.9 77 CI n/4 26.1 14.3 3.4 17.9 4.2|17.7 81 XCIII 1.5 3h 35m 2h 15m 31.3 15.2 2.6 22.8 3.9|17.8 83 XCVII 1.5 31.3 15.4 2.5 23.1 3.7117.9 83 XCVIII 1.75 from 2 to 3 h. 36.5 12.9 4.9 22.5 8.6|17.8|80 XCIV 2 less than 3 hr. 41.8|13.7 5.0 27.4 10 118.7186 XCI 2.5 4h 30m | lh 42m| 52.2|11.2| 8.5|28.0 21.2|19.7|90 LXXXIX 3.75 more than 8 h. 78.3| 7.2 11.1 27.0 41.3 18.3|73 XCII 5.0 2h 55m 33m 104.5 5.5 13.8 27.5 69 77 xcv 5.0 XCVI 6 125.4 4.2 16.0 25.2 96.0 20.2 85 xc 7 146.3 3.7 16.2 25.9 113.4 19.9178 XCIX 8.8 3h 10m 20m 183.9 2.8 17.4 24.6 153.1 20.2180 If now we consider these results, occupying ourselves first with the composition of the air which had become irrespirable — and the preceding table makes this bird's-eye view easy — we see at once that the hypothesis suggested as a heading for this sub-chapter, far from being verified, is exactly opposite to the truth. The greater the pressure, the less the oxygen of the air was exhausted, as Column 7 of Table V shows. At 8.8 atmospheres, the highest pressure I used in this first series of experiments, there remained after death 17.4 per cent of oxygen. This observation, already strange, becomes absolutely aston- ishing when we take account not only of the figure expressing the percentage, but also the number, hitherto constant in our experi- ments, which indicates the oxygen tension in the lethal air. We saw in the first chapter that this number oscillates between 3 and 4. 558 Experiments In the present experiments, Column 9 furnishes us analogous fig- ures only for the pressures between 1 and 2 atmospheres. And even here there appear already the numbers 8 and 10, which soon become 20 and 40, and finally 113 and 153 at the pressures of 7 and 8.8 atmospheres. So then, above 2 atmospheres, death in confined air cannot be attributed to lack of oxygen; we must seek some other cause. My first thought naturally turned to carbonic acid. Now considering Column 8, in which are listed numbers ob- tained by multiplying the percentage of carbonic acid by the num- ber of atmospheres, and which consequently represent the car- bonic acid tension in the lethal air, we see that, from 2 atmospheres on, these numbers oscillate between 25 and 30. If now we refer to what M. Claude Bernard" said formerly about the conditions of death of birds confined at normal pressure in superoxygenated air, we see that they die when they have formed a proportion of carbonic acid which corresponds precisely to that which we have just indicated. The numerous experiments which I myself4 have carried on in this field have led me to similar results, and I have confirmed the accuracy of the explanation given by CI. Bernard of this strange asphyxia in a medium much richer in oxygen than ordinary air. It is a real poisoning due to the carbonic acid of the blood, which cannot be eliminated because of the pressure exerted upon it by the carbonic acid contained in the ambient atmosphere. The cause of death, then, is the pressure exerted by this carbonic acid, a pressure measured exactly at one atmosphere by the per- centage of carbonic acid present. At pressures above one atmos- phere, the real pressure, the tension of the carbonic acid, is obtained by multiplying the percentage by the number of atmos- pheres, and in this way we obtained the figures in Column 8. We can now give, for death in closed vessels, at pressures greater than one atmosphere, a formula quite analogous to the one wa gave earlier (see page 552) for pressures lower than one atmos- phere, and say: The death of sparrows occurs when the tension of the carbonic acid, measured as I have just specified, is repre- sented by a figure which oscillates between approximately 24 and 30; hereafter we shall take 26 as an average number. The result of this fact is that, if we represent our results by a curve resembling that of Figure 17, in which the abscissae would represent the pressures, and the ordinates the proportions of car- bonic acid, this curve would correspond to the formula xy = 25 to Death in Closed Vessels 559 30, and consequently would also be a branch of an equilateral hyperbola. But we must note immediately that this formula begins to be true only from IV2 and especially from 2 atmospheres. Below that, the figures of Column 8 are much lower. In this case the quantity of oxygen at the bird's disposal was not sufficient to per- mit the production of a quantity of carbonic acid fatal in itself. Of course the carbonic acid tension was not negligible, especially when it reached the value of 22 or 23; but in this case we must take into account the exhaustion of the oxygen, whose very ad- vanced state is shown us by Column 9. In fact, we find here again the figures varying from 3 to 4, which we recognize as expressing the oxygen tension which is too low to support life. Influence of the temperature. The preceding results were ob- tained at temperatures above 20°. I wished to find out whether considerable cold would have much effect on the figures obtained. Here is what occurred. Experiment CII. December 12; temperature of the laboratory + 6°. House sparrow. Placed at a pressure of 6 atmospheres; closed cocks at 2 o'clock. Surrounded the apparatus completely with a mass of snow at 0°. At 4:20, sparrow found dead. At 4:25, his rectal temperature was + 4°. Lethal air: CO.- 2.9; O* 17.4. CO. x P = 17.4. Experiment CHI. December 13; temperature +6°. House sparrow. At 2 o'clock, placed at 5 atmospheres. Surrounded the apparatus with a mixture of ice and salt whose temperature dropped to 2°. The inside thermometer could not be read. At 3:35, found dead. Rectal tempera- ture, +8°; venous blood red, without gas bubbles. Lethal air: CO. 3.4; O. 15.2. CO. x P = 17.0. Experiment CIV. December 14; outside temperature +5°. House sparrow. At 2:50, taken to 4 atmospheres. Surrounded by a mixture of ice and salt. At 4:20, very sick; at 4:30, dead. Inside temperature of apparatus +1°; rectal temperature, -\-11.5°. Lethal air: CO. 5.0; O. 13.3. CO, X P = 20. We see that the effect of the cold was very important, and that the birds could not in these conditions form as much carbonic acid as at high temperatures. That is easily understood, because of the chilling of the animal, which was not compatible with the 560 Experiments exercise of the bodily functions and no longer permitted respira- tory movements. I even think that it is to the temperature that we must attribute results somewhat different from those I reported above, obtained with the same apparatus, but during a cooler season. Experiment CV. January 31. House sparrow. At 3:50, taken to 4 atmospheres. Died at 5:50. No cranial suffusions. Lethal air: CO* 5.8; O* 13.2. CO x P = 23.2. Experiment CVI. March 18. House sparrow. At 2: 10 taken to 6 atmospheres. Very sick at 3:30; found dead at 4:50. Red dots on cranium. Lethal air: CO. 3.9; O* 14.9. CO* x P = 23.4. B. Superoxygenated air: pressures below one atmosphere. It is here that I think I should place the account of the experi- ments made by the method discussed on page 536 (Sub-chap. 1), in which the sparrows were kept in closed vessels, at pressures less than one atmosphere, but in superoxygenated air. Here, down to the low limits indicated, death took place not through too low oxygen tension but through too high carbonic acid tension, that is, through a mechanism identical with the one we are discussing now. Here are the details of these experiments, all made with spar- rows; the first two are a repetition of the classic experiments of Claude Bernard. Experiment CVII. January 16. Bell-jar of one liter. The bird was brought successively three times to a 40 cm. drop in pressure, the pressure each time being restored to normal by the admission of oxygen. The, mixture then contained 91 per cent of oxygen. I left the bird at normal pressure, and closed the cocks at 3 o'clock. Died at 6:15; lived 3 hours 15 minutes. Lethal air: CO* 24.8; O* 64.5. CO= + O2 = 89.3. The ratio of the carbonic acid formed to the oxygen consumed was: CO, 24.8 = = 0.93. O2 26.5 Experiment CVIII. January 16. Bell- jar of 1 liter. Brought three times in succession to a 40 cm. drop in pressure; actual pressure, 36 cm. Closed cocks at 2; 30; death at 6:15. Pressure 34 cm. Original mix- ture: O* 82, Death in Closed Vessels 561 Lethal air: CO. 63.3; O 17.5. CO + Oa = 80.8; CO. = 0.98. CO=xP = 28.3. Experiment CIX. January 29. Bell-jar of 675 cc; mountain spar- row. Pressure lowered 50 cm., the bird became sick; oxygen admitted; second decompression carried to 60 cm., sick; oxygen admitted. Closed, cocks at 3:35. Left at normal pressure. At 5 o'clock, panting; at 6 o'clock, died without convulsions; a slight bloody suffusion on the cranium. Lethal air: CO* 24.8; O. 63.3. Experiment CX. January 30. Bell-jar of 1.3 liters. Pressure lowered 44 cm., 58 cm., 36 cm., then 48 cm. Closed cocks at 3:50; dead at 6 o'clock. The inner pressure was 25 cm. Original mixture: O. 89.2. Lethal air: CO. 72.1; O. 15.3. CO. CO. -!- O* = 87.4; = 0.97. O. CO. tension: 23.7. 26 Oxygen tension: 15.3 x — = 5.0. 76 Experiment CXI. January 31. Bell-jar of 675 cc. Pressure lowered 40 cm., 50 cm., 50 cm., and compensated by oxy- gen. The last time, the pressure was lowered 55 cm. Closed cocks at 3:20. Died at 5:15; no bloody suffusions on the skull. Original mixture: O. 79.6. Lethal air: CO. 35.3; O. 42.3. CO. CO. + O. = 77.6; = 0.94. CO. x P = 25.5. O. Experiment CXII. January 31. Bell-jar of 1.3 liters. Pressure lowered 40 cm., 50 cm., 50 cm., the last time, 43 cm. At death, the pressure is only 36 cm. Original mixture: O. 89.8. Lethal air: CO* 57.6; O. 30.1. CO. CO. + O. = 87.7; = 0.96. CO. x P = 27.2. O. Experiment CXIII. February 2. Bell- jar of 1.350 liters. Pressure lowered 30 cm., 50 cm., then 50 cm., and compensated by oxygen; the last time pressure lowered 58 cm. Closed cocks at 3:45; died at 6:45; the pressure was lowered only 51 cm. 562 Experiments Original mixture: O* 91.5. Lethal air: CO 36.0; O* 54.9. CO CO + O* = 99.6; = 0.98. CO x P = 24.2. O Experiment CXIV. February 5. Bell-jar of 1.3 liters. Pressure lowered 30 cm., 50 cm., 50 cm., the fourth time left at 45 cm. Entered at 4 o'clock. Dead at 8:15; the pressure was 38 cm. Lethal air: CO* 49.3; O 36.6. CO x P = 24.6. Experiment CXV. February 6. Bell- jar of 675 cc. Pressure lowered successively 30 cm., 50 cm., and 50 cm., and compensation made each time with oxygen. Closed cocks at 2:35; the pressure was 57 cm. Dead at 5:45. Cranial suffusions in places. Actual pressure 55 cm. Mixture before the experiment: O* 87.8. Lethal air: CO> 36.3; O 50.1. CO> CO + O = 86.4; = 0.97; CO* x P = 26.2. O* Experiment CXVI. February 19. Bell-jar of 675 cc. Pressure lowered once 30 cm., and twice lowered 50 cm.; each time, oxygen admitted. Actual pressure finally 64 cm. Closed the cocks at 1:50. Dead at 3:35; little bloody mottlings on the cranium. Jugular blood red. Lethal air: CO* 27.7; O* 54.7. 64 The CO* tension is CO* x P = 27.7 x = 23.3. 76 Experiment CXVII. February 19. Bell-jar of 1.35 liters. Pressure lowered 30 cm., 50 cm., 50 cm.; the last time left at 46 cm. Cocks closed at 2 o'clock; at 4:15, very sick. At death, the pres- sure is 43 cm. Slight cranial suffusions. Lethal air: CO* 42.4; O* 29.8. CO* x P = 24.5. Experiment CXV III. February 19. Bell-jar of 2.2 liters. Pressure lowered 30 cm., 50 cm., 50 cm., then to 34 cm. of actual pressure. Closed at 2:15; died at 6:45; enormous cranial suffusions. Actual pressure, 29 cm. Lethal air: CO* 66; O* 13.1. CO* x P = 25.2. 29 The pressure of the oxygen remaining is only 13.1 x — = 5. 76 Death in Closed Vessels 563 Experiment CXIX. February 22. Bell-jar of 2.5 liters. Pressure lowered 30 cm., 50 cm., 50 cm., then to 38 cm. Closed at 1:05. Dead at 7 o'clock. Slight suffusion on the cranium; venous blood red. Actual pressure, 34 cm. Lethal air: CO 60; O 27.4. CO x P = 26.8. All these results are summarized and grouped, following the descending order of barometric pressures, in the following table; I have added to it the experiments reported on page 537. Table VI 1 •2 3 4 5 G 7 8 9 o c ~o~ o II P ID >1 X o Compos tion of 6 u c El « £ Crt CO £ leth jl air Ofc jjfc X2 l~ S3 ftia S§ ^ 1 N C X c x Sa M'tfi 8[° o M MO £W ffl & OO 02 co2 oa S" h O CVII 76 cm. 91 91 24.8 64.5 0.93 24.8 64.5 CIX 76 91 91 24.8 63.3 0.93 24.8 63.3 CXVI 64 91 91 27.7 54.7 0.93 23.3 46.0 cxv 55 87.8 63.5 36.3 50.1 0.97 26.2 36.2 CXI 55 79.6 57.6 35.3 42.3 0.94 25.5 30.6 CXIII 51 91.5 61.4 35.7 54.9 0.98 24.2 36.8 CXVII 43 91.5 61.4 42.4 29.8 0.98 24.5 16.8 CXIV 38 91.5 61.4 49.3 36.6 0.98 24.6 18.3 CXII 36 89.8 45.9 57.6 30.1 0.96 27.2 14.2 CVIII 34 82 36.7 63.3 17.5 0.98 28.3 7.8 CXIX 34 82 36.7 60 27.4 0.98 26.8 12.2 CXVIII 29 82 36.7 66 13.1 0.98 25.2 5.0 ex 25 89.2 29.3 72.1 15.3 0.97 23.7 5.0 XLVII 18 85.9 20.3 68.1 15.4 0.96 15.2 3.6 XLVIII 14 85.9 20.3 48 23.8 0.96 | 8.8 4.3 XLIX 12.5 88.4 14.5 66 22.2 0.99 10.8 3.6 L 8 82.3 8.6 37.2 41.8 0.92 1 3.9 4.4 LI | 6.6 87 7.5 17.3 66.7 0.85 1 1.5 5.8 In this table a glance at Columns 5 and 8 are enough to prove that our expectations are realized and that, at these pressures less than one atmosphere, poisoning by carbonic acid comes when the tension of this gas can be expressed by numbers varying from 24 to 27. That is the result obtained earlier for pressures greater than IV2 atmospheres. This is deduced, as Column 5 shows, from the proportions of carbonic acid which may rise to 72 per cent. At very low pressures, below 20 centimeters, for example, the law below no longer holds; but that is easily understood. Let us take, for example, the pressure 564 Experiments of 14 centimeters, noted in Experiment XLVIII. To reach the average figure of 26, the percentage of carbonic acid in the lethal 76 air must rise to 26 x — = 141, which is evidently impossible. In 14 other words, before the bird can reach the lethal tension of carbonic acid, it exhausts the oxygen of the surrounding medium, so that it succumbs to the kind of death customary in diminished pressures, when ordinary air is used. That is why we shifted to Sub-chapter I the experiments made under these conditions. The analogy between these two kinds of experiments, apparently so different, is seen again in a rather interesting experimental de- tail, which, at first glance, seemed to me somewhat paradoxical. When I supplied pure air to a bird which was beginning to suffer from the effect of increased pressure, I did not relieve it at all; on the contrary, an evident improvement appeared when I allowed a part of its air to escape. This is easily explained; let us suppose that the bird is under a pressure of 3 atmospheres and that it has already formed 6 per cent of C02; the pressure of this gas, 6 x 3=18, is enough to make the bird ill. If I admit 3 atmospheres of pure air, the C02 tension becomes 3 x6=18, that is, it does not change at all, since although the pressure increases one-half, the percentage diminishes one-half; the bird is therefore not relieved. If, on the contrary, I let out one-half of the air, the tension becomes 6 x 1.5 =9, so that an immediate betterment results. So this apparent paradox confirms again, in an indirect way, what I have already demonstrated. The same thing holds good for experiments at low pressures with a superoxygenated atmosphere. Here, if the bird has been made ill by the carbonic acid it has formed, it is not relieved if air or oxygen is admitted; on the contrary, if the barometric pressure is lowered, it is relieved. Let us take the case of a bird at 38 cm., that is, at a half-atmosphere. Let us assume that it has already formed 30 per cent of CCX; the CO, tension is 30 x ¥2 =15 and the bird begins to suffer from it. Let us admit air until the pressure is 57 cm., that is, three-quarters of an atmosphere. The percentage will be only 30 x %=20, but the tension will be 20 x 3/4 = 15, and the bird will be in the same state as before. If, on the contrary, we remove air and drop the pressure, for example, to 19, V\ of an atmosphere, the percentage of carbonic acid will not have changed, and its tension will be only 30 x 1/4=7.5, a tension almost harmless to the bird, which will be relieved immediately. Death in Closed Vessels 565 C. Compressed air at very high pressure: fatal action of oxygen. The study of the alterations of compressed air which has be- come lethal through confinement was to give me a result that was interesting in a very different way. When we examine carefully Column 8 of Table V, we see that, from 6 atmospheres on, the number of the carbonic acid tension is a little lower than one finds at a pressure from 2 to 5 atmos- pheres, and seems to continue diminishing as the pressure in- creases. This slight difference did not impress me at first; but when I made experiments at pressures higher than those of Table III in the cylindrical glass reservoir capable of supporting a pressure of 25 atmospheres, I obtained numbers which showed me the ap- pearance of a new element in the question. Here is the report of these experiments. Experiment CXX. April 16. Linnet; taken to 20 atmospheres, from 4:55 to 5:10. Slight convulsions appear at 5:15; the feet, the head, the body quiver in spasms. Dies at 5:35. Lived 25 minutes. Lethal air: CO* 0.4. CO* x P = 8. Experiment CXX I. April 23. Sparrow; at 9:45 taken to 6 atmospheres. Dies at 11:10; lived about 1 hour 20 minutes. Lethal air: CO* 3.5; O* 16. CO* x P = 21.0. Experiment CXX II. April 23. Sparrow; taken at 3:10 to 3 atmospheres. At 4:05, very sick; at 4:50, dying. Dead at 5 o'clock; lived about 1 hour 50 minutes. Spot on the scalp; dark blood in the jugular; no gas. Lethal air: CO* 7.8; O* 10.7. CO* x P = 23.4. Experiment CXXIII. April 24. Mountain sparrow; taken at 1:40 to 5 and % atmospheres. At 3 o'clock still alive; found dead at 3:50; lived about 1 hour 30 minutes. Large scalp suffusions. Lethal air: CO2 3.8; O* 15.5. CO* x P = 21.8. Experiment CXXIV. April 26. House sparrow; at normal pressure has respiratory rate of 144. Taken to 3 atmospheres at 1 o'clock; respiratory rate 132. At 1:03, to 6 atmospheres, respiratory rate, 130; at 1:06, to 9 atmospheres, respir- atory rate 120. Closed the cocks; at 1:11, respiratory rate 106; at 1:20, 80; at 1:50, 50, very sick; found dead at 2:25. Lived about 1 hour 10 minutes. 566 Experiments Red blood in the jugular; bloody suffusions on the scalp. Lethal air: CO 2; O 17.5. CO* x P = 18. Experiment CXXV. April 26. 'House sparrow; at 4:23, normal pressure, respiratory rate 135. Began the compression. At 4: 27, 6 atmospheres, respiratory rate 96. At 4:29, 9 atmospheres, respiratory rate 90; at 4:31, 12 atmospheres, respiratory rate 90. At 4:53, very sick. Each inspiration, which is very deep, is accompanied by a quivering of the wings. At 5:10, still a few respirations; at 5: 15, dies. Lived 45 minutes. Scalp suffusions in spots; red blood in the jugular. Lethal air: CO* 1.2; O 18.4. CO* x P = 14.4. Experiment CXXVI. May 7. Sparrow taken to 15 atmospheres; closed cocks at 2:15. At 3:20, found dead. Lethal air: CO* 0.8; Cb 19.5. CO x P = 11.2. Experiment CXXV II. May 17. Sparrow at 4 atmospheres; closed cocks at 4:45. Sinks down at 5:34; dies at 6:20. Lived 1 hour 35 minutes. Red foam on the beak; scalp suffusions in blackish patches; venous blood of normal color; no gas. Lethal air: CO 5.6; Cb 13.2. CO* x P = 22.4. Experiment CXXV III. May 18. Sparrow at 8 atmospheres; 3:17. Dead at 4:55; lived 1 hour 38 minutes. Red foam on the beak; bloody suffusions in reddish patches; venous blood red and containing some gas. Lethal air: CO* 2.4; O 16.8. CO x P = 19.2. Experiment CXXIX. May 21. Sparrow at 14 atmospheres; closed the cock at 4:55. Found dead at 6 o'clock; lived less than one hour. Venous blood very red, with gas. Scalp suffusions very extensive. Lethal air: CO 0.9; O 18.5. CO2 x P = 12.6. Experiment CXXX. May 22. Sparrow; at 12 atmospheres, at 2:45. Found dead at 3:40; lived less than 55 minutes. Red blood in the jugular, with gas. Scalp suffusions. Lethal air: CO 1.3; O 19.1. CO* x P = 15.6. Death in Closed Vessels 567 Experiment CXXXI. June 18. Sparrow; taken to 14 atmospheres at 3:33. Dead at 4:12. Lived 39 minutes. Struggling, but no convulsions. Venous blood very red, with gas. Scalp suffusions very extensive, of a bright red. Lethal air: CO* 0.93. CO* x P = 13.2. Experiment CXXXII. June 19. Sparrow; taken at 3:04 to 2 atmospheres. Dead at 6:53 without convulsions, without foam on the beak; lived 3 hours 49 minutes. The cranial diploe contains bloody suffusions in small blackish patches. The color of the venous blood is normal; no gas. Lethal air: CO* 12.6; O* 3.2. CO* x P = 25.2. Experiment CXXXIII. June 19. Sparrow; taken to 17 atmospheres from 2:04 to 2:15. Dead at 2:54. Lived 39 minutes; respiration very slow, no convulsions, red froth on beak. Very extensive bloody suffusions; venous blood very red, con- taining much gas. Lethal air: CO* 0.6; O* 18.6. CO* x P — 10.2. Table VII 1 2 3 4 5 6 7 8 9 10 in 4> > .5 x mO Oo lethal air 6 u 6 8 Id CO, o3 1 h. m. h. m. CXXXII 2 3 49 3 4 41.8 12.6 3.2 25.2 6.4 0.72 CXXII 1 3 1 50 1 62.7 7.8 10.7 23.4 32.1 0.75 CXXVII 4 1 35 39 83.6 5.6 13.2 22.4 52.8 0.72 CXXIII 5 % 1 30 27 120.1 | 3.8 15.5 21.8 89.1 0.70 CXXI 1 6 1 20 22 125.4 | 3.5 16 21.0 96 0.71 CXXVIII 8 1 38 20 167.2 2.4 16.8 19.2 134.4 0.60 CXXIV 9 1 10 14 188.1 2 17.5 18.0 157.5 0.59 cxxv 12 45 6 250.8 1.2 18.5 14.4 222.8 0.50 cxxx 12 45 1 250.8 1.3 18.7 15.6 224.4 0.59 CXXIX 14 45 1 292.6 0.9 18.5 12.6 263.2 0.43 CXXXI 14 39 4 292.6 0.9 18.5 13.2 263.2 0.43 CXXVI 15 39 1 313.5 | 0.8 19.4 11.2 291 0.53 CXXXIII 17 39 3 355.3 | 0.6 18.8 10.2 319.6 0.30 cxx | 20 25 2 418.0 | 0.4 18.8 8 319.6 0.30 Before passing to the study of the results of these experiments, grouped in Table VII in increasing order of pressure, I think I should call attention to the fact that the preceding analyses of the 568 Experiments gases were made meticulously from a very special necessity which is easily seen. In fact, the least error in the calculation of the proportion of carbonic acid would cause an enormous error in the product C02 x P in the high pressures. The agreement in the results announced, on which I shall dwell now, is only the more remarkable. A glance at Column 8 of the table, which contains the numbers expressing the carbonic acid tension in the air which had become ■ ■i ■ || n a s Bi 1 EZi Fig. 21 — Confined air which has become lethal under pressure; carbonic acid content: A, calculated proportions; B, proportions found experimentally; C, superoxygenated air. irrespirable, completely confirms the suspicions which we had con- ceived on examining Table V in points relating to high pressures. In fact, the number CO, x P, when closely inspected, is never constant. It diminishes from 3 atmospheres on, and this diminu- tion is extremely rapid beginning with 8 atmospheres. Death in Closed Vessels 569 The smaller and smaller quantity of carbonic acid, following the law expressed above, is shown very clearly in the graphs in Figure 21, in which the quantity of carbonic acid is measured on the vertical axis, while the atmospheres are reckoned on that of the x's. The solid line B expresses the figures of Column 6, and the dotted line A connects the points which are calculated from the equation CO, x P = 26, an average number taken from Table VI, 26 whence CO., = — . This line, like that of the lethal proportions of P oxygen in low pressures, is a branch of equilateral hyperbola, hav- ing the coordinates as asymptotes. This constant drop of the graph below the curve which the theory indicates led me to think of the intervention of another agent than carbonic acid. Tentative experiments had already shown me that oxygen under a certain pressure is a cause of symp- toms and death. Its fatal effect seemed manifest to me here. Before trying to render this prime factor evident, I wish to call attention to a secondary point, which is, however, quite interesting. Columns 3 of Tables V and VII show that, disregarding a few exceptions which are hard to explain, the duration of life from 1 to 9 atmospheres did not increase with the pressure, or, in other words, with the quantity of air which the birds had at their dis- posal. And that is easily understood, since they did not die from having exhausted this air, but simply when they had formed a certain quantity of carbonic acid always the same, or approximately so. The annoying interference of the oxygen which I have just mentioned even lessens the duration of life, as is clearly seen from 10 atmospheres on; death comes very quickly at very high pressures. This is manifest in quite another way when we compare the duration of life not to the volume, but to the actual quantity of air contained in the receiver, or, which amounts to the same thing, to a liter of air at normal pressure; the duration of life is then ex- pressed by numbers which decrease with a truly extraordinary rapidity. This is shown by Columns 4 of Tables V and VII; we see that, even at 4 atmospheres, the duration of life is reduced by about one-half, and that at 20 atmospheres, it is only 2 minutes per liter instead of 76 minutes, as we found it at normal pressure (See Table I, Column 7). This enormous difference cannot be attributed to the carbonic acid, whose tension diminishes equally; another factor 570 Experiments evidently interferes here, and this dangerous factor is nothing but oxygen. D. Compression with air of low oxygen content. Let us now examine this hypothesis of a fatal action of the compressed oxygen with the effect of killing the bird before it has formed the percentage of carbonic acid required by the formula C02 x P = 26. Let us refer to Table VII. If the explanation I have just given of the lowness of the numbers of Column 8 (C02 x P) measuring the tension of the carbonic acid is correct, that is, if this lowness is due to the high value of the numbers of Column 5 (02 x P) , measuring the oxygen tension, the first will increase if I lower the second by lessening the factor O. without changing factor P. It was enough then to repeat the experiments, injecting into the compression apparatus not ordinary air, but air of low oxygen content. This was done in the following experiments. Experiment CXXXIV. April 20. Greenfinch (Loxia chloris, Lin.) Put into the apparatus for 5 minutes, then raised to 6 atmospheres of air; cock closed at 2:50. At 3 o'clock, we began to inject air very low in oxygen, and at 3:11, reached 22 atmospheres. The moment of death cannot be clearly determined, but the bird had no convulsive movements at any time. Considerable cranial suffusions. Lethal air: CO^ 1.1; O* 9. Initial oxygen tension: 226. * Final CO tension: 24.2. Experiment CXXXV. June 27. A sparrow is placed in the apparatus, and air in which phosphorus has burned and which has become very low in oxygen is pumped in; the pressure is taken to 5 atmospheres. The cock is closed at 3:55; the bird dies at 5:50. It lived therefore 1 hour 55 minutes; bloody suffusions, not very extensive; some gas bubbles in the right heart. Composition of lethal air: CO 4.5; O 5.. Initial oxygen tension: 50. Final CO- tension: 22.5. Experiment CXXXVI. June 29. Sparrow at 12 atmospheres, 1 of air and 11 of air in which phos- phorus has burned. Entered at 2:45; dead at 3:15; lived 30 minutes; cranial suffu- sions; gas in the right heart. Lethal air: CO* 2.1; O 4.8. Initial oxygen tension: 84. Final CO tension: 25.2. Death in Closed Vessels 571 These results entirely justify our explanation, and show that the decrease of the product CO, x P, when the pressure increases, must be attributed to the intervention of the oxygen playing a fatal part. We see furthermore that the points a and b, which represent on Figure 21 the numbers furnished by Experiments CXXXIV and CXXXVI, are placed very exactly on line A, which was plotted according to the theory. E. Compression with superoxygenated air. This fatal effect of oxygen under a sufficiently high pressure was so remarkable a phenomenon that I felt I must try to exhaust all means of proving it indisputably. Now a new method occurred to me, the opposite of the one which has just been used. I had only to make the compression with superoxygenated air, still in closed vessels. The influence of oxy- gen, if it is as serious as I thought, should bring death to animals at a moment when they were far from having furnished the same percentage of carbonic acid as at corresponding pressures in the case of ordinary air. This, indeed, happen in the following ex- periments. Experiment CXXXVII. January 16. Sparrow at 5 atmospheres, 4 of which are oxygen. Entered at 3:25; at 3:40, falls with violent convulsions; at 3:48, on its back; the cranium, previously bared of feathers, shows abun- dant bloody suffusions. At 4:35, still breathes slowly; the convulsions lasted about 15 minutes. At 4:50, dead. Rectal temperature is 18°, that of the laboratory air being 9°. Venous blood red; no gas; the heart is beating when in the outer air. The original mixture contained O: 83. The tension of this oxygen = 83 x 5 = 415, corresponding to that of 415 = 19.7 atmospheres. 20.9 Lethal air: CO 1.4; Oi 80.5. CO2 tension = 1.4 x 5 = 7.0. Experiment CXXXVIII. January 17. At 3:30 taken to 3 atmospheres, 2 of which are oxygen. At 3:50 breathes with great difficulty; uneasy. At 4:45, dead. Lethal air: CO 5.6; Cb 78.9. CO? tension = 5.6 x 3 = 16.8. The tension of the original oxygen was about 86 x 3 = 258, corre- sponding to 12.1 atmospheres, 572 Experiments Experiment CXXXIX. January 19. The sparrow being in the apparatus, a little air was removed by the pump, and replaced by oxygen which was raised to 2 atmospheres. When air was taken for analysis, the pressure fell to 1 and % atmos- pheres. Closed cocks at 2:40; dying at 4:45; found dead at 5:30. Original mixture contains 83.6 per cent of oxygen. Tension of this oxygen = 83.6 x 1.75 = 146.3, which corresponds to 7.3 atmospheres. Lethal air: CO 11.9; 0= 67.8. CO2 tension = 11.9 x 1.75 = 20.8. Experiment CXL. January 22. Put at 2 atmospheres, one of which is oxygen. Entered at 3:05; at 5:30, still breathing; found dead at 6:30. The original mixture contains O2 58.8. The oxygen tension was 117.6, corresponding to 5.6 atmospheres. Lethal air: CO 13.4; O2 44.4. CO tension = 13.4 x 2 = 26.8. Experiment CXLI. February 1. Raised to 4 atmospheres, 3 of which are oxygen. After about a half hour, slight convulsions; dies in about an hour. Cranial suffusions and venous blood very red; no gas in the blood. Original mixture: O2 75.6. Tension of this O2 = 75.6 x 4 = 302.4 corresponding to 14.4 atmos- pheres. Lethal air: CO2 2.1; O2 71.1. CO2 tension = 2.1 x 4 = 8.4. Experiment CXLII. February 17. Raised to 5 atmospheres of air, to which are added 3 V2 atmos- pheres of oxygen. After 5 minutes, convulsions ensue; the bird dies in 20 minutes. Blood red everywhere, even in the liver; no gas (cranium not examined). Lethal air: CO2 0.8; O2 47.8. CO2 tension = 0.8 x 8.5 = 6.8. The oxygen tension in the original mixture must have been about 51 x 8.5 = 433.5, corresponding to 20.7 atmospheres. Experiment CXLIII. February 19. Seltzer water apparatus. Put into the air to which V4 atmosphere of oxygen was added; closed at 4:25; dead about 6 o'clock. No bloody suffusions on the cranium; venous blood black. Lethal air: CO2 22.1; O2 3.5. CO2 tension = 22.1 x 1.25 = 27.6. The original oxygen tension must have been about 26 x 1.25 = 32.5, which corresponds to 1.5 atmospheres. Experiment CXLIV. February 20. I atmosphere of air; plus V2 of oxygen. When the bird, thought dead, is withdrawn, it still exhibits some Death in Closed Vessels 573 slight respiratory movements. Red blood in the jugular. Red spots in the cranial diploe. Lethal air: CO* 16.7; O 28.6. CO* tension = 16.7 x 1.5 = 25.1. The original oxygen tension must have been about 46 x 1.5 = 69, corresponding to 3.3 atmospheres. Experiment CXLV. February 20. At 5V2 atmospheres, 4 of which are oxygen. After 5 minutes, trembles, the head oscillates. After 10 minutes great convulsions, the feet are doubled against the belly; the convul- sions last 5 to 10 minutes, then the feet stretch out repeatedly. The bird remains prostrated; after 20 minutes, dead. Enormous cranial suffusion. Rectal temperature 26.5°. Lethal air: CO* 1; O* 82.5. CO* tension: 5.5. The oxygen tension in the original mixture was about 85 x 5.5 = 467.5, corresponding to 22.3 atmospheres. Experiment CXLVI. February 22. Raised to 2V2 atmospheres, of which V2 is oxygen. Closed at 12:55; dead at 3:55. Bloody suffusions in the thickness of the cranial diploe; red blood in the jugular vein, rapidly becomes black. Lethal air: COa 11.1; O* 33.3. CO* tension = 11.1 x 2.5 = 27.7. The original oxygen tension was about 46 x 2.5 = 115.5, which corresponds to 5.5 atmospheres. The results of these experiments are grouped in Table VIII, fol- lowing the increasing order of the oxygen tensions. Table VIII 1 2 3 4 5 6 7 8 9 10 g |3 1 u be 5 «) 3 in OSS Composition 3 >, tfl v 'u _c SOJ c S 1. rt of lethal air Ph 5 V E .0 'u Em a 3 0 X E 3 0 !/> x° * O.S E J c « 0 0 u 3 — Q 0 .2 u 3>£^ 6 C1 c- |atm. atm. h.m. h.m. CO* O* CXLIII 1.25 32.5 1.5 1 30 1 36 22.1 3.5 27.6 No cranial suffusions CXLIV 1.5 69.0 3.3 16.7 28.6 25.1 Red dots on cranium. CXLVI 2.5 115.5 5.5 3 53 11.1 33.3 27.7 Cranial suffusion. CXL 2.0 117.6 5.6 3 52 13.4 44.4 26.8 " CXXXIX 1.75 146.3 7.3 2 20 31 11.9 67.8 20.8 CXXXVIII 3.0 258.0 12.1 1 15 10 5.6 78.9 | 16.8 Convulsions, suffusions. CXLI 4.0 301.6 14.4 1 7 2.1 71.1 8.4 " CXXXVII 5.0 415.0 19.7 1 20 6 1.4 | 80.5 7.0 CXLII 8.5 433.5 |20.7 20 2 0.8 | 47.8 6.8 CXLV 5.5 467.5 | 22.3 20 1 1.0 1 82.5 5.5 574 Experiments If we examine Column 9, we see that the carbonic acid obeys the law given, up to a pressure corresponding to 5 or 6 atmospheres of air; but from there on. the product CO., x P decreases rapidly. On comparing Columns 7 and 9 with Columns 6 and 8 of Table VII, we find numbers that are quite analogous, and that indicate a simi- lar intervention of the fatal action of oxygen. It becomes very evident, when the tension of this gas can be represented by 150, that is, when it corresponds to an atmosphere and a half of pure oxygen, or 7 atmospheres of air. In Figure 7, the lower line C expresses the numbers of Column 9; we see that for the same barometric pressures it remains far below line B, which represents the results of the experiments in which ordinary air was used. Finally, Column 6 shows, as did Column 4 of Table VII, that the duration of life, referred to a liter of ordinary air under normal pressure, continues to decrease with astonishing rapidity, when the pressure, or rather the oxygen tension, increases. It is therefore overwhelmingly proved that oxygen, under a certain tension, is a dangerous agent which, in compressed air in closed vessels, first joins its action to that of the carbonic acid produced, and which for high tensions is the principal, soon the only, cause of death; this tension, measured by the expression O. x P, can be reached, according to the statement already made so often, by increasing either the barometric pressure P, or the percentage of 02. But it is established at the same time that the formula previously given, The death of sparrows occurs when the tension of the car- bonic acid, measured as I have specified, is represented by a figure which oscillates between approximately 24 and 30, expresses the truth. To prove it experimentally one need only guard against the excess of oxygen. F. Compression with ordinary air: elimination of carbonic acid. The presence of carbonic acid had prevented me, as we have just seen, from finding the real law which determines the exhaustion of the oxygen of compressed air for animals allowed to die in closed vessels. But the fatal action of compressed oxygen which the studies just discussed had revealed to me no longer permitted me to think that the simple law, established for pressures lower than one at- mosphere, could continue to be applicable to higher pressures. It was, however, necessary to determine the facts. Apparently Death in Closed Vessels 575 nothing could be simpler; I needed only to plan the experiments so that the carbonic acid would be eliminated as it was formed, so that it could not interfere with the result. But the very low capacity of the receivers which I had at my disposal made the task quite difficult, because the bird, as it stirred about, almost always finally came in contact with the potash, with resultant burns, con- siderable uneasiness, and often premature death. I did not get a series of satisfactory results until I used an apparatus whose receiver is a mercury bottle; it then was easy for me to perform a large number of experiments, thanks to the capacity and the wide opening of my receiver. Besides, its great strength permitted me to carry the compression much higher than in glass apparatuses. The only inconvenience was the opacity, which prevented me from following the phases of the experiment and determining the precise moment of the death of the birds. I filled a part of the cylinder with water containing potash in solution. The sparrow, enclosed in a little wire mesh ball, was suspended above the liquid. Under these conditions, there was no trace of carbonic acid in the air in which it stayed and died. I report here a series of experiments that are quite character- istic. Experiment CXLVII. September 18. Sparrow at 3Vi atmospheres. Left in the air in which it died 1 per cent of oxygen. Oxygen tension: O* x P = 1 x 3.25 = 3.25. Experiment CXLVIII. September 22. Sparrow at 6V4 atmospheres. Left 0.8 per cent of oxygen. 0=xP = 5. Experiment CXLIX. October 3. Sparrow at 9 atmospheres. Left 2.2 percent of oxygen. O2 x P = 20.8. Experiment CL. October 7. Sparrow at 12 atmospheres. Left 5.6 per cent of oxygen. OaP = 67.2. Experiment CLI. January 6. Sparrow at 15 atmospheres. Left 14.5 per cent of oxygen. O2 x P = 217.5. Experiment CL1I. September 30. Sparrow at 20 atmospheres. Left 18.3 per cent of oxygen. 02 x P = 366.0. Experiment CLIII. October 1. Sparrow at 24 atmospheres. Left 20.3 per cent of oxygen. Os x P = 487.2. 576 Experiments Table IX 1 2 3 4 c 4) 5 c >> O s 21.6; CO 36.3. Experiment CLXVI. July 4. Pressure 76 cm.; temperature 22°. Female dog of moderate size. At 3 o'clock, 45.3 cc. of blood, not very red, drawn from a femoral .... A Animal put into apparatus; howls and is very uneasy; pressure lowered 52 cm.; then 47 cm.; then 50 cm.; all in about a quarter of an hour. The real pressure is 26 cm. 43.1 cc. of very dark blood then drawn from the same artery . . . . B Blood A (76 cm.) contains per 100 volumes: O 18.3; CO 32.8. Blood B (26 cm.) contains per 100 volumes: O^ 9.8; CO 24.5. Experiment CLXVII. July 6. Pressure 76 cm.; temperature 24.5°. Dog of the preceding experiment, in good condition. Put into the large apparatus; in a quarter of an hour brought to 44 cm. of actual pressure; very uneasy; kept at this pressure for 20 minutes, and then 32.6 cc. of rather dark blood drawn from the left carotid .... A The animal having been brought back to normal pressure, which took about 5 minutes, 42.3 cc. of blood, evidently redder, were drawn from the left carotid immediately . . . . B Blood A (44 cm.) contains per 100 volumes: O 16.3; CO 23.3. Blood B (76 cm.) contains per 100 volumes: O* 19.8; CO 29.1. Experiment CLXVIII. July 8. Pressure 75.9 cm.; temperature 25°. Very large dog. Put into the apparatus; has a new cannula of Model A (Fig. 29) in the left carotid. Pressure lowered 20 cm. in a quarter of an hour, and left there a quarter of an hour. 39 cc. of blood then drawn with difficulty .... A Pressure lowered 30 cm., and an attempt is made to extract blood; but it is impossible, the cannula is twisted. 602 Experiments Brought back to normal pressure, the dog continues to howl and breathe very quickly and very noisily, as it has done since blood A was extracted. 48 cc. of very red blood then extracted . . . . B The animal when untied, cannot walk; it is not paralyzed in any limb, and yet cannot stand up on all-fours. Next day, same condition, except that the respiration is easy. It dies at the end of several days, having remained drowsy and unable to walk. In the autopsy a gray cerebral softening is found. Evidently bubbles had entered the circulatory system, some of which penetrated the nervous centers and cut off the circulation. Blood A (56 cm.) contains per 100 volumes: O 20.9; CO 35.3 Blood B (76 cm.) contains per 100 volumes: Ch 26.4; CO* 22.7 I shall not include in the general discussion of the experiments the preceding curious result; but I thought I should not omit it. I call the reader's attention to the localized cerebral softening due to the penetration of the air. Experiment CLXIX. April 30. Pressure 77 cm.; temperature 16°. Dog weighing 11.5 k. At 4:25, put into the apparatus, and brought in 10 minutes to 36 cm. of actual pressure. At 4:45, 46 cc. of very dark blood drawn from the right carotid .... A 5 o'clock. Returned to normal pressure; at 5:05, 46 cc. of very red blood drawn . . . . B Blood A (36 cm.) contains per 100 volumes: O 11.9; CO* 25.2 Blood B (77 cm.) contains per 100 volumes: O 20.6; CO 39.0. Experiment CLXX. May 1. Pressure 76 cm.; temperature 16°. Dog of preceding experiment, quite recovered. 4:15. 41 cc. drawn from left carotid; respiratory rate 60 .... A 4:30. Put into the large receiver; at 4:45, pressure lowered 33 cm., air admitted to 30 cm. (pressure 46 cm.). At 4:45, 38 cc. of blood drawn . . . . B Brought to 56 cm. of actual pressure; at 5:15, respiratory rate 100; 41 cc. of blood drawn . . . . C Brought slowly to normal pressure; at 6:20, respiratory rate 60; 41 cc. of blood drawn . . . . D Blood A (76 cm.) contains per 100 volumes: O 21.9; CO^ 34.7. Blood B (46 cm.) contains per 100 volumes: O 20.3; CO 30.5. Blood C (56 cm.) contains per 100 volumes: O 21.1; CO 34.7. Blood D (76 cm.) contains per 100 volumes: O 21.1; CO 35.2. The average between A and D is: O^ 21.5; CO 34.9. Experiment CLXXI. May 3. Pressure 76 cm. Young dog, very lively, weighing 4 k. Right carotid. 4:32. Put into the receiver; at 4:45, lowered 45 cm., respiratory rate 24, divided into periods of 3 or 4 medium and 1 very deep; then rest. 4:58. The decompression has varied between 44 cm. and 47 cm.; at present it is 45 cm.; 31 cm. of actual pressure. 41 cc. of blood drawn, darker than ordinary venous blood .... A Gases of the Blood 603 Brought slowly to normal pressure. At 5:07, at 25 cm.; 16 respirations of the same type. At 5:13, normal pressure; 41 cc. of blood drawn, lost; at 6:20, 16 respirations, same type; 41 cc. of blood of ordinary color drawn . . . . B Blood A (31 cm.) contains per 100 volumes: O 13.6; CO* 36.5 Blood B (76 cm.) contains per 100 volumes: O 19.4; CO 48.4 Experiment CLXXII. May 7; pressure 75 cm.; temperature 18°. Female dog weighing 11 k. 3:12. Put into receiver; at 3:25 lowered 40 cm. 3:45, a decrease of 39 cm. (36 cm. of actual pressure); 21 to 24 respirations; 41 cc. of very dark blood drawn .... A 3:50. Brought to 46 cm. pressure and maintained there. At 4:05, 41 cc. of blood, not so dark, drawn; 18 to 21 respirations . . . . B Brought to normal pressure, at 4:15; at 4:35, 30 respirations; at 5 o'clock, 41 cc. of not very red blood drawn . . . . C This dog, before blood was drawn, and after she was untied, developed strange tonic and clonic convulsions, with corneal lack of sensitivity and howls; the second attack was very severe, lasted 15 minutes at least, and was followed by a state of stupor, with little plaintive cries; hysteria? epilepsy? Blood A (36 cm.) contains per 100 volumes: O- 8.9; CO 34.3. Blood B (46 cm.) contains per 100 volumes: O 13.2; CO 40.7 Blood C (76 cm.) contains per 100 volumes: O 20.1; CO 41.1 Experiment CLXXIII. May 8. Pressure 75.5 cm.; temperature 17°. Little dog, weighing 5 k. At 4 o'clock, 33 cc. of very red blood drawn from the right carotid . . . . A At 4:28, put into the receiver. At 4:35, pressure dropped 34 cm.; 13 respirations, deep; at 4:50, pressure dropped 50 cm.; 20 respirations, shallower. At 5:05, pressure still at a diminution of 50 cm.; 18 respi- rations; 35 cc. of very dark blood drawn . . . . B Blood A (75.5 cm.) contains per 100 volumes: O 22.6; CO 39.7. Blood B (25.5 cm.) contains per 100 volumes: O 9.8; CO? 23.1 Experiment CLXXIV. May 9. Pressure 75.5 cm.; temperature 16.5°. Dog of Experiment CLXXI, still somewhat sick. Left carotid. At 3:30, drew 27.5 cc. of blood .... A At 3:50, put into receiver; at 4:03, the pressure is at 36 cm.; at 4:18, the same; 33 respirations, medium. Drew 41 cc. of very dark blood . . . . B Blood A (75.5 cm.) contains per 100 volumes: O, 13.3; CO= 34.9. Blood B (36 cm.) contains per 100 volumes: O 8.5; CO 21.4. Experiment CLXXV. May 15. Pressure 76 cm.; temperature 17°. Fat and strong female dog, which had eaten at noon. At 3:10, drew 34.5 cc. of blood from the right carotid; animal quiet .... A At 3:20, put into the apparatus, howls, is uneasy; at 3:25, pressure is 56 cm. At 3:35, pressure maintained; drew 34.5 cc. of blood, animal quiet, 30 respirations; but has been very uneasy . . . . B 604 Experiments At 3:40, pressure lowered 30 cm.; at 3:55, the same; drew 34.5 cc. of blood; animal quiet, but had been uneasy . . . . C At 4 o'clock, pressure lowered 40 cm.; animal in the same condi- tion; drew 34.5 cc. of dark blood . . . . D Blood A (76 cm.) contains per 100 volumes: O^ 17.4; CO 33.8 Blood B (56 cm.) contains per 100 volumes: O 15.5; CO 28.0 Blood C (46 cm.) contains per 100 volumes: O 12.5; CO2 26.4 Blood D (36 cm.) contains per 100 volumes: O2 10.8; CO 22.8 Experiment CLXXVI. May 22. Pressure 76 cm. Medium-sized dog, which had eaten at noon. Right carotid. At normal pressure, 13 respirations. 3:35. Put into apparatus. 4:05, pressure lowered 40 cm., maintained. 4:07, 15 respirations, somewhat irregular. 4:25, the same; drew 33.3 cc. of blood, very dark .... A 4:33, air admitted; pressure lowered 20 cm. 4: 50, drew 33.3 cc. of blood, redder than A .... B 4:55, normal pressure. 5:25, drew 33.3 cc. of blood, quite red .... C Blood A (36 cm.) contains per 100 volumes: 0^ 9.6; CO 33.9 Blood B (56 cm.) contains per 100 volumes: O 12.4; CO 35.0 Blood C (76 cm.) contains per 100 volumes: O 16.9; CO 45.7 Experiment CLXXVII. June 21. Female dog of average size, never having been used before. Cannula in the right carotid artery. 4:15, decompression begun. 4:45, decompression of 54 cm.; great uneasiness from the begin- ning. 5:15; 56.5 cm.; 120 respirations. 5:30; 57.5 cm.; I draw 50 cc. of blood, very dark A. Air admitted until the decompression is only 36 cm., then the decompression is resumed. 6:08, pressure down 50 cm.; I draw 35 cc. of blood, very dark. . B 6:20, 56 cm.; 40 cc. of blood, also very dark . . . . C 6:20, air admitted; normal pressure restored at 6:55. 7: 10, drew 57 cc. of blood, quite red . . . . D Blood A (19 cm.) contains per 100 volumes: O 4.9 Blood B (26 cm.) contains per 100 volumes: O 6.5 Blood C (21 cm.) contains per 100 volumes: O 4.5 Blood D (76 cm.) contains per 100 volumes: 0= 14.8; CO 22.1 Experiment CLXXVIII. July 3. Dog which has never been used, weighing 11 k. 2:30, I draw from the right carotid 35 cc. of blood moderately red; the animal howls and struggles .... A 2:40, decompression begins. 3 o'clock, decompression of 55 cm. 3: 11, decompression of 57 cm.; drew 35 cc. of blood, very dark . . B Admitted air. Blood A (76.5 cm.) contains per 100 volumes: 19.2 of oxygen. Blood B (19.5 cm.) contains per 100 volumes: 4.2 of oxygen. Gases of the Blood 605 Experiment CLXXIX. July 5. 76.5 cm. Dog weighing 10 k. Drew from the right carotid 35 cc. of very red blood; 38 respir- ations, with little howls .... A 3:25, put into the apparatus. 3:45, pressure 30.5 cm., struggles, howls. At 3:55, pressure 24.5; the gas machine stops. 4:05, pressure 38 cm.; machine started again; 26 respirations, quiet. 4:12, 26.5 cm.; 60 respirations, interrupted by hiccoughs; at 4:26, 19.5 cm.; 74 respirations, also with hiccoughs. 4:30, pressure 18 cm.; drew 35 cc. of very dark blood . . . B 4:42, pressure 17 cm.; 80 respirations; drew 35 cc. of very dark blood . . . . C Opened the cock; at 4:55, the pressure had risen to 26 cm.; it was maintained there, and at 5: 10, 35 cc. of dark blood drawn . . . D 5:13, returned to normal pressure. 6:00, took 35 cc. of blood, very red . . . E Blood A (76 cm.) contains per 100 volumes: O. 20.8; CO* 46.1 Blood B (18 cm.) contains per 100 volumes: O 7.6; CO 12.9 Blood C (17 cm.) contains per 100 volumes: Ch- 7.1; CO2 11.9 Blood D (26 cm.) contains per 100 volumes: O. 9.2; CO. 13.7 Blood E (76 cm.) contains per 100 volumes: O? 20.8; CO. 40.5 When, after having followed the preceding experiments, we examine Table X, which summarizes them and in which they are arranged in the order of decompression, one of the first facts to attract our attention is the remarkable variation presented by the figures in Columns 3 and 4, which express the quantities of oxygen and carbonic acid gas contained at normal pressure in 100 cc. of blood. The variations for oxygen (setting aside Experiment CLXXIV for reasons which I shall specify shortly) were from 16.9 to 22.6; those of carbonic acid, from 29.1 to 48.4. I should note that there is no proportion, either direct or inverse, between the in- creases or diminutions of these two gases, so that the variations of the total (Col. 5) , which were from 48.2 to 67.8, are not the expres- sion of any distinct law. The explanation of these variations cannot be found in the details of the experiments. All my dogs were in good health, fed on the same diet and at the same length of time before the experi- ment; I took care, as I said, to draw blood from them during a quiet period: they were, in short, as similar as possible. I am therefore led to believe that these results agree with the true state of things and that there are important differences between individuals in the oxygen content of the arterial blood, although all circumstances are similar. Furthermore, these variations are quite as apparent in the tables of analyses published by other authors; it would be a real delusion to get rid of them by getting some sort of an average. 606 Slsl OoI§ ocoin^cqosos^TfcMascqino^cqcsosc^ino Tt'in'co^©cocoa^ooasooco^o^cNCNCNo'os t>qoint-*nNco^(005oioint<;Hqc)05oN to ■*? ed m' o o co oo in ■* h cq oo' ft co £> I CN ,_( ^ CN r-< r-H ,-H t-H .-< »-l t-H »-H D--COCOCOCOCOCO-t>I> 8 Id a; o o Experiments inco^^as^cqoscqcqcqLncqo^^cqoqcqinocN esioi^wi^^^a5incDcde-i CN i-i CO y-i CO CO CN CN CN CN C- rp -^ t-- c~ co:t-:pTi-IOOOO or-asincsia30sini>(NODCD(?ooocxDincqcqoqcNit>- codrt^HiD^ncd'-JTjJ(o>cdiric6doidct-; r-i ,-i ,-J CN i-i 00 CN f\ CN 00 CN CN 00 CN CN CN i-i CN CN <-i i-i t-inroi>(£3oosioo)otoa>'HTfcoNcoo) CNlCNfo co ©as* oo c^cn os©.co <6nd co0^ in m oo •HPJ ©t> os^cNco-*CNCNOscoeNCNeNcoincO'--* oo ■* ■* ■* loo co in -^ as in ^-i ■* oocdi-hoo-* as cq rt< oq cq cq in cq cq I cn r^^i>'cd^oc^osoo^i>cdo6a'cc'ocNi'-ioci as CN CN ft .-H CN CN ft ft CN CN — i *-< ft y-i r-< r-t CM CN C^ CN CN I r-\ t-cot oqt>© >> K>! :x: l»HHHaH XH XX XX >XXXXXX>GXXXXEX>XXEXXXX xxxxxxxxxxxxxxxxxxxxxxx UUUUUUUUUUUUUUUUUUUUUUU O- > o o im os' Gases of the Blood 607 In my experiments, just one of the differences observed is ex- plained by the state of the animal, in Experiment CLXXIV. Here we were handling a small dog (4 k.) , from which five days before I had drawn 110 cc. of arterial blood, that is, about half of the amount the loss of which would have killed it immediately, and which had remained sick and without appetite ever since. In the first experiment, its blood had given 19.4 per cent of oxygen and 48.4 of carbonic acid; in the second, there was only 13.3 of oxygen and 34.9 of carbonic acid: the two gases had therefore diminished considerably. The variations of the carbonic acid are, as I said a while ago, considerably more extensive than those of the oxygen, but are no easier to explain: there is involved a collection of problems analo- gous to those which we (MM. Mathieu and Urbain and I) have already studied, and which would require very numerous experi- ments. And now having come to the point which should interest us especially, a glance at the figures in Columns 8 and 9 of Table X, compared to the corresponding figures of Columns 3 and 4, show us that in all cases, under diminished pressure, the oxygen and the carbonic acid have diminished in the arterial blood. There was no exception to this general rule. This is expressed very clearly in Figure 31 by the graphs com- posed of dashes connecting the little circles o — o — o — . In this graph, the quantities of gas are measured on the axis of the y's and the pressures on that of the x's; the points on it have been determined by the following procedure. I took the figures which express the averages and which are placed at the bottom of Table X. I assumed that the initial value, at normal pressure, of the oxygen (Col. 3) was always 20, and that that of the carbonic acid (Col. 4) was always 40. Then the values at different pressures (Cols. 8 and 9) were modified by operations like the following: Average of the experiments from 1 to 4 — Oa 19.3 (col. 3) : 20 = 16.9 (col. 8) : x = 17.5 CO2 37.7 (col. 4) : 40 = 33.2 (col. 9) : x = 35.2 Similarly, at each pressure, I made the same calculation, not for the averages, but for the extreme values of the modifications, and obtained thus the points marked by the little isolated circles which accompany the two curves representing the averages. The same data are expressed under a different form, perhaps more simple, by Columns 12, 13, 14 and 15. Columns 12 and 13 608 Experiments indicate the absolute quantity of the gases which have disappeared. Columns 14 and 15, more instructive, express the proportion which has disappeared and not the absolute quantity. They were ob- tained by operations like the following: Experiment No. 1 — O2 . . 21.6 (col. 3) : 3.0 (col. 12) = 100 : x = 13.8 (col. 14) CO . . 36.3 (col. 4) : 0.9 (col. 13) = 100 : x = 2.5 (col. 15) Examining first Column 8, we see that the quantity of oxygen IS Fig. 31 — Decrease in amount of O and CO2 in the arterial blood, when the barometric pressure is diminished. Gases of the Blood 609 contained in the arterial blood could, at pressures of 30 or 40 cm, drop to 9 cc. per 100 cc. of blood; that is, at these pressures the arterial blood contained considerably less oxygen than ordinary venous blood. The diminution of the carbonic acid was likewise (Col. 9) very considerable; the figures expressing the proportion of this gas have, in fact, dropped almost to 20 cc. per 100 cc. of blood. We shall refer later to the conclusions derived from these data. In comparing the experiments made at the same degree of de- compression, we find that the decreases in oxygen and in carbonic acid have varied peculiarly. The lowest figures of Columns 8 and 9 are not at the end, but towards the middle of the table. The re- sults of this fact are still more evident in Columns 14 and 15; there, for example, at a pressure of 36 cm., that is, about a half atmos- phere, the arterial blood has lost, in the different experiments, from 36.1 to 55.6 per cent of its oxygen, and from 16.8 to 38.6 of its carbonic acid. It is difficult to explain these differences by the different be- havior of the animals observed while the pressure was being lowered. This element may be important; but it cannot be the only one, and very probably animals with the same behavior may differ in the result for the same decompression, some losing more and others less oxygen or carbonic acid. This has interesting practical results which I shall stress in their place. Laying aside these individual differences, still more difficult to study here than in the case of normal pressure, and blending them in averages, we see (Col. 14) that on the average, the arterial blood at a pressure of 56 cm. contains 13.6 per cent less oxygen than at normal pressure; that at 46 cm., it contains 21.1 per cent less; at 36 cm., 43 per cent, and at 26 cm., 50.7 per cent. So at 26 cm., on the average, half of the oxygen of the blood has disappeared. These figures show that the diminution of this gas is far from fol- lowing Dalton's Law, which would give, for the same decompres- sions, losses of 26.3; 39.4; 52.6; 65.8 per cent. • The losses of carbonic acid (Col. 15) for the same decompres- sions, on the average, are 10.9; 14.0; 29.2; 38.2 per cent of the gas existing at normal pressure; that is evidently still farther from Dalton's Law. These figures even show that the average loss of carbonic acid is less than that of oxygen. The greatest proportion of loss, for the former gas (Col. 15) was 41.8 per cent; for the second, we twice had (Col. 14) 55.6. In one case, (Exp. CLXXII), at a pressure of 610 Experiments 46 cm., the quantity of carbonic acid had remained almost the same as at normal pressure. These results are expressed in another form in Columns 6 and 11, indicating the proportion of carbonic acid and oxygen under different pressures. We see that at normal pressure this proportion varied from 1.5 to 2.7, with an average of 1.9, whereas at low pressures it varied from 1.5 to 3.8, with an average of 2.3. In almost all cases, the figure of Column 11 is higher than the corresponding figure in Column 6, whether the latter is high or low: the exceptions (Exp. CLXXV, CLXX, CLXVII, CLXXIV) are cases in which the blood at normal pressure contained small quantities of carbonic acid, varying from 29.1 to 35 cc. These data can be expressed in a more precise manner by the following formula: The combination of oxygen with the hemoglobin is likely to be partially destroyed, to be dissociated, at low pressures; this dissociation becomes evident at a decrease of 20 cm. (pressure of 56 cm.). It increases as the decompression goes lower. At inter- vals of 10 cm., we find the averages: from 56 to 46 cm., a loss of 7.5 per cent; from 46 to 36 cm., a loss of 21.9 per cent; from 36 to 26 cm., a loss of 7.7 per cent. The greatest loss then comes at about a half atmosphere. The graph Ox of Figure 32 shows at the first glance the course of this gradual loss of oxygen; on the horizontal axis are counted the pressures, and on the vertical axis the percentages of the gases which have disappeared (Cols. 14 and 15 of Table X) . As to the carbonic acid, it behaves in about the same way; only its diminution is always less than that of the oxygen; this is easily seen on the graph C02. The graph shows again that the decrease in gases does not follow Dalton's Law (which would be represented by a line bisect- ing the angle of the coordinates). The carbonic acid is farthest from it. Yet I must say that the deviation is not very great for either gas. That is very remarkable if we refer to current opinions about the state of gases in the blood, according to the researches of M. Fernet, classic today. First, the oxygen, chemically united to the hemoglobin, could not be changed as to its proportion by decreased pressure (or increased) ; now what happens is quite different, since the decrease in oxygen is very evident and is quite near the re- quirement of the law governing simple solutions. The difficulty appears under an inverse aspect when we con- Gases of the Blood 611 sider the carbonic acid. The experiments of M. Fernet have in- spired the belief that most of the carbonic acid of the blood (0.964) is in the state of simple solution in the liquid, and that a rela- tively small proportion (0.597) is alone in the state of combination. Now what we have just said makes this interpretation of M. Fernet's experiments rather improbable. If the larger part of the Fig. 32 — Percentage decrease of O and of CO2 in the arterial blood when the barometric pressure is diminished. carbonic acid was dissolved, the escape of the carbonic acid would take place more easily and more regularly under the influence of the decompression, and the graph C02 would be closer to the bisecting line. Besides, we shall find in another part of this work other reasons for thinking that the carbonic acid of the arterial blood is, in the greater proportion, combined with carbonates and phosphates, and that only a very small part exists in a state of solution. However, these combinations are easily dissociated under the influence of a decrease in pressure. These contradictions to the conclusions of M. Fernet do not imply any criticism of his important work. For we must note that the experiments of this physicist were made in vitro, and at a low temperature, whereas mine had as instrumental apparatus the living animal itself. The presence of tissues, the continual con- sumption of oxygen, the multiplicity of surfaces of contact with 612 Experiments the blood and the air, the circulatory movements, the probable formation during the absorption of oxygen of substances capable of acting on the elimination of the carbonic acid, the increased temperature of the living body, are conditions which existed in one case and not in the other. Without mentioning the still en- tirely unknown elements of the complex problem of respiration, we have enough to give us an understanding rather than an ex- planation of the differences in our results. Furthermore, I wished myself to make experiments in vitro, in which I should make changes in pressure much greater than those obtained by M. Fernet. The report of these experiments will form subchapter V of the present chapter. The reader may have noticed that I studied the composition of the blood gases beginning with 56 cm. Between 56 cm. and 76 cm.. I thought I should not take account of any of my experiments. Here the value of the modifications found is precisely of the order of the errors of analysis. To draw any conclusions, one would have to make a considerable number of experiments and draw an aver- age which would express the direction if not the real value of the modification. Now this direction seems to me sufficiently de- termined by what we know already. The decrease of the oxygen and the carbonic acid of the blood, evident and constant at 56 cm., although very variable as to its value, surely begins considerably sooner, but at barometric levels and with an intensity which must vary from one animal to another, or in the same animal under different circumstances. On the other hand, all the experiments show that the oxygen is always given off in greater proportion than the carbonic acid. That should be enough to make us think that this rule extends to the period included in the first 20 centimeters of lowered pressure, a period which has this special importance of being the one to whose influence the majority of dwellers in high places are sub- jected. If our table of experiments shows that we did not begin at the outset of the decompression, it also shows that we did not go to the end, that is, until the diminution of pressure becomes incompatible with animal life. That was because my apparatuses did not permit me to do so, since leaks which could not be avoided in such huge receivers stopped the decrease of pressure at 17 cm., as I have said. I tried to fill this gap by an indirect means. I put a dog under the large glass bell- jar, and let it die there from decreased pressure. Gases of the Blood 613 Then, taking it out as quickly as possible, I drew blood from its left heart by means of a cannula. Here are two experiments carried out in this way. Experiment CLXXX. May 15. Dog weighing 5 k.; bell- jar of 31 liters. Left carotid exposed in advance. 5:40, put under the bell-jar, and the decrease of pressure begun, maintaining a current of air. 5:47, pressure 45 cm.; was struggling, but now remains quiet. 5:50, 45 cm.; 17 respirations, deep; remains motionless; trembles. 5:53, 35 cm.; 17 respirations; motionless, head lowered; at 5:55, 12 respirations. 5:58, pressure 25 cm.; at 6 o'clock, 22 respirations; motionless. 6:05, 16 respirations; pressure brought to 15 cm., at 6:07, can no longer remain half crouching, as it has done till now; lies down, its nose resting on the floor to support its head; takes 28 enormous respirations per minute. Pressure maintained at 15 cm. 6:10, 39 respirations less ample. 6:13, 35 cm.; at 6:15, 44 respirations; evacuation of fecal matter without apparent effort; at 6:19, 40 respirations. 6:20, I close the intake valve; the pressure drops at once to 7 cm. The dog rises on all fours, stiffens violently, but with slow regularity, ceases to breathe, and sinks down dead. I admit air: the animal's sides collapse. When taken out, it takes two or three little inspirations while the cannula is being inserted into the left heart. The heart is still beating a little; with much difficulty 32 cc. of very dark blood is drawn. The lungs are red in wide patches, sinking in water, but unfold- ing completely with insufflation. They are in a sort of fetal state. No blood in the trachea or in the bronchioles. The extracted blood contains per 100 volumes: CO 19.0; Oa 4.9. Experiment CLXXXI. May 23. Dog weighing 4 kilos. Took from the left carotid 33.3 cc. of blood. 6 o'clock. Put under the 31 liter bell-jar; pressure decrease begun. 6:06, pressure 40 cm.; at 6:08, 35 cm.; 14 respirations. 6:12, brought up to 45 cm.; 10 respirations. 6:15, pressure 31 cm.; rises, sits down, turns around. 6:17, pressure 26 cm.; seated with its head lowered, 15 respirations; raises its head when the bell- jar is struck. 6:20, pressure 15 cm.; falls down, urinates, barks faintly and plaintively. 6:21, pressure 13 cm.; gets up, barks, and falls back. 6:25, pressure 13 cm.; lying down, 9 respirations, medium. Cock closed; the pressure falls slowly to 7 cm.; the animal seems dead, when suddenly (6:27) it stands upright, stiffens slowly and strongly, and falls back. Pressure raised to 15 cm.; it seems better, moves a little; pressure dropped to 7 cm.; dies without moving. Withdrawn immediately. I extract without difficulty from the left heart 50 cc. of very dark blood . . . . B 614 Experiments At the first stroke of the pump, nothing comes. At the second, about 3 cc; at the third, a considerable quantity of gas, and at the fourth, almost nothing. The blood has not frothed perceptibly. Besides, this is the same result as in the preceding experiment and is explained by the small quantity of gas. Blood A contained per 100 volumes: CO,' 35.0; O* 19.2 Blood B contained per 100 volumes: CO? 16.2; O- 8.1 These experiments do not permit us to draw any conclusions as to the oxygen, because evidently at the return to normal pressure, the oxygen of the air contained in the pulmonary vesicles was partly dissolved in the blood of the lungs, which was then pumped into the left heart. Moreover, the arterial blood was very red, which had already perplexed F. Hoppe very much, as we saw in the historical part of this book. But the carbonic acid is another matter, and we can see that it was reduced to 19.0 cc. and 16.2 cc. The proportion which had disappeared was, in Experiment CLXXXI, 53.7 per cent. Now, referring to Table X, we find at the pressure of 17 cm. (Exp. CLXXIX) a much greater loss of 74 per cent. But in the first place, this loss is not an average, since it is the result of only two analyses made on the same animal, in the same experiment, one at 18 cm., the other at 17 cm., with a 12 minute interval. Further- more, to reach this enormous decompression, which I have not been able to reach since, I had to keep an animal for one hour at a pressure below 30 cm. I will again call attention in this Experiment CLXXIX to the very small proportion of carbonic acid which the blood retained in passing from 17 to 26 centimeters pressure (analysis D) , in spite of a quarter hour interval. I thought I should not include this figure, Number 17, Table X, in the average of Column 15 and in the graph of Figure 32, which expresses it. Another interesting point, on the contrary, is the return of nor- mal proportions of oxygen and almost normal proportions of CO. when the animal was restored to the pressure of 76 cm. (three quarters of an hour afterwards). I have had numerous examples of this return of the gases, examples still more rapid. As for the figures of the analyses B, C, D (Numbers 20, 21, 17 of Table X) , I think we must consider them as minima for carbonic acid, and I preferred to set down on the graph C02 of Figure 31 the results furnished by the experiments at 7 centimeters, which seem to be nearer the average and to comply better with the law of the graph. It would be easy for me now to draw practical conclusions from Gases of the Blood 615 the consideration of the preceding data, and show what happens to the blood of travellers who, either in a balloon, or on a mountain side, are subjected to considerable diminutions of pressure. But I think that these reflections will be better placed in the third part of this work, when I shall deduce from the whole collection of ex- perimental data the explanation of the symptoms produced by the modifications of pressure. I shall here merely summarize in this simple formula the results obtained above: When the pressure is lowered, the quantity of gases contained in the blood is equally diminished, but in a proportion a little less than that which Daltoji's Law would indicate; the blood thus loses relatively more oxygen than carbonic acid. Subchapter III. GASES OF THE BLOOD AT PRESSURES GREATER THAN ONE ATMOSPHERE 1. Experimental Set-up. The apparatus which I use for extracting the blood of animals subjected to pressures above that of the atmosphere consists (Fig. 33) of a straight cylinder of sheet steel 4 millimeters thick. The middle part of the cylinder is circular while the extremities are elliptical. The joints are fastened by many very small bolts. The elliptical form permits the insertion of the doors which close the extremities of the cylinder and which turn on the short axis. These doors consist of a cast-iron frame in the middle of which is fastened a glass porthole 18 millimeters thick, with a diameter of 10 centimeters. They are put in place by holding them obliquely and inserting them into the cylinder; then pulled back, they meet the edge and close hermetically by use of a rubber gasket. Two arms furnished with screws keep them in place; the inner pressure towards the outside does the rest. The total length of the cylinder is 1.50 meters; its diameter, in the circular part, is 40 centimeters; the total capacity therefore is about 153 liters. Compression is made by a compression pump C of the Rouquay- rolle and Denayrouze system, operated by a gas engine whose coupling gear A works the gears B; the air laden with water vapor which is thrown off by this pump and whose temperature rises 616 Experiments considerably, is conveyed through a coil immersed in cold water D, furnished with a reservoir E for the condensed water. A cock a makes or closes connection with the pump. Another cock c, whose opening can be enlarged progressively, permits one to extract air from the receiver for analysis, to main- tain a current of pure air under pressure, or to obtain a very sudden decompression. The manometer b indicates the pressure. Gases of the Blood 617 The cock d, placed on the slope of the inner lining of zinc, allows urine or the condensed water to be extracted. Finally, in f is a large orifice, which can either be closed by a screw-head, as the figure shows, or allow the insertion of a thermometer, a serre- fine with a handle, a cannula, etc. To prevent the air from escap- ing around these instruments, they are put through a rubber ball, (B. Fig. 34) held in a copper ring, whose screw thread closes it at will. This arrangement, while completely shutting out the air, gives the instruments a mobility which may be useful. When one wishes to see what is going on in the apparatus, he puts a candle opposite one of the glass portholes, and looks through the other; a dangerous proceeding, for it was under these conditions that the explosion occurred of which I shall speak in another chapter. The dog on which the operation is to be carried out is tightly fastened, the nose held in a muzzle, on a framework of iron and wood, whose form fits the inner wall of the apparatus, so that the animal, once placed within it, cannot change its position. Into one of its carotid arteries A is introduced a metal cannula S, which can, when the animal is in position, be joined to a copper tube, which screws through the wall of the apparatus, and is provided on the outside with a cock R. These arrangements having been made, cock R is closed, and the serre-fine SF is placed in the carotid, thus preventing the blood from entering the cannula. Then the door of the cylinder is ad- justed and the compression begun; it rises easily at the rate of about one atmosphere every four minutes, when all the cocks are tightly closed. It therefore takes about 40 minutes to reach 10 atmospheres, the maximum pressure which I have attained with this apparatus. Nothing now is more simple than to extract the blood of the animal, when the desired pressure has been reached. One needs only to open cock R and remove the serre-fine SF to see the carotid blood gush out with extraordinary force. In these conditions, in- deed, the animal is like a sponge powerfully squeezed by a force corresponding to 1.03 kilos, multiplied by the number of atmos- pheres and by the exterior surface of its body. The whole proce- dure then consists of fitting the glass syringe of Fig. 23 to the thick rubber tubing which adheres to the cock. Opening the cocks with precaution, one sees the plunger of the syringe raised vigorously by the pressure of the blood. One must not fail to fit its own cock to the syringe, and to close it immediately when one has secured the 618 Experiments desired quantity of blood, so as to prevent the gases, which are often given off, from escaping. When this discharge was con- siderable, I weighed the syringe to get the quantity of blood, volume readings then becoming very inexact. 2. Experiments. fig. 34 — Extraction of blood from an animal placed in compressed air. Here now is the detailed account of the experiments made in the conditions specified above. Experiment CLXXXII. July 23. Dog weighing 12 kilos. Drew from left carotid 36 cc. of blood .... A 4:30. Put into compression apparatus, and air compressed with current passing through; at 5:08, pressure of 10 atmospheres reached. Gases of the Blood 619 5:15, drew 36.7 gm. (cc?) of very red blood; gases escape in the syringe, and the blood begins to coagulate very quickly . . . . B Brought in 2 minutes to 6 atmospheres, and kept at this pressure under a current of air; at 5:45, drew 39.7 cc. of blood a little less red; no free gas . . . . C Brought suddenly to 3 atmospheres, and kept under a current of air. 6:33, drew 38.2 cc. of blood; no free gases . . . . D Decompression made slowly. At 7 o'clock, the animal is well; it survives without ill effects. Blood A (1 atm.) contains per 100 volumes: O^ 19.4; CO 35.3; N 2.2 Blood B (10 atm.) contains per 100 volumes: O 24.6; CO 36.4; N 11.3 Blood C (6 atm.) contains per 100 voolumes: O2 23.7; CO 35.6; N 8.1 Blood D (3 atm.) contains per 100 volumes: O 20.9; CO- 35.1; N 4.7 Experiment CLXXXIII. July 27. Female dog weighing 9 kilos. Drew 29.5 cc. of blood from the carotid .... A Put into compression apparatus; before each blood extraction, I maintain the determined pressure, under a current of air, for several minutes. 3:21, drew 29.5 cc. of blood at 2 atmospheres . . . . B 3:48, drew 34.3 cc. of blood at 5 atmospheres . . . . C 4:35, drew 38.2 cc. of blood at IV2 atmospheres . . . . D Up to this time, no discharge of gas in the syringe. 5:15, drew 30.7 cc. of blood at 10 atmospheres; here, small bubbles of gas .... E Decompressed in 30 minutes; died. The rest of its story will be told in Chapter VII. Blood A (1 atm.) contains per 100 volumes: 0= 18.3; CO^ 37.1; N 2.2 Blood B (2 atm.) contains per 100 volumes: O 19.1; CO 37.7; N 3.0 Blood C (5 atm.) contains per 100 volumes: O 20.6; CO? 40.5; N 6.1 Blood D (7V2 atm.) contains per 100 volumes: O 21.1; CO^ 36.8; N lost Blood E (10 atm.) contains per 100 volumes: O- 21.4; CO 36.8; N 11.4 Experiment CLXXXIV. August 5. Female dog weighing 11 kilos. Drew 29.5 cc. of blood from the carotid .... A Put into the apparatus at 5:33. Same precaution as in the pre- ceding experiment. 5:53, 3 atmospheres; drew 29.5 cc. of blood; the discharge of gas is evident . . . . B 6:28, 6 and 3A atmospheres; drew 29.5 cc. of blood; further dis- charge of gas . . . . C The animal cries and whimpers. 7:10, 9V4 atmospheres; drew 36 cc. of blood; gas in abundance . . D The cock of the cannula is opened wide; there issues 250 gm. of very red blood, which coagulates immediately; much gas is discharged. Decompressed rapidly, the animal dies immediately. The rest of its story in Chapter VII. Blood A (1 atm.) contains per 100 volumes: O? 18.4; CO* 47.7; N 2.5 Blood B (3 atm.) contains per 100 volumes: O 20.0; CO 42.2; N 4.4 Blood C (6% atm.) contains per 100 volumes: O2 21.0; CO2 41.3; N 7.1 Blood D (9y4 atm.) contains per 100 volumes: O 21.2; CO 39.8; N 9.3 620 Experiments Experiment CLXXXV. August 7. Female dog weighing 8.5 kilos. Drew at normal pressure 31.9 cc. of blood; the animal loses also, by accident, about 35 cc A 5:25, 5 atmospheres; drew 30.7 cc. of blood, from which bubbles of gas are discharged . . . . B 6:05, 8 atmospheres; drew 31.9 cc. of blood; numerous bubbles . . C 6:33, 10 atmospheres; drew 33.8 gm. of blood; gases were dis- charged in abundance, and coagulation threatened to take place rap- idly . . . . D Decompressed; the end of its story in Chapter VII. Blood A (1 atm.) contains per 100 volumes: O 22.8; CCh 50.1; N 2.3 Blood B (5 atm.) contains per 100 volumes: O* 23.9; CO 35.2; N 6.0 Blood C (8 atm.) contains per 100 volumes: O 25.4; CO* 37.6; N 9.5 Blood D (10 atm.) contains per 100 volumes: Cb 25,2; CO 39.0; N 10.0 Experiment CLXXXVI. August 8. Dog weighing 12.5 kilos. Drew 33.8 cc. of blood at normal pressure, from right carotid . . A Put into apparatus at 4:45. 5:33, 5V2 atmospheres; drew 32.9 cc. of blood; discharge of gas . . B 6:41, 10 atmospheres; drew 36.1 gm. of blood; gas in abundance in the syringe . . . . C Decompressed; the end of its story in Chapter VII. Blood A (1 atm.) contains per 100 volumes: Ch 20.2; COa 37.1; N 1.8 Blood B (5V2 atm.) contains per 100 volumes: O* 23.7; CO 35.5; N 6.7 Blood C (10 atm.) contains per 100 volumes: O2 24.7; CO 37.9; N 9.8 These different results are arranged in Table XI, by increasing order of pressures. If now we examine the figures it contains, which is easily done by an inspection of Columns 12, 13, and 14, in which are indicated the modifications in percentages of the volume of the gases ex- tracted from the blood under pressure, we see at first glance: 1) that the oxygen and nitrogen have always increased; 2) that the carbonic acid has sometimes increased and sometimes diminished. This can be shown in clearer form by making the following calculation on the different numbers. We shall assume that, at normal pressure, the blood always contains 20 volumes of oxygen, 40 volumes of carbonic acid, and 2.2 volumes of nitrogen; the quantity contained at the other pres- sures will be easily deduced from a proportion. And so, for the first experiment listed in the table, the propor- tions will be at 2 atmospheres: CO N 18.3 : 20 = 19.1 : x = 20.9 37.1 : 40 = 37.7 : x = 40.7 2.2 : 2.2 = 3.0 : x = 3.0 Gases of the Blood 621 0) DO id 0 E w CO too 2 W^ W WW & cfl B cd ca rt W) ti+j uo W) CuO S WW_M_Wt/JW)WWW oo ococoOceOcacococococo GplcOC^bOfiWCbOtijOtuO&OUOtiJO o o 0) a 01 to V a z ooocoi>i-hcnootj< V) r-l t- t» !D D» (O CO l-< ^H^HNI>NC0^000)inNC0HiH 4-17+7 l+7 177+17+ d ^OC-COUOOoOi-Hi-HOOitfOOC^OirOCN *'i>coeN«Di>cNi'^if5^H*if3cdcDoeNi i-H HNrHr1HiHNr-li- o « 4>o E 32 0 CO I> CO CN -H Oi ■>* ** aiococ-m'irit>-ci mcococococococo UO 00 00 CO CN "* CN O CN oS -I>CO t>c- £ Ot-^HO^HH oo^^cococdcdc^ in 00 oo# ^ cd 00 CJJOiHHOO^ d u >HWinNintqcccotoco^coq03 t^iricNJointninr-Hcdi>oicdcoo5t> eooo-^-^oooooo'^oooooooooooooo 0 i-HO^OCOCJit^C^Oi-H^CNCO-^CNt-; OJOOOMMCOrHiHIfirH^r-iinTji .-hCNCNCNCNCNCNCNCNCNCNCNCNCNCN Ebl NMcomiomtotot-cooioooo » 3*° £ §"S o ° 32 o CO O CO CO CN 1— iC5COCOCNCOO"5COCNi-h inmtoinc-mmtomt-tO'nmMfi cNCNincNoooqcNincsiooincNCNooeo C^CNC^CNCNi-hCSJcNC^CNCNCNCNCNi-h 6 V i-H 00 I> t- 1 1-H ,-H CO t> i-H i-H t- 00 1-H i-H rH c»iric--i>6i>ioi>i>cJt>inc~o'i> 0000 ^00 "ooo ooi* 00 10-^00 00m 00 6 00 -* "* 00 CO CN ■* -* CO CO ■* ■*_ 00 CO CN oDOTcdcoirioc^cococNcooicocNCJ ,_, ,_, r-i ,_, CNCN i-H 1-H i-H CN i-H i-H i-H CN CN e ~ 6-° X w 1-H S.1^ •"- ' S. hH S» *~ ' ^ HH>^H[>b>H^Ht>''^HHi>t> xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx xxxxxxxxxxxxxxx uuuuuuuuuuuuuuu 01 i rHcooo-^mcoir-co 35 0 i-H cn 00 -* m 622 Experiments Making averages for identical pressures, we can draw up the following table: Table XII 1 1 2 3 4 Atmospheres | Oxygen co2 N 1 _ . 20 40.0 2.2 2 20.9 40.7 3 3 21.6 37.2 3.9 5 (Exp. 4, 5, 6) 22.7 35.7 6 7 (Exp. 7, 8, 9, 10) 23.1 35.5 7 10 23.4 36.6 9.4 The results of this table are expressed in a very striking way by the following graphs (Fig. 35), in which the pressures are plotted on the horizontal axis, and the quantities of gas on the vertical scale. Let us now examine the data for each of the three gases of the blood, using the figure and the two tables. 1. Oxygen. Its increase, we have said, is constant. But the comparison of Columns 3, 8, and 12 of Table XI shows us that this increase is, at the same time, very variable for the same pressure, and very small even under the enormous pressure of 10 atmos- pheres. The variety of results should not surprise us, after what we have already seen in speaking of decreases in pressure, and after the inequalities indicated by the diverse figures in Column 3. It is impossible for us to connect this variety of results to any known condition; but it is very interesting to observe, because it can serve to give account of the intensity, very variable according to the subjects, with which the air compression acts. As to the amount of this increase, it is really very curious to see how slight it is. Its maximum, under a pressure of 10 atmos- pheres, was 26.7 per cent, that is, in volume the quantity of oxygen contained in 100 cc. of arterial blood rose from 19.4 cc. to 24.6 cc. The figures relating to intermediary pressures have the same bear- ing. The graph Ox and Column 2 of Table XII show this slowness of increase with great definiteness. We had already seen, moreover, by experiments made in ex- panded air, that the influence of barometric pressure, relative to the quantity of oxygen absorbable, is less for pressures near 76 cm. than for those which are much lower. So the figures in Column 14 of Table X show that in passing from 76 cm. to 56 cm. the oxygen lessens only by 13.6- per cent, whereas in passing from 56 cm. to 36 cm. it lessens 43—13.6=29.4 per cent. So the graph Ox (Fig. 31) , Gases of the Blood 623 which shows the changes in the oxygen content of the blood with changing pressure flattens out in the neighborhood of normal pressure. Fig. 35 — Variations of blood gases at pressures higher than one atmosphere. We can show this in a still clearer manner in another graph (Fig. 36). Let us take as the zero the barometric vacuum, let us plot the pressures in atmospheres on the axis of the x's, and let us put on the axis of the y's values proportional to the oxygen content 624 Experiments at different pressures, and we thus obtain a curve Oab (graph and vertical lines dotted) which, after rising very rapidly in the region BBSS ■8 ■-1 o to —i "SS-s Si j « - 5 * S .5 ** ■ TJ o u o 8ll Oft ►H (-1 >-( -8a sis u ca (h S S v ►■H ^ ft of zero to xk atmosphere, a little less in the region of Vz to 1 atmos- phere, levels off considerably, beyond that pressure. The figures are no less clear; assuming that the zero of the oxygen corresponds to the lethal decompression of 7 to 8 centi- Gases of the Blood 625 meters, equal to 1/10 of an atmosphere, we see, by combining Tables X and XI, that: From 1/10 to V* of an atmosphere, the proportion of oxygen has increased 7.5 From Va to Vz of an atmosphere, the proportion of oxygen has increased 5.7 From Vz to % of an atmosphere, the proportion of oxygen has increased 4.3 From % to 1 of an atmosphere, the proportion of oxygen has increased 2.5 From 0 to 1 atmosphere, the proportion of oxygen has increased 20. From 1 to 2 atmospheres, the proportion of oxygen has increased 0.9 From 2 to 3 atmospheres, the proportion of oxygen has increased 0.7 From 4 to 5 dividing by 2 the difference from 3 to 5 = 1.1 increased , Q'5 From 5 to 6 atmospheres, the proportion of oxygen has increaed 0.2 From 6 to 7 atmospheres, the proportion of oxygen has increased 0.2 From 7 to 8 atmospheres, the proportion of oxygen has increased 0.1 From 8 to 9 atmospheres, the proportion of oxygen has increased 0.1 From 9 to 10 atmospheres, the proportion of oxygen has increased 0.1 Total 23.4 In other words, these data show that, in the living organism, the absorption of oxygen by the blood increases very rapidly for pressures less than one atmosphere, but very slowly, on the con- trary, for pressures of several atmospheres. Everything seems to indicate that there exists, in the neighborhood of normal pressure, a point of chemical saturation of the oxy-hemoglobin, and that be- yond this point there is added to the blood only the oxygen dis- solved in the serum according to Dalton's Law. This will be veri- fied when I speak of the experiments performed in vitro on blood taken from the vessels. At the proper time we shall return to the reflections inspired by these interesting data. For the moment, let us be satisfied with observing that a laborer who works at a pressure of 2 to 5 atmospheres has not much more oxygen in his blood than at normal pressure. Moreover, — and this is not to be overlooked in explain- ing the unevenness of the phenomena displayed by the different workmen — I have seen animals which normally had in their blood at normal pressure more oxygen than others at 10 atmospheres; and also in the experiments at diminished pressure certain of my dogs had at normal pressure (See Table X, Experiments 4 and 11) less oxygen than others at a pressure of 56 centimeters and even of 44 centimeters (Experiments 1, 2, 5, and 8). 2. Carbonic acid. As Table XI shows (Columns 4, 9, 13) , some- times it increases, sometimes it diminishes. Its increase is always very slight (at the most, 9.2 per cent, that is, in actual quantity, 3.4 cc. per 100 cc. of blood) ; its decrease was very great (up to 29.7 626 Experiments per cent, that is, 14.9 cc. per 100 cc. of blood [in original French, 110 cc.]) . All that the figures permit us to say is that the carbonic acid always diminished when its original proportion exceeded 38 cc. per 100 cc. of blood. The averages, represented, according to the agreement fixed above, by Column 3 of Table XII and by graph CO2 of Figure 35, indicate a decrease, irregular, it is true, but constant. However, one may say that it is established, as a general fact, that the increase of pressure above normal pressure does not change very consider- ably the carbonic acid content of the blood. The result was quite different, as we have seen, for pressures below one atmosphere; but we had already seen, in the neighborhood of 76 cm., that the carbonic acid varies little, and in the figures of Column 14, for the pressure of 56 cm., we find the very low ones of 2.5 per cent and 0.8 per cent. On the contrary, at the pressure of 36 cm., for ex- ample, the blood contains an average of 29.2 per cent of carbonic acid less than at normal pressure, which corresponds to an average loss of 11.4 cc. per 100 cc. of blood. The important practical conclusion derived from this fact is that the symptoms observed in men and animals subjected to high pressures cannot be attributed to the effect of carbonic acid. We shall return to this point. If now we ask ourselves how it happens that the carbonic acid diminishes for very low pressures, without increasing above one atmosphere, the answer is hard to find. I have, however, settled upon the following explanation. The respiratory exchanges are not made, as we say in common parlance, between the blood of the lungs and the air of the atmos- phere. If it were so, this air, containing only very slight traces of carbonic acid, would play in respect to the blood with reference to the carbonic acid the role of a vacuum, and only a very small quantity would remain in the blood. But the exchanges are made between the venous blood and the air of the pulmonary vesicles. Now I found earlier 7 that this air, even after an inspiration, still contains from 6 to 8 per cent of carbonic acid. M. Grehant,8 who later did the same research by a method quite different from mine, reached a result as near mine as one could desire in such a subject. It is therefore the normal presence of this important proportion of carbonic acid in the air of the alveoli which maintains the usual quantity in the blood; this gas is thus its own obstacle, and one can easily see how an exaggerated pulmonary ventilation, lessening the Gases of the Blood 627 proportion of C02 in the alveolar air, lessens it at the same time in the blood. This carbonic acid which remains thus in the lungs represents the regular excess of the carbonic acid formed in our tissues over that which is exhaled through the trachea. This quantity will not vary, if no change is made in the conditions of metabolism and of pulmonary ventilation. Now this seems to be the case during respiration in compressed air, at least for the phenomena that are gross and apparent. If then there is produced during the same time the same quantity of CO,, the quantity which will remain in the air of the lungs will be the same; but as this quantity is com- pressed, its volume decreases inversely as the pressure, and it is clear that then its percentage in the air of the lungs, whose total volume does not change, will diminish directly as the volume. So if the air in the lungs of an animal at normal pressure contained 6 per cent of C02, at 2 atmospheres it will contain only 3 per cent, at 3 atmospheres 2 per cent, at 6 atmospheres 1 per cent, etc. Now since the pressure exerted by this carbonic acid upon the carbonic acid of the blood evidently has as a measure the product of the percentage by the barometric pressure, it will be expressed in the different cases mentioned above: at normal pressure, by 6x1 = 6; at 2 atmospheres, by 3x2 = 6; at 3 atmospheres by 2x3 = 6; etc., that is, its value always remains the same. It is therefore not astonishing that the carbonic acid content of the blood does not vary either. But why does it diminish in very low pressures? In this case, the same reasoning, the same conclusions, apparently. But here the question becomes complicated. First, if we assume that the animal is at a pressure of a half -atmosphere, the proportion of car- bonic acid in the lungs will rise to 12 per cent; the oxygen content of the air in the pulmonary vesicles is thus diminished, and the animal is forced to maintain a more active ventilation which, les- sening the tension 12 x % = 6, lets more acid escape from the blood. But the principal reason lies elsewhere than in the decrease of barometric pressure; we shall see later, in fact, that the carbonic acid content of the blood diminishes merely from breathing an air with a smaller oxygen content. It is therefore in the troubled chemical conditions of the formation of CO, that we must seek the most important cause of this diminution. No doubt the same thing is true of the diminution which coincides with pressures above one atmosphere. 3. Nitrogen. For this last gas, matters should take place with a 628 Experiments great simplicity, and, in fact, they do so. As it enters into no com- bination, its proportion in the blood depends solely on pressure; so Columns 5, 10, 14 of Table XI show us that it increases considerably. We shall see what is the importance of this considerable quantity of nitrogen when we speak of the effects of sudden decompression. And yet, strangely enough, the increase is far from following Dalton's Law. In fact, at 5 atmospheres, for example, we find in Column 5 the average number 6, instead of 11 required by Dalton's Law; at 10 atmospheres, the average number is 10.4 instead of 22. There is therefore about half as much nitrogen as the law would require. That is very striking in the graph Az in Figure 35, in which the straight line shows what the law would require. This fact is very instructive, because it shows how incomplete the intrapulmonary agitation is, at least at high pressures. Now the results given by the oxygen tend in the same direction. Ad- mitting that the hemoglobin is saturated chemically with oxygen in the neighborhood of normal pressure, the quantity of oxygen dissolved should be much greater at high pressures than experience indicates. At 10 atmospheres, for example, we should find, not 23.4 per cent, but about 29. The insufficient mixing of the air in the lung should be considered here; furthermore, this insufficiency is evident at normal pressure, because blood extracted from the artery always gains considerably in oxygen content from agitation with the air. We shall see that the same thing is true in the case of high pressures. All this can be summed up in the following sentence: in the living animal, when the barometric pressure increases, the oxygen increases in the arterial blood, but very slowly; the nitrogen in- creases more quickly, but in a quantity far from that required by Dalton's Law; as for the carbonic acid, it almost always diminishes. Subchapter IV GASES IN THE BLOOD IN ASPHYXIA COMPARED TO DECREASED PRESSURE I think I demonstrated in the first chapter that the symptoms and death in expanded air are the result of weak pressure of out- side oxygen, and that, in a word, it is a matter of simple asphyxia from lack of oxygen. If this is so, one should, in the blood of a dog subjected to Gases of the Blood 629 asphyxia, find the same low gas content as in the blood of dogs subjected to decompression. To verify this hypothesis, two methods are possible: 1) to place an animal in a current of air, which becomes progressively poorer oj o < & CO X2 lh 2h 3h 4K .0 V? Fig. 38 — Variations in the gases of the blood and the oxygen of the air in asphyxia in closed vessels, the carbonic acid being absorbed: to make the figure clearer, the ordinates corresponding to the oxy- gen content of the air are twice the height of the others. 634 Experiments but it is stranger to see that the carbonic acid diminished equally, although a considerable quantity remained in the air of the bag, which should have increased the proportion of this gas. If we wish to compare, not the trend, which quite evidently is the same, but the exact value of the variation of the blood gases in diminished pressure on the one hand, and in asphyxia on the other, we need only take the graph in Figure 31 and add to it the average results of the last experiments, making the same calculation of the numbers to bring the original value of the oxygen to 20, and that of the carbonic acid to 40. This has been done in Figure 39. On the ordinates are plotted, as usual, the numbers relating to the percentages of the gases extracted from the blood. The abscissae measure both the percentage of ambient oxygen and the barometric pressure. So 20.9 corresponds to 76 centimeters; 20.9 a half-atmosphere, 36 centimeters, corresponds to , etc. . . .; 2 that will permit us to see whether or not there is agreement be- tween the results of the two kinds of experiments. The points relating to diminutions of pressure are marked, as we have already said, by little circles connected by dashes and dots — . — .o. — . — . — o. The dotted lines express the average of the two experiments of simple asphyxia which I have just reported. Now in regard to the oxygen, we notice at once the remarkable agreement existing between the two curves; only for the rarefied air, as I have already indicated, I could not go below a pressure of 17 centimeters, corresponding to about 4.7 per cent of oxygen. Here is the first point gained. For the carbonic acid, the agreement is less perfect. But we must note first that there remained in the air on the way to ex- haustion a certain quantity of carbonic acid, without which the dotted graph would certainly have dropped more than it has. Furthermore, the irregularities between the averages connected by the line — o. — .o are very great for the carbonic acid, as is shown by the little isolated circles, which correspond to each of the ex- periments. It is therefore probable that from a very great number of experiments we should obtain averages which would be closer together; but it seemed to me unimportant to continue this investi- gation. The great interest lay in showing that, even at normal pressure, if the proportion of oxygen in the respirable air is low, we find in Gases of the Blood 635 the proportions of oxygen and carbonic acid in the arterial blood the same modifications as in the case of respiration under dimin- ished pressure. From this survey, as from that in the first chapter, 91 HI M HSSBI HHB Fig. 39 — Variations in the blood gases in asphyxia compared to decreased pressure, 636 Experiments there appears once more the proof that decompression acts as a simple asphyxiating agent. When this truth had been established, it became possible for me to find out how the gases of the venous blood vary during de- compression. I had tried repeatedly to extract the venous blood of a dog placed in my large cylinders; difficulties which all experi- menters will divine had prevented me from succeeding; clots formed in the cannulas, air bubbles, which the pressure of the blood no longer opposed, rushed into the right heart, etc. But respiration in an air whose oxygen content was gradually lessened allowed me to avoid these difficulties. And so I did in the following experiments. Experiment CXC. July 30. Dog weighing 12 kilos. Muzzle hermeti- cally closed. 2:05; Forced to breathe with the potash valves from a bag con- taining 90 liters of air. 2:10; respirations, 26; pulse, 100. Drew from the carotid 25 cc. of blood, not very red .... A 2:20; Drew from the left jugular, peripheral end, 25 cc. of blood, rather dark .... A' The animal, whose eyes are covered, remains perfectly quiet. 3:07; 22 respirations; pulse, 100. 3:10; Drew 25 cc. of blood from the carotid, almost as red as A .... B 3:15; Took sample of air from the bag . . . . b 3:20; Drew 25 cc. of venous blood . . . . B' 4: 10; Drew 25 cc. of arterial blood, dark . . . . C 4:15; Took air from the bag . . . . c The animal suddenly makes a violent effort and pulls off the rubber bag for an instant (takes one inspiration of outer air) ; con- tinued efforts and considerable panting. 4:22; 25 cc. of very dark venous blood . . . . C 4:30; pulse, 60; 18 deep respirations. 4:38; dies; a few very weak heart beats. Drew arterial blood, very dark . . . . D Took air from the bag . . . . d Summary of the Experiment Cor- spond- Arterial Venous Diff . in Airs mg Pres- sure Bloods Blood O, | COo o2 | co2 oa Normal 76 AA' 21.6 | 45.0 12.4 | 46.8 9.2 b (11.5 of 02; 2.0 of C02) 41.8 BB' 19.6 | 42.7 10.2 | 49.1 9.4 c (4.7 of 02; 2.1 of C02) 1 17.1 I CC* 8.8 | 34.4 2.2 I 36.5 6.6 Lethal d (2.7 of 02; 1 1.9 of C02) 1 9.8 D 0.4 | 23.6 Gases of the Blood 637 Experiment CXCI. October 15. Female dog weighing 13 kilos. Breathing free air; respirations, 20; pulse, 148; rectal temperature, 39.8°. 2:50; Drew 25 cc. of blood from peripheral end of jugular vein. A' 2:55; 25 cc. from carotid artery .... A 3 o'clock; Forced to breathe from a rubber bag containing 130 liters of air, through the double potash valves; the animal is very calm although it struggled considerably at the beginning of the experiment. 4 o'clock; 25 cc. of arterial blood . . . . B 4:12; 16 respirations; pulse, 86; temperature, 37.4°. 4:15; 25 cc. of venous blood . . . B' Air from the bag . . . . b Animal very quiet. 5:15; 25 cc. of venous blood . . . . C Air from the bag . . . . c Respirations, 16; pulse, 92; temperature, 36°. 6:10; 25 cc. of venous blood . . . . D' Air from the bag . . . . d Respirations, 16; pulse, 96; temperature, 35.5°. 7:10; 25 cc. of arterial blood . . . . E 25 cc. of venous blood . . . . E' Air from the bag . . . . e Respirations, 16; pulse, 100; temperature, 35.1°. Death comes at 8:45; temperature 33°. An accident prevents making an analysis of the blood. The air of the bag contains per 100 O 4.9; CO; 1.2. Summary of the Experiment ■ w>?> m ) _| 49 | C ' ' 11.3 I 43.0 36.0° d (10.6 of 02; 3.1 of C02)| 38 | D' 1 8.8 | 45.8 I — 35.5° e (7.7 of 02; 3.0 of CO.>) | 28 | EE' 10.2 | 34.5 6.0 1 45.8 1 4.2 35.1° Lethal (4.9 of Os; 1.2 of CO>)| 17 | 1 1 33.0° Experiment CXCII. November 13. Dog weighing 16 kilos. Breath- ing free air; temperature 38.5°. 2:45; Took 30 cc. of carotid blood .... A 2:54; Took 30 cc. of blood from the peripheral end of the jugular vein .... A' 2:56; We begin to force the dog to breathe from the bag containing 130 liters of air through the potash valves. 3:40; Rectal temperature 38°. 3:53; The animal is much hampered in its breathing, and has been struggling for a few minutes. Took 30 cc. of venous blood . . . . B' 4:05; Took 30 cc. of arterial blood . . . . B Air from the bag . . . . b 4: 15; Rectal temperature 36°. 638 Experiments 5 o'clock; Took 30 cc. of venous blood . . . 5:07; Took 30 cc. of arterial blood . . . . < Air from the bag . . . . c 5:15; Rectal temperature 34°. 5:20; Arterial blood, 30 cc; animal dying . 5:30; Venous blood, animal dead . . . . D' C Summary of Experiment Airs ■ be Experiment CCI. May 29. Dog blood; temperature 24°; flask of 4.330 liters. 648 Experiments At 738 mm. (deduction of the water vapor tension), the blood CO contains: Oxygen 25.6; CO, 23.0; N 2.6. = 0.89. O CO At 318 mm.: 02 23.7; C02 18.9; N 1.8. = 0.79. O CO At 128 mm.: O. 23.0; C02 16.2; N 0.5. = 0.70. O CO At 78 mm.: 02 23.0; CO* 13.7; N 0.5. = 0.59. O* co2 At 38 mm.: O, 19.3; CO, 10.8; N 0.3. = 0.55. o2 The accompanying graph (Fig. 43, A) summarizes and ex- presses the average of the results of the preceding experiments, in Fig. 43— Capacity of the blood for absorbing oxygen at pressures below one atmosphere. A. Laboratory temperature. B. Body tempera- ture. C. Living animals. Gases of the Blood 649 everything relating to oxygen. It was obtained by assuming that the initial proportion of oxygen at normal pressure was always 20 volumes per 100 volumes of blood, and by determining the value of the other numbers by proportions like the following, which applies to Experiment CXCIII: 19 (normal pressure) : 20 = 17.2 (pressure of 56 cm.) : x = 18.1. A simple glance will show that, from normal pressure to that of 10 to 15 centimeters of mercury, the blood absorbs quantities of oxygen that are almost the same; one or two volumes less, and that is all. It is even very possible that this difference affects only the oxygen dissolved in the plasma, which rises, according to M. Fernet, to 2.88 per 100 volumes of liquid. So our analyses, which go to pres- sures considerably lower than those used by M. Fernet, give results which tend in the direction of the conclusions of this physicist. But from 15 centimeters of mercury on, the oxygen escapes from the blood in a far greater proportion than the Law of Dalton would require. There occurs a dissociation of the combination of the oxygen with the hemoglobin, a dissociation whose intensity in- creases rapidly. I have made a sort of control experiment using a method nearer that of M. Fernet, since instead of extracting the oxygen progres- sively by agitation at lower and lower pressures, I measured the quantity absorbed by blood that had previously been entirely de- prived of gas. Here are the results of three experiments carried out in this way. It will be seen that they agree, in their general trend, with those obtained by the first method. Experiment CCII. December 30; pressure 762 mm. We prepare two mercury pumps and two apparatuses for extract- ing the gases of the blood, in which absolute vacuum is made. From the jugular vein of a dog by means of a syringe 138 cc. of blood is drawn, and this blood is injected into a flask full of air; the blood is defibrinated and oxygenated by long shaking in the flask. 89.5 cc. of blood measured in a graduated test tube is passed into one of the pumps; this blood has been filtered through linen and freed of fibrin and air bubbles; the gases are extracted from the blood heated to a temperature of 35° to 39°, until a dull click is heard; the blood is completely reduced. When the extraction has been made, the blood is cooled in cold water to about 10°. The analysis of the gases extracted shows that 100 cc. of blood shaken in the air at a pressure of one atmosphere has absorbed 19.8 cc. of oxygen. Air at a pressure of a half atmosphere is admitted to the empty apparatus; to do this, a long vertical tube, T (Fig. 44) is used, into 650 Experiments which mercury is poured; it is closed by a stopper with two holes, through which two glass tubes pass. One, a, is dipped into the mercury to a depth of 381 mm., half of 762 mm.; it opens into the air and has a cock r. The second tube, b, which reaches merely to the upper part of the tube full of mercury, curves outside into a siphon which is joined by a rubber tube, c, to the central tube which projects from the middle of the little mercury basin C which tops the cock R of the gas Fig. 44 — Apparatus to bring blood into contact with the air at a specified decrease in pressure. pump; when this cock is turned as the figure shows, and cock r is opened carefully, the outer air is admitted bubble by bubble through the mercury, and when the air which has come in contact with the blood has a pressure equal to a half atmosphere, the outer air ceases to enter through tube a. The blood then is agitated by raising and lowering the balloon of the extraction apparatus, and the agitation is made 25 times with air and with mercury; the blood becomes a very bright red. Gases of the Blood 651 By working the pump and holding the balloon containing the blood above the horizon, the blood is made to pass into the barometric chamber and then into a syringe. In this way 69 cc. are obtained which are introduced into the second mercury pump. The extraction of the gases gives 14.5 cc. of oxygen; that is, per 100 volumes and after corrections, 19.8, exactly like the preceding. So the blood absorbs exactly the same quantity of oxygen in both cases. Experiment CCIII. December 31. 100 cc. of dog blood absorbed at the ordinary pressure of 760 mm. 32.4 cc. of oxygen. 100 cc. of the same blood, first deprived entirely of gas, absorbed under the pressure of 24 mm., that is, at a pressure 32 times less, 26.1 cc. of oxygen. Experiment CCIV. March 20 and 21. From a branch of the femoral artery of a terrier in good health 500 gm. of blood were taken and defibrinated by agitation in a flask. In a large flask whose interior volume is equal to 4.335 liters, a vacuum is made by means of the pneumatic machine; next, the air is extracted by a mercury pump so as to bring the pressure of the remaining air to about 2 centimeters; 68 cc. of blood completely freed of gas by means of a mercury pump at 40° are injected into the flask by means of a syringe, and the blood is shaken with the rarefied air for a half hour by the hydraulic motor. After the agitation, the pressure of the rarefied atmosphere is measured and the ascertained pressure of the water vapor tension at the temperature of the labora- tory air is deducted, so as to obtain the pressure of the air assumed to be dry; it is only 152 mm. The gases are extracted from the blood agitated with the air under this low pressure by passing the blood directly from the flask into an evacuated gas pump (the flask being weighed before and after). 2.) By means of a syringe, 68 cc. of blood freed of gas and 68 cc. of air are injected into the flask; agitation for a half hour, etc In the following experiments, each time in the same way, 68 cc. of blood and 68 cc. of air are injected. Here are the results obtained after the necessary corrections: 100 gm. of blood first freed of gases At the pressure of 15 cm. absorbed 7.3 cc. of oxygen. At the pressure of 29 cm. absorbed 9.9 cc. of oxygen. At the pressure of 40 cm. absorbed 12.3 cc. of oxygen At the pressure of 51 cm. absorbed 13.2 cc. of oxygen. At the pressure of 75.6 cm. absorbed 18.5 cc. of oxygen. We conclude then from these data that down to low pressures the contradiction noted between experiments made in vitro on the capacity of blood for oxygen and the analyses of the blood of living animals exists entirely as it appeared to us at first. At all pressures, the blood, agitated in a flask, contains an almost equal quantity of oxygen (graph A of Fig. 43) , whereas in the living animal the pro- 652 Experiments portion of oxygen diminishes rapidly, as is shown by graph C, which reproduces graph Ox of Figure 31, and the analyses sum- marized in Table X. Considering this difficulty, I asked myself whether the high tem- perature of the animal's body could not cause some changes in the results I obtained at low temperatures. We knew already that to extract the oxygen of the blood completely we must add to the action of the vacuum that of a rather high temperature. I will report here an experiment which demonstrates this truth. Experiment CCV. June 24. 65 cc. of defibrinated dog blood are placed at 4 o'clock in the receiver of a pump for the extraction of gases, in which an absolute vacuum had previously been made. The temperature is only 19°. The blood is shaken repeatedly in the balloon and all the gas which will come out is extracted, but without warming it. We obtain thus, per 100 cc. of liquid, 11.2 cc. of oxygen, 20.0 cc. of carbonic acid, and 2.0 cc. of nitrogen. This procedure is repeated until 6 o'clock; no more gas has come after several pump strokes, and the blood has remained bright red. The double-boiler is heated to the boiling point, and then, with a single pump stroke, the rest of the gas is extracted; the blood turns dark immediately. The quantity just extracted represents, per 100 cc. of blood: Oxygen 13.2; CO 13.0; N 0.6. So the blood contained in all: O* 24.4 cc; CO 33.0; N 2.6. If this blood had been subjected to the experiments performed by the method previously described, and if a complete vacuum had been made in the agitation flask, at 19°, 13.2 cc. of oxygen could have still been extracted by the heat. Temperature has, therefore, a great importance. And so I set up the experiment in a slightly different manner. The agitation flask, instead of being fastened on the plank of Figure 42, was solidly fastened underneath at a certain distance, so as to dip into a bath of lukewarm water whose temperature was kept at a fairly constant degree all through the agitation. Here are the results of experiments made under these conditions. Experiment CCV I. June 3. Dog blood; shaken for xk hour, the flask of 4.330 liters being submerged in water at 40°. At 725 mm. (deduction of water vapor tension) it contains: Os 15.4 At 280 mm.: 02 13.8. At 100 mm.: Oa 8.5. Experiment CCVII. July 10. Dog blood; shaken for 20 minutes, the flask of 4.330 liters being submerged in water at 40°. At 738 mm. (with the usual deduction), the blood contains: Q2 20.1; CO, 18.8; N 1.5. Gases of the Blood 653 At 290 mm.: 02 16.4; C02 13.0; N 0.6. At 87 mm.: O* 11.3; CO 8.6; N 0.4. At 26 mm.: CK> 7.2; CO* 7.0; N 0.2. Experiment CCVIII. February 18. Defibrinated dog blood, interior temperature of the flask 38°. Agitation at normal pressure; blood con- tains O2 20.2. At 38 cm.: 02 17.7. At 19 cm.: 0» 16.4. Experiment CCIX. February 26. Defibrinated dog bleod. Agita- tion at normal pressure; interior temperature of the flask 38°; the blood contains 02 18.2; C02 10.1. At 38 cm.: 02 14.8; C02 6.8. At 19 cm.: 02 10.6; C02 7.0. These four experiments, when we get the averages, setting the origins of the graphs at 20, give us graph B of Figure 43. We see that the curve B dips much more rapidly than the preceding A, and more nearly approaches the one which, taken from Column 8 of Table X, expresses the oxygen changes in the living animal, and is represented here in C. In other words, the contradiction noted loses much importance when we supply the temperature conditions given by the bodies of warm-blooded animals. However, our analyses show that the arterial blood of a living animal subjected, for example, to a half atmosphere, could absorb a quantity of oxygen much greater than that which it really contains. That is because the intra-pulmonary agitation of the blood with the air is no longer carried on in satisfactory conditions. Even at normal pressure, as we have seen, the arterial blood is not saturated with the oxygen which it can hold; it reaches that point of satura- tion— or nearly so— only after exaggerated respiratory efforts, which bring on an exaggeration of circulatory rapidity. At a half atmosphere, to obtain the same result as at ground level, the activity of intra-pulmonary mixing would have to be doubled; the respira- tory movements must be doubled in amplitude and rapidity; the heart movements must be doubled in strength and number. That is evidently impossible. Summarizing, the conclusions of M. Fernet's work are legitimate only under the conditions of pressure and temperature (16°) at which he worked. At lower pressures, at body temperature, the part of the oxygen which he considers as chemically combined in the blood because it is independent of the pressure, really follows the pressure changes, although considerably less quickly than a 654 Experiments gas in simple solution would do. But in the living organism, this is complicated by an insufficient agitation of the blood in contact with the air, and so there results a much more rapid decrease of the oxygen of the blood than ex- periments in vitro would lead one to think. 2. Increased Pressure. To study the absorption of oxy- gen by the blood at pressures greater than one atmosphere, I had made a bronze receiver, of a ca- pacity of 175 cc, capable of resist- ing 25 atmospheres easily. (Fig. 45.) The procedure was very simple. In the apparatus, whose lower part could be unscrewed, was placed the defibrinated blood to be analyzed; I used about 100 cc. of it. Then, after the cylinder had been closed, I compressed the air by screwing on the compres- sion pump, and closed cock R when the manometer indicated that the desired pressure had been reached. I next agitated the apparatus by fastening it on the plank of Fig- ure 42. Finally, to extract the blood into the graduated syringe, I had only to fit its extremity to the capillary cock r, which I half- opened; the air pressure immedi- ately drove the blood out; a few strokes of the pump kept a con- stant pressure in the apparatus while the blood was being taken out. When I was dealing with very high pressures, when nitro- gen dissolved in quantity was given off in the syringe, I substi- tuted weight for volumetric mea- sure, since the froth did not per- mit me to determine volume exactly. When I wished to make an analysis at a certain compression, I began by supersaturating the blood by Fig. 45 — Apparatus to saturate blood with air at high pres- sures. R. Large cock by which compression is made. r. Capil- lary cock by which blood sam- ples are taken. Gases of the Blood 655 shaking it at a higher pressure, so as to be sure, when I had brought it to the desired pressure, that it really contained all the oxygen it could absorb. If several analyses at different pressures were to be made of the same blood, I followed the same procedure, beginning with the highest; this was quite legitimate, because the quantity of oxygen introduced into the apparatus under compression was al- ways much greater than the blood could absorb. The pressure re- corded in the experiment was the one read after the agitation and the absorption had been finished. An important point was first determined: namely, that the in- crease of the oxygen contained in the blood was quite temporary and disappeared rapidly when the compression was over. The following experiment proved this. Experiment CCX. June 20. Defibrinated dog blood. At normal pressure, after long agitation, contains O 20.0. 100 cc. were put into the apparatus, and the compression was carried to 12 atmospheres, with superoxygenated gas, so that the oxygen tension corresponded to 44 atmospheres of air. After an agita- tion which was insufficient for complete saturation, the blood con- tained, per 100 cc: 02 37.7. I then placed in a flask the rest of the compressed blood, which was very red and contained much gas in suspension; the flask was whirled like a sling once, and 10 minutes after being taken from the apparatus, the blood contained only 20 vol. of oxygen, as at the beginning of the experiment. We now come to the experiments carried on with care that the saturation should be complete; the pressure was made with ordi- nary air. Experiment CCXI. June 20. Defibrinated dog blood. At normal pressure contained Oa 20.0. At 12 atmospheres contained 0-> 30.0. At 8 atmospheres contained O 25.7. At 4 atmospheres contained O- 22.8. Experiment CCXII. January 22. Defibrinated dog blood. At normal pressure contained O 20.2. At 18 atmospheres contained O- 28.2. At 9 atmospheres contained O- 25.9. I particularly call attention to the following experiment, which was carried out with the greatest precautions. Experiment CCXIII. January 12. 500 cc. of blood taken from the femoral artery of a very large dog. This blood is defibrinated, filtered through linen, then shaken for a half hour with air at normal pres- sure; it contains 14.9 volumes of oxygen. It is then placed in the apparatus; for each experiment, the agita- tion lasts a half hour. The findings were: At 6 atmospheres, Os 19.2. At 12 atmospheres, O 26.0. At 18 atmospheres, O* 31.1. 656 Experiments Let us discuss the results of this last experiment. Let us call x the volume of supposed oxygen combined with the hemoglobin contained in 100 cc. of blood, a volume which, by hypothesis, would be independent of the pressure; let us call y the volume of oxygen which 100 cc. of blood would absorb in a state of simple solution as a result of agitation in the air at normal pressure; we shall have: At 1 atmosphere x + y = 14.9 (1) At 6 atmospheres x + 6y = 19.2 (2) At 12 atmospheres x -f 12y = 26.0 (3) At 18 atmospheres x + 18y = 31.1 (4) Let us subtract (1) from (4), and we get 17y = 16.2; whence y = 0.95; from the equation (1) we then get x = 14.9 — 0.95 = 13.95. Substituting these values in equations (2) and (3), we find the figures 19.6 and 25.4, instead of 19.2 and 26, differences which are quite in the order of experimental errors. :^H I ■-;-'■ • 1 - ■ I ■ - mm • -; ■ Fig. 46 — Capacity of the blood for oxygen, from a vacuum up to 18 atmos- pheres of air. Gases of the Blood 657 So the hypothesis is verified, and above 1 atmosphere, the pressure adds to the blood only the oxygen dissolved, whose in- creasing proportion follows Dalton's Law. If then we take 20 as average proportion of oxygen contained in the blood at normal pressure, and if we assume, to make the calculation easy, that there is one volume dissolved, we shall find that at 6 atmospheres there will be 25 volumes; at 12 atmospheres, 31 volumes; at 18 atmospheres, 37 volumes. These last results are marked on the graph of Figure 46 by points whose series naturally forms an absolutely straight line. Now if we had drawn on the same scale the graph of Experiment CCXIII and had then traced back the whole to its point of origin (14.9) on the line marked 20, the four points of this graph would be represented by the little crosses on the graph. We see how close they are to the theoretical points. There has been added between 1 atmosphere and vacuum a reduction of graph A of Figure 43, which completes the survey of the capacity of blood for oxygen, from the lowest to the highest pressures. The question arose whether for high pressures the temperature would cause any important difference in the capacity of the blood for oxygen. Since the experiments which I have just reported were carried on at the temperature of the laboratory, I performed another, shaking the blood in a bath kept at 40°. As the results agreed with the preceding, I thought it unnecessary to gather more data. Here is the experiment. Experiment CCXIV. January 15. 300 grams of arterial blood were drawn from a large dog, and were defibrinated and filtered through linen. I placed 130 grams in the apparatus of Figure 31; I compressed the air to 22 atmospheres, and agitated the blood and the air for a half hour, the apparatus being submerged in water at 40°. I lowered the pressure to 18 atmospheres, and 5 minutes after, I removed 28 grams of blood .... A The pressure being lowered immediately to 12 atmospheres, I agitated the blood again and removed 33 grams . . . . B A similar procedure gave me at 6 atmospheres 41 grams of blood. . . . . C Finally, at normal pressure, I had left 20 grams of blood . . . . D The analysis by the pump showed that: A (18 atmospheres) contains, per 100 volumes: O^ 35.7; N 19.2. B (12 atmospheres) contains, per 100 volumes: O 30.9; N 15.1. C (6 atmospheres) contains, per 100 volumes: O- 27.1; N 7.8. D (1 atmosphere) contains, per 100 volumes: O^ 23.0; N 1.3. 658 Experiments Using on these figures the calculations which have just been applied to Experiment CCXIII, we find for the coefficient of the oxygen dissolved 0.75 and for the values of B and C 31.2 and 26.7. The difference between the calculation and the experiment is, therefore, in the first decimals, and should not disturb us. And so at body temperature, as at laboratory temperature, when the pressure is increased, the increase in the oxygen proportion follows Dalton's Law. On the other hand, if we refer to what was observed directly in the living animal (Fig. 36, solid line) , we see that the quantity of oxygen contained in the blood is considerably less than its maxi- mum capacity in vitro. This is in part due to the fact that the oxygen in simple solutior in the serum tends to penetrate also by simple solution into all tht organic liquids and the tissues bathed by the blood, until an equilibrium of solution is established between them and this serum. The slowing up of the respiratory movements and the circula- tion of the blood, so easy to observe in cold-blooded animals at high pressures, certainly is an added factor in the diminution of the quantity of oxygen introduced into the blood, by modifying the conditions of the air-blood agitation taking place in the lungs. There would be, on the part of the organism, a struggle for equilibrium, working inversely to that which we stressed above. If we now refer to this observation already made several times that the blood in the conditions of normal respiration is never satu- rated with the oxygen that it can absorb, we shall perceive that when the increase of pressure introduces a little more oxygen into the blood, this oxygen will first be rapidly condensed by the blood corpuscles, so that the hemoglobin of the blood is completely satu- rated before a larger proportion remains in the serum. But from the purely chemical point of view, the data which I have just reported present a new interest when they are compared with those recently obtained by MM. Risler and Schutzenberger.10 According to these chemists, the blood, or rather the hemoglobin, from which all possible oxygen has been removed by the action of the vacuum or of carbon monoxide, would still contain a quan- tity almost equal to what it has just lost. There would therefore be here a sort of protoxy-hemoglobin, which the vacuum, even when aided by heat, and which the carbon monoxide could not reduce, and a deutoxy-hemoglobin, from which the vacuum and the carbon monoxide could take its second equiva- lent of oxygen. Beyond that, the hemoglobin, completely saturated, could take up no more oxygen, whose proportion would increase Gases of the Blood 659 only by simple solution in the ambient serum. That strongly recalls the mode of union of the carbonic acid with the alkaline bases, whose protocarbonates are indecomposable by a vacuum, whereas the deuto-carbonates at very low barometric pressures lose their second equivalent of acid, as we have known since the research of H. Rose. The whole blood then would behave towards oxygen as a solution of bicarbonate of soda does towards carbonic acid. In both cases, it is 1.) in solution in water and its proportion there can be indefinitely increased according to Dalton's Law; 2.) in union easily dissociated by a vacuum aided by heat; 3.) in union unaffected by a vacuum and heat. This resemblance is very striking if we note the manner in which this gas leaves the blood when the blood is agitated with air at different barometric pressures. The agitation of blood with pure air, at normal pressure, very slowly takes from it a part of its carbonic acid, without being able to take it away altogether. If the air is expanded, the gas escapes a little more quickly. However, the experiments which have just been reported above show that, even at quite low pressures, the blood does not lose its carbonic acid quickly. However, this gas leaves the blood in slightly larger proportions than the oxygen; C02 so we see the proportion lose value directly as the decompres- o2 sion is increased (Exp. CXCIX, CC, and CCI) . On the other hand, when I brought about a progressive vacuum on blood placed in the mercury pump, I found that the acid left the blood in considerable proportions only at very low pressures, almost at the same time as the oxygen. In other words, the bicar- bonates and the alkaline phospho-carbonates behave in the vicinity of a vacuum like the deutoxy-hemoglobin of which I was speaking a little while ago. 1 Note sur les analyses du ga? du sang; influence de I'eau.— Proceedings, vol. LXXIV, p. 330; 1872. The memoir is published in full in the Journal de I'Anatomie et de la Phvsiologie, vol. VIII, p. 187-200; 1872. 2 The numbers expressing the volumes of the blood gases have always been reduced to the temperature of 0° and the pressure of 76 cm. * Du siege des combustions respiratoires. Journal de I'Anatomie et de la Phvsiologie, vol. II, p. 302-322; 1865. 4 Lecons, etc., p. 119. 5 Des gas du sang. Archives de Phvsiologie, vol. IV, p. 5-26, 190-203, 304-318, 447-469, 573-587, HO -731; 1871. • Lecons, etc., p. 130 et seq. 7 Lecons sur la physiologic de la respiration, p. 161. s Comptes rcndus de la Societe de Biologie for 1871, p. 61. »Trait6 de physioloqie, Third edition, vol. V, p. 592; 1868. 10 Comptes rendus de I'Academie des sciences, vol. LXXVI, p. 440; February, 1873. Chapter III PHENOMENA PRESENTED BY ANIMALS SUBJECTED TO PRESSURES LESS THAN THAT OF THE ATMOSPHERE The phenomena presented by animals subjected to a decrease of pressure are exactly those which were noted in mountain travellers and aeronauts; however, I have some interesting details to add to what is already known. But I do not hesitate to confess that since these phenomena are of a purely descriptive nature, it seems to me that an exact analysis of them should be made only after a sufficiently detailed study of their cause; interest in them was obviously a minor matter. I think, however, that I should report here the details of some experiments. It will then be easier to analyze the observations made and to group them around the principal physiological func- tions. But the conclusions which we draw from them will be sup- ported equally by the numerous experiments reported in the first subchapter of Chapter I, and the second subchapter of Chapter II, experiments which I thought it unnecessary to describe again here. After detailing these symptoms, I shall compare them with those presented by animals asphyxiated in closed vessels at normal pressure; I shall then deduce from all these facts the method which must be used in warding off the dangers of decompression, and I shall report the experiments carried out according to this method upon animals and even upon man. 660 Symptoms of Decompression 661 Subchapter I SYMPTOMS OF DECOMPRESSION Experiment CCXV. March 2. Little dog, put into the big cylinder. 2:05; Normal pressure; respiratory rate 16. 2: 15; Pressure 40 cm. respiratory rate 16. 2:20; Pressure 26 cm. respiratory rate 24. 2:26; pressure 22 cm. respiratory rate 40. Lies down; respiration dicrotic; it breathes first by the thorax, and then the abdomen rises. 2:36; Pressure 20 cm.; respiratory rate 44. 2:42; Pressure 19 cm.; respiratory rate 36. 2:47; Pressure 18 cm.; respiratory rate 40. 2:55; Inlet cock opened a little; pressure rises to 21 cm. Respira- tory rate falls to 30. Cock closed. At 3:00, the pressure is only 19 cm.; respiratory rate remains 30. 3:05; Pressure 18 cm.; Respiratory rate 28. 3:10; Pressure 22 cm.; Respiratory rate 18. 3:14; Pressure 23 cm.; Respiratory rate 16. 3:16; Pressure 25 cm.; Respiratory rate 14. 3:18; Return to normal pressure. 3:24; Respiratory rate 14. The animal is in good condition. Experiment CCXVI. March 21. Large spaniel at 3 o'clock in the large decompression cylinder. Its rectal temperature is 38.5°. At 4:58, pressure is only 25 cm. Normal pressure rapidly restored; tem- perature of the animal dropped to 36.5°. Experiment CCXVII. April 2. Female bulldog, having already had some operations; fastened in the same apparatus. 4:40 at normal pressure respiratory rate 24, pulse 125, rectal temperature 39°. 4:45; pressure 46 cm.; respiratory rate 24, pulse 110. 4:55; pressure 36 cm., respiratory rate 22, pulse 100. 5:05; the pump is stopped and the air returns to normal pressure; respiratory rate 20, pulse 120. The femoral artery has been bared and around it has been placed a copper wire which records its movements and allows the pulse to be counted. 5:35; the pump is set in operation and has brought the pressure to 46 cm.; respiratory rate 18, pulse 104. 5:45; pressure 36 cm., respiratory rate 24, pulse 100. 6:15; pressure 41 cm., respiratory rate 18, pulse 100. 6:20; normal pressure; rectal temperature 38.8°. Experiment CCXV HI. April 23. Dog, which has been given a hypo- dermic injection of 5 centigrams of morphine hydrochloride. At 4:30, put into the large cylinder with a manometer in the left femoral artery. Respiratory rate 20, pulse 126. At 4:32, pressure is 60 cm., respiratory rate 24 and pulse 120. At 4:35, pressure is 45 cm., respiratory rate 33 and pulse 184. 662 Experiments At 4:40, pressure normal; respiratory rate has fallen to 24 and pulse to 160. The arterial pressure cannot be ascertained exactly because of clots. Experiment CCXIX. May 27. Dog, fastened in the big apparatus, femoral artery exposed and cardiometer inserted. 5:40. Normal pressure; respiratory rate 30; pulse 134; arterial pressure 16 to 18 cm. 5:55. Pressure 36 cm.; respiratory rate 60; the animal has been struggling occasionally. 6:05. Pressure 26 cm.; respiratory rate 70, uneven. Connection made between artery and manometer; mercury rises and oscillates between 16 and 18 cm. Pulse rate 160 to 180 per minute. Return to normal pressure in five minutes; respiratory rate 20. The animal returns to normal state rapidly. Experiment CCXX. April 22. Cat brought rapidly to 26 cm. of pressure under a current of air at 2:30. Cannot stand up, lies down mewing. 3:20. Respiratory rate 33. 3:30. Brought back to 36 cm. because it seemed too sick. 5:30. Still lying curled up. Taken out at 6 o'clock; did not urinate. Kept under bell, but at normal pressure, under continued current of air. April 23. 10 o'clock in the morning, taken out. Has urinated; its urine contains no sugar. Recovers entirely. Experiment CCXXI. May 14. Cat weighing 3.500 k. Hypodermic of 10 centigrams of morphine hydrochloride. It is placed under a large glass bell with a volume of 31 liters; its femoral artery is exposed, and a copper wire passed around it records the pulse. The animal remains quiet all through the experiment. At 4:30, at normal pressure, respiratory rate 25; pulse 105. Lowering of the pressure is then begun, leaving a current of air, weak but sufficient to maintain the chemical purity of the air of the bell. At 4:50, pressure 56 cm.; respiratory rate 40, pulse 120. At 5:10, pressure 46 cm.; respiratory rate 40, pulse 120. At 5:20, pressure 36 cm.; respiratory rate 48, pulse 132. At 5:30, pressure 26 cm.; the animal is much affected, weak, with frequent convulsive starts; drools; respiratory rate 56, pulse 140. Pressure is lowered slowly to 20 cm.; the animal pants, shows general convulsive movements, and dies at 5:45. The lungs are collapsed, without crepitation; superficial emphy- sema; no pulmonary apoplexy. Dark blood in the left heart. Experiment CCXXII. February 28. Temperature 13°. Three rabbits of the same litter are placed at 2 o'clock under large bells, on the apparatus in Figure 1. A current of air is maintained under different pressures. Symptoms of Decompression 663 A: the rabbit weighs 770 gm.; pressure is maintained between 70 and 76 cm. B weighs 770 gm.; pressure oscillates between 45 and 50 cm. C weighs 840 gm.; pressure oscillates between 38 and 40 cm. At 2:30: for rabbit A, respiratory rate 70; for B, 80; for C, 120. They are removed at 6 o'clock without having shown any remark- able phenomena. Temperature of A, 39.5°; of B and C, only 38°. March 3, experiment repeated with the same results. Rabbit B, which was brought to 36 cm., then shows convulsive movements, which do not last. It urinates under the bell; this urine contains no sugar. Experiment CCXXIII. March 18. Rabbit under a large bell of 31 liters. 3: 15, for a quarter of an hour has been under a current of air at diminished pressure; it has remained perfectly quiet, with a respira- tory rate of 94, the pressure being 56 cm. 3:20, pressure 46 cm., respiratory rate 86. 3:25, pressure 42 cm., respiratory rate 66. 3:30, pressure 42 cm., respiratory rate 64. 3:38, pressure 35 cm., respiratory rate 70. 3:50, pressure 15 cm., respiratory rate 90. 3:53, pressure 16 cm., respiratory rate 45, shallow. Dies at 4 o'clock. Air admitted; the animal, which was swollen, collapses. Dark blood in the left heart; a few pulmonary ecchymoses. Experiment CCXXIV. March 20. Rabbit of 2.7 kilos under the large bell; temperature 20°. Placed at 2:26 under a current of air with diminishing pressure. 2:30, pressure 56 cm., respiratory rate 105. 2:36, pressure 41 cm., respiratory rate 99. There is a leak, air enters, and the pressure falls to O; respiratory rate 81. 2:46, pressure back at 50 cm., respiratory rate 138. 2:50, pressure 44 cm., respiratory rate 105. 2:54, pressure 36 cm., respiratory rate 120. 3:10, pressure 27 cm., respiratory rate 102. Remains between 27 and 24 cm. until 4: 18; respiratory rate 84. The animal kept at the same pressure struggles violently at 6:20, falls on its back, makes 3 or 4 deep respiratory movements, then remains motionless, dies. Interior temperature of the bell is 20°; that of the rabbit 32°. Experiment CCXXV. May 22. Free rabbit in the large bell of 31 liters. At the beginning, respiratory rate 56. Pressure is rapidly lowered to 56 cm., and the animal is kept there 20 minutes; its respiratory rate increases to 60. Pressure lowered to 36 cm.; respiratory rate rises to 100. But the animal remains quiet, without apparent inconvenience. Pressure lowered to 26 cm., to 22 cm., without the rabbit seeming much affected. At 16 cm., symptoms appear. At 12 cm., it struggles violently, is seized with general convulsions, and dies in a minute. 664 Experiments The lungs are the seat of great congestion, with hemorrhagic spots and scattered emphysema. Their density is greatly increased, but they still float. Experiment CCXXVI. May 23. Rabbit. Same bell, same decom- pressions, same general results. Experiment CCXXVII. March 10. Temperature 15°. Guinea pig weighing 320 gm. placed in the bell of 27 liters. At 2:50, I open the communicating cock between this bell and a large cylinder in which the pressure has been greatly lowered; the pressure in the bell in- stantly falls to 16 cm. The animal does not appear to suffer. Respira- tory rate 129. Since the bell is not entirely air-tight, the pressure rises slowly. At 3:13, it is 21 cm.; respiratory rate 104. I then open the cock"; the pressure drops to 17 cm.; the animal falls on its side, and rises almost instantly; respiratory rate 112. At 3:32, pressure 19 cm., respiratory rate 120; animal quiet. At 3:35, third opening of the cock; pressure drops to 16.5 cm.; staggers slightly. At 3:42, the pressure has risen to 18 cm. Fourth opening of the cock; pressure falls to 13.5 cm.; the guinea pig falls on its side; respir- atory rate 108. At 3:45, pressure 14 cm.; respiratory rate 78; on its side. At 3:51, pressure risen to 17 cm. Fifth opening of the cock; pres- sure falls to 11.5 cm.; the animal, which had risen slightly, lies down slowly; respiratory rate 36. At 3:55, pressure 13 cm.; respiratory rate 69; on its side. 4:01, pressure 14.5 cm.; respiratory rate 92; recovered considerably. 4:08, pressure 14.7 cm., respiratory rate 90. Violent jerking of the feet, the subcutaneous muscles, and the head; from this point to the end, the jerking keeps increasing. 4:13, 16 cm.; respiratory rate 93. 4:15, sixth opening of the cock; pressure falls to 13.5 cm.; a little more jerking, but the animal remains on its feet; respiratory rate rises to 108. 4:21, pressure 15 cm.; respiratory rate 85. 4:30, pressure 16 cm., respiratory rate 90; seventh opening of the cock; pressure 11.5 cm.; the animal, which has been crouching, raises its head twice, then lies down slowly. The violent jerking stops for a few minutes. 4:33, pressure 13 cm.; respiratory rate 52. 4:39, pressure 15 cm.; the animal has remained lying down. Pres- sure lowered to 12 cm.; does not seem to notice it. 4:46, pressure 14.5 cm.; respiratory rate 66. 4:53, ninth opening of the cock; pressure falls to 11.5 cm.; the animal raises its head, but remains lying down. 4:55, pressure 12 cm.; respiratory rate 84. 4:58, pressure 13 cm., respiratory rate 60. 4:59, tenth opening, which lowers the pressure to 10.7 cm.; the animal struggles considerably, and gets on its side. 5:00, pressure 11 cm.; respiratory rate 55. Symptoms of Decompression 665 5:03, pressure 12 cm.; respiratory rate 60. 5:12, pressure 13 cm.; I lower it to 11.7 cm.; no apparent effect. 5:20, pressure 14 cm.; respiratory rate 65. 5:22, twelfth opening; pressure falls to 10.8 cm. The animal twists and rolls on its side, with tonic and clonic convulsions. 5:24, pressure 11.7. The convulsions have ceased; only slight quiv- ering of the feet; it remains lying down, and never gets up again. 5:37, pressure 14.7 cm.; respiratory rate 80. 5:40, pressure 15 cm.; lowered to 11.7 cm.; the animal does not move but is evidently swelling. 5:53, pressure 15.5 cm.; same state. Fourteenth opening of the cock; lowered to 12.5 cm. 6:45, pressure 19 cm.; animal in same condition. Communication with outside air opened wide. Swelling diminishes, but the animal breathes no better; it is almost insensible; its rectal temperature has fallen to 20°. It remains lying on its side and dies in the night. No ecchymoses in the lungs. Experiment CCXXVIII. June 11; temperature 21°. Guinea pig, weighing 485 grams; put under a bell of 13.5 liters. From 3:24 to 3:30, the pressure is lowered to 26 cm.; the animal has not been struggling; but then he staggers, then recovers fairly well, scratches his nose, etc. At 3:32, same state; respiratory rate 100; walks a little. At 3:34, lowered to 20 cm.; respiratory rate rises to 135; the animal remains motionless. At 3:35, pressure 17.5 cm.; lies down on its belly. At 3:40, pressure 13.7 cm.; respiratory rate 80, deep, painful; pupils soon dilate; slight convulsive jerking comes on. At 3:45, same pressure maintained; the animal falls on its side; convulsive movements, with rigidity. Belly enormously swollen. Dies at 3:49. At 4:02, rectal temperature is 34.6°. Experiment CCXXIX. June 17; temperature 22°. Guinea pig in the large bell; current of air. From 2:50 to 3:45, pressure is lowered to 36 cm. Then, progressively, from 3:45 to 4:20, to 13 cm.; respiratory rate is then 20, and the animal remains lying on its side. At 4:25, pressure lowered for an instant to 10 cm. The animal makes convulsive movements of the feet and head; the breathing is difficult and jerky. Pressure maintained at 12 cm. until 4:40, then returned to normal. Its rectal temperature is then 25°. Very soon it rises on its feet; regains strength, gets warm; at 4:50, its rectal temperature has risen to 31°. It dies. Let us now examine the results of these experiments successively from the point of view of the different physiological functions. 666 Experiments 1. Respiration. In general, the respiration quickens when the pressure is lowered. But nothing is more irregular than these modifications in the respiratory rate. Here the effect of the suddenness of the phenomena is of greatest importance. The animal is startled, stirs about, struggles; it is irritated by the expansion of gases of which I shall speak under the heading of digestion, and all these effects accelerate its breathing. But it often happens that the respiration grows slower and becomes deeper; that is almost the rule at very low pressures. This is noticed particularly when the animal re- mains quiet; agitation has always seemed to me to speed up the breathing. In a word, here as in all the other circumstances, lessening of pressure acts the same as asphyxia. We know that in asphyxia in a closed vessel there is also a phase of respiratory acceleration, followed by a phase of retardation in which the thoracic move- ments are made slowly and painfully. The experiments reported in Chapter I also show frequent examples of this respiratory acceleration in animals kept at various low pressures. But to show how difficult it would be to include all these facts in a general formula, it is sufficient to study the experiments closely, being careful especially to show by graphs the results in which comparison is difficult. In Figures 47 and 48, in which the graphs show only respira- tory movements, and in Figures 49, 50, and 51, in which the pulse rate is also plotted, the direction of the arrows indicates the series of successive alterations in pressure to which the animals were subjected. When the arrow points to the right, the pressure de- creases; towards the left, it increases. Pressures are reckoned on the axis of the abscissae; on the vertical axis are written the num- bers corresponding to the respiratory movements R and to the pulse P. Line B (Fig. 47) gives the details of Experiment CCXV, made on a dog. We see that here effects were produced in a simple and regular manner, the number of respirations increasing or decreas- ing inversely as the pressure. Line A, on the contrary (Exp. CCXVII, another dog), shows a singular complication; in a general way, the number of respira- tory movements decreases as the pressure decreases. We note similar differences with rabbits. While Experiment CCXXV shows a simple relation between the pressure and the number of respiratory movements, Experiment CCXXIV, repre- Symptoms of Decompression 667 sented by line C, and Experiment CCXXIII, represented in D, seem to defy any generalization. But the maximum of complication imaginable is furnished by Fig. 47 — Modification of the number of respiratory movements under the influence of decompression: A, B, dogs; C, D, rabbits, 668 Experiments the graph of Figure 48, representing Experiment CCXXVII, made on a guinea pig. Indeed, we find all possible combinations and the most astonish- ing differences in both the direction and the amount of the modi- fications in respiratory rate. Let us remember that this experi- ment had an exceptional duration, and that the animal had been m ■ i m m I Fig. 48 — Modification of the number of respiratory movements under the influence of decompression: Guinea pig, Experiment CCXXVII. Symptoms of Decompression 669 chilled to the point of death before being returned to normal pressure. These facts, which I might have multiplied, serve to show that outside the general rule are found numerous exceptions, which explain the lack of agreement on this subject among observers on mountains and aeronauts. We shall return to this point later. Finally, let us note that besides the rate, respiration is affected in its rhythm; it becomes irregular, often dicrotic, sometimes deeper, and I have seen it in dogs at very low pressures separated into two parts: thoracic inspiration and then diaphragmatic in- spiration. Moreover, every general movement is accompanied by a sort of anhelation. All that agrees with what has been observed in man. The lessening of the maximum of respiratory capacity was shown by an experiment made upon myself, the details of which will be given in Subchapter III. At normal pressure it was repre- sented by the number 17.3, arbitrary value; at 430 mm. of pressure, it had fallen to 11.8, and after a half-hour stay under pressures of about 420 mm., it was only 9.9. 2. Circulation. Besides the experiments reported above, I think I should give the details of one which I made upon myself. Experiment CCXXX. July 29, the temperature being 23.5°, the pressure 75.5 cm., I enter the large cylinder, and sit down there, remaining very quiet. At 2:35, my pulse rate was 64, at normal pressure. At 2:45, pressure 72 cm.; pulse rate only 60; perhaps resting alone was enough to cause this drop. At 2:55, pressure 63 cm.; pulse 63. At 3 o'clock, pressure 60 cm.; pulse 67. I am now forced, by the expansion of the intestinal gases, to open my garments wide. At 3:08, pressure 55 cm.; pulse 67. I now rise and take two or three steps in the cylinder; my pulse immediately rises to 80. I let the pressure slowly rise. At 3:15, pressure 62 cm.; pulse 63. At 3:24, pressure 72 cm.; pulse 60. At 3:28, return to normal pressure; pulse only 59. I leave the cylinder and walk rather rapidly in the laboratory; my pulse rises only to 67. I have experienced no disagreeable sensations, except the tension of intestinal gases, and a need of swallowing my saliva frequently to clear the Eustachian tube. The experiments upon myself, whose details Subchapter III of the present chapter will recount, give the same results. 670 Experiments We see that in the decompression chamber the circulatory ac- celeration appears quickly, as aeronauts had already observed. It increases considerably at the slightest movements. Experiments on animals give evidence of the same sort. They usually show remarkable agreement between the variation of the number of respiratory movements and that of the cardiac beats. Fig. 49 — Simultaneous modifications of the number of respiratory move- ments R and the pulse P under the influence of decompression. Cat, Experiment CCXXI. Figure 49 gives a remarkable example of this, taken from Ex- periment CCXXI, made on a cat. The line of the pulse is marked P; it corresponds to Column P of the ordinates. The line of the respiration is indicated by the letter R, as is the value of its ordi- nates. The pressures are reckoned on the axis of the abscissae. The same agreement, though less constant, is observed in Figure 50, which shows the observations made during Experiment CCXVIII. Finally, in Figure 51, which gives the strange results of Experi- ment CCXVII, we see that if the number of respiratory movements diminishes with the pressure, the same is approximately true of Symptoms of Decompression 671 the heart beats. The latter even follow this general rule much more exactly than the former. Because of the clots which formed in the arteries and the ap- paratuses, it has been almost impossible for me to measure in a consistent manner the modifications of the cardiac pressure. The Fig. 50— Dog, Experiment CCXVIII. Fig. 51— Dog, Experiment CCXVII. Simultaneous modifications of the number of respiratory move- ments R and the pulse P under the influence of decompression. rare observations which I could make showed only slight diminu- tions; it seemed to me that it would be necessary to go very far to obtain noteworthy differences in animals which must be kept motionless. At a pressure of 26 cm., the heart had retained the same strength as at normal pressure (Exp. CCXIX). The results would no doubt be different, if the animals were performing labor comparable to that of travellers climbing a mountain. 672 Experiments I add that under the influence of pressures which are very weak and very quickly reached, I have sometimes seen nasal and pul- monary hemorrhages. But this is a very rare symptom in animals; in fact, it is not as common in man as is ordinarily stated. 3. Digestion. As a certain degree of decompression is approached, travellers have experienced nausea; I have likewise seen my animals stagger, wag their heads with evident distress, and vomit. Almost all birds showed this symptom. Animals subjected to extreme decompressions, and especially herbivores, were swollen in a very remarkable way by the expan- sion of their intestinal gases. It seemed to me, in some cases, that this swelling was great enough to act even on the respiration and hamper its movements. I have verified upon myself this disagreeable swelling, in Ex- periment CCXXX and in several others of the same sort reported in Subchapter III; but it never brought serious inconvenience, when the garments which confined the waist were unfastened and opened; besides, the gases easily found vent through the two in- testinal orifices. I even tried direct experiments, to obtain ocular evidence of this evacuation of gas. Experiment CCXXXI. December 10. A dog, which had just been killed by direct application of electrical stimulation to the heart, was fastened on a trough and placed in the decompression cylinders. Into its rectum was inserted a glass elbow tube, which by means of rubber packing completely closed the anus. The other end of the tube was immersed several centimeters deep in a glass full of water. The decompression was then begun, and as fast as the barometer fell, bubbles of gas burst on the surface of the water, and the greater the speed of the decompression pump, the more rapidly the bubbles followed each other. However, the belly was visibly swelling. On return to normal pressure it suddenly collapsed, and water entered the rectum. Experiment CCXXXII. February 27. Dog killed by hemorrhage, and prepared like the dog in the preceding experiment. It had also in its esophagus a tube immersed a little way in the water. At the very first strokes of the pump, the air left the anus con- stantly; several times the machine was stopped, and the gaseous evac- uation ceased immediately. But no gas left by the esophagus. The pressure was lowered to 30 cm. in 2 hours and 20 minutes. On return to normal pressure, the belly collapsed. Symptoms of Decompression 673 So the expanded gases leave very easily by the anus; but the last experiment shows, strangely enough, that they cannot, in a cadaver, escape by the cardia, nor probably by the pylorus, so that the stomach is distended. But in the living being this is not the case, and eructation is produced, thanks to muscular action. This influence of decompression upon the intestinal gases is not very important, but is interesting as being the only effect (or nearly so) that it causes as a purely physical agent. On several occasions in my cylinders I have also felt nausea and sickness caused by decompression. 4. Nervous and Muscular Effects. When the pressure is lowered considerably, we have seen the muscular strength of animals diminish rapidly. Birds refuse to attempt to fly. They all quickly become and remain motionless, no matter how much one excites and threatens them, or how fierce or frightened they seemed at first; at lower pressures, they are no longer able to remain upright but crouch; at still lower pres- sures, they fall on their sides. In Subchapter III, I shall give the details of experiments in which I underwent quite low pressures. I mention here this inter- esting note that, when I wanted to raise my leg which had been bent for some time, it was seized by convulsive jerks which I could not control, but which ceased as soon as I rested it once more on the floor. Similar quiverings have been reported by aeronauts, who generally attributed them to the cold. M. Sivel, who has experienced them, compares them to the period of chill in attacks of intermittent fever. Animals subjected to rather low pressures become, as it were, insensible and indifferent to everything; it seems evident to me that sensibility as well as strength of reaction fail them at the same time. Furthermore, in man, sensorial impressions are strangely lessened in keenness; we shall see the proof of that in the story of the ascent of Croce-Spinelli and Sivel. The same thing is true of moral energy, of intellectual activity; in one of my experiments, I was surprised at not being able to multiply 28, the number of my heart-beats in a third of a minute, by 3. I had to be satisfied with writing down these numbers in my notebook; this weakness, more- over, left me quite indifferent. When decompression approaches the fatal limit, when it has lasted a long time, or when it has been brought on very suddenly, we often see occurring in the animals convulsive jerkings which 674 Experiments recall, in an exaggerated way, the trembling I myself felt. At the extreme limits, when death comes, real convulsions appear, whose violence is in proportion to the strength which the animal then retains. When the decompression has been brought on slowly, when it has lasted a long time, when the animal is much weakened and chilled, no convulsions are observed, or they are very slight. I have shown elsewhere that the same thing is true in ordinary asphyxia, in closed vessels. For example, here is an experiment. Experiment CCXXXIII. September 17. Two starlings. A. One is placed under a bell of 900 cc, inverted over a basin of water. At the end of three quarters of an hour violent convulsions occur, and the bird dies. B. The second is put under a bell of 14 liters, also inverted over water. At the end of about 6 hours, respiration seems much affected. Death occurs after 9 hours and 25 minutes, with gradual phenomena, without convulsions. The convulsions produced by decompression, by asphyxia, and, I add, by hemorrhage, are merely a violent response of the spinal cord, over-stimulated by a sudden change in the conditions of its nutrition. If the transitions are carefully managed, if there are only slow and progressive changes, we see no more violent symp- toms, no more convulsions. The experiments reported in Chapter II, Subchapters I and IV, show that in decompression carbonic acid diminishes considerably in the blood. When death is reached, when convulsions occur, the animal has lost more than two-thirds of it. Very evidently the convulsive phenomena must not be attributed to this gas, as is stated in the theory propounded in 1850 by M. Brown-Sequard, and accepted today by a great number of physiologists.1 We shall see directly, in another chapter, that carbonic acid is a narcotic of the nerves and the muscles, far from tending to over-stimulate them. Here, I simply wish to call attention to the fact that in all the experiments which this learned physiologist has brought to sup- port his statement, the oxygen diminished rapidly to the point of disappearing, while the carbonic acid itself hardly increased in the blood and the tissues. What we have just said is enough, without further insistence, to prove that it is to this sudden decrease of oxygen that we should attribute the medullary excitations and the muscular contractions. I think I should add here that in animals killed by decompres- sion, as in animals rapidly asphyxiated or bled to death, one can Symptoms of Decompression 675 see, in the moments which precede death, the intestines twisting in the belly in violent peristaltic movements. 5. Nutrition. All the phenomena which we have just reviewed are only the consequences of disturbances of the nutrition of the tissues, dis- turbances due to the lessened quantity of oxygen in the blood. Our experiments on superoxygenated atmospheres have shown, in fact, that decompression as a physical agent plays a role that is almost negligible, and that the question is exclusively of a chemical nature. We ought therefore to study carefully these nutritive dis- turbances, which manifest themselves so clearly to us by the lower- ing of temperature. We shall therefore inquire into the modifica- tions undergone by the chemical phenomena of respiration: 1.) oxygen absorption, which is the primary factor; 2.) carbon dioxide excretion, which measures the energy of the intra-organic combus- tions; and 3.) the renal excretion, which can also serve as a measure of the chemical activity of the living body. 1. Chemical phenomena of respiration. The numerous experi- ments reported in Chapter I on the death in closed vessels of ani- mals subjected to more or less weak pressures make it possible for us to calculate easily the quantity of oxygen consumed and the quantity of carbonic acid exhaled, per unit of time, for each animal species, or for each kilogram of animal. I shall do so in a moment, taking into account only the experiments in which the behavior of the animal has been noted, for it is quite evident that results can be modified, even reversed in their general direction, by the single fact of a considerable uneasiness compared to an absolute repose. But it seemed to me desirable, for this delicate verification, to carry out special experiments, in which special precautions should be taken. Besides, the experiments of Chapter I end in death, and although comparable in this respect, they cannot be as convinc- ing as those in which the animals survive. Here are some of these new data. Experiment CCXXXIV. June 30. Rats of the same litter, each weighing 50 grams. A. Confined from 4:16 to 4:58 (42 minutes) under an airtight bell, containing 3.2 liters; normal pressure. B. Confined from 4:34 to 5:18 (42 minutes) under a bell of 7.1 liters, in which the pressure is rapidly brought to 34 cm. The volume of the bell corresponds to 3.17 liters at normal pressure. 676 Experiments C. Confined from 4:30 to 5:12 (42 minutes) under a bell of 11.5 liters, in which the pressure is rapidly brought to 20 cm. The volume of the bell corresponds to 3.03 liters at normal pressure. The three animals remain quiet, except B, which moves a little. C lies on his belly, but gets up when we excite him a little; he is better towards the end of the experiment; none of them appears then to suffer from the confinement. When the experiment is over, the rectal temperature of A is 38.1°; of B, 33.1°; of C, 32.0°. The composition of the air is as follows: A. O 14.8; CO* 5.2. B. O 16.0; COa 3.9. C. O 17.2; CO* 3.2. So the oxygen consumed, in vessels containing about the same quantity of air, was for A, 6.1 per cent; for B, 4.9 per cent; for C, 3.7 per cent. Establishing now the absolute value of oxygen consumption and carbonic acid production during the 42 minutes of the experiment, we find that: Oxygen CO. A, who had at his disposal 672 cc, has consumed 195 and produced 166 cc. B, who had at his disposal 666 cc, has consumed 155 and produced 123 cc. C, who had at his disposal 636 cc, has consumed 112 and produced 97 cc. Experiment CCXXXV, June 3. Rats of the same litter. Outside temperature 25°. a. Placed from 2:20 to 4:50 (2 hours, 30 minutes) at normal pres- sure, under a bell of 7.6 liters. b. Placed from 2:40 to 5:15 (2 hours, 35 minutes) at a pressure of 50 cm., under a bell of 11.5 liters, whose capacity at this pressure corresponds at normal pressure to 7.57 liters. c Placed from 2:55 to 5:30 (2 hours, 35 minutes) at a pressure of 37 cm., under a bell of 15.5 liters, whose capacity at this pressure corresponds at normal pressure to 7.53 liters. The animals remain very calm, and do not seem inconvenienced. At the end of the experiment, the temperature of a is 35°; that of b, 34°; that of c, 32.5°. (The thermometer was not exact, and these values should be considered not as absolute, but as comparative.) Chemical analysis gave: For a, : O? 11.3; CO* 8.1. For b, : 0= 12.5; CO* 7.8. For c, : O? 13.1; CO.- 5.9. Making the same calculations as for the preceding experiment, we find that in 2 hours and 35 minutes Oxygen CO? a, who had at his disposal 1596 cc, consumed 729 and produced 615 cc. b, who had at his disposal 1589 cc, consumed 636 and produced 590 cc. c, who had at his disposal 1581 cc, consumed 587 and produced 452 cc. Symptoms of Decompression 677 If we calculate the oxygen consumption for one hour, to com- pare the results of these two experiments more easily, we find that Oxygen CO A, at normal pressure, consumed 278 cc, and formed 237 a, at normal pressure, consumed 282 cc, and formed 246 b, at 50 cm. pressure, consumed 246 cc, and formed 237 c, at 37 cm. pressure, consumed 227 cc, and formed 180 B, at 34 cm. pressure, consumed 221 cc, and formed 175 C, at 20 cm. pressure, consumed 160 cc, and 'formed 138 The remarkable agreement between experiments A and a on the one hand, c and B on the other, shows that, in spite of the causes of error inherent in our experimental procedure, — causes of error which compel us to disregard the third figure in the num- bers reported above, — we can state definitely that the oxygen con- Fig. 52 — Consumption of oxygen and production of carbonic acid at differ- ent pressures. 678 Experiments sumption in a given time diminishes when the pressure itself diminishes; this fact is shown very clearly in graph A of Figure 52, which indicates the average of the results of the two preceding experiments. The production of carbonic acid gives rise to similar conclu- sions. Graph A' expresses its different stages. Let us refer now to the experiments of Chapter I, Subchapter I, and particularly to Table I, which summarizes them. We find here all the elements necessary for our calculation. Now if, without following all the details of the experiments, we take averages at different decompressions, we see that, in one hour, a sparrow: Oxygen CO At normal pressure (Exp. 1, 2, 3, 4) consumed 147 cc. and produced 122 cc. At about 50 cm. (Exp. 5, 6, 7, 8) consumed 118 cc. and produced 97 cc. At about 30 cm. (Exp. 13, 14, 17) consumed 80 cc. and produced 65 cc. At about 24 cm. (Exp. 24,25,26,27) consumed 72 cc. and produced 57 cc. At about 20 cm. (Exp. 33) consumed 60 cc and produced — — These results are indicated by Graphs B and B' in Figure 52. We see that, in spite of the important difference of methods (since here the sparrows remained until death, and consequently towards the end of life were all subjected to the same oxygen tension, the tension which produces death) , the results have remarkable agree- ment with the preceding ones, not only as to the general direction of their variation, but even as to the proportion of this variation. I am therefore quite justified in drawing from this collection of data the conclusion that, at low barometric pressures, an animal consumes, in a given time, a considerably smaller quantity of oxy- gen, and produces a considerably smaller quantity of carbonic acid than at normal pressure. This diminution, which increases propor- tionately as the pressure is lowered, is clearly apparent at a diminu- tion of a third of an atmosphere, which corresponds to a height of more than 3000 meters above sea level. We shall refer frequently to the consequences of this important principle, which is sufficient explanation, evidently, of all the symp- toms caused by lowered pressure. 2. Urinary excretion. After having ascertained that oxygen consumption and the intra-organic combustions which result in a production of carbonic acid are considerably diminished by a stay in decompressed air, I had to investigate whether these modifica- tions of nutrition do not also appear in the urinary excretion. I have given particular attention to urea. The analyses were made sometimes by the method of M. Grehant (use of the Milon Symptoms of Decompression 679 reagent and a vacuum), sometimes by that of M. Yvon (by hypo- bromide of soda) . Dogs were used as subjects of my experiments. The animal, enclosed in advance in the cylinders in which the decompression was to be carried on, was fed on a definite diet for two or three days; then we calculated the quantity of urea excreted in 24 hours, drawing the urine two mornings in succession, because dogs which are confined urinate at very irregular intervals. Of course, the urine voided spontaneously by the animal was carefully collected. The decompression having been maintained for several hours, we made a new analysis including the urine of the day from the morning of the experiment to the next morning. Sometimes, we also collected in the same way the urine of the 24 hours following. Here are some of the results obtained. Experiment CCXXXVI. July 3. Dog weighing 12 kilos; eats every day, between 7 and 8 in the morning, 250 gm. of bread and 250 gm. of meat boiled together with 500 gm. of water. July 4, at 10 in the morning, dog's bladder emptied. July 5, bladder emptied again at the same hour; he has not uri- nated spontaneously; we obtain thus 260 cc. of urine, which treated by the Yvon method give 7248 cc. of nitrogen. We conclude then that he voided 19.4 gm. of urea. On that day, from 11 to 6, the animal was subjected to a pressure of 38 cm. After he had left the apparatus, catheterization brought 100 cc. of urine, containing 7.4 gm. of urea. The next day at 11 in the morning, another catheterization, giving 80 cc. of urine, with 4.4 gm. of urea. Produced then in these 24 hours only 11.8 gm. of urea. The next day (July 7), catheterized at 1:15; the urine, added to what he voided during the night, amounts to 240 cc, containing 15.4 gm. of urea. Experiment CCXXXVII. Same dog, kept on the same diet. Catheterized July 7 at 1:15, as has just been said, then July 8 at 10:30 (21 hours), gives 246 cc. of urine containing 19.6 gm. of urea. July 8, from 10:55 to 4:45, is kept at 38 cm. pressure. July 9, at 1:15, has given (in 27 hours) 385 cc. of urine containing 24.7 gm. of urea. If we reduce these secretions to their proportionate value for 24 hours, we find: At normal pressure: 22.4 gm. At a half-atmosphere, 21.9 gm. Experiment CCXXXVIII. July 13. Same dog, subjected to same procedure. But he is tired of being confined. From July 13, at 7:45 in the morning (fasting) to July 14 at 8 in the morning (fasting) voided 200 cc. of urine, giving 13 gm. of urea. July 14, from 8:30 in the morning to 5:45 in the evening, kept at a pressure varying from 30 cm. to 35 cm. Does not seem weakened. 680 Experiments July 15, at 8 in the morning (fasting), all the urine collected, amounting to 211 cc. with only 7 gm. of urea. In the following 24 hours, he voids 130 cc, with 8.2 gm. of urea. Experiment CCXXXIX. June 9. Dog weighing 19.3 kilos. Kept for 4 days on a ration of 375 gm. of bread, 375 gm. of meat, and 500 gm. of water. From June 9, at 10 o'clock in the morning to June 10, at 10:45, voided 276 cc. of urine, which analyzed by the Grehant method con- tains 27.9 gm. of urea. June 10, from 11:30 in the morning to 6:30 in the evening, kept between 25 and 30 cm. of pressure. On leaving the apparatus, he is very much weakened, almost refusing to stand up. Catheterization extracts only a few drops of urine. June 11, at 10:30 in the morning, the catheter brings 390 cc. of clear urine, containing neither sugar nor albumen. It gives 20.7 gm. of urea. Experiment CCXL. June 17. Same dog, kept on the same diet, but not confined. June 17, at 10 in the morning, placed in the apparatus; June 18, at the same hour, gave 370 cc. of urine, containing 27.5 gm. of urea (Yvon method). June 18, from 11 to 5:30 kept between 36 and 38 cm. pressure. Respiratory rate rises from 16 to 24 and even 30. Leaves the appara- tus a little weakened; rectal temperature has fallen from 39.2° to 39.0°. Catheterization yields 100 cc. of urine, without sugar, containing 7.5 gm. of urea; the next day at noon produces 130 cc. of urine con- taining 6 gm. of urea; about 13.5 gm. in the 24 hours. Experiment CCXLI. June 23. Same dog; regular diet, but a some- what smaller quantity. At normal pressure, in 24 hours, yields 250 cc. of urine contain- ing 20 gm. of urea (Yvon method). From 1 o'clock to 6:30 subjected to a pressure of 38 cm. Voids in the 24 hours 220 cc. of urine containing 14.4 gm. of urea. The next day, at normal pressure, yields in 24 hours 36.8 gm. of urea in 600 cc. of urine. Experiment CCXLII. October 26. Dog weighing 20.5 kilos; kept for preceding 10 days on the following daily ration: 250 gm. meat, 250 gm. bread, 500 gm. water. From October 26, at 9 in the morning, to October 27, at 9:30, voids 336 cc. of urine containing 23.4 gm. of urea (Yvon method). October 27, from 9:45 to 5, subjected to a pressure varying from 30 to 40 cm. The next day, at 9:45, yields 570 cc. of urine, with 23.5 gm. of urea. In the following 24 hours, yields 330 cc. of urine with 17.3 gm. of urea. The day after, 390 cc. of urine, with 21.8 gm. of urea. These experiments show conclusively that a stay of several hours in an atmosphere whose pressure has been lowered by more Symptoms of Decompression 681 than half diminishes considerably the quantity of urea excreted in 24 hours. Whatever may be the various causes of error inherent in the experimental procedures, the exact agreement in direction, if not in absolute value, of the variations in all the experiments established satisfactorily a degree of certainty. This decrease has not been proportional to the decrease in pres- sure; it has varied with circumstances generally unknown; its maximum was 50.8 per cent in Experiment CCXL. In examining the record of these experiments, we notice that in number CCXLII, the decrease in urea was not seen on the day of the decompression, (23.4 gm. to 23.5 gm.) but the next day (17.3 gm.) ; the day after, normalcy was almost established (21.8 gm.) . In another case, Exp. CCXLI, on the day after the stay in decom- pressed air, the quantity of urea yielded was much increased, and rose considerably above the original figure, under normal pressure. These are questions of detail for the study of which we should be forced to increase the number of experiments, taking as subject man, in whom uniformity of diet, uniformity of movement, etc., can be more exactly obtained. Disregarding these secondary points, it is established that at low pressures the decrease in activity of chemical phenomena af- fects not only those which produce carbonic acid, but also those which cause the excretion of urea. The whole combination of intra-organic acts of oxidation is therefore considerably decreased when the air is sufficiently expanded. We must note that uric acid did not seem to be increased in the urine of the dogs, when the urea diminished; at least we did not note any precipitate, either spontaneous or following the acidifica- tion of the urine. This fact supports many others in showing that urea is not a product of the oxidation of uric acid, but that these two substances proceed from different chemical transformations. 3. Sugar of the liver and of the blood, glycosuria. I have re- peatedly established the presence of sugar in the urine of animals kept for several hours at low pressures. But the phenomenon always appeared in an irregular manner, so that I have not been able to reproduce it at will in comparable experiments. On the other hand, when the decompression is great and acts for a long time, sugar is more or less decreased in the liver; it may even wholly disappear. Example: Experiment CCXLIII. August 1. Rat, kept in a large bell, with air renewed from time to time, at a pressure oscillating between 30 and 40 cm., from 1:10 to 6:45. 682 Experiments Pressure is then lowered to 8 cm.; the animal dies at the end of 5 minutes. The liver is removed immediately, thrown into boiling water, then crushed with charcoal; no trace of sugar. Here then the chemical process which transforms the glycogen of the liver into sugar is also hampered by the decreased pressure. Here again, we find the absolute similarity between death by de- compression and slow asphyxia in closed vessels. We knew that in asphyxia also glycosuria is a phenomenon which is sometimes but not always observed. We understand that multiple conditions control its appearance. In fact, it is necessary that at a certain moment the liver should still be furnishing a great quantity of sugar to the blood, and that oxidation within the blood should at the same time be greatly hindered. These are conditions which are very complex and hard to produce at will. The amount of sugar in the arterial blood should also be care- fully ascertained. Here are some experiments performed for this purpose; the analyses were made by M. Dastre, who has had great experience in this kind of research. Experiment CCXLIV. February 26. Small Havanese dog. Its arterial blood contains per kilogram 0.95 gm. of glucose. It is placed under a large bell, at a pressure of about 20 or 25 cm.; at the end of a quarter of an hour it dies, the pressure having perhaps gone too low through carelessness. The blood of the right heart contains 3.48 gm. of glucose per kilogram. Much glycogenic material in the liver. Experiment CCXLV. February 27. Small dog, puny, sickly. Its arterial blood contains 1.80 gm. of glucose. Placed for three hours, under a current of air, at a pressure vary- ing between 15 and 25 cm. Then killed by sudden decompression falling to 5 cm. Blood of the right heart contains 1.84 gm. Much sugar and glycogenic material in the liver. No urine in the bladder; the kidneys and bladder, crushed in water, do not reduce to copper reagent. The temperature was not measured; but the animal did not seem to have grown perceptibly colder. Experiment CCXLVI. March 3. Small dog. Arterial blood contains 1.5 gm. of glucose. Brought in 20 minutes to a pressure of 17 cm., where it remained for 10 minutes. Then killed quickly by decompression (9 cm.). Arterial blood, taken from the heart during the last beats, con- tains 3.3 gm. of glucose. Rectal temperature 38°. Symptoms of Decompression 683 Much sugar and glycogenic material in the liver . No urine; the bladder and kidneys, crushed with water, give no sugar. And so, when the decompression has not lasted long but has been great, sugar increases in the blood; it returns to its normal value when the decompression has been sufficiently prolonged. This difference I think can be explained in the following manner: the liver, irritated by the action of blood that has suddenly lost its oxygen, pours into the circulation a large quantity of sugar which is shown by analysis, if the animal is killed in a short time; if, on the contrary, there is some delay, this sugar disappears, and since the liver is producing less and less of it, it returns to its usual value, then lessens and finally disappears, even from the liver, as is shown by Experiment CCXLIII on the rat. 4. Temperature. It is not surprising to see the temperature of the body fall, in consequence of this lessening of the chemical phenomena of the organism. This phenomenon had already been observed in mountain as- cents. Some attributed it to the surrounding cold, others to the labor performed, and in this connection I spoke, in the historical part, of the theory of M. Lortet. But the experiments reported above, show, by many examples, that the temperature of animals subjected to decompression falls without their doing the least work, without the air being chilled, and without the possibility of attributing the phenomenon to the current of air which must be kept around them to avoid the ac- cumulation of carbonic acid. The loss is generally 2 or 3 degrees for a drop of a half or two-thirds of an atmosphere in a half-hour, for example. But that depends on the degree of the decompres- sion, its duration, and the animal species. Thus, in a large dog (Exp. CCXVI), brought in two hours to 25 cm. pressure, the temperature had dropped 2 degrees. All the experiments give similar results. I shall mention par- ticularly, because it eliminates the effect of the current of air (Exp. CCXXII), that in which three rabbits were subjected, one to a current of air at normal pressure, the second to a current under a pressure of 50 to 55 cm., the third to a current under a pressure of 40 cm., all of them for four hours. At the end of this time, the temperature was, for the first, 39.5°; for the other two, 38°. The birds mentioned in Chapter I, Subchapter I, present phenomena of the same sort, whose details it would be useless to stress. But it is with guinea pigs that I have succeeded in getting the 684 Experiments greatest drops in temperature. One of them (Exp. CCXXIX) , kept for an hour at a pressure of 35 cm., and for an hour more at 25 and even 22 cm., had a rectal temperature of only 25°, on leaving the bell. But after a few minutes the temperature rose to 31° and the animal survived. The, guinea pig of Experiment CCXXVII, whose respirations furnished the graph in Figure 48, which remained nearly four hours oscillating between 21 and 11 cm., had a tempera- ture of only 20°; it is true that he died during the night after the experiment. Decompression then is in itself a cause of a drop in body tem- perature. In balloon ascensions, this cause is added to the direct action of an extremely low environmental temperature. In moun- tain journeys, these two causes take on a more serious importance because of the expenditure of energy required by the ascent. It is within these limits that the idea of Lortet can a priori be exact; but the decompression certainly must hinder the internal oxidation from acting as it would at normal pressure; no one will ever have mountain sickness from climbing a hill 1000 meters high, even if he were loaded with the heaviest burdens. 5. Development. I think I should report here an experiment which shows that the development of chrysalises is considerably impeded by lowering the pressure. Experiment CCXLVII. June 23. Silkworm cocoons, within a day of the same age, sent from Alais by M. Raulin, are placed: A. 12 in a bell open above, and consequently at normal pressure; B. 18 in a bell of 3.2 liters, at a pressure of 50 cm.; C. 18 in a bell of 7 liters; pressure of 38 cm.; D. 18 in a bell of 13 liters; pressure of 25 cm.; E. 5 in a bell of 6 liters; pressure of 5 cm. Bell D is broken June 25; the water of the hydraulic seal enters with the air; it is left unchanged. Every other day the air is changed in bells B and C; every day that in bell E is changed. July 8, the experiment is stopped, everything is thrown open to the air, and the cocoons are opened. The cocoons of A and D have been open since morning; the moths have issued. Of the chrysalises in B, 3 are metamorphosed, but the moths have remained in the cocoon. The others show considerable signs of life but are not metamor- phosed. Those of C show some signs of life, but are not metamorphosed. The cocoons of E are not opened. July 15, 3 more chrysalises in B are metamorphosed; but all are dead. Symptoms of Decompression 685 C: all are dead too; but under the case of the chrysalis, meta- morphosis is already far advanced. D: all dead, with a considerably lower degree of development. It would be interesting to make experiments with the eggs of frogs, the larvae of insects, etc. 6. Lower limit of pressure. The degree of decompression at which the different symptoms I have just enumerated occur, that of the lower limit incompatible with life, varies according to the species. The variation depends also upon whether the animals remained calm or were restless during the experiment. In sparrows, uneasiness generally begins to appear at about a half -atmosphere. The bird becomes restless; it stops hopping about, and its breathing becomes more rapid; about 25 cm. it begins to vomit and waver on its feet; soon it falls, and if the decompression approaches the fatal limit, it whirls about and jerks convulsively. We saw above that this limit was ordinarily from 17 to 18 cm. It may vary, between rather narrow limits, for the same species, in different animals, even when all the conditions of life appear quite identical. Here is an experiment in proof. Experiment CCXLVIII. June 18. 4 sparrows: A, old, vigorous male; B, C, D, females, in good health; all together in the same cage for several days. Placed together in a large bell of 30 liters, under a current of air. A cloth covering the bell keeps them from being frightened and stirring about unequally; they remain very calm dur- ing all the first part of the experiment, that is, until they are affected by the rarefied air. Decompression begins at 4:45. At 4:49, pressure is only 38.8 cm.; B and D vomit repeatedly. At 4:52, pressure 29.8 cm.; A also vomits. At 4:53, pressure 27.8 cm.; C vomits; D is very sick. At 4:54, pressure 26.8 cm.; all panting and crouched down, except C, which is standing on its feet. At 4:55, pressure 24.8 cm.; all are walking, dragging themselves this way and that, except that A remains motionless, its beak on the floor. At 4:56, pressure 23.8 cm.; A is evidently the sickest; then come D, then B, and finally C, considerably better than the others. At 4:58, pressure 21.3 cm.; A and D seem dying; they have fallen over, panting and in convulsions. At 4:59, pressure 20.3 cm., then the cocks are opened wide; A and D remain for some time on their backs, and do not recover until after the others. At 5:30, all are well. They survive. 686 Experiments I have shown that it is possible, with suitable precautions, to reach 10 cm. (Exp. XXXIX) , a limit which agrees with that indi- cated by the calculation for the minimal pressure of oxygen. This limit must be reached very slowly. On the other hand, if the drop is sudden, the symptoms appear much sooner, and for example, death occurs suddenly between 25 and 30 cm. The same thing is true when the animal struggles. Inversely, it often happens that an animal which appears very uneasy, near death, under a very low pressure, recovers, gets up, and becomes fairly well accustomed to it. All these data, which complicate the numerical solution of the problem, agree perfectly with the observations of mountain travel- lers and with what we know of the conditions of asphyxia. The more carefully the transitions are managed, the more easily the experimental animals become accustomed to them; the greater the consumption of oxygen, the more quickly the effect of its lack will be noted. Travellers, like birds under decompression, like asphyxiated animals, in a general way, suffer more in proportion to their activity; we have had many examples of travellers being forced at certain heights to stop in order to become accustomed to conditions, and to lie down in order to lessen the consumption of oxygen. The data I have given agree with this perfectly. Add that, after a certain number of experiments, summarized in Table II, the resistance is considerably less when the tempera- ture is very low. This is an important consideration, for travellers, like aeronauts, are generally exposed to this depressing condition. Now nothing is more natural than that the consumption of oxygen should be increased by the cold, if the temperature of the body is not to be considerably lowered. Different species. If we consider the average resistance pre- sented by the different species, we find that in birds, birds of prey appear almost as sensitive to decompression as sparrows. This is a strange fact, when we consider the considerable atmospheric heights reached by the large birds of prey. The following experiment, if we compare it with the preceding one, made the same day, gives a clearer proof than those taken from Table IV. Experiment CCXLIX. June 18. Gull (Larus ridibundus Lin.) and hawk (Falco tinnunculus Lin.). Decompression was made in the same conditions of speed as for the sparrows in Experiment CCXLVIII. I summarize in the follow- ing table the phenomena presented by the three species under the same pressure. Symptoms of Decompression 687 Pressure Hawk Gull Sparrows 38.8 cm B, D vomit 34.8 cm Vomits B, D vomit 31.8 cm Staggers, vomits B, D vomit 29.8 cm Staggers, vomits A vomits 27.8 cm. Vomits Staggers, vomits C vomits; D very- sick. 20.3 cm. Lying down, very sick. Lying down, sicker than the hawk. A and D dying. 18.8 cm. Lying down, very sick. Dying; cock opened Cock opened 17.8 cm. Dying; cock opened. And so the hawk is hardly more than a centimeter ahead of the gull, and two or three ahead of the sparrows. It would be very interesting to run an experiment not merely on a zoological repre- sentative of the high-flying birds of prey, but on one of these birds itself, a condor, for example; unfortunately, physiologists are not likely to have such luck. Among the mammals, cats seem almost as susceptible as spar- rows. They are certainly more so than dogs, for whose death the pressure must be lowered to 10 or 8 centimeters. Furthermore we have seen in the historical part that cats are hard to raise at high altitudes and even die soon there. Guinea pigs and rabbits are very easy to bring to low pressures, and since their temperature drops very quickly, they reach the state of cold-blooded animals, so to speak. New-born kittens are nearly in this state; and so they die a little later than adults. I had hoped, by subjecting to decompression an animal which hibernated, to bring it to very low pressures also, thinking that it would hibernate, so to speak; but the only experiment which I tried, on a hedgehog, disappointed me. I could not go below 18 centimeters without the life of the animal seeming immediately in danger. Finally I add that, as might have been expected, cold-blooded animals resist extremely low pressures. 7. Death. I have shown above that sometimes the animal dies without any movement, sometimes rises and stiffens violently before dying, and sometimes has real convulsions. All that, we have seen, depends on the state of exhaustion of the animal, the time which the experi- ment has lasted, etc. Autopsy shows hardly any interesting results. The blood is dark everywhere, except in the pulmonary veins, where it absorbs oxygen during the return to normal pressure. It never contains free gases. 688 Experiments In mammals, the lungs are sometimes a little emphysematous; almost always they are ecchymosed in places, sometimes, but rarely, with real hemorrhage; in other cases, following sudden decompressions, I have seen them practically carnified, returned to the fetal state, and sinking in large fragments to the bottom of the water. When I discuss sudden decompressions, I shall try to explain this strange phenomenon. One curious fact is the suddenness with which rigor mortis appears. I have observed this result carefully in sparrows. If one cuts off the head of one of these birds, rigor mortis does not appear for about three-quarters of an hour, whereas it comes between 10 and 20 minutes after death in rarefied air. I shall take as examples a certain number of experiments re- ported in Chapter I. They give the data for the following table. Table XIII Experiment 3 Rigor mortis Temp, of animal Observations E s ° £ U a E H appeared after at time of rigor XIX 76 19° More than 38 min. I Head cut off. XVI 19.7 19° Less than 25 min. 24° (about) | Lived 1 h. 45m.; calm. XVII 20.8 19° Less than 20 min. 31.6° | Died in 2 m. Convuls. XVIII 27.8 19° 17 minutes 26.7° Lived 2 h. No convuls. XX 30.8|20° 15 minutes 20.5° " 6 h. 53 m. Calm. XXI 30.3120° Less than 20 min. 24° (about) " 4 h. 25 m. Calm. XXII 26.l|20° 1 Less than 17 min. 34.7° Died in 6 m. No great convulsions. XXIV 30.3|20° 1 Less than 20 min. 27° Lived 1 h. 31 m. Agitation. XXVI 24.2|20.5° About 15 min. 28° (about) Lived 2 h. 10 m. Great agitation and violent convulsions. XXVII 24.2|20.5° 11 minutes 27.2° Lived 1 h. 50 m. Ver> calm. Lived 1 h. 4 m. XXVIII 24.2 20.5° Less than 20 min. 28° (about) Agitation. We see that this is a phenomenon that is absolutely constant and independent of the speed of death, the quiet or agitation of the bird, and the degree to which its temperature has fallen. It does not exist in asphyxia in closed vessels, at normal pres- sure (except in the conditions of Experiment CCL) and I think it can be attributed only to the exhaustion of the carbonic acid of the blood and the tissues, by breathing in rarefied air. We shall see in Chapter VIII that this exhaustion is real. Symptoms of Decompression 689 Subchapter II COMPARISON OF THE PHENOMENA OF DECOMPRES- SION WITH THOSE OF ASPHYXIA IN CLOSED VESSELS I have repeatedly stressed the parallel between the phenomena of decompression and those of asphyxia in closed vessels, a paral- lel continued even in the smallest details. I did so in the first chapter, comparing the duration of life of animals in both situa- tions, under the influence of different conditions. I did so again in regard to the gases contained in the arterial blood in animals under low pressures and in those asphyxiated in closed vessels, when the carbonic acid is removed as it is produced (Chap. II, Subchap. IV). The descriptions given by countless authors who have killed animals by asphyxia agree in every point with the phenomena which we have just enumerated. The respiratory rate is shown becoming generally faster at first, then slowing up and appearing very painful when the animal suffers considerably. The pulse rate, in its number and strength, has been much less studied. But the nausea, the frightened movements, the final convulsions in the circumstances which we have specified elsewhere have all been noted. If the phenomena of nutrition have not had sufficient at- tention, we have not forgotten the drop in body temperature, and M. Claude Bernard mentioned the disappearance of the sugar of the liver in slow asphyxia. We must note, however, that in the conditions of asphyxia in which these experimenters placed their animals, the carbonic acid was stored up in the surrounding air, without their having deter- mined the influence exerted by this gas, some denying it com- pletely, others exaggerating it grossly. The phenomena relating to the decrease in oxygen absorbed, and in the carbonic acid and urea excreted by animals breathing an atmosphere low in oxygen content, have not been studied care- fully enough up to the present. I do not even know any study re- lating to urinary excretion, and that lack is easily understood; it would be exceedingly difficult to keep animals on which such an experiment could be made for a considerable length of time in rarefied air that was suitably renewed. As to the absorption of oxygen, while making several successive analyses of the air of a bell in which an animal was slowly asphyxiated, I have very often observed that the animal consumed 690 Experiments less and less oxygen for equal units of time in proportion to the progress of the experiment towards its fatal conclusion. Experiment CLXXXVII furnishes an example of this: here, carbonic acid was absorbed by potash as it was formed, so that comparison with pure expanded air is quite legitimate; in the first two hours the dog had consumed 41 per cent of the oxygen of the closed sack in which he was breathing, while in the following two hours he consumed only 36 per cent, the total volume of the sack being moreover much reduced in consequence of the absorption of the carbonic acid. The experiments which will be reported in Chapter VIII (Sub- chap. II) will give the same sort of evidence. So the lack of oxygen in the air gives the same result as its expansion. As to the lowering of temperature, the experiments of Chapter II, Subchapter IV, give us interesting figures. In Experiment CLXXXVII, in which asphyxia lasted 4 hours and 45 minutes, the temperature had fallen from 39° to 34.5°. In Experiment CLXXXVIII: duration 4 hours 30 minutes; temperature, from 38.5° to 34°. There also the two terms which we are seeking to compare at present are identical. If we consider respiratory and circulatory phenomena from the simple point of view of number of movements, we find the same general tendency and the same irregularities, in asphyxia as in decompression. Figure 53 gives an idea of their trend: the unbroken line gives the results of Experiment CLXXXVII, the dotted line those of Ex- periment CLXXXVIII. The oxygen content of the air is inscribed on the axis of the abscissae. The number of respirations (R) and of the pulse (P) on the axis of the ordinates, on different scales. We see that in these graphs is shown, after a phase of uncer- tainty and irregularity, a period of acceleration in the two types of movement, followed by a period of sudden slowing up. In some cases, at the end of life, the heart again begins to beat rapidly, but its beats are very weak. This occurred in one of the experiments reported in Subchapter II of Chapter VIII, in which the beats, after having fallen from 120 to 14 at the moment when insensitivity of the eye appeared, rose suddenly to 60 for some minutes, when respiration ceased. As to blood pressure, it drops slowly at first, then rapidly. Figure 54, whose graphs relate to Experiment CLXXXVII, shows the course of the maxima and minima, in proportion to the oxygen content of the air. Symptoms of Decompression 691 All these phenomena prove once more that the effects of de- compression are identical with those of slow asphyxia, or, in better terms, of breathing an air with low oxygen content. This identity is indicated again by an interesting coincidence. The details of the experiments reported in, the present book show that not only death but also the different symptoms appear in Fig. 53 — Asphyxia without carbonic acid. Number of heart beats P, P', and of respiration R, R', in relation to the gradual impoverishment of the air. 692 Experiments asphyxia at a degree of oxygen lack and in expanded air at a de- gree of decompression in which the oxygen tension is identical. So, in dogs, respiratory disturbances appear in confined air at about the time when there is only 12 per cent of oxygen; in pure air, they appear at about the pressure of 43 cm., a pressure which is met at about 5000 meters altitude; in both cases the oxygen ten- sion is the same, for 12 x 76 = 20.9 x 43.6. As to serious symptoms, nausea, etc., the proportion of oxygen in the confined air must drop to about 8 per cent, or the barometric pressure of the pure air must be reduced to about 30 cm., which corresponds to a height of 7300 meters; the oxygen tension is the same in both cases. Fig. 54 — Maxima and minima of cardiac pressure in asphyxia without carbonic acid. Now — new confirmation — , it is at these altitudes approximately that the symptoms and disturbances which constitute "balloon sickness" occur in aeronauts, motionless in their basket. The agreement becomes still more interesting when it concerns observations on man himself. The most important are contributed by M. Felix Leblanc,2 who had the opportunity to analyze the air of the mines of Poul- laouen and Huelgoat, in Brittany, whose treatise contains valuable information about the sensations of the miners. The pyrites which are present in abundance in the veins being worked combine with a part of the oxygen in the air, which is thus lessened without being tainted at the same time by carbonic acid or other gases, as happens in confined places. From the data reported by M. Leblanc we extract the following: A: In a place where there is only 16.7 per cent of oxygen, respiration is only slightly affected, but the air is considered "weak" by the miners; Symptoms of Decompression 693 B: With 15.3 per cent of oxygen, breathing is continuous and not very difficult. C: With 9.8 per cent of oxygen, the air is asphyxiating, and at the end of one or two minutes, fainting fits occur. M. Leblanc, who went in suddenly, almost fainted, and the master miner who accompanied him was seized by vertigo and nausea. Now, in observation A, the oxygen tension equals that existing in pure air at 60.4 cm. of pressure; which corresponds to a height of 1800 meters. For observation B, the equivalent pressure is 55.3 cm., and the altitude 2500 meters. For C, the pressure is 35.4 cm., and the altitude 6000 meters. It is absolutely certain that a dweller in the plains, suddenly transferred to heights of 1800 and particularly 2500 meters, and driven immediately to the hard work of miners, would, like them, find the air weak and breathing rather difficult. It is absolutely certain that an aeronaut who was transferred to a height of 6000 meters as suddenly as in the observation of M. Leblanc and who, like this chemist, tried to make the effort necessary to climb a slope and empty a flask full of mercury, would also experience decidedly serious symptoms. Finally— the last resemblance to which we shall call attention —the strange rapidity with which rigor mortis appears in animals dying in rarefied air is found also in death by asphyxia, when the carbonic acid formed is eliminated by absorbing it with potash. Example: Experiment CCL. March 20. At 3 o'clock, a finch is placed under a bell of 3 liters on a tripod which isolates it from a crystallizing pan full of a potash solution. An elbow tube connects this bell with an- other which rests on the water basin, and in which the water will rise proportionately with the absorption of CO., so that the pressure will always remain the same. At 4 o'clock, the bird, which was a little uneasy at the beginning, lies down and remains quiet; pants. It dies at 6:23; rectal temperature 31°. Rigidity begins in the wings at 6:34; it is complete at 6:45. Our parallel between the symptoms of decompression and those of asphyxia is therefore complete, and continues even to the least details with remarkable precision. In both cases, the whole thing is summarized in this formula: nutritional disturbances due to the introduction into the organism of an insufficient quantity of oxygen in a given time. 694 Experiments Subchapter III. MEANS OF AVERTING THE SYMPTOMS OF DECOMPRESSION The numerous data now enumerated have shown very clearly that the symptoms of decompression are due, not to the lessening of atmospheric pressure, but to the diminution of the tension of the oxygen, which no longer enters the blood, or consequently the tissues, in sufficient quantity to maintain the vital combustions at their normal rate. The preventive measures for these symptoms are naturally derived from this very idea. The tension of a gas, we have often said already, is expressed by the product P x Q, in which the barometric pressure P is multi- plied by the percentage of Q of the gas in the surrounding mixture. If then we increase the factor Q at the same time that we diminish factor P by the use of the pneumatic pump, there will be no change in the tension, and the symptoms should be averted. At the same time, if the result justifies our expectations, the theory which serves as the base will once more be verified. But the experiment, under the form I have just indicated, is very hard to carry out. We reach the same conclusions by ex- ecuting it in the conditions of the experiment whose details I shall now give. Experiment CCLI. April 23. Sparrow, under a bell of 1.5 liters, on the plate of the pneumatic machine. Outside pressure is 75 cm. 3:20, brought in a few minutes to 25 cm. pressure; respiratory rate 212. At 21 cm., whirls, falls head over heels, about to die. I restore normal pressure by admitting air very rich in oxygen (by accident, outer air enters at the same time) ; the bird recovers immediately and seems lively and well. 3:30, the air then contains 35 per cent of oxygen. I bring the bird to 18 cm. pressure; he is then very sick, with a respiratory rate of 176; I admit oxygen again, he recovers immediately. 3:40, the air contains 77.2 per cent of oxygen. The bird under 13 cm. pressure has a respiratory rate of 168, but he falls only at 10 cm. Likewise recovers immediately after the admission of super- oxygenated air. 3:50, the air contains 87.2 per cent of oxygen. The sparrow, at 10 cm., has a respiratory rate of 176, and seems in no danger; but at 8 cm., he falls on his back and is about to die. New admission of oxygen, recovers again. 4:05, the air contains 91.8 per cent of oxygen. We continue to the Symptoms of Decompression 695 pressure of 7.5 cm.; the bird is very sick, and we have barely time to open the cocks. The minimal tensions of oxygen have been successively 5.8; 6.3; 10; 9.2; 9.1. The bird survives. And so dangerous decompressions have become successively harmless, because the percentage of oxygen in the air has been sufficiently and progressively increased. We reached 12.5 cm. be- fore the symptoms which announce imminent death reappeared, and we saw a bird survive after having undergone the pro- digiously low pressure of 7.5 cm. I do not doubt that we could go even farther if we proceeded slowly enough. I have often repeated in public this very simple experiment, which can be carried out in all physics laboratories, and which is at the same time very conclusive and very impressive. Figure 55 shows the experimental set-up. By itself, it would be enough to bring conviction; but to in- crease the convincing effect, one can complete it by the following crucial experiment. Fig. 55— Bird in air increasingly expanded and increasingly oxygenated. A. Bell-jar communicating at B with the pump, at C with a barometric tube, at D with a bag full of oxygen O. 696 Experiments Experiment CCLII. April 24. Under a bell of 2.5 liters, placed on the plate of the pneumatic machine, and previously filled with air very rich in oxygen, a sparrow is placed. Outside pressure 75 cm. The air then contains 82.2 per cent of oxygen; the pressure is lowered. At 5:30, the pressure is only 13.5 cm.; the bird is uneasy and flutters in the bell. At 9.5 cm., it is very sick and about to die. Air somewhat superoxygenated is admitted. The bird recovers im- mediately. 5:38, the air contains 55.7 per cent of oxygen; we begin to lower the pressure again, without being able to go lower than 11 cm. Air somewhat superoxygenated is admitted; bird quite recovered. 5:45, the analysis of the air has been lost. In the decompression we reached only 13 cm. This time too, the bird is so sick that it re- mains some seconds motionless on its back after normal pressure is restored with ordinary air. 5:55, the air contains only 22 per cent of oxygen; so that we cannot pass below 18 cm. 6:05, this time we use ordinary air; at 20.5 cm., the bird is very sick; but he recovers perfectly under normal pressure. He has a large bloody spot on his head. The oxygen tension at the moment when pressure had to be restored was successively 10.7; 8.0; 5.0; 5.6. This last experiment can be made still more simple. Experiment CCL1II. June 5. Green grosbeak (Fringilla chloris Lin.). Put under the bell of the pneumatic machine. Pressure slowly decreased; sick at 30 cm. of actual pressure, and as it stirred about somewhat, was quite sick at 22 cm. I then let pure nitrogen enter the bell to restore normal pressure. The bird, far from recovering, dies almost immediately. It has in the cranial diploe a huge dark effusion. Whatever the operative procedure used, these different experi- ments show clearly both the cause of the symptoms resulting from decompression and the means of averting them. Evidently I could not limit myself to experiments made on animals, however convincing, when I was issuing practical precepts intended for mountain travellers and aeronauts. I resolved to begin by experimenting on myself. I had already undergone, in my large sheet-iron cylinders, rather considerable decompressions, to the point of experiencing certain discomforts. I then thought of trying the test again, so as to remove the symp- toms by breathing a superoxygenated air. I placed beside me in the apparatus a large rubber bag, con- taining air whose oxygen content was in proportion to the degree of decompression. Figure 56 shows the set-up of the experiments. I give here the details of three of them, and of a fourth which Symptoms of Decompression 697 was carried on by my regretted colleagues and friends, MM. Croce-Spinelli and Sivel. Fig. 56 — Respiration of superoxygenated air, expanded by decrease of pressure. Experiment CCLIV. February 20, 1874. Outside pressure 758 mm. 2:30, I enter and seat myself comfortably in the cylinders, hav- ing with me a bag filled with air extremely rich in oxygen; beside me, a sparrow in a cage. . My pulse rate is 64; my temperature taken under the tongue with great care is 36.5°; an expiration in a Hutchinson spirometer gives me a value fixed on the arbitrary scale as 17.3. 2:37, the door is closed, the decompression begins. 2:45, pressure 710 mm.; pulse 68. 2:58, pressure 590 mm.; pulse, 70; I am at a decompression cor- responding approximately to the elevation of Mexico, 2150 meters. 3:02; 535 mm.; pulse, 73. 3:06; 500 mm.; intestinal gases escape. 3:08; 465 mm.; pulse, 78. 3:12; 450 mm.; pulse, 84; it is the barometric pressure of Cala- marca, at 4150 meters; I have slight nausea. Experiments 3:14; 450 meters.; pulse drops to 80; nausea disappears; the ab- domen is slightly distended; my face feels congested and I have slight dizziness . 3:17; 430 mm.; pulse, 84. I breathe oxygen three times; my pulse falls to 78; dizziness. 3:21; pressure is only 418 mm.; which corresponds to the eleva- tion of Mont Blanc, 4800 meters; my pulse rate continues to drop after some breaths of oxygen; it is only 70; at each respiration, dizzi- ness. 3:23; 420 mm.; I rise breathing air; my pulse rate rises im- mediately to 96, then to 100; I have outright vertigo; I sit down again. 3:25; 445 mm.; pulse rate drops to 90, then after a breath of oxygen, to 70, at 3:26, at a pressure of 460 mm. 3:28; 450 mm.; the bird falls in its cage. 3:30; 440 mm.; pulse, 76; belching of gas. 3:32; 435 mm. Wishing to raise my right leg without leaving my chair, it was seized with convulsive trembling in the muscles of the calf and thigh, a trembling which I could not control with my hand; it ceased when I placed my foot firmly on the floor; tem- perature under the tongue is 36.8°. 3:34; 443 mm.; pulse, 80; a breath of oxygen. 3:35; 445 mm.; pulse rate falls immediately to 70; trying to whistle at this moment, I note that it is impossible. 3:37; 436 mm.; pulse, 80. 3:39; 430 mm.; I breathe into the spirometer; dizziness; I am now only 11.8 (on the arbitrary scale mentioned above). 3:43; 435 mm.; pulse, 80. 3:45; 423 mm.; pulse 90. I take several breaths of oxygen; dizzi- ness. 3:47; 423 mm.; pulse rate has fallen to 69. 3:48; 423 mm.; I move about on my chair; slight dizziness. 3:49; 425 mm.; pulse 78. 3:50; 420 mm.; pulse 86. 3:51; 418 mm.; pulse 87; I take a breath of oxygen. 3:53; 426 mm.; pulse 78. 3:55; 430 mm.; pulse 80; some breaths of oxygen; dizziness. 3:57; 430 mm.; pulse 72. 3:59; 420 mm.; pulse 84. I am quite uncomfortable; having found that the number of my heart beats for 20 seconds was 28, I have very great difficulty in multiplying this number by 3, and I write in my notebook "hard to calculate." 4:01; 413 mm.; pulse 88. 4:03; 408 mm.; pulse 92; painful nausea; dizziness; congestion in the head; convulsive trembling when I raise my leg. 4:04; 415 mm.; pulse 90; I breathe oxygen; dizziness. 4:05; 416 mm.; pulse only 75. 4:07; 420 mm.; I breathe into the spirometer, and go only to 9.9; dizziness and vertigo after having breathed. 4:09; 430 mm.; temperature under the tongue, 36.7°. Symptoms of Decompression 699 4:14; 445 mm.; pulse 78; I take three breaths of oxygen; dizziness; the pulse rate falls at once to 63. 4:18; 452 mm.; pulse 79; five times I take breaths of oxygen, each separated by two breaths of air. 4:20; 450 mm.; the pulse has gone down to 63. The bird, thrown into the air, falls whirling, and lets itself be caught in the hand. 4:24; 465 mm.; pulse 72; I make an effort and rise; the pulse rises immediately to 84. 4:26; 490 mm.; pulse 72; I take some breaths of oxygen; dizziness. 4:29; 495 mm.; pulse 60. 4:33; 500 mm.; pulse 65; several breaths of oxygen; the pulse falls to 64; I try in vain to whistle. 4:37; 540 mm.; pulse 69; the bird refuses to fly from above the cage, but is quite revived. 4:38; 555 mm.; I cannot whistle. 4:40; 590 mm.; pulse 63; I begin to be able to whistle easily enough. 4:45; 759 mm.; pulse 58; temperature under the tongue, 36.6°. The interior temperature of the apparatus has not varied. In this first experiment, the breaths of oxygenated air were intermittent, and the effect of each appeared immediately. Nausea Fig. 57 — Sudden modifications in the pulse rate by intermittent respira- tions of superoxygenated air. Upper graph, progress of decom- pression; lower graph, pulse rate; O, inspiration of oxygen. 700 Experiments disappeared and well-being was restored immediately. The pulse rate— and this is a very exact indication— dropped immediately, to return soon to its former figure. The graphs of Figure 57 show very clearly these curious changes. The hours are marked on the horizontal axis. The upper graph represents the downward course of the barometric pressure, with the elevation corresponding to certain decompressions; the lower graph indicates the variations in heart rate. At every breath of oxygen, marked O, we see an instant fall of this latter line; the demonstration is very clear. Such sudden modifications in the circulatory rhythm must necessarily have ill consequences; it is to them that I attribute the dizziness which accompanied each breath of oxygen. I add that on the evening of this experiment for several hours I felt symptoms of cerebral congestion which continued to annoy me somewhat. I wish the reader also to note the muscular trembling and the strange state of mental weakness from which I suffered on reaching the pressure of 420 mm., that is, about that of the elevation of Mont Blanc; with a pencil in my hand, I was almost incapable of multiplying 28 by 3. On the ninth of March, the next month, MM. Croce-Spinelli and Sivel, who were planning ascents to a great height, came to my laboratory with the purpose of studying upon themselves the dis- agreeable effects of decompression and the favorable influence of superoxygenated air. I can do no better than to reproduce the account which M. Croce-Spinelli drew up for me immediately, from the notes which he and M. Sivel took constantly in the apparatus, of phenomena which they both experienced. Experiment CCLV. The diminution of pressure went on regu- larly; in 35 minutes they were brought to 304 mm.; the return to normal pressure was made in 22 minutes. They therefore re- mained for 25 minutes below a pressure of 450 mm. Paris, March 10, 1874. Sir: I am transmitting to you the data which M. Sivel and I collected and the impressions we felt in your decompression bells, March 9, 1874. Emotion did not appreciably affect these observations, for I think that none existed in M. Sivel, and it was extremely weak in me during the whole experiment. The constant preoccupation of observing data explains that well enough. The experiment began at 10:31. Symptoms of Decompression 701 The first moments of the decompression gave rise to no dis- agreeable impression. At 10:34 at a pressure of 70.5 cm. of mercury I found a pulse rate of 80 in M. Sivel; and very shortly after, at G8 cm., 92 in myself. At 1:40, pressure 56 cm., the pulse rate of M. Sivel was 100; mine was also. At 1:44, pressure 51 cm., my pulse was 116, M. Sivel's 108. Beginning with a pressure of about 48 cm., oppression begins to be quite perceptible. I become lazier and am satisfied with con- sidering what effects I feel. My face feels hot, and so does M. Sivel's at a pressure of about 44 cm. Besides, I have prickly sensations in my head, an itching which feels like a scalp affection. Mental energy is not at all weakened, for we are gay and talkative. At 1:40, about 41 cm., M. Sivel breathes oxygen from the bag, not from necessity, but to lessen the considerable tension of the con- tainer, which is ready to burst. At a pressure of 40 cm., I feel un- comfortable, my head seems to be in a vise, and I feel as if I were pressing my forehead hard against a bar of small diameter. My pulse rate is 135. At 1:57, at a pressure of 39 cm., I breathe some gulps of oxygen from the bag which M. Sivel holds out to me. I feel better and my pulse rate falls to 128, although the decompression is continued. We pass each other the oxygen bag. My companion uses it un- til the maximum decompression, 5 or 6 times, often very freely, and I do 3 or 4 times, in a way that is generally more moderate and even awkward, for, feeling at first a certain distaste for breathing this gas which smells of rubber, I lose a fairly large quantity of it. However, as the pressure lowers, I overcome this repugnance more easily, and feel instinctively the necessity of absorbing this gas. At 38 and 37 cm., my pulse rate is 128 after breathing oxygen; at 35 cm., it is 132. It is certain that if oxygen were not inhaled, it would be higher. In M. Sivel, the absorption of the oxygen produced the follow- ing effects: the bell seemed to him to be moving as if he were drunk, and this effect lasted for several seconds; he had a slight sensation of seasickness. Then this discomfort vanished and his mind became keener than before the oxygen was inhaled. In me, the same impressions were present, but in a greater de- gree. Moreover, below 35 cm., my vision, which was growing dull, became very noticeably keener after the absorption of oxygen. I saw clearly after having seen dimly; the interior of the bell seemed suddenly to become lighter. At these low pressures, the mind had become very dull in both of us, but particularly in me. During the four minutes preceding the time when we reached 30.4 cm., I could only note down the pressures which M. Sivel dictated to me very loudly, and the simplest calcula- tions seemed very difficult to me. I was very deaf and had to have the pressure figures repeated several times. The air no longer seemed to conduct sound. At 11:08, at a pressure of 30.4 cm., neither M. Sivel nor I was saying a word. However, we had been very gay, very talkative and active to about 37 cm. It is true, we no longer had any oxygen, and 702 Experiments this fact caused a sort of instinctive regret in me. M. Sivel's mind then wavered a bit, and I was in a state of decided prostration. The weakness, however, had not yet reached such a point that we could not have endured (with some difficulty, it is true) two or three centi- meters more of decompression, especially M. Sivel, who throughout showed himself less affected than I. During the whole experiment, neither of us noted anv abdominal distention or pulmonary oppression, which astonished me in myself, since I have very sensitive lungs. Our faces had finally purpled. M. Sivel had become deep violet, and I, who am ordinarily pale, light violet. My right ear was very red. M. Sivel, having noted my state of great discomfort, asked me whether I thought that the decompression should be stopped. I answered yes, because there was no more oxygen. The memory of this fact did not return to me immediately after the experiment, and it is only at this moment when I am writing that it becomes very clear to me. They stopped the machine then and opened the intake cocks. Here is the pulse rate noted during the period of recompression: in me, at 52 cm., 104; at 59 cm., 100; at 66 cm., 96. In M. Sivel, at 62 cm., 98. In 7 minutes, we returned to 45 cm., and in spite of the speed of the rise in pressure, we not only felt no discomfort, but on the con- trary, experienced a very agreeable sensation, I in particular. It was not until afterwards that buzzing in the ears began in both of us. M. Sivel drank some water and ate a little, and twice felt relief when his ear suddenly became unstopped. I was more sensitive to the buzzing than he; my ear was unstopped only once, and I had severe pain. This pain increased at about 70 cm., when the operators, seeing on the outer manometer only a few centimeters of decompression left, opened the intake cock wide. That probably caused the earache which persisted in me after the experiment. On leaving the bell at 11:30, after a 59 minute experiment, I felt as if there were cotton in my ears, tightly wedged in, but I was not in pain. My head was free, but my mind a little feverish. All day I felt my ears, especially the right one, very dull. In the evening the right ear ached. I went to bed at 11, but could not get to sleep till 4 in the morning. I had not only twinges and a neuralgia in my temples, but the inner ear seemed swollen, and a pressure of the hand caused pain. I soothed the pain by wrapping my head up. As for M. Sivel, this experience left him no ill effects. I should say that my "bell companion" is of a sanguine tempera- ment, that he enjoys excellent health, and that he has a very vigorous appearance. He is used to long journeys, on land and sea, and he has made two balloon ascensions. Although of a good consti- tution, I am evidently less strong than he. I have a "lymphatico- nervous" temperament. It seems a good idea to compare the sensations felt in the bell with those I experienced in the ascent to 4600 meters, under a baro- metric pressure of 429 mm., in the company of MM. Jobert, Penaud, Dr. Petard, and Sivel. In this ascent, I felt no disagreeable sensation Symptoms of Decompression 703 caused by the decompression, nor did my companions. Now in the bell, about 50 cm., my face prickled, and M. Sivel had the same sensa- tion at 44 cm. Before 429 mm., the discomfort was already very considerable, and I had the feeling of a bar across my forehead, whereas there was nothing of the sort during the ascension. In the bell, my pulse rate was 116 at 51 cm., 135 at 40 cm., and in the basket of the balloon, it was 116 between 43 and 44 cm. The pulse rate of M. Sivel was 108 at 46.5 cm. in the bell, and 110 at 43 cm. in the basket. I noted the ear buzzing in the ascension exactly as in the bell. As the balloon descended, it seemed as if there were cotton in my ears. This impression lasted till the next day, but the pain was never more than very slight. As in the bell, the pain increased during the last centimeters of recompression, because of the rapidity of the descent. In this experiment, the two aeronauts went to a pressure of 304 mm. of mercury, corresponding to an elevation of 7300 meters. They were, consequently, much more greatly affected than I had been, not having passed 418 mm., an elevation of 5100 meters; nervous phenomena dominated the scene in them; dimness of vision, . intellectual indolence were very noticeable in M. Croce- Spinelli. M. Sivel, who entered the apparatus fasting, began to eat during the decompression; he soon stopped, and as I signed to him through the glass portholes to continue, he replied by a gesture of disgust. The favorable action of oxygen was also very evident; after several inhalations the distressing symptoms disappeared. At one time, at very low pressures, the lips and the right ear (the only one I saw) of M. Croce-Spinelli had become so purple that I was pre- paring to open the cocks, when he put the oxygen tube to his mouth; the effect, that is, the return to normal color, was in- stantaneous. M. Croce-Spinelli told me when he had left the ap- paratus, that he resorted to oxygen at that time because he could hardly see his paper, which suddenly at the first inhalation ap- peared to him very white, as if he were dazzled. In these two experiments, oxygen had been used only intermit- tently, to lessen for some instants the severity of the symptoms of decompression. I wanted to operate a little differently, letting the discomforts come on to a certain degree, then breathing super- oxygenated air continuously, still decreasing the barometric pres- sure, and seeing what would happen. Here is the account of two experiments carried on according to this procedure. Experiment CCLVI. March 28. I enter the apparatus at 10:55; the door is closed at 11:04; my pulse rate is 58. Barometric pressure, 761 mm. 704 Experiments 11:10; pressure 715 mm.; pulse 62. 11:20; 580 mm.; pulse 63. 11:23; 535 mm.; pulse, 63; slight nausea. 11:25; 510 mm.; gas escaping above and below. 11:27; 495 mm.; pulse, 66. 11:31; 455 mm.; pulse, 64; nausea; gas escapes, and yet the abdo- men remains somewhat distended. 11:33; 435 mm.; pulse, 70; act of whistling, which I manage very well at normal pressure and which had become difficult at 520 mm., is completely impossible. 11:35; 425 mm.; pulse, 72; a little trouble with vision, which is less clear. 11:37; 412 mm.; pulse, 76; I am quite uncomfortable, with my eyes somewhat affected. I begin then to inhale continuously from the bag full of super- oxygenated air which I have beside me; the exhaled air goes outside. Occasionally I am dizzy, then every symptom disappears, and until the end of the experiment, I am in a state of perfect comfort. The pulse rate, which had fallen instantly to 63, is still falling, although the decompression progresses. 11:41; pressure, 408 mm.; pulse, 60. 11:46; 382 mm.; pulse, 63. 11:47; 380 mm.; gas escapes by the mouth and anus; perfect com- fort. 11:48; 369 mm.; pulse, 58; more gas. 11:51; 355 mm.; pulse, 59. 11:52; 350 mm.; more gas. 11:55; 338 mm.; I make efforts to open and close a flask; the pulse rises to 63; pressure begins to rise again. 11:59; 400 mm.; pulse, 60. 12 (noon); 440 mm.; impossible to whistle. 12:02; 490 mm., pulse, 60; impossible to whistle; I stop breathing superoxygenated air. 12:03; 520 mm.; impossible to whistle; pulse, 56. 12:05; 540 mm.; I begin to be able to whistle. 12:07; 570 mm.; I whistle very well; pulse, 59. 12:10; return to normal pressure; pulse, 52. This experiment shows very clearly that continuous inhalations of oxygen, after having checked painful symptoms, prevent them from reappearing, although the barometric pressure continues to fall. Nothing is more conclusive. The decompression reached was 338 mm., corresponding to the elevation of about 6500 meters, that is, a little more than that of Chimborazo. Figure 58 shows the different phases through which the heart beats passed before and during inhalations of oxygen, whose begin- ning is marked by 0. Among other phenomena which continued in spite of the in- haling of oxygen, because they depend entirely upon the decrease Symptoms of Decompression 705 of the density of the air, I shall mention the evacuations of gas and the inability to whistle, which had already been noted in the pre- .5 u ™ tuo ft X o T3 O o 3 ceding experiment, but of which neither aeronauts nor mountain climbers speak; it was observed below 500 mm. 706 Experiments The following experiment, conducted in the same manner, is even more striking because of the enormous decompression to which I subjected myself without harm. Experiment CCLVII. March 30. I enter the apparatus at 10:15; pressure 759 mm. I have with me a sparrow, whose rectal temper- ature is 41.9°, a rat, and a candle. 10:22; they close the door; pulse rate, 60. 10:29; pressure 710 mm.; pulse, 63. 10:34; 665 mm.; pulse, 64. 10:40; 640 mm.; pulse, 65; I see bubbles of gas appearing in the water I have beside me in a glass. 10:43; 605 mm. 10:46; 580 mm.; pulse, 66. At 555 mm., I whistle easily enough; the flame of the candle grows rather blue, the wick lengthens; it is almost half the length of the flame. At 510 mm., impossible to whistle high notes. 10:53; 480 mm.; pulse, 70; a little discomfort. 10:55; 455 mm.; pulse, 78; a feeling of congestion in the head; gas escaping above and below. 10:58; 430 mm.; pulse, 80; the bird vomits, appears quite sick, but remains perched; the rat seems quite calm. 11:00; 410 mm.; pulse, 86; I place before my mouth the tube of the oxygen bag, which the decompression has distended, and breathe a very highly superoxygenated mixture; dizziness. 11:02; 400 mm.; pulse has dropped to 64; the bird vomits again; the rat seems very uneasy. 11:05; 378 mm.; pulse, 66; impossible to whistle. 11:09; 360 mm.; pulse, 72; a little discomfort, although I have breathed oxygen continuously, but at a distance, it is true. I then take the discharge tube in my mouth, without closing the nostrils, and keep it there until the end of the experiment. The discomfort dis- appears immediately. 11:11; 348 mm.; pulse, 66; the sparrow's respiratory rate is 126. 11:14; 323 mm.; pulse, 64; the sparrow, which is vomiting hard, nevertheless remains on its perch. 11:17; 310 mm.; I have a little discomfort, with a pulse of 75. 11:19; 300 mm.; the sparrow is very sick. 11:22; 295 mm.; pulse, 64; my discomfort has entirely disappeared. 11:24; 288 mm. 11:27; 280 mm.; pulse, 66; the flame of the candle is very blue; the wick is about % the length of the flame. 11:33; 258 mm.; pulse, 70; the bird vomits and seems extremely sick, but it still remains on its perch. 11:34; 255 mm. 11:36; 248 mm.; pulse, 64; I let the pressure increase. 11:38; 290 mm.; pulse, 63. 11:40; 340 mm.; the rectal temperature of the sparrow is only 36.4°. 11:43; 390 mm.; pulse, 54; I stop breathing oxygen. Symptoms of Decompression 707 11:44; 420 mm.; impossible to whistle; the bird is still very sick, crouching on its perch. 11:46; 480 mm.; impossible to whistle. 11:47; 550 mm.; still impossible to whistle; pulse, 66. 11:48; 580 mm.; I can whistle the low notes, but not the high ones. 11:49; 630 mm.; I can whistle very well. 11:51; returned to normal pressure; pulse, only 52. The rectal temperature of the sparrow is 36.1°; that of the rat, 34°; my tempera- ture under the tongue is 36.5°. At 3:30, the sparrow's rectal temperature is still only 38.7°. Here is an experiment in which in an hour and a quarter I reached a minimum pressure of 248 millimeters, that is, less than a third of normal pressure, during which experiment I remained 45 minutes below 400 millimeters, without having experienced dis- comfort from the moment when I began to breathe the super- oxygenated air regularly. My pulse, as the lower graph in Figure 59 shows, remained from then on at its normal figure; it even dropped towards the end, either because of the long rest in a seated posture, or under the influence of breathing superoxy- genated air. Beside me, a sparrow and a rat were very sick, and ™~1 70 - \^PRES iSlONS ~jj 60 — X V \ SO - X V \ 40 — V f 30 — ^ k / 1 25 - 80 70 CAOURICHN PULSATION KA .- 88<0"r 1 IS ^ ^^-^ , / J 1° " s \ ^^ — " > — 1 x= *^^— — , 1 — ^^ 60 50 | — ■ ^""Vw ^s ^^ : 1 0"20 30 40 50 iV! 10 20 30 '.0 1«| Fig. 59 — Modifications in the pulse rate, during decompression, by contin- uous breathing of oxygen. (Exper. CCLVII.) 708 Experiments their temperature dropped several degrees. As for me, far from running any risk, I felt none of the slight discomforts of decom- pression, nausea, headache, or congestion of the head, nor did I feel any after leaving the apparatus. It even seemed to me as if I could have gone lower yet, with no inconvenience, and I was quite ready to do so, had not my steam pumps, weary with work, refused to continue exhausting the air of the cylinders. Perhaps I must blame the complicity of the people witnessing the experiment, who frequently came and looked at me through the portholes and, in spite of the quite natural appearance of my face, seemed greatly terrified at seeing me exposed to this enormous diminution of pressure. In fact, it corresponded to more than 8800 meters, that is, an elevation greater than that which mountain travellers and aeronauts, except MM. Coxwell and Glaisher, have ever been able to reach. I felt no discomfort at this pressure which was nearly fatal to the two brave Englishmen, and at which a few months later MM. Croce-Spinelli and Sivel were to perish. 1 See his experimental researches on the physiological properties and the uses of red blood and dark blood. Journal dc la physiologic de I'homme et dcs animaux; 1858, p. 90, 101, 105. 3 Recherches sur la composition de I'air de quelqucs mines (Annates de chimie et de physique, Third series, vol. XV), Chapter IV ACTION OF COMPRESSED AIR ON ANIMALS Subchapter I TOXIC ACTION OF OXYGEN AT HIGH TENSION The experiments reported in Chapter I, Subchapter II, have brought us to this remarkable conclusion, that compressed air, or, to speak more exactly, the oxygen which has reached a certain tension constitutes a dangerous element, often even fatal, for ani- mal life. This unexpected revelation, which is deduced from all our series of experiments in such a way as to be convincing to the most suspicious mind, deserved deep study. The symptoms of this unknown sort of poisoning in its different degrees had to be analyzed; the concentrations at which oxygen becomes dangerous had to be determined, both as to its tension in the exterior respira- tory medium and as to its proportion in the interior respiratory medium, the blood; an explanation had to be found for its inner mode of action upon the different anatomical elements. This new problem left far behind it in scientific interest the analysis of some modifications in the respiratory and circulatory rhythms hitherto studied by the authors who gave their atten- tion to compressed air. I devoted myself to it at the very beginning with all the concentration of which I was capable. Having demon- strated successively that compressed air acts only by the tension of the oxygen which it contains, and that this oxygen can kill animals rapidly with convulsive symptoms, following the usual 709 710 Experiments method of physiologists, I had to set aside for the moment the effects of low concentrations of oxygen, which are hard to esti- mate, and study first the violent symptoms caused by high concen- trations. In the first place, I investigated the action of oxygen under high tension, generally adding to the manometric pressure a percentage of oxygen sufficient to produce a value much greater than that in the air which we breathe. I think it advisable to report here a certain number of experi- ments which will permit me to give first a description of the symp- toms resulting from what I shall call, if only for convenience in nomenclature, poisoning by oxygen. Already we have noted the convulsions which had attacked sparrows subjected to this dangerous agent. The following ex- periments, almost all performed in the Seltzer water apparatus, will furnish us new examples. Experiment CCLVIIK January 29. House sparrow subjected to 6 atmospheres, 5 of which were oxygen, from 3:50 to 3:58. The mix- ture contained 81 per cent of oxygen, and the tension of this gas was 486 therefore equivalent to 81 x 6 = 486, which corresponds to = 23.2 atmospheres of air. 20.9 At 4:03, violent convulsions, the head hanging down; whirling. I lower the pressure and bring it to 3.5 atmospheres. During the decompression, new convulsions. Immediately after, third attack; then new attacks, weaker and weaker, at 4:06, 4:11, 4:14. During the attacks, and in the intervals, the respirations are very deep and very hasty; the beak is wide open. The attacks come oftener at intervals of 1 to 2 minutes, becoming weaker and weaker. They subside about 4:40; the bird remains lying on its back, its respirations become rarer and rarer, and cease at 5 o'clock, without any other movement. At 5:10, the rectal temperature is 24°. Experiment CCLIX. February 2. House sparrow, subjected to 6 atmospheres, 5 of which are oxygen. The oxygen tension is about 450. After 5 minutes, strange tremors, a quivering through the whole body; then it remains motionless, its beak down. After 10 minutes, an attack of strong convulsions; another at 12 minutes; a third, weaker, at 17 minutes. The bird is very sick, breathes from 50 to 70 times a minute, its beak wide open. Brought back carefully to normal pressure; recovers a very little; rectal temperature, 34° to 35°. In its cage it has new convulsive attacks; at the end of a quarter of an hour, gets up on its feet; but when it is threatened with the finger, it draws back walking on the whole tarsus, and falls backwards. Compressed Air; (X Poisoning 711 After 2 or 3 hours, seems fairly well recovered, but dies in the night. Experiment CCLX. February 5. Sparrow subjected to 5 atmos- pheres, 4 of which are oxygen. The oxygen tension is about 400. After about 15 minutes, strong convulsions occur; I allow 2 or 3 attacks, then restore normal pressure. The rectal temperature is 32°. The bird has evidently retained all its intelligence; it pecks viciously when a finger is presented to it, and uses its wings and feet strongly. One hour afterwards, its temperature is 34°. It has had more of the slight convulsive attacks, and cannot keep on its feet. 3 hours afterwards, its rectal temperature has risen to 39.5°. Survives. Experiment CCLXI. February 26. Sparrow; rectal temperature 40.5°. Subjected to 5 atmospheres, 4 of which are oxygen (tension of about 400). At the end of 5 minutes, beginning of uneasiness. I restore normal pressure rapidly by the capillary cock. The temperature is 40.3°, but it rises rapidly to 40.5° after respi- ration in the air. The bird is very vigorous and very vicious. Red cranial suffusions, in abundant spots. The bird walks, runs, climbs about the cage, but does not fly. If it is tossed into the air, it has great difficulty in flying and soon falls; it then refuses to fly up from the ground. Survives; the next day, it flies very well; the suffusions persist for several days. Experiment CCLX1I. March 2. Sparrow at 5 atmospheres, 4 of which are oxygen. After 5 or 7 minutes, convulsions begin; at the first appearance, I open the little cock. The rectal temperature rises to 41°, but very slowly after 38°. Small bloody suffusions. Experiment CCLXIII. May 23. At 4 o'clock, sparrow taken to 5 atmospheres, 4 of which are oxygen. Tension about 400. After 15 minutes, slight convulsions; at 20 minutes, severe con- vulsions, two or three attacks. At 30 minutes, taken out. Rectal temperature, 33°. At 5:45, rectal temperature, 35°; still trembling, quite sick. At 7 o'clock, dead; muscular contractions singularly slow. Experiment CCLXIV. February 12. Sparrow; cylindrical appara- tus. At normal pressure, respiratory rate, 135. Raised to 3 atmospheres of air, respiratory rate, 115. At 4:20, I pass a current of oxygen into the apparatus, and raise the pressure to 2 superoxygenated atmospheres. 712 Experiments At 4:30, new ventilation, and pressure raised to 3 atmospheres. At 4:40, the same; pressure at 4 atmospheres. At 4:55, the same, 5V4 atmospheres; little convulsions begin to appear. At 5:06, new ventilation carried to 6 atmospheres. Convulsions return, in spasms. Dead about 6:50. The air then contained 73 per cent of oxygen and 0.5 per cent of carbonic acid. The oxygen tension P x 0-> = 438 corresponds to 21 atmospheres of air. Blood very red in the jugular. Bloody suffusions extending over the whole cranium. Experiment CCLXV. March 29. Sparrow placed in the small Seltzer water apparatus. At 2:50 we begin to compress oxygen up to 8 atmospheres; the capillary cock being open, the compression maintained is carried on in a current of air delivering more than a liter per minute. At 3:15 great convulsions occur; I allow two attacks to succeed each other, at three minutes interval. Then, rapid decompression. The bird pecks the finger which I offer it, and appears intelligent. Its rectal temperature is 32°. When out of the apparatus, it has a third attack, and dies at 3:22. The blood of the jugular vein is dark and contains no free gases. Experiment CCLXVI. July 9. Sparrow taken to 7 atmospheres of superoxygenated air. After 10 minutes, seized by tonic convulsions. Taken out after 15 minutes; the convulsions continue, or rather the bird is in constant opisthotonos. From time to time, the stiffness increases; the bird cries out, spreads its wings, and wraps itself in them; the tail feathers are spread out. Remains sensitive and appears intelligent. The attacks of rigor are some of them spontaneous, others clearly provokable by stimuli. It dies 20 minutes afterwards. Experiment CCLXVII. July 18. Sparrow taken to 5 atmospheres of superoxygenated air. After 5 minutes, vomits, and appears in very bad shape. But the convulsions do not come until about 20 minutes after, and they are violent. Taken out 5 minutes afterwards, it continues to have convulsions and stiffness with opisthotonos. Pecks the finger presented to it. Its rectal temperature is 37°. Two hours after, is perfectly recovered; its temperature has risen to 41°. Experiment CCLXVIII. May 24, 1874. Experiment made before a Committee of the Academy of Sciences. Sparrow taken to 6 atmospheres, superoxygenated. It is 4 o'clock. After about 15 minutes, slight convulsions occur, soon followed by severe attacks. Compressed Air; O, Poisoning 713 The bird is removed; it has large ecchymoses on the cranium. Its rectal temperature is only 30°. Remains very sick and dies in the night. The data which have just been given permit us from now on to describe the violent symptoms due to compressed air, to too high oxygen tension, and to prepare the physiological analysis of this poisoning. The first question which we should ask ourselves is as follows: at what oxygen tension do the convulsive symptoms appear? Let us collect in a table (Table XIV) the experiments of Chapter I and those which precede. Table XIV 1 2 3 4 5 6 _ C u ■§! C a Experiment a a u 3 Numbers t>u £& CO Symptoms and observations lid CQ Cu re Sic *2 Equiva atmosp of air atm. CXXXIX 1.75 150 7 No convulsions CXXXVIII 3 260 13 Id. CXLI 4 300 15 Convulsions. CXX I 20 abt. 420 20 Convulsions; the apparatus leaks. Convulsions; withdrawn, survives. CCLX 5 id. I abt. 21 32° CCLXI 5 id. id. 40.2° Withdrawn after first conv., survives CCLXII 5 id. id. 38° Id. CCLXVII 5 id. id. 37° Id. CCLXIII 5 id. id. 33° Conv.; withdrawn after 30 min., dies. CXXXVII 5 id. id.. 18° Violent conv., dies in 25 minutes. CXLII 8.5 430 21.5 Id.; dies in 20 min. cclxiv 6 440 22 Id. CXLV 5.5 460 23 27° Id.; dies in 20 min. CCLXVIII 6 30° Id.; dies during the night. CCLVIII 6 480 24 Id.; dies. CCLIX 6 id. (?) I id.(?) 35° Id.; withdrawn; dies during night CCLXV 1 8 32° Id.; withdrawn; dies at once We see from an examination of this table that the convulsions begin to appear with an oxygen tension expressed by the figure 300, which, if we used pure air, would correspond to about 15 atmospheres. The harmful effects were observed much sooner, as graph A of Figure 22 shows, which expresses the proportion of oxygen re- maining in the compressed air in which the birds died, when we took care to eliminate the carbonic acid formed. The harmful effects are very clear beginning with 6 and especially with 12 atmospheres. But the convulsions appear surely only between 15 and 20 atmospheres. Experiment CXX, in which a linnet was taken to 20 atmospheres of air, shows their appearance; only they were 714 Experiments considerably weaker than those obtained with superoxygenated air. Furthermore, in Experiment CXXXIII, in which the pressure was 17 atmospheres, there were no convulsions. This apparent contradiction is explained by the simultaneous influence of the carbonic acid produced, which, being stored in the organism, plays a very pronounced anesthetic part there, as we shall see in a spe- cial chapter. Now we shall show in a moment that anesthetics stop or hinder the convulsions due to oxygen. Let us give now a brief description of these convulsions; we shall have to return to them when we have studied them in dogs. These convulsions occur at the end of a variable time, generally from 5 to 10 minutes; the bird shakes its head and feet as if it were walking on hot coals. There are strange tremblings, quiver- ings through the whole body. Soon, in more serious cases, it half- opens its wings, moves them quickly, and falling on its back, it whirls rapidly in the receiver, beating the air with its wings violently, its feet curled up against its belly; these phenomena last for a few minutes, then grow calm, then reappear in attacks which are more and more frequent and less and less strong until death. During the attacks, and in the intervals, the respirations are very deep and very hasty; the beak is very wide open. At very high pressures, death comes at the first attack. These remarkable symptoms continue to appear after the bird, removed from the influence of oxygen, has been restored to the open air under normal pressure; they may even then end in death. These attacks are often very clearly provokable, like those of strychnine (See Experiment CCLXVI) ; their general appearance recalls at the same time the irregular quiverings of poisoning by phenol,1 and the tonic and clonic convulsions of convulsive strych- nine attacks. Neither sensitivity nor intelligence seems affected; the bird, taken from the receiver, looks at and tries to peck the finger which threatens it; it closes its eyelids when some object approaches its eye. General locomotion is evidently much affected, besides the convulsive attacks, of course; the bird has ataxic movements; in certain cases, it can hardly stand on its feet; in others, it can walk, but not fly. Finally — and this is the most important point of this research, after the observations of these symptoms — the inner temperature drops in all cases rapidly and considerably. It falls 10 and 15 degrees; I call particular attention to Experiment CCLV, in which, Compressed Air; 02 Poisoning 715 although the temperature had fallen to 32° in less than a half- hour, it rose rather quickly to nearly 40° and the bird survived. I shall later dwell upon this remarkable fact, to which at present I merely call attention; it shows very clearly that the symptoms of oxygen poisoning are not due to an exaggerated activity im- parted to the intra-organic combustions. The first idea which would come to mind, and I admit freely that it came to mine immediately, is that under the influence of this super-saturation of oxygen the animal tissues would be con- sumed excessively, that an increase in the temperature would re- sult, and that the convulsions which appeared could be compared to those which precede the death of animals over-heated in a drying-oven. Now we can state immediately that this is not true, although later I shall analyze this important phenomenon thor- oughly. Finally I shall say a few words of a symptom always present in birds in cases of oxygen poisoning, a symptom which I have designated by the expression "bloody suffusions of the cranium." They are hemorrhages which fill the cranial diploe; in the mildest cases they consist only of very small dots; these dots are replaced by wide spots which become confluent in severe cases, and the spongy tissue of the bone fills with blood. They always begin in the occipital, but may affect the whole cranium. They appear before the convulsions, and when the bird does not die, they are not absorbed for several weeks. Although they always exist when the symptoms due to oxygen become serious, they are not especially characteristic of this poisoning. Since my attention was called to their existence, I have found them quite often in asphyxia and death by decompression. In fact, they were noted in some of the experiments reported in Chapter I; when they are not mentioned, it simply means that no one looked for them. I should add that I never saw them so extensive or so deep as in oxygen poisoning. I have no understanding of their mech- anism; they appear without any convulsive phenomenon, and autopsies have not shown any apoplexies in any other part of the body. Let us now analyze a little more deeply the phenomena just described. Upon what anatomical element does excessive oxygen act? What is the cause of the convulsions? Is the heart directly attacked, as it is by such a great number of poisons? The data which have just been reported would be insufficient to permit us to reply completely to these different questions. 716 Experiments We have had to use the best physiological reagent, the frog. Experiment CCLXIX. February 27. Frog subjected at 2 o'clock to 7 atmospheres, 6 of which were oxygen. The oxygen tension corre- sponds to 505. In the evening, at 7 o'clock, nothing particular; seems a little uneasy. February 28, at 9 o'clock in the morning, dead. No reflex actions of any sort; the motor nerves and the muscles are excitable. The heart, of a fine carmine red, beats slowly when exposed. Free gases in the blood. The lethal air contains no trace of carbonic acid. Experiment CCLXX. March 4. Frog subjected at 4 o'clock to 5 atmospheres, 4 of which were oxygen; the tension of this gas is about 300. At 10 o'clock in the evening, swollen. On March 5, at 2 o'clock, seems dead. The heart no longer beats spontaneously, but is excitable; the motor nerves and the muscles are excitable. By cutting through the spinal cord in the back, movements in the lower limbs are caused. Experiment CCLXXI. February 29. Frog subjected at 6 o'clock to 4 atmospheres, 3 of which were oxygen. The tension of this gas is 254. The next day, March 1, at 3 o'clock, it is rigid and swollen, seems to have convulsive movements when one raps on the table. At 7 o'clock in the evening, is much weaker. March 2, at 1 o'clock, dead, stiff. The heart beats, the nerves and the members are excitable; no movement is produced when the spinal cord is cut. The lethal air contains no trace of carbonic acid. Experiment CCLXXII. April 18. Frog subjected at 6 o'clock in the evening to 4V2 atmospheres of superoxygenated air. The oxygen tension is represented by 335. Temperature 15°. The next day, nothing especial in the appearance of the frog. April 20, found dead at 1 o'clock. The heart, very pink, is still beating a little. The muscles are perfectly contractile. Experiment CCLXXIII. June 17. Frog subjected at 4:30 to a pres- sure of 5 superoxygenated atmospheres. The heart is laid bare, temperature 20°. June 18, at 11 o'clock in the morning, very weak, prostrated. No respiratory movements. Pulsations of the ventricles, rare, irregular; but the auricles alone beat 40 times per minute. At 3 o'clock, decompression. A few weak heart beats yet. There are no reflex acts, but the motor nerves and the muscles are quite excitable. Sugar in the liver, in a rather large quantity. We conclude from all these experiments that oxygen does not kill by acting on the heart, the motor nerves, or the muscles. But Compressed Air; 02 Poisoning 717 the reflex acts of the spinal cord,- after being considerably excited, are checked. The fact that the convulsions come from the spinal cord, com- municating its excitation to the muscles by means of the motor nerves, is abundantly proved by experiments in which the motor nerve has been cut: Example: Experiment CCLXXIV. June 20. Frog; left sciatic nerve cut. 3 o'clock in the afternoon; subjected to 3 superoxygenated atmos- pheres, containing 60.5 per cent of oxygen, 3 x 60.5 = 181.5 = 9 atmos- pheres of air. Respiration ceases for a moment. June 21. Respirations very rare; eyes protruding with widely rounded pupils; frog is swollen, rather weak; no convulsions. June 22. 11 o'clock in the morning. No respiration; weak; eyes closed by the transparent lid. Clonic convulsions beginning in the right front leg, then becoming generalized, except in the left hind foot; then general stiffness; then weakness. These attacks are excitable at will, by shock; but the frog soon seems insensible, as if dead. Sudden decompression; no effect. In the outer air, does not breathe; the heart, exposed, beats 50 times per minute; the blood, which was red at first, grows progressively darker. After about a quarter hour, excitation brings on new convulsive attacks, like the preceding. On exciting the right hind foot, move- ments of the right front leg are produced, but not of the left. Frequently fibrillary contractions, in the muscles of the chest especially and also in the limbs, except the left hind foot. During the convulsions, the heart does not seem altered. Dies about 2 o'clock. So section of a motor nerve prevented all convulsive move- ment, fibrillary or generalized, from appearing in the correspond- ing muscles. Since oxygen injures the spinal cord, like strychnine, phenol, etc., convulsions should be prevented by chloroform, which, as I have shown before,2 acts particularly on the spinal cord. In fact, this very thing happened in the following experiment. Experiment CCLXXV. February 26. Etherized sparrow, put into the receiver; rouses during the compression. I put some drops of ether into the vessel in which the oxygen sucked in by the pump is bub- bling in the potash, and raise the pressure to 5 atmospheres, 4 of which are oxygen. The bird becomes unconscious again, after some quiverings of the feet; he dies slowly, in 25 minutes, without any convulsion. Huge cranial suffusions. The lethal air contains CO, 2; O? 76. The original pressure of the oxygen was therefore about 78x5 = 390, corresponding to 19 atmos- pheres of air. 718 Experiments This experiment shows not only that anesthesia prevents con- vulsions from oxygen, like those of other poisons of the spinal cord, but also that it does not prevent death from coming, al- though it comes calmly. The following experiment, in which the animal was removed after the action of the oxygen, its convul- sions appearing gradually as consciousness returned, is still more convincing. Experiment CCLXXVI. February 24. Chloroformed rat, nearly died during anesthesia. Begins to be sensitive after about a half-hour. Rectal temper- ature 35°. Subjected to 5 atmospheres, and after 10 minutes to 6V2 atmos- pheres of oxygen. At the end of 20 minutes of compression seems very sick; a few slight quiverings; the convulsions not appearing, it is withdrawn. Rectal temperature 34°. Put back into the cage, remains stretched out; it is soon seized by convulsions; stiffening of the tail, etc. They appear spontaneously or as soon as the animal is touched. One hour after, same condition; temperature 32°. 2V2 hours after, very slight convulsions; temperature 28°. Evi- dently dying. February 25. Found dead and cold. I do not dwell upon this point, because the experiments made on dogs will give us analogous data. Before coming to the experiments on dogs, I think I should report one more which was performed on sparrows, and in which we see demonstrated the important part played by the blood in oxygen poisoning. Experiment CCLXXVIL July 17. Two sparrows are subjected, from 5:02 to 5:07, to 8 atmospheres of superoxygenated air, in which the oxygen tension is equivalent to 424, that is, 20 atmospheres of air. One, A, is in good shape; the other, B, which weighs 20 gm., was bled at 4 o'clock of 0.7 cc. of blood from the jugular; it is still very weak; its rectal temperature is only 32°, while A's is 42°. At 5:10 or 5:12, A shows slight convulsive shivers, and about 5:20 real convulsions, which last until 5:33, when he dies. B is not affected until 5:25 and then slightly; no general quiverings, but great efforts in breathing, stiffness, etc., which become true convulsions, of the feet, if not of the wings, about 5:35; he has a few of them, then remains on his back as if dead. Decompression at 5:45. A, rectal temperature 31°. B, rectal temperature 28°. Enormous cranial suffusions on the two birds. B is still breathing; his rectal temperature drops and is 25° at 6 Compressed Air; CX Poisoning 719 o'clock; he dies then. When the muscles were pinched, they con- tracted slowly and strongly as if with cramps. So in the animal which had been bled the symptoms appeared much more slowly than in the healthy animal. That is the effect both of the general weakening he had undergone and of the di- minished quantity of blood, which, since it contained a smaller- quantity of oxygen, could carry this dangerous agent to the spinal cord only in smaller proportion. It would be premature to dwell at this moment on the part played by the blood in oxygen poisoning. This question will recur in a much more significant manner when we have studied the experiments made on dogs, which I shall now report in detail. When I used dogs as experimental animals, my special purpose was to investigate the proportion of oxygen contained in the blood when the convulsive symptoms occurred. I intended also to continue at the same time, thanks to the use of superoxygenated compressed atmospheres, the research of the proportions estab- lished in the living animal between the tension of the oxygen in the respiratory medium and the oxygen content of the arterial blood, proportions studied in Subchapter III of Chapter I up to 10 atmospheres of air only. The experimental animal was fastened on his board as is ex- plained in the subchapter just mentioned. To succeed in making him breathe compressed oxygen, I had recourse to a special device, not having at my disposal the quantity of oxygen necessary to compress this gas to several atmospheres in a receiver of 150 liters capacity. I fixed in the dog's trachea a metallic tube as wide as possible, and connected it with a rubber bag having a capacity of about 30 liters. This bag was placed beside the animal, and the air injected into the chamber by the pump compressed both the oxygen and the animal at the same time. The experiment never lasted long enough for the dog to exhaust the oxygen entirely. But as the expirations were made into the bag, carbonic acid was stored up there, which consequently accumulated also in the blood. And so we should not take account of the proportion of this gas shown by the analyses; I thought, however, that I should indicate it as a matter of information in the account of the experiments. In a certain number of cases, to avoid this accumulation, I attached to the tube which went from the trachea to the bag, a flask in which the superoxygenated air bubbled in a solution of potash; in other cases, the solution was in the bag itself. These experiments, 720 Experiments compared to those in which no such precaution had been taken, allow me to state that in the latter the influence of the carbonic acid was quite negligible; that will be explained naturally, when we discuss poisoning by carbonic acid in Chapter VIII. Here now is the report of a certain number of experiments. Experiment CCLXXVIII. November 16. Black dog, short-haired, new subject, weighing about 12 kilograms. It is fastened on its back, and in its trachea is inserted a metal tube, at the end of which is a rubber tube considerably narrower. Respiration is carried on in series of extreme frequency, separated by a few intervals of calm. At the end of about a half-hour, the rectal temperature is 36° (in a healthy dog the same thermometer gives 38.5°). Then from the left carotid 35 cc. of blood is drawn, which is imme- diately taken to the pump for extracting gases .... A The dog is next placed in the compression apparatus; to the tube in its trachea is then fitted a rubber bag containing oxygen; then the animal is fastened as explained above. Pressure is begun at 3:56. At 4:21, the pressure is 5 atmospheres; I draw 38 cc. of very red blood, not letting gas escape . . . . B At 4:40, at 7 atmospheres, drew 31 cc. of very red blood, in which escape of gas is at least doubtful . . . . C Pressure is raised to 8 atmospheres, and at 4:45 decompression is made suddenly in 3V2 minutes. The animal is immediately withdrawn from the apparatus; there are no free gases in either the arterial or the venous blood; the heart sounds are normal, without any gurgling indicating the presence of gas. The rectal temperature is 30°. There has been an evacuation of fecal matter, and the mouth is full of froth. The paws are much stiffened; when the animal is unfastened, he is in very pronounced opisthotonos; the whole body is in tonic convul- sion. Fecal matter continues to be discharged. The eye closes when the cornea, but not when the conjunctiva, is touched; the pupils, much dilated, do not contract in light. The arterial pressure in the carotid varies between 9 and 12 centimeters. The symptoms continue to increase in intensity. About 5 o'clock, the convulsions are extremely violent; in the midst of continuous stiffenings, there appear clonic convulsions of the limbs, the neck, and the jaws. The eyes are convulsed. The penis is so retracted that to catheterize the animal the prepuce has to be slit its whole length; no urine in the bladder. The animal froths terribly. About 5:30, the temperature is 29 degrees. Vomiting begins. The convulsions appear like fits, with no real rest in the interval; it appears much like successive strychnine attacks, except for the almost com- plete permanency of the stiffenings and the opisthotonos. Clonic convulsions are caused by touching the animal, by hitting the table, Compressed Air; (X Poisoning 721 by inserting the thermometer into the depths of the rectum. During the attacks, the respiration stops, but the heart continues to beat. Gradually intervals of comparative repose appear. The animal begins to grind its teeth with such extraordinary force that one would expect them to break. The temperature rises again; at 6 o'clock it is 31°. 6:15; now and then, the stiffness disappears; the respiration is better; the tail moves. 6:45; the animal is still lying on its side; the clonic convulsions are like those of phenol, in that they almost imitate the motions of walking; they follow each other in attacks separated by an interval of relative repose. At each attack, violent opisthotonos, with quiv- ering of the jaws, then a snapping of the teeth; from time to time, general stiffening with motionlessness, the stiffening less than at the beginning. The pupils are still insensitive to light. The temperature is 32 degrees. The heart beats hard and fast. The next day, at 11 o'clock in the morning, the animal, in whose trachea the cannula has been left, is lying as on the day before; it is in opisthotonos with permanent contractions of the limbs; the anal sphincter is closed; weak, but almost continuous quiverings. Viscous salivation, as well as watering of the eyes, has continued; the pupils are dilated; the cornea is sensitive, but not the conjunctiva. Respira- tion quite calm; pulse 80, weak; temperature 27°. I administered chloroform until the cornea lost sensitivity; the stiffening and quivering disappear to reappear soon. The animal dies during the day. Now here is the result of the analyses: A: Ordinary air, normal pressure; 100 cc. of blood contain O, 15.5 cc; CO? 22.9.3 B: 5 atmospheres of superoxygenated air: 100 cc. of blood con- tain 02 24.0; CO 63. C: 7 atmospheres of superoxygenated air: 100 cc. of blood con- tain 02 31.5; C02 54.6. The air of the bag, after the experiment, contained per 100, O, 66; CO, 5.4. The original composition was therefore about 75 per cent of oxygen. The oxygen tension in B was about 70 x 5 = 350. In C, it was about 68 x 7 = 476. It was raised to 66 x 8 = 528, which corresponds to about 26 atmospheres of air. This experiment is particularly remarkable; here is an animal which, after being exposed for three-quarters of an hour to an oxygen tension corresponding to nearly 26 atmospheres of air, died after about 24 hours of violent convulsions. Experiment CCLXXIX. November 20. Rather young dog, weigh- ing about 8 kilograms. Tube placed in the trachea. ~% After a quarter of an hour, the rectal temperature is 39.4°; pulse 722 Experiments 144, respiratory rate 24; blood pressure in the carotid varies between 15 and 17 cm. of mercury. At 3:38, drew 38 cc. of blood .... A Placed in the apparatus at 4: 10, with a bag full of a mixture with 89.5 per cent of oxygen. At 4:30, pressure is 5 atmospheres, maintained there. At 4:38, drew 43 cc. of very red blood; no gas escapes . . . . B At 4:40, decompression in 1% minutes. The animal is immediately withdrawn, the bag is removed, and it is noted that it has already vomited in the apparatus. It vomits again. It shows attacks of stiffening without clonic jerks. The temper- ature is 36.5°: the arterial pressure from 11 to 12 cm.; pulse is 140, respiratory rate 24. These attacks of convulsive stiffening last about 20 minutes. At 6 o'clock, the temperature is 35°, the arterial pressure 12 cm., the pulse 140. The dog begins to be able to stand on its feet. At 6:30, the animal, whose cannula has been removed, remains lying down with a sort of muscular trembling, resembling that of phenol poisoning. Its eyes are sensitive, and the pupils contract and dilate as if by tremors which are related to the quivering of the limbs. There are occasional stiffenings of the front feet, but they can easily be bent. The next day, in good health. The analyses gave the following results: A: Air, normal pressure; 100 cc. of blood contain: O, 17.0; CO: 39.0. B: 5 atmospheres of superoxygenated air: 100 cc. of blood con- tain: CX 24.8; CO, 75.0. The gas in the bag after the experiment contains 76.2 of oxygen and 8.1 of carbonic acid. The oxygen tension in B was then about 77 x 5 = 385. Experiment CCLXXX. November 25. Dog of average size. Tube in the trachea; left carotid exposed. Rectal temperature 38. IV 3:12; drew 33 cc. of blood; the animal breathes quietly .... A Placed in the apparatus at 3:55, with oxygen bag; between the bag and the tube in the trachea a flask is placed, at the bottom of which are bits of potash; by this means I intend to diminish the proportion of carbonic acid stored in the bag. 4:25; pressure 7 atmospheres; at 4:28, with great difficulty drew 23 cc. of blood . . . . B 4:38, pressure 7 xk atmospheres; sudden decompression. Withdrawn at 4:45, the animal's eyes are sensitive; its tempera- ture is 36°; there are stiffenings of the hind legs and the neck; the respiration seems suspended, the heart beats very feebly. After 10 mmutes the stiffenings increase, but the respiration re- turns, and the heart beats more quickly and strongly. Soon after, the animal again becomes limp, as it was when it was taken from the apparatus; its respiration is weak; it dies at 5:50, without moving. At 5:20, its temperature was 34.5°; at 5:50, it had fallen to 33.5°. Compressed Air; 02 Poisoning 723 At 5:05, I drew 33 cc. of blood from the carotid . . . . C At 5:30, drew 33 cc. of blood also from the carotid . . . . D The autopsy shows the heart full of dark blood on the right, a little red on the left. There are in the bladder some drops of urine with an exceedingly high sugar content. The liver contains much sugar. Blood A (air, normal pressure) contained . . O, 14.4; C02 41.0 Blood B (oxygen, 7 atmospheres) contained . . O, 24.1; C02 68.5 Blood C (air, normal pressure, 40 min. after decompression) con- tained . . O, 15.8; CO, 16.5 Blood D (air, 70 min. after decompression) contained O, 15.8; C02 28.3 The gas in the bag contained before the experiment 79 per cent of oxygen; the oxygen tension in B was probably 74 x 7 = 518; it rose to a maximum of 550 at 4:38. Experiment CCLXXXI. November 27. Shepherd dog, weighing 16 kilos. Tube in the trachea; rectal temperature 38.5°. At 4:50, drew 33 cc. of blood from the left carotid A Placed at 5:08 in the compression apparatus with the oxygen bag, without the potash flask. At 5:12, pressure is 1% atmospheres; drew 33 cc. of blood, very red B At 5:48, 7 atmospheres; this pressure maintained, and at 5:50, drew 39 cc. of very red blood, without free gases C At 5:53, decompressed in 2 minutes. Withdrawn; temperature 38.5°. Is stiffened, and every three or four minutes, enormous tonic convulsion, with very violent opis- thotonos, suspension of respiration, the heart continuing to beat, al- though more slowly. The eye lacks sensitivity. The excitability is much less evident than in strychnine poisoning. There are 4 or 5 of these frightful convulsions during which it seems as if the animal is going to fall from the table. At 6:10, I administer to the dog a mixture of chloroform and ether; at the beginning, it seems as if the convulsions grow worse. But at the end of 2 or 3 minutes they disappear, and there are only quiverings of the front legs, like those caused by phenol, which dis- appear in their turn, as does the stiffening; the animal becomes re- laxed and calm. 6:15, the anesthetic withdrawn. Sensitivity returns, then some fits of stiffening; but there are no more great convulsions. Tempera- ture 39°. 6:22; drew 33 cc. of blood, medium red D 6:45; the temperature is 38.5°. 7 o'clock; drew 33 cc. of blood, very dark E The next day, the animal is quite recovered. Blood A (air) . . contains, in 100 cc. . . 02 16.9; CO, 33.1 Blood B (oxygen, 1% atm.) contains, in 100 cc. 02 21.4; CO, 36.6 Blood C (oxygen, 7 atm.) . . contains, in 100 cc. 02 32.5; CO, 73.8; N 4.1 724 Experiments Blood D (air, 27 min. after decompression) . contains, in 100 cc. 02 16.9; C02 21.0 Blood E (air, 67 min. after decompression) . contains, in 100 cc. O, 17.0; CO, 31.5 The bag contained after the experiment a mixture of CO2 10.7 and 02 70 per cent. Therefore the oxygen pressure when blood B was drawn was about 1.75 x 79 = 138, and when blood C was drawn, about 7 x 71 = 497. Experiment CCLXXXII. December 3. Dog. Tube in the trachea; rectal temperature 38°; respirations extraor- dinarily rapid. 3:20; blood drawn from the left carotid, 33 cc A The oxygen bag is attached to the cannula in the trachea; a flask at the bottom of which there are a few bits of potash is placed where the air will pass over it. 3:30; drew 33 cc. of blood considerably redder; respiration has become much slower B 3:45; placed in the large compression apparatus. 4 o'clock; pressure is 3% atmospheres; drew 33 cc. of very red blood; no gas C A series of petty accidents occur; at 4:40, I wish to decompress suddenly; but the rubber bag gets in front of the opening, and the decompression is not finished until 5:45. The animal has neither convulsions nor quiverings; its tempera- ture is 36°. Blood A (air, normal pressure) . . contains . . . 02 18.1; CO, 24.9 Blood B (oxygen, normal pressure) contains . . . O2 20.9; CO, 33.7 Blood C (oxygen, 3V2 atmospheres) contains . . . 02 27.5; C02 56.5 The air of the bag contained before the experiment 85 per cent of oxygen; when blood C was drawn, the tension was about 80 x 3.5 = 280. Experiment CCLXXXIII. December 10. Vigorous dog, weighing 12.5 kilos. At 3:45, tube placed in the trachea; the respiration becomes panting. 3:55; drew 33 cc. of blood; the temperature is 38.5° A 4:10; forced to breathe from the rubber bag containing oxygen. 4: 18; drew 33 cc. of blood, redder B 4:35; placed in the large apparatus with the rubber bag, in which a potash wash has been placed. 5:05; the pressure is 6 atmospheres; drew 38 cc. of blood. . . C 5:35; the pressure is 9 atmospheres; drew 35 cc. of blood. . . D Some very small bubbles of gas appear. 5:38; decompression in 3 or 4 minutes. When the animal is taken out, it is dead. The right auricle is still beating. The venous blood is quite red, and when it is caught in a glass, small bubbles of gas escape which come to the surface or re- main clinging to the walls of the glass. Same phenomenon for the Compressed Air; 02 Poisoning 725 arterial blood, only the bubbles are much smaller. The muscles and the motor nerves respond to electricity. When I drew blood D, the blood came with great difficulty into the syringe in slow spurts. Probably the animal was dying at that very moment; he had been observed to breathe up to that time; after- wards, not. At 7 o'clock, no rigor mortis. Blood A (air, normal pressure) O. 19.8; C02 20.9; N 2.1 Blood B (oxygen at 88%, normal pressure) . O. 20.9; CO, 34.5; N 1.5 Blood C (oxygen, 6 atmospheres) 02 26.3; C02 63.5; N 3.9 Blood D (oxygen, 9 atmospheres) 02 30.7; CO, 61.5; N 5.5 The air of the bag, before the experiment, contained 88 per cent of oxygen. So, taking account of the respiratory alteration, the oxygen tension, when blood C was drawn, could be expressed by 80 x 6 = 480, and when blood D was drawn, by 78 x 9 = 702. Experiment CCLXXXIV. December 17. Young dog, weighing. 7.5 kilos. 3:30; rectal temperature 39°. Tube placed in the trachea; respirations very rapid. 3:40; drew 33 cc. of blood from the carotid, not very red. ... A 3:42; forced to breathe from the oxygen bag, with a potash wash in the bag. 3:50; rectal temperature, 38.8°; drew 33 cc. of very red blood. B Placed in the compression apparatus at 4:05. 4:50; 7 atmospheres; we try in vain to extract blood. Taken to 7 and % atmospheres, and decompressed suddenly. Withdrawn; temperature 37°. A few stiff enings and clonic con- vulsions. The heart beats slowly, the blood is very dark. Dies at 5: 10, without a last sigh, with complete resolution. No urine in the bladder. But the kidneys, crushed with sulfate of soda and animal charcoal, give a yellow precipitate with very good Bareswill's reagent. The blood, treated in the same way, gives a similar enormous precipitate; the potash browns the boiling liquid. Blood A (air, normal pressure) contains O* 12.1; C02 29.6 Blood B (oxygen at 91%, normal pressure) contains 02 14.1; CO, 24.5 The oxygen tension was about 7.75 x 80 = 620. Experiment CCLXXXV. December 20. Very vigorous dog, weigh- ing 16.5 kilos. Rectal temperature 38.5°. 3:55; drew 33 cc. of rather dark blood. Respirations a little slow A 4 o'clock; tube in the trachea; very much exaggerated respira- tions for 4 to 5 minutes; then, period of calm, followed by other ex- aggerated respirations. At 4: 10, while I am preparing to draw blood, the respirations grow calm and return to normal type. At 4:12, drew 33 cc. of blood, less dark B 4:30; placed in the compression apparatus, with rubber bag. 5:05; pressure is 6 and % atmospheres; drew 40 cc. of very red blood, from which very small bubbles of gas escape C 5:12; decompressed suddenly. 726 Experiments When placed upon the table, has abundant froth in the mouth; is in very violent opisthotonos, replaced from time to time by a pleurosthotonos on the right side; at times strong clonic convulsions, with a few intervals of complete repose. During the attacks, respira- tion stops, and it is very difficult to detect the heart beats. The eye remains sensitive. At 5:15, the temperature is 36.7°, and the pulse only 20. At 5:30; respiratory rate 48, pulse 112. At 5:38, a little while after a strong convulsion, I draw 33 cc. of very red blood D At 5:45, temperature 35°. I had the dog inhale chloroform through the trachea; respiration is very active; the feet are then stiffened. Soon the respiration stops in its turn; the eyes are very much swollen. I use artificial respiration; the heart resumes strongly enough, and respiration returns; then everything stops in spite of artificial respiration, and the animal dies about 6 o'clock. The serum of the blood, treated by sulfate of soda and animal charcoal, gives with copper reagent a very abundant yellowish-red precipitate. Blood A (air, normal pressure, normal respiration) 02 15.1; CO, 40.8 Blood B (air, normal pressure, tracheal respiration) O, 20.3; CO; 24.0 Blood C (oxygen, 6% atmospheres) 02 34.6; C02 92.5; N 3.6 Blood D (during convulsions) O, 19.0; C02 14.8 The composition of the air of the bag, before the experiment, be- ing 80% of oxygen, the tension at the time of drawing blood was about 6.75 x 84 = 567. Experiment CCLXXXVI. January 22. Temperature 16°. Large dog. At 3:10, tube placed in the trachea; rectal temperature 39.5°. At 3:30, the animal breathing slowly and deeply, 33 cc. of carotid blood drawn A At 3:40, dog is placed in the compression cylinder, with the rubber bag containing air with 88.6% oxygen. At 4 o'clock, pressure is 4 atmospheres; then 33 cc. of very red blood drawn B At 4:15, pressure is 6V2 atmospheres. Drew 38 cc. of very red blood, which coagulates very rapidly C At 4:17, decompressed in 2 minutes. Taken out in strong convulsions. They consist of attacks of stiff- ness of the paws and of the body in opisthotonos, so strong that the dog can be carried by one paw, like a piece of wood. (See Fig. 61.) They can be brought on at will. Rectal temperature 37°. At 4:40, drew 33 cc. of moderately red blood; the temperature has dropped to 36° D The convulsions continue to decrease; the cannula is removed. At 5:35, the convulsions have stopped. I draw a little carotid blood, which, boiled with charcoal and sulfate of soda, gives a very strong Compressed Air; O, Poisoning 727 reduction of the copper reagent. Nothing by sulfate of lime or nitric acid. The animal is placed in a cage fitted to collect the urine. This urine, the next day, reduces copper reagent, giving an abundant yellow precipitate. Blood A (air, normal pressure) . . . . O, 15.8; CO, 43.0 Blood B (oxygen; 4 atmospheres) O, 23.9; CO, 59.0 Blood C (oxygen; 6V2 atmospheres) O, 28.7; CO, 69.4 Blood D (air; returned to normal pressure, convulsions) 02 12.4; CO,9.9 The bag contained at the beginning air with 88.6% of oxygen. At the moment when blood B was drawn, the oxygen tension was about equivalent to 320, representing 16 atmospheres. For blood C, the figures would be 480 and 24 atmospheres. Experiment CCLXXXVII. January 23. Temperature 16°. Large dog. Rectal temperature 39°. Tube placed in the trachea at 3:15. Its respiratory rhythm does not change noticeably; it was very rapid. At 3:53, its temperature dropped to 38.5°. 33 cc. of moderately red blood drawn from the carotid A At 4:02, placed in the apparatus with the bag containing super- oxygenated air. At 4: 15, pressure is 2 and % atmospheres. I drew 45 cc. of very red blood, containing no free gases, with a manifest tendency to coagulation. An accident prevents me from analyzing it for its gaseous content. At 4:38, pressure is 7% atmospheres. I again draw 45 cc. of very red blood, coagulating rapidly, in which no free gases appeared B At 4:40, decompression in 2 minutes. Taken out in strong convulsions. Rectal temperature 37°. The convulsions, at first rather moderate, with intervals of flaccidity, continue to increase in strength. In the intervals of tonic convulsions, the animal moves its feet as if it were walking. The tonic convulsions are so strong that the animal can be lifted like a piece of wood, by one foot. Its feet are stiff, its body in right pleurosthotonos, with opisthotonos of the neck, its eyes open, pro- truding; the pupils dilated; it is vomiting. At 5 o'clock it dies. The heart continues to beat for some minutes. At 5:10, drew 33 cc. of very dark blood with a catheter from the left heart, which is no longer beating C There is no urine in the bladder; very severe pulmonary con- gestion. Blood A (air, normal pressure) O, 17.2; CO, 22.3 Blood B (oxygen, 7Va atmospheres) 02 30.1; CO, 72.3 Blood C (after death) O, 1.4; CO, 29.0 The air of the rubber bag, analyzed after the animal had been taken from the apparatus, contained O, 74%; CO, 10%. At the moment when blood B was drawn, the oxygen tension was about 540, equivalent to 27 atmospheres. 728 Experiments Experiment CCLXXXVIII. January 24, temperature 17°. Vigor- ous bulldog. Rectal temperature 38.5°. At 2:30, 33 cc. of carotid blood drawn; the animal breathes quietly, by natural channels A Tube placed in the trachea; respiration becomes much more rapid. At 2:45, 33 cc. of blood drawn B At 3:25, the animal is placed in the apparatus, with the bag containing superoxygenated air. At 3:45, pressure 4 atmospheres, 41 cc. of blood drawn C At 4:03, pressure has risen to 6 and % atmospheres; 57 cc. of blood drawn D At 4:07, decompression in 3 minutes. Rectal temperature 37°; the animal is in strong convulsions. At 4:33, the rectal temperature has fallen to 36°. At 4:35, I administer chloroform; the first application causes con- vulsions, which soon cease, and the animal becomes insensible and in resolution. I stop administering chloroform at 4:45. Up to 5:55, there are no more convulsions. Then they reappear. The animal survives. Blood A (air, normal pressure, respiration by natural channels) 02 16.0; C02 41.5 Blood B (air, normal pressure, tracheal respiration) 02 23.4; CO. 15.2 Blood C (oxygen, pressure 4 atmospheres) . . . 02 28.5; CO, 68.3 Blood D (oxygen, pressure 6% atmospheres) . . . 02 30.7; C02 82.0 Since the bag from which the animal had breathed contained after the experiment 74.5% of oxygen and 8.6% of carbonic acid, we can reckon at 300 the oxygen tension at the moment when blood C was drawn, that is, 15 atmospheres of air, and at 510 at the moment when blood D was drawn, that is, 25 to 26 atmospheres. Experiment CCLXXXIX. January 28. Large dog, fasting since the morning of January 27. At 2:35, I draw 33 cc. of carotid blood, moderately red. ... A I mix a few cubic centimeters of it with distilled water, to ex- amine it for sugar (a). The rectal temperature is 38°. The trachea is not opened, but the muzzle, pictured in Figure 37, is fitted to the animal, and at 3:15 the dog is placed in the apparatus with the oxygen bag. At 3:50, the pressure is 6% atmospheres. Decompression is made in 5 minutes. The animal is in strong convulsions; tonic stiff enings, clonic con- vulsions. Attacks provoked at will. At 4 o'clock, I draw during the convulsions 23 cc. of dark carotid blood B Rectal temperature is only 36.5°. At 4:25, drew 33 cc. of moderately red blood; the animal has just had an attack C At 4:50, the temperature is only 36". Compressed Air; 02 Poisoning 729 At 5:10, another 33 cc. of blood, which is redder; the convulsions had ceased a few minutes before D At 6 o'clock, the animal is no longer in convulsions; when com- pletely unfastened and placed on the floor, it walks like a hyena, hind quarters very low. It is set aside for the collection of the urine. It does not urinate until the next day at 3 o'clock; no sugar. At that time, its temperature has risen to 39.5°. Blood a, boiled with charcoal, does not reduce Fehling's solution. On the contrary, a mixture of bloods B, C, D, boiled in a similar way, gives a very considerable reduction. A part of the colorless liquid obtained by boiling this blood with the addition of water and much charcoal, being placed on the drying-stove, with brewer's yeast, in a tube inverted over mercury, ferments and gives off a gas which is absorbed by potash. Another part, cooled with copper reagent, dis- colors it and precipitates. Blood A (air, normal pressure) contained 02 16.0; C02 44.5 Blood B (in open air, convulsions) .... contained 02 9.7; C02 48.2 Blood C (after 25 min. in the open air) contained 02 13.9; CO, 10.5 Blood D (after 1 h. 10 min. in the open air) contained 02 18.5; C02 19.0 The air of the bag after the experiment contained 61.5% of oxygen and 12.9% of carbonic acid. The oxygen tension had risen to nearly 420, that is, 21 atmospheres of air. Experiment CCXC. February 4. Large dog, which had not eaten since the day before in the morning. Rectal temperature 37.5°. At 3:15, 33 cc. of rather red blood drawn from the carotid. . . A A small quantity of this blood is boiled with water, sulfate of soda, and charcoal. The animal, furnished with the muzzle and the oxygen bag, is placed in the apparatus at 4 o'clock. At 4:40, I make the decompression in a few minutes; the pressure had reached 7 Vz atmospheres. The animal is in excitable convulsions; its temperature is only 36°. At 5:20, drew 33 cc. of very red blood B The animal had just had convulsions, and in the interval breathed very rapidly. At 5:40, drew another 33 cc. of blood C The convulsions are over at the time; the animal, when unfastened, cannot walk. It survives; the urine which it voids during the night contains no sugar; the very abundant saliva found in the muzzle did not con- tain any either. On the other hand, blood B was certainly richer in sugar than blood A. Blood A (before the experiment) contained 02 18.7; C02 44.0 Blood B (afterwards, during the convuls.) contained 02 23.2; C02 19.4 Blood C (convulsions over) contained 02 20.3; CO. 22.0 The air of the bag, after the experiment, contained 57.6% of oxygen and 7.4% of carbonic acid. The oxygen tension had therefore risen to about 440, that is, 22 atmospheres. 730 Experiments Experiment CCXCI. February 5. Terrier, medium size, fasting since the preceding evening. Rectal temperature 39.5°. At 5 o'clock, put into the apparatus with the muzzle and the oxygen bag. At 5:40, pressure is 7 and Vz atmospheres. From 5:40 to 5:45, decompression. Is in strong convulsions, with violent snapping of the teeth. Temperature 38°. Dies at 6 o'clock. The air of the bag, after the experiment, contained 77.2% of oxygen and 8% of carbonic acid. The oxygen tension had been about 560, corresponding to 28 atmospheres of air. Experiment CCXCII. February 7. Vigorous poodle. Temperature 39.8°. Took blood from the carotid to analyze for sugar a At 4 o'clock, muzzle and oxygen bag; the compression begins. At 4:43, the pressure is 7% atmospheres; rapid decompression. Taken out of the apparatus, the dog has 2 or 3 convulsions; its tem- perature is 38°; it dies while we are drawing a little very dark arterial blood, which is treated with sulfate of soda b a and b are treated in the same way, with the same addition of water and according to the method of CI. Bernard. Now 5 cc. of the filtered liquid furnished by a reduce only 10 drops of copper reagent, while the same volume of the liquid in b reduces 15. The air of the bag before the experiment contained 90% of oxygen. After the experiment, there was only 76.5% with 10.7% of carbonic acid. The oxygen tension had therefore risen to about 600, which cor- responds to 30 atmospheres of air. Experiment CCXCIII. February 18. Dog weighing 10 kilos, fast- ing since the morning of February 17. Rectal temperature 40°. At 1:30, I put a tube in its trachea. At 2 o'clock, its rectal temperature is only 39.8°. From 2:05 to 2:20 (15 minutes), I force it to inspire and expire in a rubber bag containing 41 liters of air; towards the end, the ani- mal experiences a certain respiratory difficulty, takes great inspira- tions, and struggles a little. I call the air of this bag a. At 2:45, I take 25 gm. of blood from the carotid and mix it with 25 gm. of sulfate of soda and 10 gm. of distilled water . . . . x At 2:55, put into the compression apparatus, with the oxygen bag, in which is a little alkalinized water. At 3:16, pressure is 5% atmospheres; decompression in 2V2 min- utes. The dog displays only slight convulsions, lasting hardly quarter of an hour. He has salivated very abundantly; his temperature is 38°. At 3:25, drew 25 gm. of carotid blood which is treated like blood x y At 3:40, drew 33 cc. of blood; the animal' has been breathing quietly for some time A Compressed Air; O. Poisoning 731 From 3:43 to 3:58 (15 minutes), I make the dog breathe in a bag containing the same quantity of air as bag a; I call this air b. The animal suffers also at the end of this respiratory period. At 4:20, the animal being very quiet, I draw 33 cc. of carotid blood B At 4:45, rectal temperature 36.5°. At 6 o'clock, drew 33 cc. of blood C Immediately after, his temperature is 37°. At 6:15, I draw more blood which I treat like x and y z Rectal temperature 37°. I remove the tracheal cannula; the dog can walk a little. At 7: 10, his temperature has risen to 39°. He survives. Since the air of the bag contained before the experiment 90.8% of oxygen, and after the experiment, 77.3% of oxygen and 8.4% of carbonic acid, the tension rose to 440, that is, 22 atmospheres of air. Blood A (22 min. after the decompression) contained 02 17.5; C02 20.0 Blood B (1 hour after the decompression) contained O, 17.2; C02 17.0 Blood C (2 hours 40 minutes after the decompression) contained O, 16.3; CO, 26.5 The liquids produced by boiling bloods x, y and z give the follow- ing results: 5 cc. of the liquid furnished by x (before the compression) dis- color 15 drops of copper reagent. 5 cc. of the liquid furnished by y (10 minutes after the decom- pression) discolor 35 drops of copper reagent. 5 cc. of liquid furnished by z (3 hours after the decompression) discolor 15 drops of copper reagent. The analyses of airs a and b show that: 1. In a, before oxygenated compression, the dog consumed in 15 minutes 4.89 liters of oxygen, and produced 2.99 liters of CO.; that is, in one hour 15.56 liters of oxygen and 9.98 liters of CO2. 2. In b, after the compression, the dog consumed in 25 minutes only 3.37 liters of oxygen, and produced only 1.88 liters of CO?; that is, in one hour 8.88 liters of oxygen and 4.51 liters of CO,. Experiment CCXCIV. February 23. Strong female spaniel. Rectal temperature 39°. At 2:15, I put a tube into the trachea; the respirations become •very rapid, 110; pulse 120. At 2:40, took from the carotid 25 gm. of blood, which is treated as usual in the test for sugar x At 2:40, the rectal temperature is 38°. The respiration grows calm, and falls to 40 per minute. From 2:45 to 3 o'clock (15 minutes), the animal breathes in a closed bag, containing 47.14 liters of air. The breathing, calm at first, becomes difficult at the end of 7 or 8 minutes. I call the air of this bag a At 2:45, the rectal temperature is still 38°. At 3:15, put into the apparatus with the oxygen bag. At 3:40, pressure is 6 and % atmospheres; decompressed sud- 732 Experiments denly. Is in quite strong convulsions. White foam very abundant in the mouth. Rectal temperature 37°. At 3:45, drew a little blood for sugar analysis; the animal is in convulsions y At 4 o'clock, the animal is calm; respiratory rate 14, pulse 60. From 4:12 to 4:27 (15 minutes), made to breathe in the same quantity of pure air as above b The respirations remain calm the whole time. At 5 o'clock, rectal temperature still 37°. The animal, when put on the floor, walks quite well. It survives. The air of the oxygen bag contained at the beginning of the ex- periment 86.4% of oxygen; at the end, it contained only 68.1% with 10.4% of carbonic acid. The oxygen tension then must have risen to about 460, or 23 atmospheres. The liquid furnished by blood x discolors per 5 cc. between 10 and 15 drops of copper reagent; that of blood y discolors between 15 and 20. As to the consumption of oxygen, it was in experiment a 3.95 liters, and in experiment b it fell to 2.15 liters. The production of carbonic acid also dropped from 2.41 liters to 1.99 liters. Experiment CCXCV. February 24. Female dog weighing 17 kilos. 2:55; respiration by natural channels, calm; vaginal temperature 40°. I draw 33 cc. of carotid blood A 3:12; I place a tube in the trachea; rapid respirations; then 1 take 500 gm. of arterial blood. 3:47; took 25 cc. of blood (temperature 39°) B From 4:10 to 4:40, placed in the apparatus with a bag contain- ing air with 93% oxygen. Pressure rises to 6 and % atmospheres. Decompressed suddenly, found dead, limp, temperature 37°. The oxygen tension had risen to about 580, that is, 29 atmos- pheres of air. Blood A (natural respiration) Oz 17.0; CO> 38.5 Blood B (tracheal respiration, copious bleeding) O, 16.5; C02 14.4 Experiment CCXCV I. February 25. Dog weighing 15 kilos. While he is breathing by the natural channels, I draw 33 cc. of carotid blood A Rectal temperature is 40°. I then place a tube in the trachea, and extract in one hour 400 cc. of arterial blood. He does not make any extraordinary or rapid respirations, but his temperature drops to 37.5°; I take the last 33 cc. of blood for analysis B From 3:45 to 4:40, raised to the pressure of 6V2 atmospheres, with a bag containing air with 90% of oxygen. Taken out in strong convulsions, excitable by the introduction of the thermometer into the rectum. Temperature 36°. The convulsions continue, and the animal dies during the night. The maximum oxygen tension was about 520, corresponding to 26 atmospheres of air. Compressed Air; O, Poisoning 733 Blood A (natural respiration) 02 19.0; C02 42.0 Blood B (tracheal respiration, copious bleeding) . . 02 13.1; C02 13.2 Experiment CCXCVII. May 24, 1874. Experiment made before the committee of the Academy of Sciences. Female dog of moderate size. Tube in the trachea. Oxygen bag. Compression taken to 7 atmospheres. At that time (5:30), I draw 35 cc. of carotid blood, from which some free gases escape. This blood contains 33.2 cc. of oxygen per 100 cc. of blood, 76 of carbonic acid, and 6.6 of nitrogen. Sudden decompression at 5:35; the animal has no convulsions. A quarter of an hour afterwards, they occur in fits, and can be pro- duced; at certain moments, the dog becomes as stiff as wood. She is chloroformed; the convulsions cease, but reappear when consciousness returns. At 6:30, lying on her side, constantly makes the movements of walking with her two front feet. At 7:30, rigidity again. The next day, at noon, this rigidity persists. The animal has re- mained all night lying on the ground, without having moved from the spot. The eye lacks sensitivity, the pupil does not react to light; the rectal temperature is 23°, that of the room being 19°. The dog dies during the day. I hope that the reader will not object to this long series of descriptions. The symptoms which I am studying at present seemed to me so important that it was necessary to give many examples in detail. The questions which present themselves are numerous. We are now well enough informed to settle almost all of them. But first, according to our custom, we should draw up a table (Table XV) which summarizes the principal results of the data which we have just reported. I listed the experiments according to the increasing oxygen tension, expressed in Column 4 by its real value, and in Column 5 by the equivalent in atmospheres. We are now ready to make a complete description of the fatal effects of oxygen, to describe its symptoms, and even to analyze the mechanism of the poisoning. Let us first discuss the concentrations. The convulsive symptoms, as Columns 5 and 10 of the table show us, did not appear clearly until about 19 atmospheres. Dogs, then, seem a little less sensitive than birds, upon comparing this result with that in Table XIV. That would not be surprising, but I do not hesitate to say that on this point my experiments do not furnish sufficiently definite information. I can only say that the duration of the compression has much to do with the intensity of the symptoms of oxygen poisoning. 734 Experiments §| «*; S> O Ui 1 3 O ,_, a; o .s c 8 c 2 ° %'£ Is CJ _ Q) O W c o °w > 8g CJ 3 Is |3 wc tuo""1 G H i-i 03 OJO . 3T3 ii 2 P I'd e ° k convulsions; sur- d. O2 consumption after than before, h sugar in the blood. | Moderate convulsions; survived. Os consumption less after than before. Sugar in blood. 2 a §§ 55 w 3 m.S (saaaSap) o ' o Tt-iO q ! ITS o inq 1 1 00 '00 00 ajnjBjaduiaj, ed to ai cd CO 1 CO 1 1 006 c-^ t> cd t-^ ie}D3H co . co coco CO 1 CO co coco 1 ' ■*co coco coco d ot>m OO m pqmo o Tf<0 1 I0.®10 , O ^00 CO oiin T^ ! eddoi rjJ 1 o'esi 1 1 o'i>cd 1 1 pooiq am cNcom cot- •* i •*' -< i— i ■* — I CN 1 1 CN^h CN 1 ' jo sase§ jo uoijisoduioo rnOlin oeo o I>05 IO t- CNCO 1 1 "^ N. °°. , coo r-^ C^«S< co oi coed cd coo 1 ii>i>ed 1 1 d rHNN rHCN i-t i -i «— t i— < CN CN 1 IHrHrH ' ' fc 1 IX irn iesi I , , io 1 | '•c ! ! ! CM §Bq x 1 1 w 1 CO !d led 'in 1 M 1 1 1 1 03 1 \<6 aq; ui sjaquinu punoH ^ o> i«^ PS 0) UI}B x ui uoisua} ., § lO :cs i j ; | ICN 1 1 1 :(M 1 1 1 in 3 03 Eh jo ahiBA 6 d x =o 1 O O IO i o i i 0 0 geq aq} ut 100 1 CN 'CO CO icsi i ^< | ! | 3 ! ] icn : 1 1 ■* ! 1 > CO "O jo uoisuax C c/i V _o 8 0) s< '58 t-l 03 CO 0) U a f-i g 4) >> £ O u u 0) ci 1 0 II co > a d ci fco trachea 22 min. after dec 1 hr. id. 2 hr. 40 min. id. (D .go CO Q, 0) W £ (U O fH . 0} £ ** oico £&* <10co o cd 2 6 w c'.S O 03 U n u Fh 3 03 3 la oo ci en cu "c3 0* moo ih C^fj com ^^ u ~CC < u IT u <<< IT < IT LT .3 •G'S'S -co < uoissaaduioo aqj jo uoijBjna 1 I o CO in CO o 1 in CN fie X X X X X t-i > X X X U O U X J J -] X X u u u u u u u U u u u u Compressed Air; CX Poisoning 735 w T3 a a 0 a 1 I g * °^ s CO Sco 5 . o W o T3 • - ft) a I O £ 5 a P o U'e "Si =38 ps-S .2 "(0 J^ > w C 8>; if3 3 "ox .2 ^ 0) 3 > a > ... v 5Po w . g| ox> Co ON CO. k 5 .2 'w C U w m o 'cdoi co oioi oj ■^mco rHMWOin .-I r^ CO »H i-J coco ocnco inMooo .-Jin edcN •* r-l toco Oiocq , CN0O*tf 1 «Ncom i o CD CO coo CNC-ici om r-n'oO Tfl CO in co CD 00 r-ICN in co coca Oi ^ in as o Tf rH cn CD t^ t-H CM CO >-l .-1 qi;mt- CO CO COO r-H CNCNCO mom , in'T^^H i --HCNCO 1 CM CO CO NrHTf c^o.-i rHCO i-HCN cq oo iri iri ICO^f 1 CN 1 i *« «o i in in cn l tHCN in o in || c^Tfcd i l^HCNCN 1 1 1 1 27 26.0 27.5 .... | 320 480 - 140 500 300 510 520 ooo iineoco i co-^m i O : OO I-* i Nin i i : m ! in in u aj 3 ed d 1 ftd ft w 13 0) o g 8 03 CN . 2« CO 5-1 X .-CI 5JS i & O 03 $ - a CO C jg "a «••- ir <-* tf*> co 1 £mt~ tj < < «S En ■g .s« > > X X X X X X X X X J J J u u u u u u 1— ( X X > X X u X X X ►J -) u u u u u u 736 Experiments eg &0 (saa.i2ap) oaruBJadiuax pooiq aq; jo saseS jo uoiiisoduio3 Seq aqi ui "oo saaqumu punon •ui;b ui uoisu3j jo ahiBA d x • o Seq aqj ui "O jo uoisuax T3 s O 0.jh 3 cd cd a 3 . a; a> t/i OJ 3 C c3 B ■H£ xi -*-' o M 2 T3 «* "8 .S Q Q^ Q u v~ o wo cd iri ai cd COCO COCO coo ocoq oScd o>cot> eo ro cococo co ©in co O^ CN-<$i HCOtOO 1-HCX10Q.-I I— I I— 1 | CO OS CO t— 1 'CO I CM 1 ico 1(N 05 1 CN IO CO cooo co coo .as 9 e uoissajduioo aqj jo uoi^BJna II o oj CJ 5 « ■g u Compressed Air; 02 Poisoning 737 I have sometimes seen them occur at pressures hardly over 10 atmospheres of air, and even result in death. Here, for example, are three experiments. Experiment CCXCVUI. April 26. A rabbit and two sparrows are placed in the large compressed air receiver. From 1:45 to 2:45, the pressure is raised to 10 atmospheres. About 5 o'clock, on looking through the windows of the apparatus, we see the animals are dead. Experiment CCXCIX. April 30. Dog weighing 4.300 kilos. At 9:45, placed, free, in the large receiver. The pressure is raised to 10 atmospheres at 10:30; then the little exhaust cock is opened, so that a current of air under 10 atmospheres is maintained; the pressure even rises to 11 atmospheres at 10:45; at that time we look in through the portholes and see the dog lying on its back, in a kind of convulsion. The pressure is lowered to 10, and almost immediately the animal recovers, stands up on his feet, and barks wildly. At noon, the pressure is still 10 atmospheres; the dog has remained standing and begins to bark furiously when anyone approaches the apparatus. The current of air under pressure is maintained. At 2: 15, the animal is lying down, struggling half convulsively. It dies at 5 o'clock; as the cock has been closed for some time, a sample of air is taken which appears practically pure (O. 19.8; C02 0.4). Experiment CCC. February 15. Two mountain sparrows are kept, from 11:30 to 5:30, under a pressure of air varying from 8x/2 to 9V2 atmospheres; constant current of air. One of them (A), at the end of a stay of several hours, gives increasing signs of discomfort. Very slow decompression. A is much weakened, has convulsive movements of the wings, feet, and tail; its temperature, which was 41° at the beginning, is only 33.8°. At 7 o'clock in the evening, it still has convulsive movements, leans backward on its tail. The other sparrow seems quite well. Its temperature is 39°. Both die during the night. I do not dwell on these last experiments. To return to those summarized in Table XV, we see that though for compressions of short duration convulsions begin to appear with an oxygen tension a little lower than the value of 19 atmospheres of air, they are strong and constant above 20 atmospheres, and always entail a very rapid death when above 27 atmospheres. In the only experiment (Experiment CCLXXXIII) in which the oxygen ten- sion rose to the value of 35 atmospheres, the animal was already dead when taken from the apparatus. Let us consider now the oxygen content of the arterial blood, 738 Experiments as shown in Column 7 of the table. We find rather large differences there. Whereas, for example, in Experiment CCLXXXI, in which the oxygen proportion rose from 14.9 to 32.5, although seized by violent convulsions, the animal survived, the dog in Experiment CCLXXXVII died in 20 minutes, without having in its blood more than 30.1% of oxygen, the initial proportion being 17.2. All the results show that it would be impossible to fix exactly either the absolute quantity of oxygen with which convulsions and death occur or its proportional increase. Yet whenever the animal died, the quantity of oxygen always exceeded 30 volumes per 100 vol- umes of blood. The average increase is, we see, very slight, since it oscillates between a third or a half above what exists normally. If, in order to examine their general course with more profit, we express by graphs, in our usual manner, the results contained in Column 7, we get Figure 60. The many variations which we noted are shown here very clearly. But if we slide all these lines up vertically, making the origin of each the number 20, and if we take the average of the different points corresponding to about the same pressure, we get definitely a line of remarkable regularity, that is, a straight line. So, in the living animal, we find confirmed the experiments in vitro included in Subchapter V of Chapter II: from one atmosphere on, there is added to the biood only dissolved oxygen. It is a fact worth noting that convulsions may appear when the blood has an oxygen content appearing sometimes in healthy ani- mals, which they may almost reach after rapid respiration. We see first then that it is not the proportion oi oxygen contained in the blood which is of itself dangerous; we see next that the increase of this proportion, even to a high degree, does not constitute the danger. This increase must be permanent, must be the result, not of a better saturation of the corpuscles as an effect of more com- plete aeration, a saturation which the reducing action of the tissues soon restores to the normal degree, but of a saturation due to the fact that the tissues themselves are saturated with oxygen and in equilibrium with the blood. That is why the convulsions occur only after the compression has lasted some time. The tissues must be impregnated with oxygen in addition to what the blood, loaded with it in the lungs, brings them and incessantly gives over to them. At the beginning of these experiments I asked myself whether the blood was not directly altered by the excess of oxygen, and did Compressed Air; O, Poisoning 739 not thus become the cause of the convulsive symptoms. Inspection of the corpuscles through the microscope, it is true, showed me no alteration of forms and dimensions; but that did not satisfy me. I Fig. 60 — Dogs poisoned by oxygen: increasing oxygen content of their arterial blood. 740 Experiments resolved then to inject into a healthy dog blood which had been greatly superoxygenated. I did so in the following experiments. Experiment CCCI. June 30. Defibrinated dog blood, shaken in the apparatus pictured in Figure 45, under a pressure of 10 atmos- pheres of air with 65% of oxygen. Next the excess of gas was expelled by whirling the flask containing the blood at the end of a cord, like a sling. It then contained 24 volumes of oxygen per 100 volumes of blood. I injected 200 cc. of it into the femoral vein of a female dog weighing 6 kilos. No symptom, not even apparent discomfort. Experiment CCCII. July 23. Defibrinated dog blood; treated like the preceding at 10 superoxygenated atmospheres; it contained 34 volumes of oxygen. I bled a little dog weighing 1640 gm. from the carotid; I took from him 20 cc. of very red blood (this blood clotted with extraor- dinary rapidity), containing only 7.3% of oxygen, with 33% of car- bonic acid; the arterial pressure was 13 cm. I injected into his jugular vein 35 cc. of the blood supersaturated with oxygen, which had been whirled like a sling. No effect. Experiment CCC1II. August 10. Defibrinated dog blood, treated as above, at 10 superoxygenated atmospheres; contained 33 volumes of oxygen. Little dog weighing 2085 gm.; rectal temperature 36°; pulse 160; respiratory rate 50. I took 100 cc. of blood from him; he became very weak; his temperature fell to 34.5°; pulse 128; respiratory rate 30. I then injected into his jugular 110 cc. of superoxygenated blood; immediately the animal revives, and when put down on the floor, seems only a little weak. No after-effect. And so in conditions of compression, that is, oxygen saturation, similar to and even greater than those which caused death, the blood acquired no dangerous quality, and can be substituted safely, in a very great proportion (1/19 of the weight of the body) for the blood of another animal. I must add that the agitation in compressed oxygen had lasted only a very short time, less than one hour. We shall see in Subchapter III of Chapter VI other experiments made from another point of view with blood shaken for several hours with compressed oxygen. But let us come to the description of the convulsive attack itself. It is truly curious and terrifying. Let us take a case of average intensity. When the animal is taken from the apparatus, it is generally in severe tonic con- vulsions; the four feet are stiff, the trunk is bent back or a little to Compressed Air; O., Poisoning 741 one side, the eyes protrude, the pupils are dilated, the jaws are clenched. Ophthalmoscopic examination shows copious hemor- rhage at the back of the eye. Soon there occurs a sort of relaxing to which succeeds a new fit of stiffness with clonic convulsions re- sembling both a strychnine crisis and an attack of tetanus. These fits during the intervals of which the dog does not relax completely, but remains in opisthotonos, breathing with great difficulty, check the respiration, the heart still continuing to beat, although often with surprising slowness; the arterial pressure drops considerably. Sensitivity remains and one can excite new convulsions by it. After some time, these convulsive periods, which at first appear every five or six minutes, become rarer, then less violent; the stiffness 'J.iSjifip^uh Fig. 61 — Dog during the tonic convulsions of oxygen poisoning. 742 Experiments lessens in the intervals, and finally all symptoms disappear at the end of a few minutes or, at the most, a few hours. In lighter cases, instead of attacks so violent that one can lift the animal by a single foot, stiff as a piece of wood, as Figure 61 shows, we observe irregular movements, local convulsions, symp- toms, in a word, which are much like those of poisoning by phenol. We sometimes see acts which seem to indicate a certain mental dis- turbance. In very serious cases, on the contrary, the stiffness is continual, with a few clonic increases from time to time; the teeth grind and clench so as to appear nearly ready to break, and death may occur after one or two attacks, separated by a few minutes. We then find the blood red, even in the portal system; then it turns dark. When the animal no longer makes any movement, the heart still continues to beat for a few minutes. At other times, as in Experiments CCLXXVIII and CCXCVII, the convulsions last nearly 24 hours before ending in death. We find no congestions or ecchymoses in the lungs and the nervous centers. Only consistently in sparrows, we see the cranial diploe filled with a hemorrhage in dots, in smaller or larger spots, or even in a sheet covering the occipital region, and, in the most violent cases, the whole extent of the cranium. These bloody suffusions, the cause of which does not seem to me easy to explain, are invariably present in oxygen poisoning. They appear some time before the moment of death. But they are not peculiar to this kind of death, and in the preceding experiments we find them noted, even in simple asphyxia, under diminution of pressure (See Experiments CCLII and CCLIII). The appearance of the symptoms which we have just described seems to indicate that the toxic action produces its effect on the nervous centers, as do strychnine, phenol, and other poisons which cause convulsions. This conjecture is corroborated by the fact that inhalations of chloroform stop the convulsions momentarily, although they reappear when the anesthesia has worn off. Let us remember that, according to our experiments on frogs, if the sciatic nerve has been cut in the hind leg, there are no convulsions in the muscles animated by this nerve. To summarize all these facts, I shall quote here the con- clusions of the report which I had the honor to make on this subject to the Academy of Sciences, February 17, 1873. Compressed Air; 02 Poisoning 743 1. Oxygen acts like a poison which is rapidly fatal, when its quantity in the arterial blood rises to about 35 cubic centimeters per 100 cubic centimeters of liquid; 2. The poisoning is characterized by convulsions which, according to the intensity of the symptoms, represent the different types of tetanus, strychnine, phenol, epilepsy, etc.; 3. These symptoms, which are quieted by chloroform, are due to an exaggeration of the excito-motor power of the spinal cord; 4. They are accompanied by a considerable and constant drop of the body temperature. It is this last point, purposely set aside until now, that I shall discuss next. 2. The Diminution of Oxidations by Oxygen Poisoning. When for the first time I saw a sparrow struggling in violent convulsions under the influence of compressed oxygen, I imagined at first that the intra-organic oxidations had been so overstimulated in this bird that it was dying from burning itself out too quickly, producing thus a quantity of exaggerated heat, which perhaps be- came the direct cause of death. I thought therefore that the thermometer would show me a rise in the bird's temperature. Great was my surprise when I noted an absolutely opposite result. In fact, in all the experiments, as the numbers listed in Column 5 of Table XIV and Column 9 of Table XV show, the temperature of the experimental animals dropped considerably, before and during the convulsions due to the oxygen. At the beginning of the poisoning, when the convulsive symp- toms were just commencing to appear, the temperature fell (Ex- periments CCLXI, CCLXII, CCLXVII) . During the convulsions, it falls more, and when the convulsions are to end in death, it reaches very low figures (Experiments CCXCIII, CCLXXXI, CCLXXVIII, CCXCVII), especially in birds, in which it goes below 30, and sometimes even below 20 degrees (Experiment CXXXVII). If, on the contrary, the animal is to survive, its temperature rises and returns in a few hours to its normal value (Experiments CCLX, CCLXII, CCLXVII, CCLXXXIX, CCXCIII) . It is, therefore, a firmly established fact that the excess of oxy- genation of the organism results in a diminution of intensity in the chemical acts which produce the animal heat. If the falling of the temperature of the body has given us a certain though indirect demonstration of this strange fact, we should find the direct proof when we examine either the absorp- 744 Experiments tion of the oxygen or the two important excretions of urea and carbonic acid. Pulmonary exchange. Let us speak first of the consumption of oxygen and the production of carbonic acid, which are measured by the same experiment. The experiments reported in Chapter I on birds which died in confined and compressed air show that these two phenomena less- ened in intensity during the compression. But it is not possible to draw any conclusion, because the carbonic acid which is stored up in the tissues of the animal adds its action to that of the oxygen, and we shall see in Chapter VIII that carbonic acid also diminishes the oxidations. As to the experiments reported in the present chapter, they can- not furnish any information as to what takes place during the com- pression. I therefore had to plan special experiments; unfortunately, the problem presented more serious difficulties than one might have supposed at first glance. In dealing with animals kept in closed vessels, as the idea was to turn out, for the reason which has just been stated it was neces- sary to eliminate the carbonic acid and keep to the measurement of the oxygen consumed. Now under the influence of pressure, there must be dissolved, in the very body of the animal, a certain quantity of oxygen which it is impossible to estimate and subtract from the total quantity of oxygen that has disappeared. That is not all. In the numerous experiments which I have tried by this method, I took care always to act comparatively, to put simultaneously two identical animals, one under a bell of known capacity at normal pressure, the other in a compression receiver at a determined pressure, with a potash solution which absorbed the carbonic acid as it was formed. After a certain time had elapsed, I analyzed the two airs, and I could easily determine the quantity of oxygen absorbed by each of the two animals during a certain unit of time. Unfortunately, the percentage analyses made neces- sarily upon a small volume taken from the total mass of air in the experiment have to be multiplied by this mass, to get the total con- sumption, and the causes of error of either chemical or physiologi- cal nature then assume a value so great that they exceeded the differences noted between the two analyses. I therefore had to give up this type of experiment completely. I used two others, which are not subject to the same criticism. The first is a little indirect. It consists of comparing the quantity Compressed Air; O. Poisoning 745 of carbonic acid given off by the same animal placed successively in a closed vessel, in ordinary air or in a superoxygenated air at the same degree of compression. The special action of the carbonic acid is thus eliminated, because it is obviously the same in both cases. Here are the details of an experiment conducted in this way. Experiment CCCIV. Albino rat. Rectal temperature 38°. May 10. Placed from 4:05 to 6:35 (2 hours 30 minutes) in the large receiver made of a mercury bottle (containing 3 liters), under a pressure of 3V4 atmospheres of air. When he is taken out, his temperature has fallen to 30°; he is quite sick, breathes slowly and deeply, but recovers quite quickly. The air of the flask contains 12.5% of oxygen, and 6.6% of car- bonic acid. May 12. The animal has recovered perfectly; we begin again the same experiment, as to pressure and length; but this time we use air containing about 60% of oxygen. The tension of this gas corresponds then to that of compressed air from 9 to 10 atmospheres. At decompression, the animal is found very low, not sensitive to pinching, but sensitive in the cornea. His rectal temperature is only 23.8°. He does not move, and dies at the end of a half-hour; no gas in the blood vessels. The air in the receiver contained only 5.3% of carbonic acid. Experiment CCCV. July 1. A. Two sparrows weighing together 38 gm. are subjected to a pressure of 5 atmospheres of air for 32 minutes, in the Seltzer water receiver. Taken out after sudden decompression, seem very well, with slight bloody suffusions on the cranium. During this time they consumed 3.9% of oxygen, and produced 2.8% of carbonic acid. B. Two other sparrows, weighing together 39 gm., are placed next in the same apparatus, at the same pressure, but in air containing 72.6% of oxygen; the tension, 5 x 72.6 = 363.0, corresponds to about that of 18 atmospheres of air. They remain in the apparatus for 27 minutes. At the end of 5 minutes there occurred in the two birds convul- sions which lasted with intensity for 15 minutes. Then the sparrows remain lying on their backs, panting heavily. One of them dies at the end of an hour; the other, after seeming to recover, but keeping up incessant muscular quiverings, is seized with convulsions after an hour and a half, and dies in a half hour. Both immediately take on rigor mortis; moderate bloody suffu- sions. In 27 minutes they consumed 2.05% of oxygen, 1.07 in the 'first 17 minutes and only 0.35 in the last 10; they produced in the first 17 minutes 1.07% of carbonic acid, and 0.28 in the rest of the time, in all 1.35. We see from these figures that in 10 minutes at 3 atmospheres of air 1.2% of oxygen was consumed and 0.8% of carbonic acid was 746 Experiments formed, while at a tension corresponding to 18 atmospheres of air the consumption was only 0.7 and the production 0.5. These experiments show very clearly that the absorption of oxygen and the production of carbonic acid decrease when the oxygen tension increases; the difference increases in proportion to the length of the experiment. Experiment CCCVI shows that at 9 or 10 atmospheres of air this effect is produced clearly, and that at this low pressure death may occur after an exposure that has been prolonged enough. The second experimental method I used consisted of collecting and measuring all the carbonic acid produced by an animal during a certain time under different pressures but in a current of air that is always pure. Experiment CCCVI. Rat weighing 160 gm. July 28. Placed for a half hour in the Seltzer water apparatus, at normal pressure, under a current of air providing 2 liters per min- ute. The apparatus is immersed in water at 20°. The air which escapes is collected in a bag, and then connected with the potash bubbler of Figure 65, which absorbs all the carbonic acid from it; the carbonic acid is then extracted by one stroke in the mercury pump. The temperature of the animal dropped from 38° to 37.5°. It produced 247 cc. of carbonic acid. August 2. Same animal, same general arrangements. Kept under a current of air but this time at a pressure of 9 atmospheres, during the same length of time. On being taken from the apparatus, its temperature has dropped from 38.1° to 34.6°. Produced 176 cc. of carbonic acid. In two of the experiments (CCXCIII and CCXCIV) made on dogs, which were reported in the preceding subchapter, I measured the oxygen consumption, and at the same time the production of carbonic acid, not during the compression, but during the moments following the decompression, and even in the midst of an attack of convulsions. This measurement was interesting only from the comparative point of view. The method which I used, which makes no claim to absolute accuracy, allows me to compare what a dog was capable of absorbing and producing before being subjected to compressed air with what he consumes and produces when he has been taken from the cylinder. The experimental animals had a tube in the trachea. I con- nected this tube with a bag filled with a known volume of air and let the animal breathe into the bag for a certain time. Since the Compressed Air; 02 Poisoning 747 operation was repeated several minutes after the decompression, two chemical analyses allowed me to determine the quantity of the gases absorbed and given off in both cases. Experiment CCXCIII shows that although before the compres- sion the dog had consumed in a quarter of an hour 4.89 liters of oxygen and produced 2.99 liters of CO., after he had been taken from the apparatus in the same time he consumed only 2.02 liters and formed only 1.12 liters. Similarly, in Experiment CCXCIV, the consumption of oxygen fell from 3.95 liters to 2.15 liters, and the production of carbonic acid from 2.41 liters to 1.99 liters. The decrease in the production of carbonic acid through the superoxygenation of the organism is indicated again by the study of the numbers listed in Column 8 of Table XV. If we examine Experiments CCLXXX, CCLXXXI, CCLXXXV, CCLXXXVI, CCLXXXVII, CCLXXXIX, CCXC, CCXCIII, we see that some minutes after the decompression we find in the blood only minimal proportions of carbonic acid. And this fact is all the more remark- able because, in the conditions in which the experiments were made, carbonic acid had been stored up in the blood in consider- able quantity during the compression. Now when the animal was restored to the open air, this acid lessened to far below the normal proportion; in Experiment CCLXXXIX, it fell to 10.5 volumes per 100 volumes of blood, although its regular proportion, before the compression, was 44.5; in Experiment CCLXXXVI, the proportion before the compression being 43.0, it became 69.4 during the com- pression, and dropped to 9.9, 20 minutes after; in Experiment CCLXXXV, the same figures were 40.8, then 92.5, and finally 14.8. It is quite clear then that, in consequence of the exaggerated superoxygenation of the organism, carbonic acid ceased to be pro- duced in the tissues, and to pass into the blood, or at least that these phenomena were considerably slackened. This would have been manifest even during the compression, if I had been able to keep the animals in a current of compressed oxygen, to avoid the storing up of the carbonic acid due to the confinement. Furthermore, the experiments reported in Chapter II, in which we were dealing with pressures which were rather low but were made with almost pure air, showed, as we have noted, a diminution of the carbonic acid of the blood (See Table XII). It appears from these data that the pulmonary ventilation would be capable of removing from the blood much more considerable proportions of carbonic acid than one would have thought, of al- most exhausting, in a word, the bicarbonates and the phospho-car- 748 Experiments bonates, if the organism did not unceasingly furnish the venous blood with a constant source of this gas. We shall return to these data in another chapter, but it would be interesting to see, by a simple experiment, in which the same blood would be forced by a pump to pass constantly through the lungs, in which artificial res- piration would be maintained, how much carbonic acid this blood could lose. Before leaving this subject, let us say that the carbonic acid re- appears but slowly in normal proportion in the arterial blood, when the superoxygenated animal recovers and lives. In Experiment CCLXXXIX, at the end of 1 hour and 15 minutes the proportion of carbonic acid was only 19.0; in Experiment CCXCIII, after 2 hours and 40 minutes, it had risen only to 26.5; but in Experiment CCLXXXI, at the end of 67 minutes it had returned to its original figure, 31.5. Let us note that this tendency to return to the normal proportion does not always indicate that the animal will survive, as Experiment CCLXXX shows. Excretion of Urea. I now come to the urea. The experiments were conducted like those in the case of diminished pressure. The animal, subjected to a fixed diet for several days, was kept for several hours in compressed air, with a suitable current of air. The urine voided spontaneously or collected with a catheter in the pre- ceding 24 hours was compared with that given in the 24 hours in which the compression took place. The account of the experiments will give the necessary details. Experiment CCCVII. Dog weighing 12 kilos, eats every day at 7 o'clock in the morning a soup composed of 250 gm. of bread, 250 gm. of meat, and 500 gm. of water. July 25, at 8 o'clock in the morning, catheterized the animal, which was then placed in a cage where the urine can be collected; he does not urinate, and July 26, at 8 o'clock, another catheterization gives 280 cc. of urine. This urine, analyzed by the Yvon process, gives 4500 cc. of nitrogen, that is, 12.1 gm. of urea. July 26, from 9 o'clock to 3 o'clock, is subjected to a pressure of 8 atmospheres, under a current of air. Decompressed from 3 o'clock to 5 o'clock, is taken out in good condition. His rectal temperature is 35.5°. July 27, at 8 o'clock in the morning (rectal temperature 35.7°) he is catheterized and the urine thus obtained is added to what he voided spontaneously. The total is 350 cc. of urine, which gives only 1398 cc. of nitrogen corresponding to 3.7 gm. of urea. I must add that the animal would eat only half his meal. July 28, at 8 o'clock in the morning, catheterized again; there are 520 cc. of urine giving 3838 cc. of nitrogen, that is, 10.3 gm. of urea. During this day, the animal had absolutely refused to eat. Compressed Air; 0_, Poisoning 749 Experiment CCCVIII. Dog weighing 16 kilos; since July 31, eats every day 250 gm. of bread, 250 gm. of meat. August 3, at 8:30, catheterized. August 4, at 8:30, catheterized, and this urine added (100 cc.) to what was voided in the 24 hours (475 cc.) It gives, by the Yvon pro- cedure, 8062 cc. of nitrogen, that is, 21.6 gm. of urea. Rectal temper- ature 35.8°. At 9 o'clock in the morning, placed in the apparatus, where the pressure rises to 8 atmospheres; decompression begun at 4:50, still under a current of air; the animal is removed from the apparatus at 6:20; he is in good condition; his temperature is 35.5°. August 5, at 8:30 in the morning, the catheter drew 245 cc. of urine; there was none in the apparatus. It gave only 6329 cc. of nitrogen, corresponding to 16.9 gm. of urea. These examples are enough to show that the chemical phenomena on which depend the formation of urea and analogous- products are impeded in the same manner as those which determine the production of carbonic acid. Sugar of the Blood; Glycosuria. A search for sugar in the blood and the urine shows us another chemical transformation, the de- struction of this sugar, impeded by the action of oxygen under ten- sion. In Experiment CCLXXXVI, the dog, which survived after convulsions of extreme violence, voided after the decompression urine with great sugar content; in Experiment CCLXXXI, which ended in rapid death, the few drops of urine which the bladder contained had high sugar content. This glycosuria, however, is not constant (Experiment CCXC) . Experiments CCLXXXV, CCLXXXVI, CCLXXXIX, CCXC, CCXCII, CCXCIII, and CCXCIV, that is, all in which the blood was tested for sugar, showed first that there is always much glucose in the arterial blood of a dog which has been subjected to com- pression. But as we always find glucose in arterial blood when it is treated according to the method of M. CI. Bernard by boiling with sulfate of soda, comparative experiments CCLXXXIX, CCXC, CCXCII, CCXCIII, CCXCIV had to be made on the blood before and after compression, which showed very clearly that the latter contains more sugar than the former. Experiment CCXCIII proves besides that this excess of sugar disappears at the end of some time. So the sugar which comes from the liver is much less rapidly broken down in the organism under the influence of compressed oxygen than at normal pressure, so that it is stored up in the blood to the point of producing glycosuria. As to the production of the hepatic glucose itself, it is hampered by the sufficiently prolonged action of oxygen at high tension, as the following experiments prove. 750 Experiments Experiment CCCIX. March 7. Albino rat. Rectal temperature 39.6°. Kept for three hours in compressed air at 12 atmospheres, above a potash solution which absorbs the carbonic acid as it is formed. Withdrawn suddenly, its rectal temperature is only 35.5°; it dies quickly with air in its heart. Its liver does not contain sugar; much glycogenic material. Experiment CCCX. March 15. Albino rat; rectal temperature 39.9°. At 12 atmospheres of air for 3 hours, with potash. Withdrawn; temperature 37.2°; dies like the rat in the preceding experiment. No sugar in the liver. In summary, consumption of oxygen, production of carbonic acid and urea, breaking down of glucose in the blood, all chemical phenomena which can be measured easily, appear to be consider- ably slowed down by the action of oxygen under high tension. And as these are the phenomena which determine the production of heat, it is not surprising to see that the temperature of the animals drops considerably. Nor is it astonishing to see that death is the consequence of such a depression in the intensity of the physico- chemical acts of nutrition. But the violent excitation, the constant convulsions which ac- company this death are still unexplainable by the depression alone; still less explainable is the persistence of the symptoms after nor- mal pressure has been restored. In fact, in studying diminished pressure, we have noted a diminution of the chemical acts, analogous to what increased pressure revealed, and yet the con- vulsive struggling which precedes death by rapid decompression is in no way comparable to the violent convulsions due to oxygen and, furthermore, the return to free air marks irrevocably the end of all these symptoms. This shows then that during compression the regular chemical acts of nutrition have been not only slowed up, but also modified; it is supposable that the result of this deviation has been the forma- tion of some substance capable of playing a toxic part, a substance which, persisting after decompression, would continue to cause the symptoms and might bring on death, a substance the elimination or destruction of which would be necessary for a return to the state of health. The chapter especially devoted to the study of fermentations will confirm us in this idea, and will even permit us to express it with more precision and clarity. Compressed Air; CX Poisoning 751 3. Aquatic or Invertebrate Animals. The experiments reported up to this point were made only with vertebrate air-breathing animals: mammals, birds, frogs. It was in- teresting to study the action of oxygen at very high tension on in- vertebrate air-breathing animals and on aquatic animals. Experiment CCCXI. April 25. Beetles, flies, caterpillars; centi- pedes; woodlice; arranged in two similar groups. A. Placed in a corked flask; ordinary air, normal pressure. B. In the compression apparatus, and taken to 6 superoxygenated atmospheres; the pressure falls to 2 atmospheres. April 26. All alive except the flies in B. Experiment CCCXII. May 12. Lizard; golden beetles; carpenter bee, loaded with mites; drone, red fleas; flies; spiders; woodlice; centipedes. At 5 o'clock in the evening, taken to 6 superoxygenated atmos- pheres. May 13; 10 o'clock in the morning, decompressed. The drone, the flies, the woodlice are dead, as are several red fleas; the others still move their feet a little, as does the carpenter bee. The lizard has spontaneous and excitable convulsions; he dies some hours afterwards. The beetles, the spiders, the mites, the centipedes are in good condition and survive. Experiment CCCXIII. May 14. Golden beetle, bees, ants, red fleas, wood fleas; flies; woodlice; spiders; snails; earthworms. At 5 o'clock in the evening, placed in the cylindrical glass appara- tus, with branches, earth, etc., to allow them to separate from each other. Taken to 5 superoxygenated atmospheres. May 15, 2 o'clock. All dead except the spiders, the earthworms, which are twisted and intertwined, and the snails. ,A11 die in the open air. Experiment CCCXIV. May 16. A Capricorn beetle, 1 dragon fly, 1 blue butterfly, several bees, drones, ants, red fleas, flies, syrphus flies; centipedes, geophiles; wood- lice; spiders. At 11 o'clock in the morning, taken to 5 superoxygenated atmos- pheres; at 1 o'clock raised to 6; at 2 o'clock to 11 atmospheres. Almost immediately all fall to the bottom, motionless, except the ants and the centipedes, which run up and down. The flies die in a half hour at most. 4 o'clock; none of the insects are moving. Decompression made. The bees, the flies, the syrphus flies, and the butterfly are dead. The Capricorn beetle, the dragon fly, the drones, the fleas, the ants, the woodlice are still moving a little. The myriapods and the spiders are in good condition. 752 Experiments The next day, all are dead except the myriapods. Experiment CCCXV. June 23. Silkworm cocoons, sent by M. Raulin, from Alais, all of the same day. A. 12 are placed in an open bell-jar. B. 6 in the cylindrical glass apparatus, at 5 superoxygenated atmospheres. C. (By some mistake, probably of the proof-reader, the conditions in C were not given; the pressure was probably much higher than in B. Translator.) The air was changed every other day. July 8. A. All have emerged. B. No motion. C. All dead; the skin of the chrysalises is not separable; they evi- dently were killed very soon. So the formidable influence of compressed oxygen is felt by in- vertebrate animals as well as those belonging to the higher types. The animals which in the simultaneous experiments first felt the fatal effects of oxygen were the flies; after them the bees and the butterflies; then the dragon flies and the fleas; considerably later, the ants and the coleoptera (longicorn and carabic) . The woodlice, and especially the arachnids (spiders, acaridae) and the myriapods (centipedes, geophiles) are much more resistant. Then come the earthworms and the snails, at least for length of life, if not for lethal concentration. The great importance of this kind of research is to show that death from excess of oxygen does not depend upon a mechanism peculiar to animals with red corpuscles, but is a general fact. There is present a profound modification in the metabolism of the tissues. We should note that these animals never seemed excited; on the contrary, they quickly become motionless and fixed in some corner of the apparatus, and die without showing any convulsion. As a type of aquatic animal to be studied, I generally used young eels, called "de la montee", the hearts of which one can easily see beating. Experiment CCCXV I. April 1. Small eels "de la montee", trans- parent, temperature 15°. A. 5 are placed in a well-corked test tube; B. At three o'clock, 5 are placed in the cylindrical apparatus and raised to 11 atmospheres of an air with 50% of oxygen. Oxygen ten- sion 550, corresponding to about 26 atmospheres of air. In the evening at 7:30, nothing particular apparent. April 2, 1 o'clock. A: in good condition. B: dead, stiff, not transparent, and not contractile when stimu- lated electrically. Compressed Air; 02 Poisoning 753 Experiment CCCXVII. April 2. Similar eels. A: these are the same ones as A of the preceding experiment. B: at 3 o'clock, 5 are placed in the apparatus at 5% atmospheres of air with 57.5% of oxygen. The tension is therefore 316, correspond- ing to 15 atmospheres of air. April 3, 10 o'clock in the morning; A, very lively; when quiet, respiratory rate 78 and pulse 40. B: move when the apparatus is shaken, but not spontaneously. Pulse 20 at the most; respirations, when eels are quiet, are not visible; after they were shaken, I counted 22. From time to time, violent struggling. 6 o'clock in the evening; in convulsions and are twisted in the shape of an 8. April 4, 1 o'clock. B: all dead, opaque. Experiment CCCXVIII. April 4. Similar eels. A: These are the eels of the two preceding experiments. B: at 4 o'clock, 5 are placed under pressure of 10 atmospheres of air. April 5, 9 o'clock in the morning: A: very lively, 66 very ample respirations; pulse 26. B: at the bottom of the apparatus, hardly moving; respirations invisible; pulse 20. April 7. Same, all living; rapid decompression. Experiment CCCXIX. July 8. Eels, not transparent. At 5 o'clock in the evening, under compression of 10 atmospheres of air containing 50% of oxygen; the apparatus is shaken to saturate the water containing the eels. July 9, 1 o'clock; all dead, opaque. I tip the apparatus so that not the air but the water will escape; this water, when collected in the syringe, froths, and is taken to the mercury pump. It contains 14 volumes of oxygen per 100 volumes of liquid, and the same quantity of nitrogen. Much weaker pressures are enough to kill aquatic animals when their action is continued long enough. Experiment CCCXX. May 20. Frog tadpoles, several days out of the egg and in very good condition in the laboratory. A: 5 in a little corked flask, with water, at normal pressure. B: 5 in a flask with water, all in the glass compression apparatus, at 7 atmospheres of air. May 22: all living. May 24: all living in A, all dead in B, probably since the day before. Experiment CCCXXI. May 24. Same experiment, with similar animals; 7 atmospheres of air. May 27; all the tadpoles in the compressed air are dead. So aquatic animals are killed like air-breathing animals, when 754 • Experiments oxygen is dissolved in the water in sufficient quantity. A pressure of 15 atmospheres kills them quickly and they cannot live in 7 atmospheres. The transparency of the eels allowed us to note a con- siderable slowing down of the heart beats, while the respirations weakened so as to be almost invisible. In another part of the book we shall draw conclusions from these last experiments from the point of view of the physics of the earth. It is enough here to note the generality of the fatal action of compressed oxygen, which acts upon warm-blooded animals as well as upon cold-blooded animals, upon vertebrates and inverte- brates, upon animals which live in the water and those which breathe air, upon adult animals and those in the process of develop- ment. Chapters V and VI will permit us to extend this formula to plants, to ferments, in a word, to every living thing. Subchapter II ACTION OF COMPRESSED AIR AT LOW PRESSURES (FROM 1 TO 5 ATMOSPHERES) The great interest attached to the toxic action of oxygen at high tension has caused me, as I said when I began this chapter, to begin this exposition as well as my research by a detailed analysis of the effects of this poison of a new type. I confess that I have long neglected, almost scorned, this study of the effects of slightly compressed air which French and German doctors have so long been testing, as we saw in the first part of this book. I could not, however, help being somewhat interested in it. My researches even gave it a new interest, unknown to former experimenters. In fact, the experiments which have just been reported have shown that poisoning by oxygen at high tension first checks the intra-organic combustions, lessens the quantity of oxygen absorbed, of urea excreted, and consequently lowers the temperature of the body in warm-blooded animals. Now it is evident from the experi- ments contained in Chapter III, that the same physiological effects also result from diminished pressure, or, to speak more exactly, from too low tension of the oxygen breathed. Quite naturally then it was desirable to know where between these two extremes, which are equally dangerous, is the point where the organic combustions are at their maximum intensity. Besides, it was proved by the same experiments that prolonged Compressed Air; Low Pressures 755 exposure to a much rarefied air on the one hand, or to a very much compressed air on the other is fatal to animals, even if the modifi- cations of pressure are not such that they bring on the rapid symp- toms of asphyxia or of poisoning by oxygen. It is very important to determine what barometric pressure is most favorable to life. And it is by no means proved that this favorable point coincides with the maximum of combustion which we shall try to determine at the same time; this even seems improbable a priori. It was with the purpose of settling these two questions that the experiments reported in the present subchapter were undertaken. However, I must remind the reader again that I am acting as an experimental physiologist and not as a hygienist or a doctor. To study the continued effect of compressed air, I used the lower ani- mals exclusively, because they are much better adapted to experi- ments in which a prolonged stay in almost confined air is indis- pensable, and because they do not present the physiological in- equalities which so seriously complicate researches on the metabo- lism of higher animals. Everything seemed to indicate to me that the maxima which I was seeking were included between normal pressure and 5 atmos- pheres. This is suggested by graph A of Figure 22, which expresses the oxygen content of the compressed and confined air in which animals died without the interference of carbonic acid. It was be- tween these limits then that I made my investigations. In fixing these limits I had a reason of another sort, which is also important. It was absolutely proved by the experiments on diminution as well as on increase of pressure that the latter acts only as modifier of the oxygen tension, so that an air rich in oxygen and below one atmosphere in pressure produces the same effects as an air poor in oxygen but sufficiently compressed. In the preceding subchapter I repeatedly obtained the oxygen tension (02 x P) by multiplying the factor pressure (P) by the factor of oxygen per- centage (02) . So ordinary air at normal pressure has as its value, from the point of view which interests us, 20.9; at two atmospheres, this value becomes 2 x 20.9 = 41.8; at five atmospheres, 5 x 20.9 = 104.5. That is, one can use either ordinary air at two atmospheres of pressure or air with 41.8% of oxygen under normal pressure (if care is taken to remove the carbonic acid, the toxic acid of which might complicate the symptoms) ; and ordinary air at 5 atmos- pheres, or, obviously, pure oxygen. This observation presents very great practical interest, because it permits experimentation at normal pressure, that is, in material 756 Experiments conditions easy to realize which do not require, as do high pres- sures, the use of expensive and fragile glass apparatuses. Finally, it seemed to me that I simply could not neglect these modifications in the circulation and the respiration, which before my time interested so many observers, whose statements, as we saw in the historical part, are far from being always in harmony. I was particularly anxious to measure the mechanical action of com- pressed air, acting upon the gaseous reservoirs of the organism, that is, the intestine and the lung. In consequence, the experiments reported in this subchapter will naturally be divided into two categories: in some, the super- oxygenated air will act for only a short time, several hours, a day at the most; in others, its action will be continued until it is ascer- tained whether or not it has any effect. 1. Short Stay in Compressed Air. A. Experiments Made Upon Myself. I shall first report the experiments made upon myself with the purpose of investigating on the one hand the respiratory and cir- culatory phenomena, and on the other hand the action of com- pressed air upon the excretion of urea, that is, upon one of the evidences of intra-organic combustions. For this part of my researches, Dr. Jourdanet lent me a chamber which he has had made for therapeutic applications, and in which an ingenious arrangement allows one to secure at will an increase or a diminution in pressure. This chamber, the general aspect of which is given in Figure 62, measures 2.58 meters in height and 1.46 meters in diameter, and consequently contains about 3*4 cubic meters of air; it is closed by two doors, one inside and the other outside, on rollers guided by grooves; these doors are fastened together, when they are closed, by three long screws, which pass through holes cut through their walls. As they are fitted tightly on the walls of the cylinder by rubber gaskets, there is always one of them closed hermetically, for compressed as well as for expanded air. A rubber tube communi- cates with one or the other of the decompression or compression pumps; communication with the outer air is secured by openings which are not seen in the figure and which are controlled by inner cocks, which the experimenter manages; another cock permits his assistants to make the decompression if any accident happens to him. On both the inside and the outside are precision thermometers and manometers. In this apparatus, operating at full speed, in one hour I can Compressed Air; Low Pressures 757 reach one atmosphere of pressure above normal, at the same time being under a current of pure air which is sufficiently strong to keep the temperature in the chamber from rising more than 2 or. 5 degrees. Fig. 62 — Apparatus of M. Jourdanet for the therapeutic use of compressed or expanded air. The number of heart beats was counted for five minutes, to avoid causes of error against which often no precautions are taken. The number of respirations was counted for 5 and often 10 minutes. 758 Experiments To measure the quantity of air expired, I found nothing more convenient or more accurate than a gasometer. The one I had made especially for this purpose and which is pictured in Figure 63, has several dials, by means of which one can estimate the volume of air which has passed through the apparatus to within 50 cc. Fig. 63 — Gas meter for measuring respiratory movements. When it was necessary to measure the maximum expirations, I stood up, with my garments loosened, and after the inspiration, I took in my mouth, without any supplementary tube, the pipe leading to the gasometer and exhaled rather slowly until the lungs were empty, my nose, of course, being closed tightly by my left hand; I thus made at least 10 expirations, of which I took the average. The same arrangement was used when I wished to exhale into a rubber bag to check the quantity of carbonic acid produced in a given time. I generally breathed for 10 minutes into the bags; then the air from them was passed for a whole night through the potash bubblers which I shall describe later; there it was completely freed Compressed Air; Low Pressures 759 of its carbonic acid; the potash solution was then analyzed in the mercury pump. But to measure the regular respirations, the arrangement was more complicated; I had to have an apparatus which operated without the least attention, for we know how easily the respiratory movements are modified, when one wishes to examine them. The arrangement in Figure 64 gives excellent results, as many test ex- periments have shown me. A rubber mouthpiece, which is applied to the dental arches and 760 Experiments which the lips support without inconvenience or effort, is con- nected by a large rubber tube and a Y-shaped piece of copper to two glass tubes, each of which contains a membraneous valve, like those used by MM. Denayrouze in their well-known apparatuses; these valves are excellent, very delicate, and hold very well, if they are kept wet. As they are placed in opposite directions, one per- mits only the intake of inspired air, the other the escape of expired air, which a rubber tube suitably placed conducts to the gasometer. Of course the nose is closed the whole time by a sort of pincer to which one easily becomes accustomed. I breathed thus for 10 and sometimes 20 minutes, remaining in perfect calmness, reading, and merely looking at the time or count- ing my respirations; sometimes the assistant did this for me, look- ing in through one of the glass portholes. Besides, I regulated all the other conditions of my life very care- fully; every day I went to the laboratory and sat there from 2 to 6 hours in or out of the apparatus; I took no other exercise. It was with all these precautions that the following experiments were carried on. Experiment CCCXXII. November 6. I begin by putting myself regularly on the following diet, which previous tests showed me was suitable. My weight is 73 kilos; height, 1.73 meters. At lunch (12:15); two medium sized eggs, 70 gm. of lean mutton, 140 gm. of bread, 800 cc. of a mixture half wine and half water. At dinner (7 o'clock) : 120 gm. of lean beef, 200 gm. of mashed potatoes, 6 brandied cherries, bread and wine as at lunch. November 7. After having emptied my bladder at noon, I keep my urine until Nov. 8, at noon .... A I do the same the following days. This day I remain at normal pressure. November 8. I place myself in the cylinder from 3 o'clock to 6 o'clock; but I keep a current of air at normal pressure. Urine from Nov. 8 to Nov. 9 B November 9. Seated at 2:45 in the open apparatus; pulse 78; respiratory rate 8; maximum expiration 3.7 liters. At 3:18, compression begun. At 3:45, pressure +30 cm. At 4 o'clock, pressure +45 cm.; pulse 80; maximum expiration 4 liters. At 4:12, pressure +53 cm. At 4:42, same pressure; pulse 72. At 5:10, same pressure; respiratory rate 8.2; maximum expiration 4 liters. At 5:32, the pressure was maintained at the same level; I begin the decompression; I leave the apparatus at 6:53. At normal pressure, maximum expiration 3.7 liters. Compressed Air; Low Pressures 761 Urine from Nov. 9 to Nov. 10 .... C. November 10. Seated in the apparatus at 2:35. Maximum expiration 3.8 liters; calm respiration is 7.6 per minute, equivalent to 6.3 liters, or 0.83 liters for each expiration; pulse 68. Closed the doors at 2:55. At 3:20, compression of +37 cm.; maximum expiration 3.8 liters. At 3:38, +56 cm.; maximum expiration 4 liters. At 3:50, same pressure; 8.1 respirations per minute, equivalent to 6.7 liters, or 0.82 liters per expiration. At 4:25, same pressure; calm expirations give 6.2 liters per minute, without counting the number. At 4:50, same; 6.5 liters per minute. At 5 o'clock, the same; pulse 69. At 5:10, the same; maximum expiration 4 liters. At 5:37, the same; began the decompression. At 5:45, pulse 63. At 6:15, pressure +15 cm.; pulse 60. At 6:20, pressure +10 cm.; calm expirations give 6.2 liters per minute. Normal pressure at 6:30. Urine from Nov. 10 to Nov. 11 .... D November 11. End of the experiment at noon. The urine was analyzed by the Grehant method, but the analysis was lost. Experiment CCCXXIII. November 15. I enter the apparatus with a rather severe cold in the head, a cough, and tracheal pains showing the beginning of a cold in the chest. At 2:40, at normal pressure, my maximum expiration gives 3.75 liters. At 2:50, pulse 77.7. From 2:55 to 3:05 ,breathed quietly into a bag .... A Ordinary expirations as reckoned on the gasometer give 6.5 liters per minute. Respiratory rate 9. At 3:10, compression begun. At 3:55, compression of +52 cm.; pulse 65. At 4 o'clock, compression +60 cm.; maximum expiration 4.08 liters. At 4:20, compression +56 cm.; respiratory rate 7.5. At 4:30, same; pulse 62.5. Calm expirations give 5.86 liters per minute. From 4:45 to 4:50, breathed quietly into a bag . . . . B At 4:52, began the decompression. At 5 o'clock, pressure +40 cm.; calm expirations give 5.93 liters per minute. At 5:15, pressure +32 cm.; the snuffles which had left me begin again as does the heaviness in the head; some minutes after, (pres- sure +20 cm.) the cough reappears. At 5:55, normal pressure. Pulse 65; the pulmonary ventilation gives 6.28 liters per minute; maximum expiration is 3.8 liters. 762 Experiments The cold in the head stops in the night and the cold in the chest disappears. Gas A gives for 10 min. 2.643 liters of C02, that is, for 1 hour 15.858 liters Gas B gives for 10 min. 2.710 liters of CCX, that is, for 1 hour 16.260 liters. Experiment CCCXXIV. December 17. Barometric pressure 74 cm.; I begin again the diet of Experiment CCCXXII. The urine was collected from noon December 17. December 11. Remained at normal pressure. Urine from Dec. 17 to Dec. 18 noon .... A December 18. At normal pressure, from 2:30 to 3 o'clock, the maximum expiration is 3.76 liters; quiet pulmonary ventilation is 6.54 liters per minute; pulse 81. At 3 o'clock, began the compression. At 3:44, compression +48 cm.; the maximum expiration gives 3.96 liters. At 4:30, same pressure; pulse 79; pulmonary ventilation 6.74 liters per minute; 8.3 average respirations per minute. At 5:12, compression -4-52 cm.; decompression begun. At 6: 15, normal pressure; pulse 59; 8 average respirations; maxi- mum expiration 3.81 liters. At 7:30, pulse 60. At 8:15, pulse 83. Urine from Dec. 18 to Dec. 19 at noon . . . . B December 19. Barometric pressure 74 cm. At 9:30 in the morning, pulse 64, and respiratory rate 8; at noon, same. At 2 o'clock, still normal pressure, pulse 68. At 2:20, compression begun. At 3:10, compression -(-45 cm. At 3:35, compression +54 cm. At 3:50, compression +56 cm.; pulse 82; maximum expiration 3.92 liters. At 4 o'clock, same; began the decompression. At 4:45, compression +37 cm. At 5:50, normal pressure; pulse 68; maximum expiration 3.80 liters. Urine from Dec. 19 to Dec. 20, at noon . . . . C December 20, pressure 74 cm. At 4 o'clock, normal pressure; pulse 85; respiratory rate 6.5. At 4: 10, began the compression. At 5:10, compression +50 cm.; 6.6 calm expirations; I begin the decompression. At 5:30, compression +41 cm.; pulse 66; 6 respirations. At 6:15, normal pressure; pulse 58; 5.6 calm expirations per minute. Urine from Dec. 20 to Dec. 21, at noon . . . . D December 21, normal pressure; same diet. Urine from Dec. 21 to Dec. 22 at noon . . . . E December 22, normal pressure; same diet. Urine from Dec. 22 to Dec. 23, at noon . . . . F Compressed Air; Low Pressures 763 The analysis of the urines by hypobromite of soda gives: A (normal pressure) 1650 cc. containing 20.15 gm. of urea. B (compressed air) 2010 cc. containing 24.72 gm. of urea. C (compressed air) 1990 cc. containing 26.04 gm. of urea. D (low compression) 2255 cc. containing 21.18 gm. of urea. E (normal pressure) 2080 cc. containing 20.80 gm. of urea. F (normal pressure) 2125 cc. containing 22.50 gm. of urea. Experiment CCCXXV. February 9. M. Regnard, one of my assist- ants, 27 years, weighing 75.5 kilos, height 1.83 meters. At 1:45, normal pressure; pulse 70; respiratory rate 15.6; pulmon- ary ventilation of 12.28 liters per minute. Maximum expiratory capacity 4.15 liters. At 2 o'clock, began the compression. At 2:45, compression of +52 cm., left until 4 o'clock. At that time, pulse 57, respiratory rate 14.6; pulmonary ventilation 13.22 liters; maximum expiration 4.64 liters. At 4:20, began the decompression. At 5:30, normal pressure; pulse 56; respiration 16; pulmonary ventilation 13.02 liters; maximum expiration 4.60 liters. Let us see now in summary what these experiments have given us in regard to each important physiological function. The follow- ing table will aid our survey. Table XVI 1 2 3 4 5 6 7 8 9 10 11 12 13 Before the compression During the compression After the compression G E a P . 5 - 3 3 Experiment o>N 1 r i>§ 6 c o>% R r numbers « C ao 4>m cues Si 01 P CA o 2 atmospheres of air. B. Ordinary air. May 13. The barley has sprouted in both; A seems a little better and is greener. But on the following days, B has the advantage, and on May 20, the sprouts in A are only 2 to 3 cm. high, whereas those in B are 8 to 9 cm. high. However, the analysis of the air in B discloses no more oxygen, and there is 25.4% of carbonic acid; in A, there is 19.9% of C02, and only 71.6% of oxygen. The average oxygen tension then was about 4 atmospheres of air. C. Low Pressures : Superoxygenated Air. Experiment CCCLXXX. November 4. Sowings of barley and cress on wet paper. A. At a pressure of 3 atmospheres of an air containing 86.9% of oxygen. The tension of this gas is then 260, corresponding to about 12 Vz atmospheres of air. B. Normal pressure, ordinary air. November 7. Nothing in A; a few sprouts in B. November 11. Nothing in A; all have germinated in B. The air in A still contains 86.2% of oxygen, with 0.7% of carbonic acid. The seeds in A are sown on wet earth. November 20, the cress begins to sprout, but the barley is dead. Experiment CCCLXXXI. May 31. Sowings of barley seeds on wet paper. A. 5 gm. in the cylindrical reservoir at 3 and Vs atmospheres of an air containing 54% of oxygen; the tension corresponds to 180, that is, about 9 atmospheres of air. Experiments on Plants 795 B. 8 gm., normal pressure, ordinary air, bell of 1840 cc. June 3. No germination. Air changed in B. and oxygen changed in A. After this, the air in A contains 46.2% of oxygen, the pressure is dropped to 3 atmospheres; the tension then is 138, that is, a little less than 7 atmospheres. June 7. A. A very few radicles; the pressure has fallen fo 2 atmospheres; the air contains 2% of CO, and 41.2% of oxygen. B. The shoots are 3 to 5 cm. high and are very green. The air contains 8% of CO, and 11.2% of oxygen. Assuming for A an average pressure of 2 V% atmospheres, we find that in 4 days, the seeds in A have consumed, per 10 gm., 136 cc. of oxygen, and those in B 225 cc. The seeds in A are sown on wet earth and develop. Table XVII summarizes the principal results of the experiments above. They are arranged by the increasing order of oxygen ten- sions expressed in atmospheres. The different methods used agree in showing that even a slight increase in oxygen tension acts unfavorably on germination; be- ginning with two atmospheres or 40% of oxygen, it is manifestly delayed. At 5 atmospheres, which corresponds to pure oxygen, the delay in germination is very great. Above 7 atmospheres, the seeds merely send out a few radicles, no stalk appearing. Finally, at about 10 atmospheres, the barley seeds, when brought back to normal pressure, are dead and do not germinate, whereas cress seeds are resistant and sprout, although somewhat slowly (Exp. CCCLXXX) . Now cress seeds have thin, dry cotyledons and contain no albu- men. I wondered whether the death of the barley seeds did not result from some chemical change in their considerable albumen content. My experiments on fermentation, which will be reported in this chapter, have convinced me of the truth of this hypothesis. Besides, we see by Experiment CCCLXXI that fleshy seeds like those of the castor bean and melon were much more affected by the pressure than those of the marvel-of-Peru, which are more like cress seeds. In conclusion, I call attention to the fact that to obtain conclu- sive results, the seeds must be wet. Otherwise, the oxygen, in spite of the high tension, would not kill them. Example: Experiment CCCLXXXII. July 19. Dry wheat placed in a flask; in another, wheat previously moistened, which however is not covered with water, 796 Experiments The two flasks are subjected to 15 atmospheres of an air containing 70% of oxygen. July 31. Decompression and sowing. The dry wheat sprouts very well; the other rots in the ground without sprouting. TABLE XVII Experiment Number e-a PQ a o3g£ >.ja in 3'££ ra c <" QS. Species Tested Comparison with normal pressure CCCLXXVII1 CCCLXXVII CCCLXII CCCLXXVIII CCCLXXVII CCCLXXII CCCLXVI CCCLXXVIII CCCLXVII CCCLXV CCCLXXV CCCLXXVII CCCLXXIV CCCLXXVI CCCLXXIX CCCLXIX CCCLXIII CCCLXXX CCCLXXI CCCLXIV CCCLXXXI CCCLXVIII H U I 1% U U 13 2 II I 1V2 I iy2 1 1% l 6 |2 |18 |2 |43 12 I 9 12 I 8 I 2V2 I 18 2V2 I 21/2 I 12 2% I 2% I 10 I 3V4 4 4% 5 5 16 |S 101 43| I 21 HI I 7 HO [13 10 CCCLXX 7 3 7 7 8 1 7 1 10 10 14| 3 12V2 7 1 Barley and cress Barley and cress Barley id. Barley and cress Barley id. id. id. id. id. Barley and cress id. Barley Cress Barley Barley and cress Barley Barley and cress I Four o'clocks I -j Castor bean [ Melon Barley id. id. Cress Barley Cress As well as in air Longer; but less healthy Somewhat backward Slightly delayed Longer, but less healthy Somewhat backward id. id. A little paler Evident delay Delayed Delayed and very un- healthy Delayed Only a few seeds sprouted Sprout, not very green Very much delayed Very much delayed Very much delayed, but sprouts wefl in open aii- Very much delayed, especially the barley Germinate, but do not grow, even in open air Does not germinate, even in open air A few rootlets A few rootlets; sprouts in open air Does not germinate, even in open air Germinates after being taken into open air Nothing; dead. Nothing sprouts at nor- mal pressure. Experiments on Plants 797 2. Vegetation. Experiments on vegetation are very hard to perform, as is easily understood, because of the small size of the glass receivers and their lack of transparency. Yet here are a few which are suf- ficiently conclusive. Experiment CCCLXXXIII. April 28. Barley sprouted 10 to 12 cm. high in the large Seltzer water receivers (2 liters). A, which is in the receiver with a wire jacket, is closed and left at normal pressure. B, in a receiver without a jacket, which lets more light through, is taken to 3 superoxygenated atmospheres, changed tv/ice a day. May 7. In A, the sprouts have more than doubled their length; B has not changed: left in open air, the stalks turn yellow and die. Experiment CCCLXXXIV. July 25. Little sensitive plants 6 to 8 cm. high, healthy, in a pot. A. Placed, in the pot, in a receiver of 1 liter, with wire mesh jacket; left at normal pressure, well corked. B. Another pot in a similar receiver, without the wire mesh jacket, and consequently under better lighting conditions. Carried to 6 atmospheres of air. By evening B has lost sensitivity. July 26. The leaves in B are falling. July 27. B completely dead; A healthy. Experiment CCCLXXXV. August 1. Sensitive plants like those in the preceding experiment. Same receivers. A. At 3 atmospheres. B. Under normal pressure. August 5. Both sensitive and healthy. Experiment CCCLXXXVI. July 25. Small sensitive plants, quite sensitive. A. Cylindrical apparatus at 4 atmospheres with 80% of oxygen; tension 320, equivalent to nearly 16 atmospheres of air. B. Normal pressure, air. July 27. A, dead; B quite sensitive. So sensitive plants die quickly at 6 atmospheres of air, and it is more than probable that the other green plants would die at the same pressure, although much less rapidly. Plants, therefore, seem to dread excessive oxygen tension still more than animals, even warm-blooded animals. 798 Experiments Subchapter III SUMMARY The experiments included in the present chapter prove in sum- mary that at pressures above or below one atmosphere, the germi- nation and the vegetation of green plants are delayed, even ar- rested. Just as for animals, this fatal effect is due not to the pres- sure itself, but to the oxygen tension, either too weak, whence there results a kind of asphyxia, or too strong, killing the seeds or the plants. In the third part of this book, we shall draw from these data the conclusions which they permit in regard to the geographical distribution of plants and the appearance of plant life on the sur- face of the earth. 1 P. Bert. Sur les mouvements de la sensitive, Second memoir. Societe des sciences physiques et naturelles de Bordeaux, Vol. VIII, p. 1-58, 1870. 2 Dobereiner, Experiences sur la germination dans fair condense ou rarefie. Biblioth. univ. de Geneve, Vol. XXII, p. 121, 1823. Chapter VI EFFECT OF CHANGES IN BAROMETRIC PRESSURE ON FERMENTS, POISONS, VIRUSES AND ANTOMICAL ELEMENTS The admirable researches of M. Pasteur have shown that the phenomena known by the name of fermentations belong to two very distinct categories. Some are related to the development of microscopic living beings, vegetable or animal, such as alcoholic, acetic, and butyric fermentations and putrefaction. Others are caused by the action, still not understood, of substances produced by living beings, but soluble in water, and keeping their power after being isolated from the liquids in which they existed, and even after being dried; such is the transformation of starch into glucose under the influence of animal or vegetable diastase; or the formation of the essence of bitter almonds by synaptase acting on the amygdalin, etc. It was quite natural to inquire whether changes in the baro- metric pressure (we can now say in the tension of the ambient, oxygen) would have any appreciable effect on these phenomena. In the first place, for true fermentations, it was simply a question of whether an agent which according to its concentrations is both so necessary and so dangerous as oxygen, the lack of which ends life and the excess of which kills animals and plants which are visible to the naked eye and are of a rather complex anatomical organization, would have no effect upon microscopic beings, re- duced to cellular structure. As for the false fermentations, the zymotic fermentations, since they surely play a very great part in the chemical phenomena of metabolism in all living beings, it was interesting to find out whether oxygen tension could act upon them. Poisons and viruses, which resemble the ferments of these two classes from so many points of view, also deserved to be tested. 799 800 Experiments And finally, after studying these varieties of free anatomical ele- ments, I thought I should investigate the effect of changes in the oxygen tension upon the different anatomical elements, which in combination constitute a living being. The strange effects of increased pressure were to engage my attention particularly. Nevertheless I made a few experiments with rarefied air; but I combined my report of them with that of the others, since generally they were made simultaneously. Finally I should say that I employed in turn according to the best interest of the experiments either ordinary air compressed, or superoxygenated air compressed, or superoxygenated air at normal pressure. I consider that all my previous researches have suffi- ciently demonstrated this truth, that the effect of the compression is nothing but the effect of oxygen at high tension. Furthermore, for the questions discussed in this chapter, the experiments con- stitute a control which is proof in itself. Subchapter I FERMENTATIONS BY ORGANISMS 1. Putrefaction. As a type and as a subject of study I selected the fermentations of putrefaction in particular. Certainly, from the standpoint of chemistry, the phenomena presented by putrefaction are extremely complex and hard to follow. But its consistency, the facility with which it is produced, and its characteristic outward signs which are easy to observe seemed to me very advantageous for my pur- pose. And so I shall begin by reporting the principal experiments which I performed on this important subject. I shall first take up the putrefaction of meat. A. Meat. Experiment CCCLXXXVI. July 21. Temperature 22°. Muscles of a dog killed some hours before. 100 gm., cut in pieces, are placed: A, in a flask of 2 liters, at normal pressure; B, in a flask of 4.250 liters, at a pressure of 38 cm.; C, in the Seltzer water receiver, containing 1050 cc, in which I compress to 5% atmospheres a superoxygenated air containing 75.7% of oxygen. Oxygen tension: 75.7 x 5.5 = 416, equivalent to about 20.8 atmos- pheres. Fermentations by Organisms ' 801 July 25. A. The manometric tube attached indicates about 1 cm. (mercury) excess pressure. The meat is evidently very rotten. The air of the flask is horribly foul; it contains 38% of carbonic acid, but no trace of oxygen. Therefore 410 cc. of oxygen were consumed and 760 cc. of carbonic acid produced. B. The pressure has dropped 1 cm. at the most; the meat looks rather rosy. The air of the flask is a little less foul than that in A; it contains 30.9% of C02, but no trace of oxygen. Therefore 440 cc. of oxygen were consumed and 649 cc. of C02 were produced. C. Pressure maintained well. The meat is amber colored. The air of the receiver has no odor; it contains 7.2% of C02 and 69% of oxygen. Therefore about 357 cc. of oxygen were consumed and 396 cc. of CO? were produced. Experiment CCCLXXXVII. July 27. 7 o'clock in the evening. Temperature 23°. A small dog having died the evening before, its hind feet, weighing 95 gm., were placed: A, under a bell of 3.200 liters, full of air at normal pressure; the bell being tightly closed. B, in the Seltzer water apparatus (1050 cc), with 4 superoxygen- ated atmospheres. July 28. At 5 o'clock, the air is changed in A and in B, which is kept at 7 atmospheres. July 29. 2 o'clock. A. The air, which has no odor, contains: 02 17.1; CO, 1.8. The meat is reddish. B. The air has no odor, and contains: 02 65.5; C02 0.8. The oxygen tension therefore was at the beginning about 66 x 7 = 462, equivalent to 23 atmospheres of air. The meat is yellowish. I change the pressure to 6V4 atmospheres. July 31. 5 o'clock in the evening. Temperature 23°. A. The air smells very bad; it contains: 02 3.8; CO., 17.2; therefore, since July 29, 534 cc. of oxygen has been consumed and 117 cc. of C02 has been formed. B. No odor. 32 cc. of oxygen has been consumed, and 50 cc. of C02 formed. A is taken out and the air changed, with the same bell; the meat has a terrible odor; the hairs and the epidermis are coming off. B is taken to 6 atmospheres. August 3. 2 o'clock. Temperature 21°. A. Air has a disgusting stench; covered with mold. The air contains no trace of oxygen, but 23.9 of CO.; since July 31, 651 cc. of oxygen has been consumed and 741 cc. of CO.. has been formed. B. No odor, no mold. The air contains 59.2 of oxygen and 5.2 of C02. Therefore 348 cc. of oxygen has been consumed, and 212 cc. of CO, formed. B is taken out and put on a plate in the laboratory. The next day it begins to smell bad; on August 7, mold appears on it. Experiment CCCLXXXVIII. November 14. Temperature 14°. A. I place in the cylindrical glass apparatus two mutton cutlets, and subject them to a pressure of 11 atmospheres, with air containing 802 • Experiments 79.9% of oxygen. The tension of this gas is therefore 879, correspond- ing to about 44 atmospheres of air. B. Another cutlet is hung up in a huge closed bell. November 19. B is foul. A looks good. The manometer has fallen to 7 atmospheres. The air, which has absolutely no odor, contains 78.4% of oxygen and not a trace of carbonic acid. I raise the pressure again to 11 atmospheres with new oxygen. November 21. Still no bad odor in A; appearance good. I take a fresh cutlet C, and hang it in a bell absolutely full of water. I then admit to this bell a certain quantity of compressed air coming from A; some water remains at the bottom of the bell. A then drops to 6.5 atmospheres. November 24. No odor in A. A very slight leak is permitted so that on November 25 the pressure is normal; the cutlets have a yel- lowish color. B is then in complete putrefaction. C is yellowish, and the water has risen in its bell. December 13. I open the apparatus and end the experiment. A. Meat, rose colored, a little acid; faint odor of pickle. I have the cutlets broiled; they have an insipid, but not repulsive taste. B had to be disposed of December 10, reduced to absolute decay. C. Meat flabby, pink, a little acid; disagreeable odor, not that of ordinary putrefaction. Experiment CCCLXXXIX. November 22. A. In the Seltzer water receiver (1050 cc.) are placed two cutlets, which are taken to 8 superoxygenated atmospheres. B. Another cutlet is placed in oxygen under a bell. C. A third, under a bell, in air. November 24. A has dropped to 2 atmospheres; I take it back to 8 atmospheres; the meat is a dull red. B is bright red. C is of ordinary color. December 1. A has no bad odor; normal consistency; alkaline reaction; yellowish appearance. B. Bad odor; alkaline reaction. C. Absolutely foul odor; flesh diffluent; acid reaction; darkens paper with lead acetate. Experiment CCCXC. December 11. Under two bells inverted over water, one of which, A, contains air, the other, B, oxygen, fragments of muscle are hung. January 8. The air is foul in both bells; A shows a great deal of mold; B, only a little. Experiment CCCXCI. December 19. Three pieces of lean meat are cut as nearly alike in iorm as possible. A. One, weighing 45 gm., is hung under a closed bell, of 11.5 liters, full of ordinary air. B. The second, weighing 40 gm., is hung in a bell of 3.2 liters, which contains air with 90% oxygen. Fermentations by Organisms 803 C. The third, weighing 35 gm., is placed in the cylindrical glass apparatus, and subjected to the pressure of 10 atmospheres of air con- taining 88% of oxygen; the oxygen tension therefore is 880, corre- sponding to 44 atmospheres of air. December 26. Samples of air are taken from the three bells with- out the air being renewed. A. The meat looks bad; the lower part is evidently putrefied. The air has an insipid odor, slightly gamy. The air contains: O, 12.2; C02 6.4. B. The meat has about the same appearance. Insipid odor. The air contains: 02 70; CO, 12.9. C. The meat looks good but rather brown. No odor. The composi- tion of the air has not changed. January 8. Samples of air are taken again, and the experiment is stopped. A. Meat very acid, with a horrible odor; softened. The air con- tains 7% of oxygen and 12.3% of CO.. B. Meat very acid; odor very bad, but not as strong as A. The air contains 40% of oxygen and 38.2% of CO.. C. Meat a little acid, grayish, firm, with a slight sourish odor, which is not disagreeable. Cooked, it is insipid, but without a bad taste. The composition of the air has not changed. If we try to deter- mine, in these two periods, the quantity of oxygen which has been consumed, and the quantity of CO. which has been produced by the meat placed in these different conditions, we get the following results, in which all are reduced to an equal weight, 100 gm. of meat. From December 19 to 26: A (ordinary air, normal pressure) has consumed 2.2 liters of oxygen and produced 1.6 liters of C02. B (air with 90% of oxygen, normal pressure) has consumed 1.7 liters of oxygen and produced 1.2 liters of C02. C (air with 88% of oxygen, 10 atmospheres) has consumed 0 liters of oxygen and produced 0 liters of CO.. From December 26 to January 8: A (air with 12.2% of oxygen) consumed 1.3 liters of oxygen and produced 1.4 liters of C02. B (air with 70% of oxygen) has consumed 2.6 liters of oxygen and produced 2 liters Of C02. C (air with 88% of oxygen, 10 atmospheres) has consumed 0 liters of oxygen and produced 0 liters of CO,. I call particular attention to this experiment. It shows that in twenty days the meat in compressed oxygen consumed no oxygen and produced no carbonic acid; it showed no sign of putrefaction. We see, furthermore, that the meat consumed less oxygen in air with 90% of oxygen than in air with 21%, but more in air with 70% than in air with 12. 804 Experiments Experiment CCCXCII. January 17. Pieces of meat equal in weight and similar in form. A. Placed in a bell of 15.5 liters, in which the pressure is lowered to a half-atmosphere. B. Bell of 7.1 liters; ordinary air, at normal pressure. C. Bell of 2.6 liters; air at normal pressure, containing 59% of oxygen. D. Bell of 3.2 liters; air at normal pressure, containing 59.8% of oxygen. All these bells are hermetically closed, with hydraulic seal. January 23. The meat least altered in appearance is that in A; those most altered are in C and D. Air samples are taken: B contains 13.5% of oxygen and 7.2% of carbonic acid. A contains 16.4% of oxygen and 5.3% of carbonis acid. C contains 25.2% of oxygen and 19.1% of carbonic acid. D contains 36.0% of oxygen and 17.3% of carbonic acid. We can calculate easily by means of these data that in 6 days: A (ordinary air, at V2 atmosphere) had consumed 343 cc. of oxy- gen and formed 418 of CO2. B (ordinary air, at 1 atmosphere) had consumed 524 cc. of oxygen and formed 514 of CO». C (superoxygenated air, corresponding to 2x/2 atmospheres) had consumed 642 cc. of oxygen and formed 496 of C02. D (superoxygenated air, corresponding to 3 atmospheres) had consumed 761 cc. of oxygen and formed 556 of CO2. The consumption of oxygen then consistently increased from V2 atmosphere to 3 atmospheres. Experiment CCCXCIH. January 14. Pieces of beef are placed in two small flasks (A and A'), through the stoppers of which a capil- lary tube passes; they are then placed in the cylindrical apparatus under a pressure of 10 superoxygenated atmospheres. January 27. Decompression; the meat, slightly brownish, does not seem spoiled. The capillary tubes are rapidly sealed with boiling wax, and the two flasks are inverted in vessels full of water. Two pieces of meat are placed in the same way beside them (B and B'). February 10. B and B' are evidently rotten, and smell bad through the corks. A has admitted a little water; since then, the meat has become red again; the water is slightly bloody and covered with mold. A', on the contrary, is very firm, very wholesome, amber in color. March 25. Same appearance; the water has continued to rise in A. This flask is opened; it smells very bad. May 22. End of the experiment. The controls B and B' are in foul decay; through the microscope we see in it many vibriones, but no more distinct muscular fibers; only a few of Bowman's disks. For some days we have noticed that bubbles of gas are escaping through the pores of the cork in A'. The meat has become red, but it is firm and stiff. It smells bad and is negative to reagents. Through the microscope we see a few scattered vibriones; the muscular fibers have remained well striated. The air of this flask contained 75% of gas soluble in a potash solution. Fermentations by Organisms 805 Experiment CCCXCIV. June 19. Temperature 18°. Placed in two flasks with cork stoppers water in which fragments of meat have been macerated: A. Kept as control. B. Cork pierced by a hole, flask shaken until all its walls are wet, then placed in the large mercury receiver, in which compression is made to 20 atmospheres with 88% of oxygen. The pressure therefore corresponds to 88 atmospheres. June 24. Temperature 19°. The pressure is still 13.5 atmospheres. A is red and smells bad. Decompression is made and B is immediately sealed; it is amber colored and seems to have no odor. July 6. A is very red, rather alkaline; its odor is foul; there is no mold on the surface of it; the very abundant precipitate contains great numbers of very active vibriones, whose extremity ends in a refracting enlargement, and also very active bacteria termo. (The microscopic observations are made with the aid of M. Gayon, assistant to M. Pasteur, at the Normal School.) B had begun to redden a few days before; the cork was evidently imperfect. The liquid is covered with greenish mold, consisting of a penicillium with elliptical glossy spores (virens?); it is very slightly alkaline. It exhales a faint odor of mold, but not of putrefaction. There are no vibriones in it, but very small and very active bacteria, and besides, long filaments of unknown nature. Experiment CCCXCV. June 26, 1874. Temperature 19°. Two thin pieces of meat are placed each in a flask: One, A, is corked and kept as control. The second, B, is corked, the cork pierced by a hole, then taken to 15 superoxygenated amospheres. I added a little water, then shook it so as to wet the walls and the cork. July 21. Decompression made. A has smelled very bad, for some time, through the cork, and is evidently entirely decayed. B is yel- lowish, seems wholesome, and exhales no odor. The cork has been almost entirely driven in. However I cover the whole orifice of the flask with boiling wax. August 3. Same condition. The flasks are kept the rest of the year, and the meat in B keeps the same appearance. January 16, 1875, I show A and B to the Society of Biology. A is completely rotten. B has exactly the same appearance as on July 21. June 28, 1875, I show these flasks to the Academy of Sciences; same appearance. August 3, opened in the chemistry laboratory of M. Chevreul, before M. Cloez; sourish, agreeable odor; slightly acid reaction. The flask being broken, right in the laboratory I place the meat, without precautions, in a flask with a ground stopper. August 7, same odor and same appearance; no trace of putre- faction. Experiment CCCXCV I. June 25. Two pieces of meat, weighing 31 gm., are cut in similar form. 806 Experiments One, A, is hung in a bell of 11.5 liters full of air, with hydraulic seal. The other, B, is placed in the glass cylindrical apparatus (capacity 650 cc.) at the bottom of which are a few cubic centimeters of water. Compression is made to IOV2 atmospheres, with air containing 81.1% of oxygen (tension 850 = 42.5 atmospheres of air), and then the apparatus is shaken so as to wet all its walls. June 30. A, horribly rotten, covered with mold; the air contains 16.3% of oxygen, and 2.8% of carbonic acid. Therefore 522 cc. of oxygen were consumed, and 328 cc. of car- bonic acid were formed. B. Amber colored; no odor. The air has retained almost exactly its original composition, since it contains 80.4% of oxygen and no carbonic acid. Therefore 49 cc. of oxygen were consumed. Pressure lowered to 2.75 atmospheres; oxygen tension: 220 = 11 atmospheres. July 12. B left in the same air; same appearance; still the same odor. But the air contains only 69% of oxygen, with 12% of CO,. Therefore 210 cc. of oxygen were consumed, and 21 cc. of car- bonic acid freed. The pressure is lowered to 2.5 atmospheres; the tension is only 172 = 8.6 atmospheres. July 21. Same pressure, same air. The appearance is the same; there is no odor. The air contains only 57,2% of oxygen, with 23% of CO2. Therefore 1583 cc. of oxygen were consumed. July 27, same appearance; still no odor. Without uncorking the apparatus, I empty it completely, ventilate it with oxygen, and raise the pressure again to 10 V2 atmospheres. The air then contains 77.6% of oxygen, and 1.2% of CO=, oxygen tension 814 = 40.7 atmospheres of air. At the same time, I suspend in a bell of 15.5 liters a piece of meat weighing 20 gm. C. August 3. B. The pressure has been maintained; the meat has still the same appearance. The air, which has no odor, contains 74.9% of oxygen and 3.2% of CO.. We see easily that, applying it to 100 gm. of meat, 390 cc. of oxygen have been consumed, and 397 cc. of CO- formed. C. The meat is alkaline, foul. The air contains 16.2% of oxygen and 3.6% of CO,. Therefore, per 100 gm. of meat, 2295 cc. of oxygen have been consumed and 3605 cc. of CO, freed. August 5. Decompression made for the meat which was at 10 atmospheres. It is yellow, quite firm, and has no odor. I put it in a test glass which had been kept in boiling water, and close it with a rubber stopper which also had been kept a long time in boiling water. January 18, 1875. The meat has kept nearly its original appear- ance. When opened, it is hardly softened, but smells very bad. Nega- tive to reagent papers. Fermentations by Organisms 807 Experiment CCCXCVII. July 21, 1874. 6 o'clock in the evening. Pieces of meat placed: A. In a corked matrass; B, in a similar matrass, the neck of which I draw out in a flame, leaving only a little orifice. I put it into the iron apparatus, and raise the pressure to 15 superoxygenated atmospheres. July 22. The pressure has fallen; I take B out, and shake it so that all the walls are wet. Then I put it back and raise the pressure to 8V2 superoxygenated atmospheres. A begins to smell bad. July 23. Taken to 12 superoxygenated atmospheres. July 24. Taken to 15 superoxygenated atmospheres. July 30. The pressure is 14 atmospheres; I make the decompres- sion, and close the tapering end of B with a flame; no odor, amber color. A smells simply horrible. January 17, 1875. Presented to the Society of Biology. A is a mass of decay horrible in appearance and odor. B, which I do not open, has retained its original form and appear- ance. One merely sees some white spots which seem to be fat. May 27, 1875. A is horrible; no fibers recognizable through the microscope. B has burst in the night; the meat is amber colored; it has kept its consistency, its fibers with their striae; slightly alkaline; rather weak odor of decay. Experiment CCCXCVIII. January 22. Strips of meat, each weigh- ing 20 gm., suspended: A. In the glass compression apparatus at 5 atmospheres of air, which represent 3250 cc. of air. B. In a bell containing 2500 cc. of air, at normal pressure. C. In a bell of 7100 cc, at a half -atmosphere. January 26. The three pieces of meat have an alkaline reaction. A has a slight odor. B smells considerably worse than C. The air of A contains 20.4% of oxygen; that of B 16.5%; that of C 19.2%. From these figures we draw the conclusion that in apparatus A 100 grams of meat have consumed 81 cc. of oxygen; in bell B, 550 cc, and in bell C, only 300 cc Experiment CCCXCIX. January 28. Strips of meat, each weigh- ing 39 grams, placed in the same apparatuses as in the preceding experiment: A. At 3 atmospheres of air, potash solution in the bottom of the apparatus. B. Normal pressure. C. A third of an atmosphere. February 2. A little odor in all; all the meat alkaline. A contains 12.9% of oxygen. B 16.1%. C 18.2%. Therefore per 100 grams there was a consumption of -oxygen: in A of 405 cc; in B of 313 cc; in C of 103 cc. 808 Experiments We must note that the oxygen tension had diminished in A, since at the end of the experiment it was only 12.9 x 3 = 38.7, that is, less than 2 atmospheres of air. Experiment CCCC. February 3. Strips of meat weighing 39 grams. Same bells; but a solution of potash at the bottom of the bells, and papers saturated with potash on the walls: A. Normal pressure. B. A third of an atmosphere. February 8. The air in A contains 10.9% of oxygen; that of B 15.6%. No carbonic acid. Whence, per 100 grams, consumption of 249 cc. in A; of only 141 cc. in B. Experiment CCCCI. February 10. Strips of 43 grams. Same appa- ratuses. Potash in both. A. Normal pressure. B. 3 atmospheres of air. February 13. The air in A contains 20.1% of oxygen; that in B 18.9. Whence a consumption, per 100 grams: in A of 1'9 cc. of oxygen; in B, of 38 cc. Experime7it CCCCII. February 16. Strips of meat weighing 50 grams each. Potash in the receivers. A. Normal pressure. Bell containing 2.450 liters of air, that is, 512 cc. of oxygen. B. Cylindrical glass apparatus, at 4 atmospheres of air, containing a quantity of oxygen corresponding to 504 cc, at normal pressure. February 19. A. Bad odor; its air contains 16.8% of oxygen. B. Odor not quite so bad; the air contains 16.4% of oxygen. Whence, per 100 grams, consumption in A of 101 cc. of oxygen; in B of 109 cc. Experiment CCCCIII. February 22. 30 grams of meat. Same apparatuses as in the preceding experiment. Potash in both: A. Normal pressure. B. 4 atmospheres of air. February 24. No odor in either. The air of A contains 21.0% of oxygen; that in B 20.8%. Experiment CCCCIV. March 17. Pieces of meat and water; in 2 small matrasses tapered in a flame. A. At normal pressure. B. B'. At 15 atmospheres of a compression made with air con- taining 80% of oxygen. March 26. Decompression. A rotten, foul. B has no odor and is negative to reagent papers. I close B' with the flame. May 15. B' has a good appearance; the liquid in which the meat is lying has the natural light red color. June 10. The appearance of.B' changed a few days before; it has lost its light red color. During the night of June 9 - 10, the matrass burst; the pieces of meat have a foul odor, with a slightly alkaline Fermentations by Organisms 809 reaction; but they have kept their form, and the muscular striae are easily seen through the microscope. A, on the contrary, is a mass of horrible decay, and the striae cannot be recognized. Experiment CCCCV. May 28. Meat in pieces, in 2 matrasses drawn out in a flame and open at the extremity. A. Left in open air. B. Placed at 8 superoxygenated atmospheres. Since the apparatus has a leak, compression is made several times, up to 23 superoxygenated atmospheres; for several days the pressure remains at 15 atmospheres. June 26. A has been horribly decayed for a long time. B. Has no odor; is amber colored. June 28. I present the matrass B to the Academy of Sciences; I open it in the meeting; the meat is negative and has only a slight sour- ish odor, not disagreeable. I recork the matrass without special care, with a hollowed out cork, and take it to the laboratory. July 3. No odor. July 11. Very slight odor. July 19. The meat is covered with mold, but does not have an odor of decay. Experiment CCCCV I. November 29. Barometric pressure 758 mm.; temperature 14°. From the top of three bells pieces of meat are hung, each weighing 25 gm. A solution of potash at the bottom of each bell will absorb the carbonic acid as it is produced. The cork of the bell allows passage of an elbow tube, the extrem- ity of which, being immersed in mercury, will serve as a manometer. Bell A (4.6 liters) contains normal air. Bell B (1.9 liters) contains air with 45.5% of oxygen. Bell C (1.5 liters) contains air with 91.7% of oxygen. December 4. The bells are opened and the air analyzed; the b'aro- metric pressure is 735 mm.; temperature 14°. The meat in bell C does not smell as bad as the others. The absorption of C02 has caused a drop of 2.7 cm. in bell A, one of 10 cm. in B, and 10 cm. in C. There is no carbonic acid in any of the bells. The air in A now contains only 17.2% of oxygen; that in B only 35.3%; that in C still contains 91.5%. Simple calculations, in which account is taken of the barometric pressure and the difference in tension in the bells, show that: A, which had at its disposal 961 cc. of oxygen, consumed 258 cc. of it B, which had at its disposal 867 cc. of oxygen, consumed 284 cc. of it C, which had at its disposal 1376 cc. of oxygen, consumed 183 cc. of it If we consider first those of our experiments which dealt with decreased pressure, we see clearly that in rarefied air putrefaction was considerably delayed and oxidation diminished. In Experiment CCCXCII, whereas a certain weight of muscles had, in a certain time, at normal pressure consumed 524 cc. of 810 Experiments oxygen and formed 514 cc. of carbonic acid, the consumption of oxygen at a half-atmosphere had dropped to 343 cc. and the pro- duction of carbonic acid to 418 cc. The same result in Experiment CCCXCVIII, in which the consumption of oxygen had dropped from 550 cc. to 300 cc, for the same change in pressure; further- more, meat kept in decompressed air did not smell nearly as bad as the other. Finally, in Experiment CCCXCIX, at a third of an atmosphere, the consumption of oxygen was exactly a third of that at normal pressure. But these results are not very extraordinary; it has been known for a long time that putrefaction does not take place in a vacuum, and it was quite natural to think that it would become less active in proportion as the air was more rarefied. The effects of increased oxygen tension were much more inter- esting to study. The most salient fact shown me by the experiments is that in air which is sufficiently compressed putrefaction does not take place, that no disagreeable odor appears, and that the muscle keeps its normal appearance, except its color; its microscopic structure is not perceptibly altered (Exp. CCCXCIII and CCCCIV) . Almost all the experiments reported above present remarkable examples of this fact. But that is not all; when the excess pressure is reduced, and when sufficient precautions are taken to protect against germs brought from outside, putrefaction does not appear; so that for weeks, for months, meat in a fresh state can be kept at normal pressure. I call particular attention to this point of view in the experiments in which I cooked and ate meat kept thus .for 20 days (Exp. CCCXCI) , or a month (Exp. CCCLXXXVIII) . To secure conclusive and constant results, the greatest precau- tions in detail are necessary. I did not always take them at the outset; whence there result, in certain of the preceding experi- ments and in others on blood, milk, etc., apparent exceptions, which I included nevertheless, because they are instructive. And so, in my first experiments, when I wished to preserve a substance, after subjecting it to compression, I closed with a good cork stopper the flask in which it was placed; this stopper was pierced by a hole, and when I had withdrawn the flask from the apparatus, I applied over this small orifice a drop of melted wax, with which, moreover, I sealed the whole stopper. I soon found out that this precaution was insufficient. The stoppers, even when new, well washed, and heated, too often con- Fermentations by Organisms 811 ceal germs which are still active. I then had recourse to matrasses, balloons, tubes, which I tapered in a flame, after having placed the experimental substances within; the almost capillary hole of the part tapered out permitted an equilibrium of pressure to be established. I next perceived, at my cost, that the germs which remained in a dry state on the walls of the little receiver were sufficient, espe- cially when we were dealing with putrefaction, with which my dis- section laboratory was crammed, to affect the phenomena. I could guard against these with certainty only by adding a little water and shaking the receiver carefully, before subjecting it to com- pression, so as to kill at the same time both the germs contained in the substance and those on the walls which were wet. It must not be thought, however, I make haste to say, that this method of preservation has a practical value; meat which has been compressed has an insipid taste which makes it disagreeable. This taste is probably due in part to the acid developed in it during the compression, an acid which is not volatile, nor odoriferous, and which is probably lactic acid. This meat, which does not decay, absorbs infinitely less oxygen than that which remains under normal conditions. That was studied particularly in Experiments CCCLXXXVI and CCCLXXXVII. But the most remarkable example is furnished by Experiment CCCXCI, in which in 20 days meat placed under a compression of oxygen equivalent to 44 atmospheres of air consumed no oxygen and produced no carbonic acid; whereas a similar weight of the same meat left at normal pressure had consumed 3.5 liters of oxy- gen and formed 3 liters of carbonic acid. If pressure is lowered to normal, and sufficient precautions are taken to keep out the dust of the air, the meat, which will be pre- served without decay indefinitely, as we have just said, will con- sume only very small quantities of oxygen. The following ex- periment shows this clearly. Experiment CCCCVII. February 20. 15 pieces of meat, each weighing 1 gm., are placed in 15 tubes. Then these tubes are drawn out in a flame and subjected to 15 superoxygenated atmospheres in the iron apparatus. March 3. Decompression is made carefully and the 15 tubes are closed by the flame. The analysis of 3 of them, made immediately, gives 70 to 80% of oxygen. March 13. One of the tubes is broken under mercury; meat amber in color, no odor, acid reaction. There is 6.2% of carbonic acid and 77.8% of oxygen. 812 Experiments The piece of meat is then placed without precautions in a tube closed with a cork (a). In the same way, in another tube, is placed 1 gm. of fresh muscle (b). March 19. The piece (a) has produced very little CO2 and con- sumed little oxygen. The piece (b) has consumed all the oxygen of the tube, that is, 7 cc. March 27. Another tube, opened in the same way under mercury, contains 11.0% of CO, and 74.2% of oxygen. The piece of meat is placed in a graduated tube full of air and well corked (c) ; another piece, fresh, of the same weight, is placed in the same way in a graduated tube of the same capacity (d). April 10. Tube c contains 1.6 cc. of COa and 2.8 cc. of oxygen, that is, 7.3% of CO, and 12.7% of oxygen; tube d contains 6.2 cc. of CO, and 0.2 cc. of oxygen, that is, 28% of CO, and only 0.6% of oxygen. These results agree with those of the experiments of M. Pasteur, showing that the consumption of oxygen by organic substances is extremely low, when microscopic living beings are kept from developing there. To the proofs he has furnished I shall add the following experiment, in which the action of antiseptics has given the same result as that of oxygen at high tension. Experiment CCCCVIII. June 26. A. 14 grams of muscles with a little water are placed in a corked flask, containing 590 cc. of air, and inverted over water. B. 40 grams, in a flask of 750 cc. are moistened with a few drops of phenol and then shaken. The flask is corked and inverted beside A. C. 40 grams; flask of 780 cc; I add to it 2 grams of chloral, which, as it dissolves, whitens the meat; well shaken, corked, inverted near the others. July 12. A. Is decayed; exhales a foul odor; the air (strong explo- sion when it is uncorked under mercury, so that a part of the gas cannot be collected under the test glass) contains 35% of CO, but no trace of oxygen. B. No odor of putrefaction; the air contains 18.6% of oxygen and 1.1% of CO,. C. No odor; the air contains 18.1% of oxygen and 0.9% of CO,. And so, proportioning the figures to 100 grams of muscles, we see that those which have putrefied have exhausted the 880 cc. of oxygen which they had at their disposal, and formed 1512 cc. of CO. (without counting that which escaped when the flask was uncorked) ; on the contrary, 100 grams preserved by phenol have consumed only 35.1 cc. of oxygen and formed 21.9 cc. of CCX; 100 grams preserved by chloral have consumed 35.3 cc. of oxygen and formed 15.0 cc. of CCX. Let us return now to the action of the oxygen, and let us take Fermentations by Organisms 813 as the measure of the intensity of the phenomena of putrefaction the consumption of this gas in a given time. We shall state here that we are relying both on experiments made in compressed air, and on those in which high oxygen ten- sion was obtained by increasing not the pressure, but the percentage under ordinary barometric pressure. We are sufficiently justified in this identification by all that we have hitherto observed. Experiment CCCXCII shows us that the quantity of oxygen consumed increases with a tension corresponding to 2 and even to 3 atmospheres of air; Experiments CCCXCIX and CCCCI give the same result for 3 atmospheres; but Experiment CCCXCI shows, in its first part, that there is a decrease at the tension of 4V2 at- Fig. 74 — Oxygen consumption and carbonic acid production by a piece of meat in an atmosphere of constant oxygen content. mospheres; finally, Experiment CCCCII shows equality of con- sumption at 4 atmospheres. It seems then, at first, that the maximum consumption of oxygen occurs between 3 and 4 atmospheres. But the question is more difficult to settle than one would think at first, and requires experi- ments carried on with special precautions. In fact, in Experiment CCCXCII, for example, the air of bell D, in which the oxygen ten- sion corresponded at first to 3 atmospheres of air, and in which there was more active oxidation, corresponded to less than 2 at- mospheres at the end of the experiment. One must use here an 814 Experiments experimental device which allows one to keep the same oxygen tension for the whole duration of the experiment and to dispose of the carbonic acid as it is produced. For this purpose, I set up the apparatus pictured in Figure 74. It is a flask C (sometimes a bell) full of superoxygenated mix- ture, proportioned in advance; at the bottom is a solution of potash whose carbonic acid content has also been determined by means of the mercury pump. A piece of meat, of known weight, is sus- pended in it. The absorption of the oxygen and the fixation of the CO. cause pure oxygen contained in a graduated test tube E to enter the flask, bubble by bubble; a flask-valve P prevents the air of the flask from flowing back in case its volume changes (tem- perature, decrease of pressure, etc.). Several apparatuses are placed thus which operate simultaneously and in identical condi- tions, except the oxygen content of the air of the flasks. When the experiment is over, analysis of the air of the flasks, the height of the column of water in the test tube, and the quantity of C02 con- tained in the potash give all the elements of the problem. But first I had to determine the degree of accuracy of this experimental method. It was easy to make the test by using ordi- nary air and making several simultaneous experiments under iden- tical conditions. Here is the result. Experiment CCCCIX. January 18. Pieces of meat weighing 25 gm., in 4 bells of equal size with ordinary air. January 22. The analysis of the potash solutions shows that the production of carbonic acid was 195.8 cc; 197.8 cc; 204.8 cc. and 206.8 cc. The margin for error, then, for carbonic acid is about 5%. Let us see now the results of the experiments. Experiment CCCCX. January 4. Pressure 745 mm.; temperature 16°. Piece of meat weighing 25 gm., at the top of 2 bells. A contains normal air. B contains air with 49.6% of oxygen. January 7. We find by analysis of the bells and the potash solu- tions that: A has produced 232 cc. of C02. B has produced 245 cc. of CO,. Experiment CCCCXI. January 24. Pressure 761 mm.; temperature 12°. Same experimental set-up, 3 bells. They contain: A ordinary air, B air with 53% of oxygen, C air with 79.7% of oxygen. January 29. Analyzed the potashes. A produced 223 cc. of carbonic acid. B produced 270 cc. of carbonic acid. C produced 250 cc. of carbonic acid. Fermentations by Organisms 815 Experiment CCCCXII. February 1. Instead of bells, of unequal volumes, we use flasks of small dimensions, as is represented in Figure 74. In flask A is ordinary air; in B, air with 37.3% of oxygen; in C, air with 61.2%; in D, air with 81%. February 7. Experiment ended; the analysis of the potash solu- tions shows that: A has produced 317 cc. of carbonic acid. B has produced 326 cc. of carbonic acid. C has produced 393 cc. of carbonic acid. D has produced 328 cc. of carbonic acid. Experiment CCCCXIII. February 14. Temperature 16°. Same apparatuses. In flask A, ordinary air. In flask B, air with 41.5% of oxygen. February 17. Ended the experiment. A produced 130 cc. of carbonic acid. B produced 178 cc. of carbonic acid. If we call the quantity of carbonic acid produced under normal pressure 100 in each of these experiments, we shall obtain by simple proportions the following figures, which show the course of the production of carbonic acid. Ordinary air (1 atmosphere) there are 100 cc. of C02 CCCCXII Air with 37.3% of O, (1.8 atmospheres) there are 103 cc of CO, CCCCXIII Air with 41.5% of O, (2 atmospheres) there are 129 cc. of C02 CCCCX Air with 49.6% of Oa (2.3 atmospheres) there are 106 cc. of CO, CCCCXI. Air with 53% of 02 (2.5 atmospheres) there are 121 cc. of CO. CCCCXII Air with 61.2% of O, (2.9 atmospheres) there are 124 cc. of CO, CCCCXI Air with 79.7% of 02 (3.8 atmospheres) there are 112 cc. of CO, CCCCXII. Air with 81% of O, (3.9 atmospheres) there are 103 cc. of CO, It appears from these figures that the maximum of combustion in tissues takes place above normal pressure, at about three atmos- pheres. This was the conclusion which we had already reached in Subchapter II of Chapter IV, for combustions investigated in living beings. When pressures become very high, the decrease of oxidations in the tissues becomes extremely clear. At 23 atmospheres, the proportion of oxygen consumed has lessened in the ratio of 534 to 32 (Experiment CCCLXXXVII). In Experiment CCCXCVI, con- sumption at normal pressure in 5 days was 522 cc. of oxygen, whereas it was only 49 cc. in compressed air at a tension equivalent to 42.5 atmospheres of air, and in the 9 following summer days, although the tension had been lowered to 11 atmospheres, only 210 cc. of oxygen were consumed. 816 Experiments We see then that the tension figure, at which the rapid oxida- tions due to the ferments of putrefaction begin to decrease, coin- cides exactly with that at which the fatal effect of oxygen begins to appear. Therefore the anatomical elements of a complex organi- zation are susceptible to the same concentration as those which live isolated, under the form of microzoa and microphytes. We shall gain new confirmation of these facts when we take up the effects of compressed oxygen on plants and germination. Similarly, Experiment CCCLXXXVI shows us that the pressure of 21 atmospheres completely kills the microscopic beings of putre- faction, as it kills higher animals. Let us add finally that meat which was preserved thus intact during compression and after compression is none the less an ex- cellent medium for the development of microscopic organisms, and that putrefaction occurs rapidly in it, when germs brought by the air come in contact with it in sufficient quantity. Experiment CCCXCIV, in which germs penetrated into the flask through an imperceptible crack in the cork, is quite characteristic. But for microscopic beings, as for those of great size, the crop is propor- tional to the sowing; it is not surprising therefore that under these conditions putrefaction in meat which has been subjected to high compression takes place rather slowly (Exp. CCCCVII), and that in certain cases (Exp. CCCCV) , when the chances of the experi- ment have allowed the germs of molds, and not the vibriones of putrefaction, to enter the tubes, putrefaction was replaced by a microscopic vegetation. I have sometimes seen meat kept in vessels closed by the flame after the phase of oxygenated compression, remain in a state of good preservation for weeks and months, then begin to putrefy; Experiments CCCXCVII and CCCCIV give examples of this. In this case, in my opinion, the oxygen did not kill all the vibriones of putrefaction; it left some, merely sick, numbed, as it were, which regained new activity in time. That happens, too, when meat has been heated to a temperature considerably below the boiling point; it happens in an apparatus in which a vacuum has been made by boiling, when air is admitted through carded cotton, if the filter is insufficient; it happens, in a word, whenever the ferments are either in very small numbers or altered by some strange circum- stance. Of course I had to study the putrefaction of some other sub- stances. I record my experiments here. Fermentations by Organisms 817 B. Blood. Experiment CCCCXIV. June 9. Defibrinated dog's blood. A. 30 cc. placed in a flask at normal pressure. B. 30 cc. in another flask closed by a cork with a hole. Placed in the iron apparatus and taken to 12 superoxygenated atmospheres. The pressure falls in the days following, and cannot be kept above 8 atmospheres. June 13. B is decompressed and sealed. June 18. A. Horrible odor; B. slight odor. Experiment CCCCXV. June 19; 1874. Dog blood, fresh, defibri- nated. A. In a corked flask, ordinary air. B. Flask closed by a stopper of cork with a hole, subjected after agitation to 20 superoxygenated atmospheres, equivalent to 88 atmos- pheres of air. June 24. A. Smells very bad. B. Decompressed, no odor, is translucent, as if varnished; I seal the orifice of the flask with wax. July 6. A. Wrinkled layer on the surface; repulsive odor. No globules visible; vibriones with a shiny terminal point, quite numer- ous, and also motionless bacilli; crystals of hemoglobin. B. The blood has become slightly turbid; no white layer on the surface; strange odor, very slightly putrid. Blood corpuscles pink and extraordinarily pale; no crystals; some few vibriones with shiny point. July 12. B. Still no putrid odor. The stopper is merely put back on B, without being sealed again. In the following months, it is opened frequently and closed without precaution; the stopper even happens to fall on the floor and is put back without any care. Nevertheless the putrid odor does not appear clearly. January 16, 1875. Presented to the Society of Biology. A. Is horribly putrid. B. Can be sniffed without disgust, but does have a slight odor. Experiment CCCCXV I. July 21. Dog blood, defibrinated. In equal quantities in: A. Matrass closed with a cork stopper. B. Similar matrass drawn out in the flame; it is subjected to 15 superoxygenated atmospheres. July 22. A. Begins to smell bad. B. Pressure has fallen; I take B out and shake it to moisten the walls of the matrass; then I take it to 8V2 superoxygenated atmos- pheres. July 23. Raised to 12 atmospheres. July 24. Raised to 15 atmospheres. July 30. A. Smells horribly bad. B. Still 14 atmospheres; decompressed; no odor; closed the pointed end of the matrass with the flame. A drop of this blood, examined through the microscope, shows no corpuscles; it looks as if it were varnished. 818 Experiments And so, as a result of compression, when the experiment has been well conducted, the blood is preserved without putrefying, both in the compressed air, and on being removed from the com- pressed air. The only change consists of the varnished appearance which it takes on, due to the fact that the hemoglobin leaves the corpuscles and is dissolved in the serum. This always occurs, moreover, in dead blood, and even in blood which has putrefied in closed vessels, after the putrid fermentation is over. Not only are the vibriones killed thus before beginning their work, but when blood in the process of putrefaction is compressed, the putrefaction ceases, and the characteristic odor decreases to the point of disappearing. But experiments on blood present a difficulty about which I should like to say a few words now, because it caused failure in a number of my experiments at the beginning, and because it might, if I did not mention it, cause uncertainty in the minds of those who would like to run control experiments on my work. I often saw blood which had kept well in the apparatus decay rapidly at normal pressure, even in vessels carefully closed by the flame. When I examined these data carefully, I found that this happened only in experiments made in tubes, never in those made in matrasses. This peculiarity results, as I suspected immediately, from the fact that the thickness of the layer of blood is different in the two operative methods. I then perceived that oxygen, even at the highest tensions, pene- trates the blood only a little way. Example: Experiment CCCCXVII. December 2. 100 cc. of blood are placed in a test tube with a foot; they rise to a height of 10 cm.; compression in the mercury bottle to 20 superoxygenated atmospheres. December 6. Instantaneous decompression; very little gas escapes from the liquid; no froth. The floating serum rises to a height of 3 cm.; below is a layer of very red blood 3 cm. thick; the rest of the blood is quite dark. It is then quite evident that there can be an excess of oxygen only in the superficial layers of the liquid, and that consequently vibriones in the deep layers will not be affected by the oxygen, or at least only slightly. Thence arises the putrefaction which ap- pears more or less quickly, and which in one case I saw appear during the compression; the variations result from many circum- stances in the multiplicity of which the height of the column used stands out definitely. One should never use blood in a thickness of more than a half-centimeter, if one is to be absolutely certain of succeeding. Fermentations by Organisms 819 C. Eggs. Experiment CCCCXVIII. June 19. Eggs beaten and well shaken. Placed in equal quantities in: A. Flask with stopper, ordinary air. B. Flask closed with a cork stopper with a hole, subjected, after agitation, to 20 superoxygenated atmospheres, equivalent to 88 atmos- pheres of air. June 24. A. Foul, with mold on the surface. B. Decompressed, no odor. The flask has been uncorked by the expansion of gases; the stopper has to be cut and replaced. The flask therefore remains open to the outer air for about 5 minutes. I seal it carefully. June 28. A. Is completely mottled. B. Appears wholesome, the yolk clearly floats on top. July 6. A. Horrible odor; the stopper pops out when the flask is opened; the egg is all mottled and greenish. B. There are still two layers; yolk greenish; no odor; there is mold on the lower surface of the stopper. July 12. B, which was recorked without precaution, has no putrid odor. Experiment CCCCXIX. July 21, 1874. Beaten egg. A. In a matrass closed with cork stopper. B. In a similar matrass, drawn out in a flame. Subjected to 15 superoxygenated atmospheres, shaken. July 30. A. Smells horribly bad and is mottled. B. Decompressed; has no odor, and its two layers are very clearly separated. I close it with the flame. At the end of several months, B begins to coagulate in a mass. January 18, 1875. A. Horrible odor; is only a greenish pulp, very alkaline. B. I open the matrass; the egg is entirely coagulated; yolk reddish; no disagreeable odor; reaction clearly acid. Experiment CCCCXX. May 29. Beaten egg. A. In an open matrass, covered with a paper cone; normal pres- sure. B. In a matrass drawn out in a flame. Taken to 23 superoxygen- ated atmospheres. June 5. A. Exhales a horrible odor. The compression apparatus has leaked; I make a recompression several times; it finally drops to 5 atmospheres. June 26. Decompression. A. Is coagulated, foul, with a dark layer at the bottom of the glass. B. Is divided into two very definite layers, not coagulated, with- out odor. Experiment CCCCXXI. March 17. Beaten eggs, in 2 tubes. A. Closed with a stopper, free air. B. Drawn out in a flame; at 15 atmospheres of air containing 80% of oxygen. 820 Experiments March 26. Decompression. A. Foul odor; coagulation; I close it with a flame. B. No odor; liquid in two clearly distinct layers; closed with a flame. May 15. A. Explosion when the tube is opened; foul odor; vege- tation on the surface. B. Not coagulated; no explosion when the tube is opened; very slight acidity; agreeable sourish odor, like that of cider; no vegetation on the surface; closed with a flame. June 10. Spontaneous explosion of tube B; however, little odor.; matter acid, coagulated. Eggs then do not decay either during or after decompression when they are protected from the germs of the air. But they finally have an acid reaction, which, without developing an odor, causes their albumen to coagulate. That would be an exceedingly interesting chemical phenomenon to study in detail. These different experiments then show very clearly that when the experimental precautions which I have stressed are taken, meat, eggs, blood, that is, the most corruptible of substances, are preserved without putrefaction by oxygen at high tension. When withdrawn from the apparatus and kept in closed vessels, they remain indefinitely without putrefying, but at the same time under- going certain changes which would make them unfit for customary uses. 2. Coagulation of Milk. Milk, upon which I experimented from the double point of view of putrefaction and coagulation, caused me a good deal of trouble on the latter score. Experiment CCCCXXII. August 8. Milk, placed in 3 small well- washed bottles. A. Left at normal pressure. B. Placed in a compression receiver and taken to 4 atmospheres of air. C. Taken to 7 atmospheres of air with 70% of oxygen, equivalent to 24 atmospheres of air. August 15. A. B. C. Milk sour; all clotted. Experiment CCCCXXIII. January 27. Milk placed in 2 small simi- lar bottles. A. Closed with a cork stopper. B. The same, but the stopper has a glass capillary tube through it; the bottle is subjected, in the glass cylindrical receiver, to a pres- sure of 10 atmospheres, with air containing 84% of oxygen. The oxy- gen tension, 840, is therefore equivalent to 42 atmospheres of air. B. Appears to be curding a little more slowly than A. Fermentations by Organisms 821 February 3. Decompressed B and closed the hole with burning wax. A and B have the same appearance. May 22. A. The stopper blows out when I open the flask. Very strong butyric odor; very acid reaction. Numerous very active vib- riones, some of which are oval and wide, are to be seen in it. B. The stopper does not blow out; very slight butyric odor, very acid reaction. A few bacillus vibriones, very small and active. Experiment CCCCXXIV. May 22. Temperature 18°. Boiled milk, placed in four flasks well-washed with hot alkaline water. A, A', two flasks well corked and sealed. B, B', two flasks, closed with a cork stopper pierced by a hole, taken to 10 atmospheres of air with 70% of oxygen, which is equiv- alent to 35 atmospheres of air. May 24. Decompressed B and B' and closed the holes with melted wax. The four flasks appear curded to the same degree. Experiment CCCCXXV. May 26. Boiled milk, with the addition of water alkalinized by carbonate of soda. A, A'. Two flasks are closed and sealed. B, B'. Two others, whose stoppers are pierced by a hole, are placed in the cylindrical glass apparatus under a pressure of 10 atmos- pheres of air with 70% of oxygen, or about 35 atmospheres of air. June 1. AA' is partly coagulated. BB' is hardly coagulated at all. June 3. Decompressed BB' and closed the holes with melted wax. The liquid is less clearly coagulated in BB' than in AA'. June 26. BB' are less clearly coagulated than AA'. BB' are neutral or hardly acid. AA' are extremely acid. Experiment CCCCXXVI. August 7, 1874. Boiled milk, placed in two matrasses, in which the liquid occupies only a small part. A, closed with a stopper of new and well heated cork. B, drawn out in a flame, except a little hole in the extremity; taken to and kept at a pressure of between 8 and 12 superoxygenated atmospheres. August 17. A, yellowish clot with mold; foul. B, decompressed, closed with a flame; white clot. January 18, 1875. A, yellowish mass with deep yellow skin. Smells bad; alkaline reaction. B, very white and very clean clot; has no bad odor. Experiment CCCCXXVII. August 7, 1874. Boiled milk, with the addition of alkalinized water; arranged as in the preceding experi- ment; one of the matrasses, B, placed beside the one of the experi- ment above. August 17, at decompression, same difference in the general appearance. January 18, 1875. A, foul; yellowish with a yellow skin; alkaline. B, fresh odor, sourish; white, clean clot; reaction quite acid. 822 Experiments Experiment CCCCXXVIII. January 20. Boiled milk, in tubes, diluted with water. A, normal pressure. B, 21 superoxygenated atmospheres; tube drawn out in the flame. The pressure falls repeatedly. January 25. Decompression made. May 17. A, foul odor; thick mold on the surface; liquid yellowish with clots. B, very slight butyric odor, not disagreeable; acid; liquid very white with lumps; a few globules of milk recognizable through the microscope. Experiment CCCCXXIX. January 20. Milk with the addition of a solution of soda. Experiment made at the same time as the preceding one. May 17. The milk which was not compressed has a foul odor; the other has no odor. Experiment CCCCXXX. March 16. Boiled milk, in tubes. A, normal pressure. B, at 10 superoxygenated atmospheres, in the cylindrical glass apparatus. March 18. The milk is clotting perceptibly at the same time in A and in B. We see that for milk as for the other substances putrefaction has been checked by compressed air; on the condition of giving up corks and using exclusively tubes or matrasses closed with a flame. But coagulation was not prevented, nor was rapid acidification; these changes did not even seem delayed appreciably. A previous strong alkalinization of the milk did not check them either; how- ever, in this case, an evident delay resulted. Could it be that oxygen under high tension really has no effect on the lactic vibriones discovered by M. Pasteur: Or could it be that coagulation of milk is not the work of these microscopic beings, but instead of some agent invulnerable to oxygen, as soluble fer- ments are, as we shall see? Before giving an answer to these questions, I had to reflect on the experimental cause of error revealed to me by my experiments on blood. The thickness of the layers of the liquid which com- pressed oxygen must saturate to carry out its destructive work might play an important part here. I had to eliminate this harmful influence; and so I did, for ex- ample, in the following experiments. Fermentations by Organisms 823 Experiment CCCCXXXI. August 10. Boiled milk; placed in a layer 2 to 3 millimeters thick in two new, well- washed crystallizing pans: A, in the open air, under a glass which kept out dust; B, at 25 atmospheres of superoxygenated air. August 14. Decompressed. A has been coagulated since August 11, and smells very bad. B is liquid, has no odor, and seems quite normal. Experiment CCCCXXXII. May 25. On the bottom of 6 tubes a few drops of boiled milk (depth y2 centimeter) are carefully dropped. A. 2 tubes are closed with a flame and kept as controls. B. The other 4, drawn out in the flame but open, are subjected to 15 superoxygenated atmospheres in the glass cylinder. June 1. Decompressed. A has been coagulated since May 27. B is not coagulated; closed with the flame. June 6. B not yet coagulated. These experiments prove very clearly that oxygen under high tension prevents the coagulation of milk, that is, kills the vibriones which cause lactic fermentation. As the action of these vibriones takes place very rapidly, to check it oxygen must be used in a very high concentration upon a thin layer of liquid, which must be saturated rapidly. For putrefaction, which works much more slowly, these excessive precautions are not necessary; since milk does not, like blood, consume the oxygen as it penetrates the liquid, the oxygen has time to go to the bottom of the tubes and kill there the agents of putrefaction. That explains why it is so easy by compressed air to prevent milk from putrefying, and so hard to prevent it from coagulating. 3. Alteration in urine. Since the research of M. Van Tieghem, we know that the trans- formation of urea to carbonate of ammonia is a true fermentation, due to the development of a microphyte, of a torula. Therefore I studied it somewhat in detail. Experiment CCCCXXXI1I. August 8. Temperature 27°. Urine of the day before, quite acid; in equal quantities in three small bottles covered by paper cones, and placed: A, at normal pressure, under a bell; B, in the small Seltzer water receiver, at 4 atmospheres of air; C, in the cylindrical glass receiver, at 7 atmospheres of an air containing 70% of oxygen, which corresponds to 24 atmospheres of air. August 11. A, quite turbid, foul, but still acid. B, decompressed; a little turbid, a little bad odor. Taken to 5 atmospheres of air. C, decompressed; no turbidness; fresh odor. Taken to 5 atmos- pheres with 71% of oxygen, that is, about 18 atmospheres of air. 824 Experiments August 15. A, completely turbid, very alkaline, horribly foul. B, turbid, fairly alkaline, not quite so foul. C, slightly turbid, a little alkaline, begins to smell bad. Experiment CCCCXXXIV. May 13. Fresh urine, very acid, in two similar flasks. A, corked, at normal pressure; B, taken to 10 atmospheres of superoxygenated air. May 18. A, turbid, neutral. B, clear, acid. Experiment CCCCXXXV. June 19. Mixture of fresh urine and urine already spoiled. A, flask with a stopper. B, flask with a cork stopper with a hole, taken to 20 atmospheres of superoxygenated air, corresponding to 88 atmospheres of air. June 24. A, turbid, smells bad; I close the hole in the stopper with wax. B, decompressed; clear, no odor. July 6. A, strong odor; turbid; a film on the surface, in which there are myriads of moving organisms and rounded crystals. Strongly alkaline; to acidify a certain quantity, it is necessary to add 4 drops of sulphuric acid. B, no odor; turbid; film; moving protozoa, but no crystals. Not very alkaline; a single drop of sulphuric acid acidifies the same quantity as in A. July 30. A is horribly foul and very alkaline; B, which had the stopper replaced without care, has no odor and is not very alkaline. However the two urines give, by the Yvon method, the same quantity of nitrogen (3.5 to 3.7 per cubic 'centimeter) . Experiment CCCCXXXVI. July 21, 1874. Fresh urine, in equal quantities in two equal matrasses: A, closed with a cork stopper; B, drawn out in a flame, with a tiny orifice. Placed at 15 super- oxygenated atmospheres; matrass shaken. July 30. A, turbid, very bad odor. B, clear and has no odor. While I was trying to close the matrass with a flame, it broke; I decanted the urine into a similar matrass which also broke, then finally into a closed tube well washed with boiling water, and then closed with a flame. In the following months, the turbidness in A keeps increasing; foul odor; color deeper and deeper. On the contrary, B remains limpid and pale in color. January 16, 1875. Presented to the Society of Biology. A, very dark-colored, turbid, foul; B, clear, with a slight flaky deposit. January 18. A, dark-colored, turbid, foul, very alkaline. Analysis by the Yvon process gives 5.8 cc. of nitrogen for 1 cc. of urine; but by the Grc'hant process we get only 2 cc. of nitrogen, that is, 0.5 centigrams of urea; that is because the Yvon process includes the carbonate of ammonia. Fermentations by Organisms 825 B, clear; odor quite fresh; normal acidity. The Yvon process gives 6.1 cc. of nitrogen for 1 cc. of urine; the Grehant process gives 6.0 cc, that is, 1.6 cgm. of urea. May 17. Urine B, which was closed with a flame, is neutral, with hardly any smell; there is a thick vegetation on its surface. Analysis by the Grehant process gives 1.5 cc. of nitrogen for 1 cc. of urine, corresponding to 0.4 cgm. of urea. Experiment CCCCXXXVII. May 20. Fresh urine, in three tubes; to each of them I add a small piece of Musculus paper, laden with urinous ferment, which M. Pasteur sent me; this paper, prepared more than six months before, is still very powerful: A, in open air; B and B', at 21 atmospheres of air with 81% of oxygen. May 24. Decompression. A, strong odor; very alkaline. B, B', slight odor; B neutral, B' very slightly alkaline. Experiment CCCCXXXVIII. May 28. Fresh urine, in two mat- rasses closed with a cork stopper which is hollowed out; A, in open air; B, at 23 superoxygenated atmospheres, which fall slowly to 5. June 26. Decompression. A has been foul and turbid for some time. B, clear with a slight deposit, no odor, closed with wax. June 28. Presented to the Institute, closed without care, and taken back to the laboratory. July 11. Is covered with a green mold, but has no odor of ammonia. So urine is preserved with all its qualities, its color, its odor, its normal acidity, and urea is kept in it in its original proportion. Experiment CCCCXXXVI, which was performed with particular care, is quite conclusive in reference to all of these properties. The agreement of the figures given by the Grehant process and the Yvon process for the quantity of nitrogen extracted from the com- pressed urine shows that there was no carbonate of ammonia formed in it, whereas there was much in the urine left at normal pressure. But if, as in Experiments CCCCXXXV and CCCCXXXVII, a considerable quantity of ferment is added to the fresh urine, altera- tion will begin. That evidently, as we have already decided in regard to blood and milk, is the result of the fact that the oxygen does not have time to kill the ferments before they have begun to act upon the fermentable matter; however, even in these cases, their action is delayed. I must say, however, that these experiments on urine should be resumed with special persistence; when the Musculus paper is used, 826 Experiments there seems to be something complex, the simultaneous action of an organic ferment and a soluble ferment. 4. Brewers Yeast. Brewers yeast is killed by compressed air, as is shown by the following experiment. Experiment CCCCXXXIX. June 26. Pieces of very active brew- ers yeast are placed: A, in a closed flask, normal pressure. B, in a flask taken to 15 superoxygenated atmospheres. July 21. A, decayed, with a foul odor; no recognizable trace through the microscope. B, decompressed; good, fresh odor; seems wholesome outwardly and through the microscope. However, when placed in water with glucose in it, it decays without fermenting, turning acid. So the yeast lost all its power and life; yet it was preserved from putrefaction by the very agent that killed it. It is not surprising then that at normal pressure, fermentation by yeast proceeds more energetically than in compressed oxygen. Examples: Experiment CCCCXL. August 6. Brewers yeast is added to equal quantities of a solution of glucose, at the bottom of four similar tubes: A, 2 left at normal pressure; B, 2 taken to 10 superoxygenated atmospheres. August 8. A, 5 cc. of liquid reduce between 20 and 30 drops of blue reagent. B, 5 cc. reduce between 40 and 45 drops. So compressed yeast consumed much less sugar than the other. Experiment CCCCXLI. May 13. 50 cc. of glucose solution are placed in two flasks, with a piece of brewers yeast of the same weight. A, closed, left at normal pressure. B, taken to 10 atmospheres of an air with 76% of oxygen; tension corresponding to 38 atmospheres of air. May 18. A, 5 cc. of the liquid reduce 1.3 cc. of Fehling's solution. B, 5 cc. reduce 5 cc. The liquid in which the yeast was subjected to compression therefore contained much more glucose than the other. Experiment CCCCXLII. December 2. Into each of four tubes are poured 3 cc. of a weak glucose solution and a piece of brewers yeast as big as the head of a pin. A and A', drawn out in the flame, are kept at normal pressure. B and B' are taken to 18 superoxygenated atmospheres. December 8. Decompression; A and A' contain no trace of glu- cose. B and B' contain 15.6 mg. of glucose. Fermentations by Organisms 827 5. Wine Ferments. The same thing is true for the two fermentations which appear so often in wine, and follow the development of mycoderma aceti and mycoderma vini. In the following experiments, the two myco- derms are generally used simultaneously. Experiment CCCCXLIII. August 8. Temperature 27°. Wine de- cidedly acid, placed in equal quantities in 3 small bottles; I add to each a small quantity of acetic ferment in full activity: A, left at normal pressure, covered with a paper cone turned over it. B, taken to 4 atmospheres of ordinary air. C, to 7 atmospheres of air with 70% of oxygen; tension equiv- alent to 24 atmospheres of air. • August 11. A. The wine is covered with a very definite white membrane. B, very slight film over almost the entire surface. C, a few very slight small spots. B and C remain under compression. August 15. A, very thick membrane. B, pellicle a little thicker than on August 11. C, spots as on August 11. Experiment CCCCXLIV. August 15. I add to wine placed in a thin layer at the bottom of two matrasses films of mycoderm of vinegar. A is closed and inverted over water. B is agitated for a long time by a current of almost pure oxygen; then I close the matrass, and invert it beside A. August 17. A is covered with a white film of mycoderms. B has nothing on the surface. August 19. A, thick pellicle. B, slight film. August 21. A, quite thick membrane. B, the film slightly thickened. Experiment CCCCXLV. January 27. Ordinary wine placed in two vials; on the surface is spread a little mycoderm from wine ex- posed in the laboratory, on which had been sown mycoderma aceti. This wine contained 11.9% of alcohol and its equivalent' of acidity was 0.08. A, with a cork stopper, and left at normal pressure; B, closed similarly with a stopper with a hole, and taken to 10 atmospheres of an air with 84% of oxygen; tension equivalent to 42 atmospheres of ordinary air. February 3. A, slight film on the surface. B, decompressed; nothing on the surface; stopper sealed with wax. February 17. A, thick membrane. B, nothing on the surface. May 24. Shown to the Committee of the Academy of Sciences. 828 Experiments A, turbid, with a thick layer of mold on the surface; micro- scopic examination shows that there are present only mycoderma vini and some ferments of bitters. When filtered and tasted, it is a horrible parody of wine. It has only 9% of alcohol and its equivalent of acidity is only 0.045. B, very clear, but very much "faded"', with a slight deposit of coloring matter, in which are present a little mycoderma vini and numerous filaments of ferment of bitters. As for the taste, it is not acid, but rather a little bitter, arid is like good Burgundy which is too old; it was a very mediocre wine. It still contains 11% of alcohol and its equivalent of acidity is 0.07. When exposed to the air, the next day it is extremely acid and quite unfit for prinking. (The chemical analyses were made in the laboratory of M. Schutzenberger, and the microscopic examinations were made by M. Gayon.) Experiment CCCCXLVI. February 24. Fine Burgundy wine. A, kept as control in a full flask, well corked and lying on its side. B, flask almost full, at normal pressure; I sow on top of it myco- derm of vinegar, and close it. C, large test glass with a strong stopper of new cork with a hole in it. I sow on top of it more mycoderms than on B. Taken to 10 superoxygenated atmospheres. March 1. B is covered with mycoderms. C, which I decompress in 24 hours has no sign of them; I seal the hole in the cork. May 17. The three flasks are taken to the laboratory of M. H. Ste.-Cl. Deville, and uncorked before MM. Deville, Boussingault, Debray, etc. A, fine red color; no deposit. Very firm in taste, no bitterness. B, horrible weak wine, turbid, pale. C, color very fine, a little amber. Deposit abundant, very adher- ent. Agreeable odor. Taste not acid, but a little flat and definitely bitter, although not too disagreeable. Absolutely like our good Bur- gundy wines, when they begin to be slightly bitter. Experiment CCCCXLVII. June 19. Ordinary wine; placed in two flasks and in it are sown mycoderms very active in the laboratory. A, well closed; normal pressure. B, closed, with a hole in the cork; taken to 20 atmospheres of air with 88% of oxygen, corresponding to 88 atmospheres of air. June 24. A, covered with mycoderms. B, decompressed, without mycoderms, but with a deposit of color- ing matter; so it is "faded". Well sealed. July 6. A, clear wine, rosy, with a film of mycoderma vini on the surface, and a gelatinous, flaky deposit, containing much mycoderma aceti. Strong odor of vinegar. To neutralize the acidity, I had to use a quantity of lime water 2.3 times greater than for B. Fermentations by Organisms 829 B, clear, pale; on the surface, iridescent film, without organisms; deposit of coloring matter. Very weak acid odor. Experiment CCCCXLVIII. June 26. Good Burgundy wine in a flask taken to 15 atmospheres of superoxygenated air. July 21. Decompressed. Very pale color of Rancio wine. No longer has any bouquet. No acidity; very weak, with a slight taste of boiled wine. Experiment CCCCXLIX. July 21, 1874. Ordinary wine, in two matrasses one quarter full. A, sowed mycoderms of wine; closed, sealed, at normal pressure. B, sowed similarly; the matrass is drawn out in the flame, and taken to 15 superoxygenated atmospheres. July 30. A, covered with mycoderms. B, without mycoderms, but pale, with adherent deposit. Decom- pressed, closed with a flame. January 18, 1875. A, very thick membrane on the surface; very pronounced acetic odor; taste of vinegar. The acidity, measured by soda and litmus, is 6 times stronger than in B. It turns the solution of potassium bichromate green in sulphuric acid; therefore it still contains alcohol. B, color very pale; very thin films on the surface and on the walls of the vessel; definite winy odor, taste not very acid, an extremely weak wine. Still contains alcohol. Experiment CCCCL. May 20. Wine in tubes, on the surface of which mycoderms have been sown; A, in open air, covered with an inverted cone. B, at 21 atmospheres of an air with 81% of oxygen. May 24. Decompressed. A, thick layer of mycoderms, liquid turbid. B, "faded", yellowish; precipitate of coloring matter; no myco- derms; clear liquid. I boil wine in balloon flasks; during the boiling, I close each flask with a stopper furnished with a long tube curved and drawn out, through which the air enters slowly, cooling as it enters. When the liquid is cool, I open the flasks for an instant and throw into one, A', the contents of tube A; into the other, B', the contents of tube B. May 31. A', thick pellicles. B', no mycoderms. Experiment CCCCLI. May 28. Wine in a matrass; mycoderms sowed on the surface; A, open air; B, at 23 superoxygenated atmospheres, which in the last days of the compression, fall to 5. May 31. A is covered with a continuous film. June 26. Decompression. A, thick layer of mycoderms; liquid very turbid. B, liquid very clear, with deposit of coloring matter; nothing on the surface. 830 Experiments So under the influence of oxygen at high tension, the mycoderm which consumes the alcohol entirely and the one which merely transforms it into acetic acid are absolutely killed. The wine thus retains its alcohol and its acid content (Exp. CCCCXLV) . The effect of the oxygen begins to appear before the tension which corresponds to 5 atmospheres of air (Exp. CCCCXLIV.) However the wine undergoes certain alterations. The coloring matter is precipitated in the form of films adhering to the vessel, it "fades" more or less completely, and sometimes has a beautiful, slightly amber color (Exp. CCCCXLV) , sometimes a tint like Rancio wine (Exp. CCCCXLVIII) or finally an almost entire loss of color (Exp. CCCCXLIX). In taste, the wine appears to age rapidly (Exp. CCCCXLVI) ; it even becomes quite bitter (Exp. CCCCXLV) or very much weak- ened (Exp. CCCCXLVI) . It loses its bouquet, and sometimes has a slightly cooked flavor (Exp. CCCCXLVIII) . In a word, the wine appears to undergo the alterations produced by excessive heating, brought on by contact with the air. I will call attention to the fact that in all these experiments the pressure was extremely high, carried no doubt far beyond what would be needed to kill the germs. A weaker pressure per- haps would not change the wine, and yet would preserve it from harmful fermentations. Perhaps it would even be slightly im- proved, as happens in the case of harsh and raw wines when they are heated in accordance with the rules established by M. Pasteur. Besides, the wines were tasted after a fairly long time. Possibly if they had been tasted immediately, a certain improvement would have been noted. All these questions, moderately interesting from the scientific point of view, take on a considerable importance when considered from another point of view. However, I could not turn aside unduly from my general studies to investigate them, and after noting the preceding facts, I had to postpone until another time detailed re- searches and practical applications, if possibly there are any. I merely report here an experiment which proves that the limit at which oxygen at high tension acts unfavorably on wine is quite low; hence we conclude that its favorable concentration, if there is one, as the preceding experiments seem to indicate, might be ob- tained industrially, since ordinary air could be used. Experiment CCCCLII. July 15. Good red wine in two sealed bottles the corks of which are pierced by a hole. A, in the air, upright, Fermentations by Organisms 831 B, at 10 atmospheres of air, upright. July 29. Decompressed. The appearance of A has not changed. B is violet colored, with a colored precipitate, abundant, adhering to the vessel. October 4. Tasted. A, good taste, quite good bouquet. B, colorless, bouquet lost, smells flat. 6. Molds. In a great number of experiments, generally made with another purpose, several of which have already been reported, I have ob- served that oxygen at high tension kills microscopic organisms, animal or vegetable, besides ferments. Liquids suited to the de- velopment of infusoria contain no trace of them after a certain time in compressed oxygen; they are completely purified of them, when they already contained them, both animal and vegetable, both simple monads and the highest infusoria in the series. Evidently these facts have only a slight importance, considering all those which we have already enumerated, and so we shall not give a report of any special experiment. The universality of the fatal effect of oxygen at high tension has been sufficiently estab- lished by all the experiments reported hitherto. It would be a strange philosophy to imagine — and yet eminent intellects have made this serious mistake in the matter of so-called spontaneous generation — that microscopic dimensions can give special powers to beings of that size, and authorize in their favor infringements of the most general rules of nature. Quite naturally molds have behaved like the so-called higher plants. And yet it seems worth while to report here a few experi- ments which deal principally with them. These data may be useful, in fact, in solving questions relating to the general theory of fer- mentations. Experiment CCCCLIII. June 26, 1874. Two pieces of wet bread, measuring a few cubic centimeters, are placed: A, in a large flask closed with a cork stopper. B, in a small flask closed similarly but with a cork pierced by a hole. Taken to 15 superoxygenated atmospheres. July 21. A has for several days been in deliquescence and is cov- ered with green mold. B, white, firm, very fresh in appearance; no vegetation. January 18, 1875. A is only shapeless fragments, in which there is no sugar left; neutral to litmus. B presents exactly the same appearance as on July 21. When opened, it has a slight acid odor, agreeable, which is not that of acetic acid, but is like that of lactic acid. It turns litmus a deep red ,and owes this effect to an acid which resists prolonged boiling and com- 832 Experiments plete dehydration. It precipitates copper reagent in abundance; it is turned completely blue by iodine. Experiment CCCCLIV. July 21, 1874. Bread cut in small pieces, moistened, and placed: A, in a closed matrass; B, in a matrass drawn out in a flame; it is subjected to 15 super- oxygenated atmospheres. July 30. A, covered with mold. B, has not changed in appearance. January 18, 1875. A, in decay. B, which I do not open, looks the same as on July 30. August 3. B is opened m the laboratory of M. Cloez and in his presence; the appearance has not changed; the reaction is slightly but clearly acid; odor sourish, agreeable. I call attention to this acid reaction presented by the bread in spite of its apparent preservation and the complete lack of mold. We had already noted a similar reaction in meat and egg, protected against putrefaction by compression. I observed it when I used cooked starch instead of bread to simplify experimental conditions. Experiment CCCCLV. July 21, 1874. I scatter over starch cooked with a good deal of water various dusts taken from a corner of the laboratory. A, closed matrass, normal pressure; B, matrass drawn out in a flame, 15 superoxygenated atmos- pheres. July 30. Decompressed B; while it was being closed with a flame, the matrass broke. I immediately poured the contents into a tube washed in boiling water, which I closed at once with a flame. January 18, 1875. A, covered with mold, contains neither sugar nor starch. B, clean, without mold, contains much glucose, and is colored very blue by the aqueous solution of iodine. Experiment CCCCLV I. August 7, 1874. Starch cooked and much diluted with water: A, in a matrass closed with a stopper. B, in a matrass, drawn out in a flame, maintained between 8 and 12 superoxygenated atmospheres, until August 17, when I decom- press it and close it with a flame. January 18, 1875. A, foul, neutral; B, no change in outer appearance; sourish and perfumed odor, recalling that of cider. Very acid, it is colored blue by iodine and contains glucose. M. Schutzenberger, who consented to examine this substance, found in it volatile acids, acetic and formic, and a fixed acid, giving, with zinc, crystals of the same form as the lactates. Fermentations by Organisms 833 Experiment CCCCLVII. July 5, 1875. Cooked starch and water; glass tubes. A, closed with a flame, ordinary air; B, drawn out in a flame; taken to 15 superoxygenated atmos- pheres. July 17. Decompressed; B closed with a flame. November 16, 1876. A, neutral, contains much glucose; no odor. B, clearly acid; much glucose; no noticeable odor. FRUITS. Experiment CCCCLVIII. June 26, 1874. A, 3 entire cherries, very ripe, are placed in a small flask with a little water. Taken to 15 superoxygenated atmospheres. B, unfermented juice of cherries left at normal pressure, in a closed flask; C, unfermented juice of cherries, placed beside A. July 21. B, evidently spoiled, covered with mold. A and C, in very good condition, have a rather deep color. January 18, 1875. B is a horrible magma. A. The cherries are very fine and very firm, absolutely just as they were July 21. November 30, 1876. The cherries in A still look the same. May 1, 1877. Same. Experiment CCCCLIX. May 28. Matrass containing: A and B, whole cherries; A' and B', pears. A and A' are left in the air, covered by an inverted paper cone. B and B' are placed in 23 superoxygenated atmospheres; the pressure gradually falls to 5 atmospheres. Beginning with May 31, A and A' are covered with mold. June 26. A and A' are molded, the pears in shapeless pulp. B and B' have no mold; the cherries are brown, the pears amber colored. Experiment CCCCLX. January 20. Juice of pounded onion with powdered chalk added; tubes: A, normal pressure; B, at 21 superoxygenated atmospheres. January 23. Decompressed; the tubes closed with a flame. May 17. A, neutral; abundant vegetation on the surface. B, neutral; no mold. Experiment CCCCLXI. July 5, 1875. Stoned cherries, to which a little glucose is added. Placed in columns about 10 cm. high in three tubes, taken to 15 superoxygenated atmospheres. July 17. Decompressed; the cherries taste like cooked cherries but too acid. Tubes closed with a flame. November 16, 1876. The appearance of the cherries has not changed; no explosion when the tubes are opened; cherries taste like brandied cherries, but too acid. By the method of oily drops, M. Dastre finds much alcohol in them; he estimates the proportion of it at 1%. 834 Experiments Experiment CCCCLXII. July 5. Apricots and cherries in flasks. A, in open air; B, at 8 superoxygenated atmospheres. July 9. A, covered with mold. B, without mold; the apricots have a strange pungent odor. Experiment CCCCLXIII. July 15. Apples, pears, grapes, in separate bottles, closed by sealed stoppers which are pierced by holes. A, in the open air. B, at 10 atmospheres of air. July 29. Decompression. A, the apples and pears are spoiling; liquid is issuing from them; the grapes are putrefying; all of the grapes have fallen from the stalk, which is left hanging; mold; closed with wax. B, apples and pears have become brown, and seem cooked; grapes well preserved; no mold; closed with wax. October 4. A: fruits completely decayed; B, apples and pears softened, taste like cooked fruits; grapes with mold, but the fruit still clings to the stalk. Experiment CCCCLXIV. September 23. Reine-daude plums, ripe, very wholesome: A: normal pressure; B: 15 superoxygenated atmospheres. September 29. A: intact; normal taste; B: also intact in appearance; taste of cooked plums. Fruits then are perfectly preserved, as far as form is concerned, in oxygen at high tension; they are protected from mold. The cherries in Experiment CCCCLVIII, kept unchanged in appearance for 3 years, after return to normal pressure, give a striking ex- ample of that. But their color changes, their taste especially, which is more or less like cooked or brandied fruit. This research should be continued from the chemical point of view, especially consider- ing the production of alcohol noted in Experiment CCCCLXI. The relation of these data to those noted by MM. Bellamy, Lechartier, and Pasteur should be investigated. Subchapter II DIASTATIC FERMENTATIONS I now come to the study of the effect (if there is one) of oxygen at high tension upon the ferments which are soluble in water and precipitated by alcohol, which are called diastatic ferments, zymotic, or false ferments, etc. Diastatic Fermentations 835 1. Saliva and Diastase. The zymotic fermentation upon which I was to experiment most frequently is that by which diastase transforms starch into glu- cose. Besides the considerable interest presented by this phe- nomenon, which plays so great a part in the digestion of animals (saliva and pancreatic juice) , in their nutrition (hepatic glyco- genosis), that of plants and germination, I was influenced by the ease with which one can measure its effects exactly. The first question to be settled was whether the diastatic ferment is killed by oxygen at high tension, as the organic ferments so surely are. The following experiment will give the answer. Experiment CCCCLXV. June 26. Diastase is dissolved in a little water and placed in two tubes: A: normal pressure. B: at 15 superoxygenated atmospheres. July 21. Decompressed B, which has no odor and has retained the most energetic transforming power, whereas A smells bad and no longer has any effect on cooked starch. Experiment CCCCLXVI. February 16. Diastase and water in a tube drawn out. Placed at 15 atmospheres of superoxygenated air. May 5. Decompressed, has retained all its effect. I make a new solution of diastase in a tube which I close with a flame, as 1 also do with the first. May 17. The diastase which was compressed still acts upon starch; it has no odor. The other has a butyric odor and no strength left. So diastase, far from being spoiled by oxygen at high tension, is preserved perfectly in it. It even appears that it remains power- ful almost indefinitely, in all probability because of the destruc- tion by the compressed air of the organic ferments, which would have caused it to putrefy at normal pressure. We get the same result when we experiment upon, not pure diastase dissolved in water, but the complex mixture which con- stitutes the buccal saliva. Example: Experiment CCCCLXV II. July 21, 1874. Human saliva diluted with water and placed in a matrass drawn out in a flame, and subjected to 15 atmospheres of superoxygenated air. July 30, I make the decompression and close the end of the tube which was drawn out. January 18, 1875. This saliva, which has no odor and appears quite normal, neutral to reagents, has a powerful transforming effect upon starch cooked in glucose. So saliva is preserved in compressed air; but I must confess that it keeps very well in open air also. Unfiltered human saliva, 836 Experiments placed in a closed tube January 18, was still active February 12; although a very small orifice was left open in the tube then, the saliva still had considerable activity May 17. The same thing is true of the pancreatic juice and in general of the soluble ferments, which even resist beginning putrefaction. But now, even if it is preserved in compressed air, does the ferment retain its activity there? And does it act there with more or less energy than at normal pressure? Experiments will give the answer. I call attention to the fact that I took raw starch in suspension in water, because cooked starch is transformed instantaneously on contact with saliva. Experiment CCCCLXVIII. July 18. My saliva, filtered, is mixed with a certain quantity of water holding raw starch in suspension; it is mixed carefully and placed in 3 open tubes: A. Left at normal pressure. B. Taken to a half-atmosphere. C. At 8 superoxygenated atmospheres. The tubes and apparatuses are placed in identical conditions of temperature. July 20. Withdrew the tubes, filtered the liquids rapidly, and tested them with Fehling's reagent. A. 5 cc. reduce from 75 to 85 drops of copper reagent. B. 5 cc. reduce from 65 to 75 drops of copper reagent. C. 3 cc. reduce from 50 to 60 drops of copper reagent. Experiment CCCCLXIX. May 26. Filtered saliva, mixed with raw starch in suspension in an equal volume of water. The liquid, well mixed, is placed in equal quantities in 2 tubes, one of which, A, is left at normal pressure, the other, B, is subjected to 15 superoxygen- ated atmospheres. June 3. A evidently contains much more sugar than B. However the deposit at the bottom of tube A is colored an intense blue by iodine, whereas that in B gives only a greenish discoloration. Experiment CCCCLXX. January 20. Saliva, raw starch, and water. Well mixed and placed in tubes. We make sure that the mixture contains no glucose. A. At normal pressure, covered with an inverted paper cone. B. At 21 atmospheres of superoxygenated air. Both are placed in the drying-oven, at 30 degrees. January 25. Tested with copper reagent. A. 7 cc. reduce 35 drops. B. 7 cc. reduce only 14 drops. Experiment CCCCLXXI. March 22. Saliva, raw starch, and water. Mixture placed in tubes. A, A'. At normal pressure. B, B'. At 9 superoxygenated atmospheres. March 24. Tested with copper reagent. Diastatic Fermentations 837 A and A' contain a little more glucose than B and B'; slight, but evident difference; examinations made with great care on white paper. Experiment CCCCLXXII. May 25. Saliva, raw starch, and water. Equal quantities in six tubes. A. Three are drawn out in the flame and left at normal pressure. B. Three at 15 atmospheres of superoxygenated air. May 27. Analyses of the tubes by M. Dastre. A. Contain 2.2 mg.; 2.9 mg.; 1.7 mg.; an average of 2.3 mg. of glucose. B. Contain 1.6 mg.; 1.9 mg.; 1.7 mg.; an average of 1.7 mg. of glucose. In these experiments, the transformation of starch into sugar continued to operate in compressed oxygen, but its intensity has evidently diminished. But to obtain this result, one must not wait too long, but must examine the liquids after a very few days. Otherwise, especially if diastase was used, the result would be just the opposite, and the compressed liquid would be richer in sugar than the other. This happened, for example, in the following experiments. Experiment CCCCLXXIII. June 26. Raw starch in suspension in water, mixed with a certain quantity of diastase. Well shaken; placed in 2 tubes: A. Normal pressure. B. 15 superoxygenated atmospheres. July 21. A, 5 cc. reduce 25 drops of copper reagent. B left under compression till then; 5 cc. reduce 40 drops. In both there is still some starch. Experiment CCCCLXXIV. March 1. Saliva, raw starch, water, equal quantities in 12 tubes: A. Six are drawn out in the flame and left at normal pressure. B. Six are placed at 15 superoxygenated atmospheres. March 28. Analysis of the tubes by M. Dastre. A. 2 tubes contain quantities of glucose proportional to the num- bers 45 and 39; hence, an average quantity of 1.7 mg. B. 3 tubes analyzed contain quantities of glucose proportional to the numbers 111, 119, 115; hence an average quantity of 4.6 mg. of glucose. That is easily explained; the diastase which had been left in the air had altered a little, whereas that which was under compression had kept its properties and continued to act. 2. Pepsin. Experiment CCCCLXXV. February 16. Boudaut pepsin; three tubes, in each of which are placed 2 grams of pepsin with 5 cc. of distilled water. 838 Experiments A. In the air, covered with a paper cone. B and B'. In 15 atmospheres of superoxygenated air. March 5. Decompression. A. Smells rather strong and is covered with mold which forms a stopper; very acid. B and B'. No odor; no mold; acid. I put B and B' each in a glass with 10 grams of cooked white of egg which has been cut into pieces; the glasses, which are of the same size, are next filled with water acidulated with hydrochloric acid. I take 2 grams of powdered pepsin, place them in 5 cc. of dis- tilled water, and add 10 grams of the cooked white of egg, and the same quantity of acidulated water. The three glasses are placed in the drying oven at 38 degrees. March 8. There remain in each glass 2 grams of insipid white of egg. So pepsin, after being subjected to the effect of oxygen at high tension, behaved absolutely as before. 3. Inversive Ferment of Yeast. The ferment which I used, like the myrosine and emulsine to be discussed in the following sections, had been prepared by M Schiitzenberger, then head of the laboratory of chemical research of the Faculty of Sciences. Experiment CCCCLXXV (2). February 16. Placed 5 cc. of liquid in three tubes drawn out in the flame. A. In open air, covered by a paper cone. B and B\ At 15 atmospheres of superoxygenated air. March 5. Decompression; I close the three tubes with the flame; but first I make sure that the ferment in tubes A and B transforms cane sugar rapidly into glucose. March 15. Placed in the drying oven, in which the temperature varies from 25 to 40 degrees. March 25. Withdrawn from the drying oven; A, B, and B' ai*e still potent. May 17. A is alkaline and foul; has no potency. B and B' are acid, have no odor, and have kept their power. 4. Myrosin. Experiment CCCCLXXV I. February 16; in 3 tubes drawn out in the flame; liquid to a height of 5 cm. A. Free air, covered with a paper cone. B and B'. At 15 atmospheres of superoxygenated air. March 5. Decompressed; A and B act perfectly upon potash my- ronate to give essence of mustard. March 15. Placed in the drying oven, from 25 to 40 degrees. March 25. Taken from the drying oven; A and B are still potent. May 17. A, B, and B' are still potent, but the last two have more energetic action. Anatomical Elements 839 5. Emulsin. Experiment CCCCLXXVI (2). February 16. This experiment was performed at the same time and under the same conditions as the three preceding ones. March 15. There is much mold on the emulsin which was not compressed; no molds on the other, any more than on the other tubes. The formation of the essence of bitter almond on contact with amygdalin takes place in both liquids, March 25, when taken from the drying oven. May 11. The emulsin which was not compressed is covered with mold, alkaline, foul, and impotent. The other seems fresh, has no odor, is slightly acid, and acts energetically and rapidly. In summary, all the soluble false ferments upon which we ex- perimented, salivary diastase, pepsin, inversive ferment, myrosin, emulsin, have given us the same result and have kept their char- acteristic power after the prolonged effect of oxygen at high tension. And even more, since the oxygen frees them of the germs of mold, vibriones, etc., which sooner or later destroy them in the open air, they remain themselves for an apparently indefinite time. This remarkable power can perhaps be used in practice, and especially in therapy. It would be a good idea, I feel sure, to substitute for powders and extracts, so harmful to the digestive juices, the juices themselves, previously subjecting them to a sufficient pressure, to prevent putrefaction in them. But I can merely suggest this idea here. Subchapter III EFFECT OF OXYGEN AT HIGH TENSION UPON THE ANATOMICAL ELEMENTS After noting, in Chapter IV, the rapidly fatal effect of oxygen at high tension upon the higher animals, we tried to analyze this effect, according to the methods introduced by M. Claude Bernard in toxicology. Sectioning of the nerves, examination of the heart, use of anesthetics, and the injection of the blood of animals killed by oxygen into the veins of other animals have showed us that the violent symptoms which precede and bring on death, are the result of an over-excitement of the nervous centers, so that I was led to compare the effect of oxygen with that of strychnine and phenol. After death, the muscles are still contractile, the nerves are 840 Experiments excitable, the reflex acts are possible, and the heart is still beating. But does this mean that the nervous anatomical elements alone are attacked by oxygen? All that we have said hitherto is opposed to that hypothesis; the considerable decrease of the intra-organic oxidations, the death of lower animals, the death of plants and ferments, all these phenomena show a universality of effect which evidently must extend to the anatomical elements of the higher animals. Yet I could not be satisfied in this case, any more than in any other, with conclusions drawn from analogy. I thought direct experiments necessary; but I confess that, seeing how well they agreed with what appeared so probable, I did not make their number very great. Experiment CCCCLXXVII. February 20. The hind-quarters of a frog are cut in two, following the vertebral axis. A. One of these parts is left at normal pressure, hung in a closed test glass, at the bottom of which water is placed to prevent desic- cation. B. The other is hung similarly in the cylindrical glass apparatus, in which the pressure is raised to 10 atmospheres of air with 80% of oxygen. February 24. A. The sciatic nerve is no longer excitable; the muscles still contract under the influence of a rather weak current; they are neutral in reaction. B. Neither the muscles nor the nerves are excitable by the strong- est currents. There is evident rigidity, and the muscles are very acid. Experiment CCCCLXXVIII. March 2, 2 o'clock. Halves of frogs arranged as in the preceding experiment; A at normal pressure, B at 15 superoxygenated atmospheres. March 3. 4 o'clock. A: sciatic nerve quite excitable; muscular contraction very strong and very sudden, as in the normal state. B: The sciatic nerve can no longer be excited by any current. The muscles still contract; but the contraction is slow, resembles a kind of a cramp, and lasts after the stimulus has ceased. Experiment CCCCLXXIX. April 8. Experiment still arranged in the same way; A at normal pressure, B at 3 atmospheres of air con- taining 50% of oxygen, which corresponds in tension to 7.5 atmos- pheres of air. April 10. A. Muscular contractions obtained with the inductor- ium, the movable coil being 16 cm. from the exterior of the fixed coil. B. To get contractions, it is necessary to bring the coil to 5 centi- meters. The contraction is accompanied by contracture. Experiment CCCCLXXX. June 12, 4 o'clock. The hearts of 4 frogs are removed. These hearts are placed 2 by 2 in a capsule in which they lie in the vitreous humor of a dog. A. Left at normal pressure. Anatomical Elements 84] B. Compressed in the cylindrical glass apparatus to 10 superoxy- genated atmospheres. 6 o'clock. A. The hearts are still beating occasionally, especially the auricles; they can be stimulated. B. They have completely stopped, and cannot be revived by stim- ulation. These data show that muscular contractility, motor nerve ex- citability, and the rhythmic action of the nerve ganglia of the heart stop much sooner in oxygen under high tension than under normal pressure with ordinary air. In other words, the muscular, nerve, and ganglionic anatomical elements, like the free elements which constitute the ferments, are killed by compressed oxygen. Other researches, in which I used the method of animal grafting, the only one which could inform us on this point, show that not only the vital properties of the higher order, the animal order, are destroyed in the muscular and nervous elements, but that all the anatomical elements are killed by oxygen at high tension. In fact, the grafts carried out with parts subjected in advance to its effect were absorbed without having become adherent. Experiment CCCCLXXX1. March 15. Tails of rats, with skin re- moved, are hung in closed glass tubes, with a little water at the bottom. One of them, A, is left at normal pressure. The other, B, the stopper of which is pierced by a hole, is subjected to 10 atmospheres of superoxygenated air, from March 16 to March 20. Temperature 12 degrees. March 20. A smells rather bad. B no odor. Grafted under the skin of the back of two rats. No complication. July 16. Graft A has taken root perfectly. B is almost entirely absorbed. Experiment CCCCLXXXI (2). March 22. Tails of rats, with skin removed, hung in tubes, above a little water. A. Normal pressure. B. At 9 superoxygenated atmospheres. March 24. Grafted on two rats. No complications. June 1. A, graft has taken root perfectly. B. Almost entirely absorbed. The transfusion of blood, which is only a particular case of the general method of animal grafting, also shows that the blood which has undergone the prolonged action of compressed oxygen is incapable of maintaining life; its anatomical elements, its cor- puscles, are killed and their introduction into the organism even causes death. Example: 842 Experiments Experiment CCCCLXXXII. April 20. 100 cc. of dog blood, defibri- nated, are shaken continuously for 18 hours in the apparatus pictured in Figure 45, with oxygen compressed to 18 atmospheres. April 21, from a little dog (weighing 5 kilograms) 100 cc. of blood are taken, a loss of blood which certainly would 2 not have killed him, and into his femoral vein is slowly injected the 100 cc. of blood which had been shaken and deprived of free gases. The injection is made at 11 o'clock. Immediately after, the animal begins to run; but he soon retires to a corner, falls into a sort of somnolence, and dies at 5:30; his rectal temperature at this time is 29.5°. So the anatomical elements of the bones and the cellular tissue were killed by the oxygen at high tension; the blood acquired toxic properties; grafts were absorbed without having made vas- cular adherences. If they did not cause cellulitis, that is probably because the oxygen had killed all the atmospheric germs which might have lodged there; besides, I obtained similar results before. We conclude from these data that the death of higher animals in compressed oxygen, although its immediate cause is the super- excitation of the central nervous system, as we have demonstrated, is really due to a general effect of the oxygen upon the whole organism. But the nervous elements, which are more susceptible, react first, disturb the vital mechanisms, so that death occurs before the other elements are noticeably affected. Hence we draw again the conclusion that the death of the anatomical elements has nothing to do with putrefaction; it is not the first stage of putrefaction, as might have been thought with apparent reason; it is quite a different thing, because pressure, which hastens death, prevents putrefaction. Subchapter IV ON THE USE OF OXYGEN AT HIGH TENSION AS AN EXPERIMENTAL METHOD The data which have just been reported in the two preceding subchapters seem to me to present considerable interest, not only in themselves, but from the point of view of the use of oxygen at high tension as an experimental method. We have seen, in fact, that the microscopic organisms which constitute the true ferments and that anatomical elements, isolated or grouped in tissues, are killed by oxygen; that on the contrary the unformed ferments, the Dry-rot; Venoms; Viruses 843 soluble ferments, the diastases, resist it perfectly and are even preserved by it. We possess then a valuable instrument of differentiation to dis- tinguish what belongs to one or the other of the two classes of fermentations. If we are dealing with a true fermentation, it will be checked completely by compressed oxygen, under a tension corresponding to about 30 atmospheres of air, and since the ferment is killed, it will not appear again, even when the pressure becomes normal once more. If the fermentation is due to the presence of a sub- stance analogous to diastase, this substance, when subjected to compressed air, should keep its active properties there almost in- definitely, as a subsequent experiment will show. I make haste to say, however, that although it is very easy to decide in this way whether a given phenomenon is a true fermenta- tion, the method will not distinguish between a pseudo-fermenta- tion and the result of a simple oxidation. An example taken from the dry rot of fruit will explain my idea. 1. Dry Rot of Fruit. Certain fruits, for example medlars and service-apples, are com- monly attacked by dry rot, so that, since they can be eaten only in this condition, it is generally confused with ripeness. Is dry rot the final stage in a vital evolution of the cells of the fruit? Is it the result of the reaction of a diastatic matter previously formed on the tannin, which disappears during the dry rot? Or, finally, the result of an oxidation of this tannin, the disappearance of which takes from the fruit its disagreeable taste? Let us see first what experiments say. Experiment CCCCLXXXIII. September 29. Service-apples not affected by dry rot, in good condition, placed carefully in test glasses. A, left in open air. B, subjected to a pressure of 10 superoxygenated atmospheres. October 4. Decompressed. A, beginning to rot. B, evidently still more rotten. Experiment CCCCLXXXIV. November 5. Medlars not affected by dry rot. A, at normal pressure. B, at 17 atmospheres in air containing 78% of oxygen. November 11. Decompressed. A, still very hard, do not suffer dry rot until a week after. B, completely rotten, and consequently, from the sudden decom- pression and the escape of gases, cracked and burst. 844 Experiments So not only was dry rot not checked by the effect of oxygen at high tension, but, on the contrary, it was accelerated. That alone is enough to show us that we are not dealing with an act of cellular life. But is it a diastatic act? Are we dealing with a direct oxida- tion? Oxidations of this sort are not checked by oxygen at high tension; at least, that is the case with pyrogallate of potash. Experiment CCCCLXXXV. February 10. At the bottom of a glass is a solution of pyrogallic acid; a little capsule containing potash floats on the surface. The whole is subjected to 10 superoxygenated atmospheres in the cylindrical glass apparatus. February 13. The apparatus is shaken without being opened; as soon as the potash touches the acid, the liquid reddens instantaneously, certainly more rapidly than it would have done at normal pressure. The acceleration of dry rot in compressed oxygen seems to indi- cate that it is the result of an oxidation. The following experiment seems to demonstrate this fact. Experiment CCCCLXXXVI. November 12. Very hard medlars are pounded in a mortar, and the paste thus obtained is poured into a glass. Two hours after, dry rot has begun on the surface of the pasty mass. In summary, we see, thanks to the use of oxygen at high tension, that dry rot is certainly not an act in the life of the cells of the fruit, but very probably the result of a direct oxidation. 2. Ripening of Fruits. The same question can be asked about the regular ripening of fruits. If this is a phenomenon of diastatic type, it will continue in compressed oxygen; if it is an act of cellular life, it will be checked. The experiment is quite difficult to carry out, because we must use fruits which ripen easily and quickly off the tree, which are not too subject to harmful changes, and which are small enough to be penetrated by the oxygen rapidly. Experiment CCCCLXXXVII. July 9. Gooseberries which are hardly pink, beginning to ripen. A, at normal pressure. B, in the cylindrical glass apparatus. July 17. Decompressed. A, very red, sweet, tender, quite ripe. B, have not changed color; are firm and hard, acid, with the taste of rather tart cooked gooseberries. Dry-rot; Venoms; Viruses 845 Experiment CCCCLXXXVIII. July 19. Plums beginning to ripen. A, normal pressure. B, 15 superoxygenated atmospheres. July 26. Decompressed. A, are eatable, softened, and quite yellow. B, have become a dark brown color; remained very hard, ex- tremely acid, with the odor and taste of cooked plums. The two examples are sufficient to show very clearly that the ripening of fruits is a vital act, due to a certain cellular evolution, and consequently essentially different from dry rot, with which it is often confused. I call attention to this cooked taste which fruits acquire under the influence of compressed oxygen. It was noted in the experi- ments of Subchapter I, in reference to the development of mold. It is evidently due either to an exaggerated oxidation or to the effect of a diastatic pseudo-ferment. 3. Venoms. The only venom upon which I could experiment is scorpion's venom, the dried vesicles of which I kept for several years; it came from the Buthus occitanns (Amor.) and had been sent me from the south of Algeria. Experiment CCCCLXXXIX. December 2. Twelve dried scorpion's vesicles; they are crushed with a little water; then they are subjected to the pressure of 18 superoxygenated atmospheres. (The liquid is neutral, and has no effect upon starch.) December 8. Decompression. The liquid part (A) is inoculated under the skin of a big rat, and a part of the solid fragments, crushed in water (B), is inoculated subcutaneously on the left thigh, at the level of the sciatic nerve, of a young rat. A quarter of an hour later, I look at rat A, and am much sur- prised to see it already on its side, its eyes are watering and lack sensitivity, its breathing is slow and difficult, its heart is beating irregularly. It has, especially in the hind legs, very strong tonic convulsions, which become remittent, and the animal dies in about a half -hour. The muscles for some moments have exhibited very strange fibrillary movements. The nerves no longer have any power over the muscles. The lungs are quite healthy; the blood in the heart is dark, on the left as well as on the right; the heart is in diastole; the blood turns red in the air and coagulates very well; the corpuscles are intact; rigor mortis comes on very quickly. Rat B is affected a half-hour after the inoculation. At first, cries indicating local pain; then general palsy, slowness of motion; respiration very irregular, sometimes remains 5 or 6 seconds without breathing; the pulse follows the respiration. 846 Experiments The left hind leg remains almost constantly stiff (local action?). Sensitivity continues to decrease, disappearing in the eye (the cornea - last) before the limbs. Slight convulsions, which seem to be excited by pinching. After three quarters of an hour, it remains' lying on its side; the temperature drops rapidly; after an hour and a half, it is 29°. It dies in about 2 hours. Hemorrhage in the brain and the cerebellum; no local inflamma- tion. So the effect of scorpion's poison persists with all its character- istics which I noted before,3 after the venom had been subjected to oxygen at high tension. Besides, I was not at all surprised, be- cause venom resists (the venom of the scorpion, without even being dissolved by it) even the action of pure alcohol. 4. Viruses. I was able to make a greater number of experiments on viruses. A. Vaccine. Experiment CCCCXC. November 10. Twelve newly born babies are vaccinated with vaccine taken from the same child; two leave the hospital before pustules develop; in a third, the vaccine does not take; in the other 9, pustules develop to the number of 35 (from 1 to 6) per 54 punctures. From the same vaccine-bearing child and from the same pustules, Bretonneau tubes are filled, which from November 11 to November 18 are subjected to a pressure of 23 superoxygenated atmospheres. November 18. With the compressed vaccine seven newly born children are vaccinated. Four of them leave the next day but one, before any development could be noted; on the other three the vaccine takes, and produces 13 pustules (6, 6, 1) from 18 punctures. (Operations performed by Dr. Budin, then an intern.) So clear an experiment seems to me sufficient for drawing con- clusions. And my conclusion is that the vaccine virus, which re- sists so completely the action of oxygen at high tension, does not owe its special power to living organisms (bacteria, vibriones) or to cells (leucocytes, special corpuscles), acting like true ferments. And yet I am far from denying that the corpuscles, irregular in form and dimensions, which float in the vaccine, contain in them the virulent principle, as seems very probable since the research of M. Chauveau. But I am certain that living organisms are not there. Perhaps the virulent material is thus precipitated in insoluble flakes; perhaps these corpuscles are endowed with the power of fixing the active principle, as the blood corpuscles fix the hemo- Dry-rot; Venoms; Viruses 847 globin and the amylaceous corpuscles of the green cells fix the chlorophyll. B. Glanders. Experiment CCCCXCI. July 15. Pus of glanders sent from Alfort by Professor Trasbot. Equal quantities are placed in two small bottles, to a depth of about 1 centimeter. A, at normal pressure. B, taken to 20 superoxygenated atmospheres. July 21. Decompressed. A is decayed. B has no odor. The same day, these two puses are inoculated in two horses. A, has only local symptoms, evidently due to the putrid inocu- lation, loosening of the skin and abscess; gets well. B, dies of the glanders, after showing, M. Trasbot writes me, "as complete an eruption as possible." Our conclusions for the virus of glanders and the corpuscles which it contains, upon the virulent role of which M. Chauveau has dwelt, will be identical therefore to those which we drew from the experiments on the vaccine-virus. Here too it is not a matter of microscopic organisms acting like true ferments. C. Anthrax. The researches of M. Davaine have called attention to the part which may be played in the infection of the virus of anthrax by microscopic organisms, the "bacteridies," which he found exist and are constantly present in virulent liquids. Experiments made by dilutions, nitrations, and precipitations have led this learned phy- sician to declare that these "bacteridies" were really the agents of the virulence, and that, when introduced into the blood of a healthy animal, they bring on death by their prodigiously rapid development. So that anthrax would definitely be a true parasitic disease. But all these methods are open to one objection. These micro- scopic organisms, whose nature is not yet clearly understood, may be only the vehicle, not the original cause of the virulent agent with which they might be merely laden. I therefore had to begin experiments following the new method, but taking the greatest precautions: 1). that the layer of blood be thin enough to be penetrated by the oxygen; 2). that there should not remain within the limits of the blood any isolated spots which would dry out and then resist perfectly the action of the oxygen. 848 Experiments Experiment CCCCXCII. October 6. Blood from a sheep sick with the anthrax (sent by Professor Trasbot). This blood inoculated in guinea pigs was followed to the fourth virulent generation, Subjected in a thin layer to 20 superoxygenated atmospheres. October 9. Decompressed; inoculated in a guinea pig. October 10. The animal dies at 1 o'clock p. m. Experiment CCCCXCIII. November 20. Professor Trasbot sends me serum taken from a sheep which had been inoculated with the blood of a horse which had died of anthrax; many "bacteridies." I inject Vz cc. under the skin of a guinea pig. November 21. The animal was found dead in the morning. I take a little of its blood, which contains "bacteridies," mix it with the serum which flowed from the spot of inoculation, and subject it, in a thin layer (about 3 mm.), to the action of 20 atmospheres of superoxygenated air. November 30. Decompression; the blood is red to the bottom. Injection into two guinea pigs. December 1. Both found dead in the morning. I give a subcutaneous inoculation with their blood to a guinea pig and a dog. December 2. The guinea pig and the dog are dead. Here are experiments in which the "bacteridies" must have been killed by the compressed oxygen, and in which nevertheless the blood kept all its virulence; the second is particularly conclu- sive, for in Experiment CCCCXCII the duration of the compres- sion perhaps had not been sufficient. They prove then that this dangerous property was not due, at least in the blood which I used, to the existence of these tiny organisms. I also saw them corrobo- rated by experiments which cannot be reported here but in which I saw the virulent matter precipitated from the same blood by alcohol, filtered, then dried, without losing its dangerous power, which it could still transmit, as before, from generation to genera- tion. And yet I think it would be unwise to apply this conclusion to all the bloods called "charbonneux" (containing the germs of anthrax) , and that it would be necessary first to make many more experiments, using bloods from various sources, for it might be that several diseases are confused under the common name charbon (anthrax) .4 Ferments, etc., Summary 849 Subchapter V SUMMARY As a result of these numerous experiments, we are now in a position to state the first cause of the death of animals and plants subjected to a fairly high oxygen tension. Let us set aside the violent convulsions displayed by the higher animals and go to the bottom of the phenomena. Life is only the result of a complex and harmonious combination of chemical changes belonging to the group of fermentations; some are due to the direct intervention of the formed elements of the body; others are the consequence of the action of unstable and soluble substances, like diastase, previously formed by the action of the formed elements. In the interior of each of the anatomical elements the vital activity is maintained only by the action of these substances which are created, act, are transformed, and are de- stroyed there. But that life may be maintained, the multiple phenomena must go on with constant regularity, or rather harmony. When their intensity alone is modified, without their relations being altered, vital activity decreases, sometimes is even halted, possibly for a long time, and then reappears when more favorable conditions occur. This happens through cold, through desiccation, and, to return to our subject, through decreased pressure. Seeds, pre- served intact in a vacuum, germinate when returned to the air; meat, which has remained fresh in a vacuum, decays when oxygen restores activity to its vibriones. When, on the contrary, it is not merely the quantity, but also the quality of the chemical changes that is altered, symptoms appear, the details of which are far from being known and which have such consequences that even if normal conditions are re- stored, the vital activity is not resumed. This happens through heat, through excessive moisture, and through increased pressure. Seeds kept apparently intact in compressed air do not germinate when returned to normal pressure, and it is in vain that oxygen at its usual tension comes in contact with the definitely dead vibri- ones which swarmed upon the meat previously subjected to com- pressed oxygen. We do not need to go as far as death to show these important differences. An animal subjected to decompression is seized, at a certain moment, by convulsions, which a return to normal pressure checks immediately: Sublata causa, tollitur ejfectus (If the cause 850 Experiments is removed, so also is the effect) . But the convulsions due to ex- cessive pressure continue even when the apparent cause has been removed; that is because the real cause, the chemical change, still exists, still operates, and excites the nervous centers. Under the influence of oxygen at high tension, within the in- terior of the anatomical elements, either isolated in individual cells or grouped in tissues, chemical alterations take place, which pro- duce lasting substances, the presence of which disturbs the harmony necessary for the continuance of life, in the element first, then in the complex being. These are, indeed, rather vague terms, but this vagueness results from the general condition of science and should not be made a reproach against me. What do we know about the molecular transformations which take place regularly in the tissues and in the interior and on the surface of the anatomical elements? The little knowledge we have I have subjected to experimentation; 1 have seen that the transformation of starch into glucose, that the reduction of glucose into its primary elements are delayed by oxygen under high tension. Now these are general acts which appear, we know, in the life of a mycoderm cell, as in the cell of a mammal or a bird. They are delayed, but yet the soluble ferment which produces them is not altered at all, and will resume all its activity later, at normal pressure. Why then, after this return to normal pressure, does not life reappear, as after the suspension due to a vacuum or to cold? Can it be that the ferment, whose regular action has diminished, has acquired a new one, which has produced this lasting substance the origin of which we are seeking? Has the fermentable matter, on the contrary, changed so that now it withstands the action of the preserved ferment? It is very difficult to answer these questions today. All that I can say is that the substances subjected to compression: meat, eggs, milk, and bread, soon give an acid reaction, due probably in part to lactic acid. It is not impossible that the presence of this acid in the interior of the anatomical elements is the cause of death. But without discussing any longer phenomena the inner signifi- cance of which we cannot explain, we are justified by the numer- ous experiments, the report of which has filled so many pages, in saying that, under the influence of oxygen at high tension, within each anatomical element chemical alterations take place which are incompatible with the life of this element. When this is granted, all the varied phenomena which we have enumerated are easily connected and explained. Ferments, etc., Summary 851 Are we dealing with a living being reduced in its elementary structure to a single cell or a small number of cells? Since its vital activity is generally manifested to us by phenomena known by the name of true fermentations (alcoholic, acetic, lactic, and putrefactive), its death will result in the permanent stoppage of these phenomena, unless new ferments are sowed. Or, to go at once to the opposite extreme, are we dealing with an animal which is very complex in its structure? The anatomical elements which form its tissues are threatened with death. Those among them which in biochemistry played the part of formed fer- ments cease to act, or lose energy of action. The phenomena of zymotic fermentation which take place both without and within them lose intensity and degenerate. Their personal qualities, their contractility, their power of transmitting stimuli or of changing them into reaction become modified and tend to disappear. Hence come the general lessening of the chemical phenomena of life; the decrease in oxygen consumption, in carbonic acid pro- duction, and in excretion of urea; the appearance in the urine of sugar which is no longer sufficiently broken down; and finally, an enormous lowering of the temperature. And at the same time, — since whenever a great and rapid dis- turbance affects the equilibrium of the functions of a higher animal (hemorrhage, asphyxia, etc.) , it is the central nervous system which, as it is the first to be stimulated, shows by its violent reac- tions the danger which threatens the whole organism, — there appear these convulsions which give evidence by their persistence after a return to normal pressure that a profound chemical change has taken place in the tissues of the spinal cord or in the blood which supplies them and would thus bring them a kind of poison. Last come the muscular contractions modified in their behavior, like cramps, such as occur in every dying muscle. Between these two extremes, the isolated cell and the warm- blooded vertebrate, all the intermediaries: on the one hand, molds, algae, seeds, vascular plants; on the other, annelids, mollusks, in- sects, fish, reptiles. The whole aggregation of living beings, in a word, dies absolutely when the oxygen tension rises high enough. Not one, we can affirm, would withstand a tension corresponding to the pressure of 20 atmospheres of air. We shall return to the inferences suggested by this unexpected phenomenon. iSee my Memoire sur la -vita-lite des tissus anlmaitx (Annates des sciences natureltes. Zoologie, 1866). , , . , .. A , . ,' ., , 2 Paul Bert. Note on a certain sign of approaching death in dogs subjected to rapid blood- letting (Memo-ire de la Societe des sciences de Bordeaux, Vol. IV, p. 75, 1866). 3 Contributions to the study of venoms: scorpion venom. Comptes rendus de la bocxeU de biologie pour 1865, p. 136. . . . ^ , , „, ,, . 4 See the discussions of MM. Davaine, Jaillart, and Leplat: Comptes rendus de I Acadimte des sciences, Vol. LXI, 1865. Chapter VII EFFECTS OF SUDDEN CHANGES IN BAROMETRIC PRESSURE Hitherto, I have spoken. only of the phenomena following grad- ual changes in the amount of the barometric pressure, which are, as we have seen, phenomena of the physico-chemical type, result- ing from the presence in the blood of larger or smaller quantities of oxygen. But it is only in these conditions of gradual change that I could be brought to deny the effect of the pressure as a direct agency, of the physico-mechaniccu1 type. Of course it may be dif- ferent when we are dealing with sudden and considerable changes. The experiments reported in this chapter were intended to settle this question. Subchapter I EFFECT OF SUDDEN INCREASES IN PRESSURE This part of the work will not be long. The sudden increase of pressure seems to have no appreciable effect on animals. At first, when it was a matter of animals previously subjected to a very low pressure, like that discussed in Chapters I and III, the restoration of normal pressure had no apparent ill consequence. But on the contrary, when the decompression was very great, its favorable effect appeared immediately, and the animal returned at once to a normal state. We could see it then perceptibly "deflate," especially in the case of a herbivorous mammal, as a result of the return to their original volume of the intestinal gases, which the decompression had expanded. The experiments on sudden increase of pressure were made on rats or birds placed in the Seltzer water receiver. This receiver 852 Sudden Changes in Pressure 853 by means of a copper tube was put in communication with the large metal receiver (Fig. 33) in which the pressure had been raised to 10 atmospheres, then the communication cock c was opened, and the equilibrium of pressure suddenly established. The animal then seemed to cower, to crouch, as if frightened; but after a few minutes, regained all its liveliness. There is no reason for surprise at these negative results, because we have seen that workmen in caissons and divers in suits are subjected to sudden pressures of several atmospheres without feel- ing other inconveniences than more or less keen pains in the ears, which pains animals do not seem to feel, since in animals, no doubt, the Eustachian tube opens more easily than ours. The effect of sudden increases of barometric pressure, almost non-existent in air-breathing animals, is, on the contrary, very con- siderable in fish provided with a swimming bladder. Whether the bladder is closed or not, as soon as the pressure of the air above the water in which the fish is swimming is increased a little, the fish drops to the bottom of the vessel, from which the greatest muscular efforts can raise it only for an instant. But after several days during which the pressure has been maintained, it regains complete freedom of action. That is because during this interval a new secretion of oxygen has restored to its swimming bladder its original volume and to its body its original density. All these facts, which I have often witnessed, have been completely described and explained by Dr. Armand Moreau. Subchapter II INFLUENCE OF SUDDEN DECREASE OF PRESSURE BEGINNING WITH ONE ATMOSPHERE The study of this influence presents great difficulties without being particularly interesting. As a matter of fact, for slight de- compressions, no matter how suddenly they are produced, the result is almost negligible in air-breathing animals; for great decompres- sions, it is combined with that of anoxemia, beside which it is of only slight importance. When a sudden drop to a half-atmosphere is made, the animals tremble, leap, sometimes whirl, but soon recover, or at least show only the symptoms of asphyxia due to the low oxygen content of their blood. 854 Experiments These evidences of distress are no doubt due to the sudden ex- pansion of all the gaseous reservoirs of the organism, and we can see that they are especially important in birds, in which these reservoirs extend through the whole body; but equilibrium is re- established almost immediately in the latter, because of the com- munication of the air sacs with the trachea and consequently with the interior. Mammals, and especially the herbivores, are a little swollen by the expansion of the intestines and the stomach, but they quickly expel the gases which distress them. This is shown by the following experiment: Experiment CCCCXCIV. June 9. Dog, just killed by electrical stimulation of the heart. There is introduced into the rectum, by the help of a little bladder which completely covers the anus, a glass elbow tube, the end of which is immersed several millimeters in a glass full of water. The animal is thus placed in one of the large cylinders of Figure 27. Then decompression to 34 cm. is made as rapidly as possible; during this time bubbles of gas quickly follow each other escaping from the anal tube; however the abdominal wall is evidently swelling. Air is admitted; the wall collapses; there is still a considerable quantity of gas in the intestine. The same effect is produced, as has been known for a long time, in fish provided with a swimming bladder opening into the esopha- gus, like the carp. If the decompression is not made too quickly, one can see bubbles of gas from the bladders escaping from their mouths; then, when normal pressure is restored, they drop to the bottom of the water, since their density has become too great. Under these conditions they return with difficulty to the surface to swallow air and thus fill their bladders again; to get definite information on this direct absorption, which might be doubted, I made the following experiment: Experiment CCCCXCV. June 1. A carp weighing a half-pound is subjected, in the water, to a decompression of two-thirds of an atmos- phere. It throws off a great quantity of air. The crystallizing dish in which it is swimming is then placed under a bell containing a mixture of air, oxygen, and hydrogen in proportions not fixed. June 3. The fish dies; its swimming bladder contains 11.4 cc. of gas of the following composition per 100: hydrogen 33.3; oxygen 16.7; nitrogen 50.0. Let me say in passing that carp, in the natural state, when com- ing to the surface of the water to swallow air, do not admit it to the bladder, and probably use it only to aerate their gills more thor- oughly. For example: Experiment CCCCXCVI. June 5. Carp weighing 200 gm. The ves- Sudden Changes in Pressure 855 sel in which it is swimming is placed under a bell containing a mix- ture of oxygen and hydrogen unproportioned. June 9. The fish is killed. There is no hydrogen in the swimming bladder. Fish with closed bladders, becoming lighter than the water when decompression is made, come to the surface and die on account of the bursting of the overinflated bladder. This fact has long been well known to fishermen, who pierce the bladder with a pointed piece of iron or wood, so that the entrails may not burst and soil the fish. The same phenomenon (I mention this so as not to return to this type of data again) may be observed in fish with closed bladders kept for several days under increased pressure: Experiment CCCCXCVII. May 4. Sticklebacks in the glass cylin- drical apparatus. Subjected to a pressure of 2 atmospheres, they sink to the bottom immediately. May 10. Swim freely. Decompression made; come to the surface immediately. When removed, they die. So these fish had formed in their bladders a sufficient quantity of gas to regain freedom of movement, with their original density. But the decompression was fatal to them. The closed air bladder is therefore very unsuitably called "swim- ming" bladder, because it is harmful to the fish and compels it to remain at a certain depth of water, under pain of bursting at the surface or sinking indefinitely into the depths, if it passes the narrow limits between which it is permitted to move vertically. I succeeded in getting a result similar to that of Experiment CCCCXCVII with frogs rapidly decompressed from 5 to 6 atmos- pheres to normal pressure. When the air of the lungs expanded enormously, the tracheal opening closed; the stomach issued through the mouth, the lungs burst, and the body was transformed into a sort of overinflated balloon. All that is simple and to be expected. But let us return to air-breathing animals. When very rapid decompression is made, they too die almost at once. Can an im- portant part in this death be attributed to the suddenness of the decompression? That almost reverts to the question which we have already asked. Is the purely mechanical or physical effect of the decompression perceptible? The experiments reported in the preceding chapters show that it is very slight at any rate, be- cause an animal can, for example (Experiment CCLI), be brought 856 Experiments very rapidly without inconvenience to a pressure of 7 cm., if the air has a high oxygen content. Let us now examine the results of a few experiments made especially with a view to sudden decompression: Experiment CCCCXCVIII. March 2. Dog weighing 2.300 kilos, placed in a bell of 31 liters capacity. This bell (Fig. 27, C) is con- nected by a rubber tube with thick walls to a huge receiver of sheet- iron (B) in which the pressure has been brought to a 10 cm. A commu- nication cock is opened, and the pressure falls immediately in the bell to 12 cm. Immediately convulsive struggling, howls, foamy nasal hem- orrhage; dead in 3 or 4 minutes. The lungs display ecchymoses which do not disappear entirely after insufflation. Bronchi and trachea full of bloody foam. Dark blood in the left cavities of the heart, very dark blood on the right, without free gases. Experiment CCCCXCIX. March 7. Large cat. Same experimental procedure. Pressure is brought suddenly to 16 cm.; the animal rears up almost immediately, struggles violently, yawns. At the end of 2 min- utes, falls on its side, its tongue is dark; at 3 minutes, its pupils dilate, shivers occur in the cutaneous muscles. Dead after 6 minutes. With- drawn immediately, the animal, which is much swollen, collapses when normal pressure is restored; no gas in the blood; dark blood in the left heart, still more in the right heart; pulmonary veins red; pulmonary ecchymoses. Experiment D. March 15. Sparrow placed immediately by a sim- ilar arrangement at 12 cm. pressure. Struggling; very speedy death without true convulsions. No free gases in the blood. Experiment DI. June 18. Cat brought very rapidly to a pressure of 12 cm. Dies after a very rapid phase of convulsions. Lungs congested, expand and become blanched when insufflated; the most congested parts do not sink in water. No gas in the blood, examined with great care. Experiment DII. December 16. Two rats, placed in a bell of 2 liters, are brought as rapidly as possible (2 or 3 minutes) to a pres- sure of 4.5 cm. They whirl, leap, die without true convulsions. With- drawn immediately, and opened, one, A, in the air, the other, B, under water: the hearts are still beating. A. Blood examined by a magnifying-glass in the vessels ,then with a microscope; no gas bubbles. Lungs very red in places, the red pieces sink in water; they expand with insufflation. B. No bubbles of gas can be seen escaping under water. Experiment Dili. December 16. Rat killed by the same process, at the same pressure; but kept for 10 minutes at 4.5 cm. No gas in the blood, meticulous examination. Lungs adherent to the thorax, but regain normal position when it is opened; reddish with small dots, all parts float. The liver macerated with charcoal shows an enormous quantity of sugar. Sudden Changes in Pressure 857 When we compare these few data with those which have already been reported and in which the decompression was made very sud- denly, we see that the physical phenomena amount to very little, even when the rapidity of the experiment should have increased their importance. We have already spoken of the expansion of the intestinal gases; when the vacuum is made suddenly, they do not have time to escape, and must contribute a part, though small, to the distress of the animal. The pulmonary ecchymoses mean nothing, because we find them in simple asphyxia, at normal pressure. The pulmonary hemorrhages are not a constant fact; besides, we see them occur in certain cases when the pressure was dimin- ished slowly; it is therefore difficult to ascribe them to the sud- denness of the decompression. I should rather think that the sud- denness caused the strange appearance of the lungs of the dog in Experiment CLXXX, "The lungs are red in large patches, sinking in water, but expanding completely after insufflation." This sort of fetal state seems to me to be due to a sort of suction exercised in spots by the pressure of 7 cm. under which the animal died. We saw in the historical part of this work that former authors attached much importance to this phenomenon which some of them considered constant and extending to the whole lung. We have reported on this point the observations of Musschenbroeck, Guideus, and Veratti. I myself have never seen the lungs of animals which were killed by sudden decompression completely collapsed and heavier than water in their entire mass. No doubt, as the ancients thought with- out expressing themselves very clearly, when the weight of the air is reduced to an amount below the strength of pulmonary elasticity, the lung should collapse and a relative vacuum be made in the pleura. But in the first place, this can happen only at pressures lower than those at which animals die, because the pulmonary elasticity of a dog, even in the condition of maximum inspiration, even added to the negative pressure, does not go beyond 5 or 6 centimeters of mercury; this value is still less for smaller animals. Finally, even supposing this empty space exists in the pleura, it is evident that, when normal pressure is reestablished, the lungs will be retracted to their original position, or the ribs would be broken under the atmospheric pressure, as I formerly showed experi- mentally; so that, even if this phenomenon occurred, there will be no trace of it in the autopsy. For the pulmonary retraction to 858 Experiments persist, either at the time of the sudden reestablishment of normal pressure some vesicle must be broken, thus allowing the air to penetrate the pleura; or after a long stay in the vacuum, gas or liquids must be emitted, and it is probably for this reason that, according to Veratti, the lungs are found in this state only when the animals have remained some time under the pneumatic bell. As to the escape of gas into the blood, to which former authors, since Robert Boyle, have attributed such an important part, and which F. Hoppe considered the principal cause of death, I must say that I have found no free gases in the blood vessels when the decompression was sudden any more than when it was more care- fully controlled. And yet in vitro the liberation of the gases of the blood begins under low decompression. For instance: Experiment DIV. June 23. Two glass tubes are filled, one with blood, defibrinated and settled, the other with water. Two hours after, no gas bubble having escaped, we begin to lower the pressure, stopping for 5 minutes every 10 centimeters. At a pressure of 66 cm., no bubbles of gas escape; at 56 cm., noth- ing; at 46 cm., bubbles appear on the walls of the tubes, both in the water and in the blood; at 36 cm., the escape is abundant in both tubes. An escape of gas must therefore take place in the blood vessels, and first in the venous system where the pressure is less. But we must note that the oxygen, granting that it leaves the blood, must be immediately absorbed by the tissues, which are eager for it; that the carbonic acid must pass through the pulmonary membranes with the greatest ease; and that the escape is limited to the nitro- gen, the proportion of which (from 1 to 2 per 100 volumes of blood) is so slight. And, as the escape is very slow, it no doubt has time to diffuse by way of the lungs. So that whether blood is drawn from the living animal, as we succeeded in doing at a pressure of 17 centimeters (Experiment CLXXIX) or the blood of an animal killed by sudden or slow decompression is examined, no free gases are found in it. (See particularly Experiments DI, DII, and Dili, in which search for gases was made with the greatest care.) Sudden Changes in Pressure 859 Subchapter III EFFECT OF SUDDEN DECREASE OF PRESSURE BEGINNING WITH SEVERAL ATMOSPHERES The subject of our researches here becomes much more interest- ing. Indeed, it draws nearer the phenomena which we mentioned in the historical part, in speaking of laborers who work on the piers of bridges and of divers in suits. I shall begin, as usual, by a detailed account of a certain number of experiments. I report first those in which the decompression was made without interruption and as rapidly as possible. 1. Decompression without Interruption. A. Experiments Made on Sparrows. Experiment DV. July 20. House sparrow. Seltzer water receiver. Brought in 20 minutes to 8 atmospheres; left for 5 minutes under pressure. Opened the large cock first, and made the decompression in a few seconds. Struggled at the moment of decompression, then did not appear sick, and survived. Experiment DVI. August 3. House sparrow. Same apparatus. Taken to 8 atmospheres at 12:30. At 2 o'clock, sick; at 2:45, very sick. Took a sample of air which contained 2.1% of CO.. Tension: 2.1 x 8 = 16.8. Opened the large cock suddenly; the bird fell backward violently; rose immediately: its rectal temperature was 25°, that of the outer air being 20°, blood of the jugular veins very red; no gas seen. Re- mained on its back and died in 10 minutes. At death, the venous blood is dark; bubbles of gas seen in the jugulars. Experiment DVII. May 1. House sparrow. Glass cylindrical re- ceiver . 2:05, raised to 10 atmospheres; surrounded by papers wet in potash solution so that the C02 is absorbed as it is produced. At 3:40, the bird appears dead; the pressure is 9Vz atmospheres; the air contains 14.1% of oxygen, and no doubt very little carbonic acid. Decompression made rapidly. Almost immediately, the bird, which raised its head at the moment when the cock was opened, became very lively; bloody suffusions on the cranium. Survived. Experiment DVIII. May 10. House sparrow. Cylindrical appara- tus. From 4:15 to 4:20, raised to 16 atmospheres. After 5 or 6 min- utes shows quiverings with great distress, slight convulsions, etc. characteristic of poisoning by oxygen, the tension of which was 16 x 20.9 = 334. At 4:30, decompression made in 1 minute; did not 860 Experiments seem to suffer from the decompression; no gas in the jugulars, in which the blood was very red. Enormous bloody suffusions on the cranium. Rectal temperature 35°. At 4:35, great convulsions, died. Rectal temperature 34°. The blood was very red in the left heart, without gas. In the right heart and the jugulars, it was dark with gas in very small bubbles; these bubbles were present in the portal system. Experiment DIX. October 27. Sparrow (cylindrical receiver). Taken to 8 atmospheres. Decompression made in 5 seconds. Taken from the apparatus, did not seem at all inconvenienced. Experiment DX. October 27. Sparrow (cylindrical receiver). Taken to 10 atmospheres. Decompression made in 5 seconds. No symptom, survived. Experiment DXI. October 27. Sparrow (cylindrical receiver.) Taken to 12 atmospheres. During this time remained motionless at the bottom of the apparatus. When sudden decompression was made, darted to the top of the cylinder, then fell back. Was dead before being taken from the apparatus. Air in quantity in the jugulars and the right heart. Experiment DXII. October 27. Sparrow (cylindrical receiver). Taken to 14 atmospheres. Sudden decompression; died in a few minutes. Air in quantity in the jugulars and the right heart. Experiment DXIII. October 27. Sparrow (cylindrical receiver.) Taken to 14 atmospheres. Sudden decompression, without symp- toms. Found dead the next day. Experiment DXIV. October 27. Sparrow; cylindrical apparatus. Taken to 15 atmospheres, and suddenly decompressed immediately. Removed from the apparatus, could not walk, flapped its wings, had convulsions, and soon died. Air in quantity in the jugular veins and the right heart. Experiment DXV. June 29. Two sparrows were taken in one hour to a pressure of 7 atmospheres under a current of air maintained by the large sheet-iron cylinder. At this moment, the rubber communi- cation tube burst; the decompression was instantaneous. The two birds died in a quarter of an hour. We must add to these experiments made on sparrows the results of a great number of others already reported with another purpose in the subchapter of Chapter I. We shall return to them later. For the moment I set aside the discussion which these experi- ments deserve and report those made on mammals. First, rats, for which we generally used the small glass appa- ratuses. Sudden Changes in Pressure 861 B. Experiments Made on Rats. Experiment DXVI. August 9, 1871. Rat. Seltzer water receiver. 9:25, placed at 7 atmospheres. 10:10, pressure fell to 6V2; the animal is rolled up in a ball, with hair bristling; respiratory rate 75. 1 open the large cock suddenly; the animal arouses immediately, and does not seem to be in pain. Experiment DXVII. August 10. Same animal, same apparatus. 4:10, placed at 6 atmospheres. 5:25, respirations difficult, dicrotic; the animal is lying curled up on the bottom of the vessel. Took sample of air, which contained 5.2% of CO,. Tension: 5.2 x 6 = 31.2. The pressure then falls to 5V2. I open the large cock suddenly. The animal almost immediately stands up on his feet, and seems quite well. Experiment DXVI II. August 12. Same animal, same apparatus. At 4:15, placed at 6V2 atmospheres. The apparatus leaks; at 6 o'clock, the pressure is 4V2 atmospheres; the animal is very sick. I take a sample of air, which contains 6.1% of CO,. Tension: 6.1 x 4.5 = 27.4. I open the cock wide; the rat does not recover immediately, but he is well the next day. All the experiments reported next were made in the large cylinder of sheet-iron pictured in Figure 33. The large cock which is opened suddenly is the one lettered c: Experiment DXIX. May 24. Two rats in the large cylindrical apparatus (experiment made before the Committee of the Institute). They are taken to 8V2 atmospheres; the decompression is made in 2 minutes. The rats run about when taken from the apparatus; a few minutes after, they become paralyzed and die. Gas is found in the whole venous system. C. Experiments Made on Rabbits. Experiment DXX. June 22. Rabbit. Taken to 8 atmospheres. Decompressed in 3 minutes. Ears bright red; no symptom either immediate or later. Experiment DXXI. November 7. Two rabbits. Taken to 7 atmospheres. Decompressed in 2V2 minutes. No symptoms. Experiment DXXII. November 10. Same animals. Taken to BVs atmospheres; decompressed in 2V4 minutes. No symptom either immediate or delayed. Experiment DXXIII. November 15. Rabbit. Taken to 6V2 atmospheres. Decompressed in 412 minutes. No effect. D. Experiments Made on Cats. Experiment DXXIV. May 23. Male cat, extraordinarily vigorous and wild. Taken to 10 atmospheres. Sudden decompression. Leaps 862 Experiments out of the apparatus, apparently well, and hides under a piece of furniture. Half an hour later, it is found there paraplegic. The hind legs are stiff, with the claws extruded; they are sensitive, as is the tail, but are no longer under voluntary control. Bloody urine con- taining spermatozoa is drawn from the animal. The anal sphincter is contracted. May 24. Same condition; except that the tail and the hindquar- ters are entirely without sensitivity and are relaxed. By pinching a foot, very distinct reflex movements are obtained, which, however, do not pass from one member to the other. The bladder is enormously distended by urine containing much blood. The anal and vesical sphincters are strongly contracted. The animal mews faintly; it is very weak, drags itself along with difficulty by its front feet; rectal temperature 33°. Killed by section of the medulla. Vesical mucous membrane shows hemorrhages in dots; no blood in the ureters or in the pelvis of the kidneys. Nothing unusual in the lungs, heart, or brain. No hemorrhage or congestion of the spinal cord; but on the level of the last two thoracic and the first two lumbar vertebrae there exists a softening of the spinal cord so advanced that at certain points (last thoracic), the spinal marrow runs like cream. The microscope shows the nervous elements intact, without a trace of bloody effusion. Experiment DXXV. June 17. Cat. From 12:20 to 1:30, taken to 10 atmospheres. At 1:39, decom- pressed suddenly in 3 minutes. When taken from the apparatus, runs in all directions as if panic-stricken. At 1:48, begins to be paralyzed in the hindquarters; at 1:50, lies on its side, unable to rise. Pupils contracted, the left more than the right; rectal temperature 39.5°; pulse 140, regular; respiratory rate 36, difficult, irregular. Motility and sensitivity completely gone in the hindquarters and the tail. 2 o'clock. No respirations; action of the heart still regular. Immediate autopsy. Auricles still contract; on pricking the right auricle, frothy blood containing air issues; the left auricle, on the contrary, contains no air. On exposing the spinal marrow, we see in veins of the meninges a great quantity of small air bubbles; these bubbles also issue from the vessels of the spinal marrow when it is cross-sectioned. No sign of hemorrhage or congestion in the cord. Experiment DXXVI. June 22. Cat of Experiment DLXVII (placed with the rabbit of DXX). 3:20, began the compression. At 4 o'clock, 5V2 atmospheres; the motor stops. Began again at 4:20; at 4:45, 8 atmospheres. Current of air maintained under pressure. At 4:50, decompression in 3 minutes. The cat leaps out of the apparatus and flees. At 5 o'clock, it is seized by an attack of con- vulsions, with violent struggling which lasts about 5 minutes. During these disordered and indescribable movements, the hindquarters pro- gressively stiffen and become motionless, while the forequarters and the head are prey to the strangest contortions. Repeatedly the animal, Sudden Changes in Pressure 863 which is curled up, turns backwards and bites his hind legs and thighs with a kind of fury. After 5 minutes, relatively calm; the left pupil dilated inordinately; almost complete paraplegia. Defecation by intestinal contraction, the anal sphincter not being paralyzed. Urination; no blood or sperm. 5:30. I show the animal to the Society of Biology; the paraplegia is complete as to movement and sensitivity. The pupils are in their normal state. 5:45. Apparent improvement; the left leg is sensitive, and the animal moves it a little, and when I support it, even leans on it a little; nothing in the right leg. 6:15. The right leg recovers a little in its turn; the tail begins to be sensitive. June 23. The paraplegia has become complete again, and has even spread a little into the lower dorsal region. The following days, paral- ysis still more complete and extending a little higher. Dies June 26, the bladder distended; it could not be made to urinate; it ate. Autopsy. All the spinal marrow is softened a little; it is diffluent below the cervical enlargement. At this precise point, it is a little yellowish, and contains a little altered blood and some granular bodies in the process of formation; the veins of the meninges contain a mix- ture of air and blood; air escapes from the vessels of the spinal cord. Sugar in the liver, a little in the urine, which also contains a little blood. E. Experiments Made on Dogs. Experiment DXXVII. May 17. Dog weighing 4 kilos. Pressure raised to 4 atmospheres. After about Va of an hour, opened the large cock suddenly; decompression in less than 2 minutes. The animal is in good shape. Experiment DXXVIII. June 18. Small dog. Taken in one hour to 10 atmospheres; stays there about 1 hour; decompressed in 3 minutes. The animal cannot get out of the apparatus; there are no other move- ments than those of respiration; constant cries of pain. Placed on the autopsy table, gas is observed in the jugular which has been exposed. Through the jugular a cannula is passed into the right heart, from which is extracted 33.9 cc. of gas containing 20.8% of CO. and 79.2% of nitrogen, with some traces of oxygen. The right heart and the veins are full of gas and frothy blood; the same thing is true of the veins of the pia-mater and the choroid plexuses. Stom- ach much distended by gases. Experiment DXX1X. July 9. Dog weighing 12 kilos. 1:45: taken to 5 atmospheres; left 30 minutes under a current of air. Decompressed in 2 minutes. No immediate or delayed symptom. Experiment DXXX. July 13. Dog which has lost much blood. Taken to 6 atmospheres and decompressed in 2 minutes. The animal drags its hind legs and walks on its nails; after an hour, walks better, but lies down again as soon as we stop stimulating him. Better {he next day. 864 Experiments Experiment DXXXI. July 17. Dog of Experiment DXXIX and Experiment DLXXI (slow decompression). From 1:36 to 2 o'clock, taken to 6 atmospheres; left 30 min. Decompressed in 2 minutes; comes out in good condition, shakes himself, and walks very well. No symptom. Experiment DXXXII. July 22. Dog. From 5:30 to 6:10 taken to 6V2 atmospheres. I then draw blood from which no free gases escape in the syringe. However this blood contains 7.7% of nitrogen. At 6:40, reached 8V2 atmospheres; decom- pressed in 3 minutes. At 6:50, I draw blood from the carotid; this blood contains 2% of nitrogen. The animal has remained fastened on the operating table; while sewing up the wound in the neck, I see bubbles of air in the jugular; it begins then to take deep breaths, which end in death at 7:15. No gas is found in the blood of the right or left heart; but there are nu- merous bubbles in all the little veins of the general and the portal systems. The stomach is enormously distended; 550 cc. of gas is drawn from it; the intestine contains much gaseous froth and is swollen with it. Experiment DXXXI1I. July 24. Dog of Experiment DXXXI. From 3:30 to 3:55, taken to 6 atmospheres; left 2 hours under a current of air. Decompressed in 2 minutes, no symptom. Experiment DXXX1V. July 25. Dog of preceding experiment. From 2 o'clock to 2:45, taken to 7 atmospheres. Decompressed immediately in 2 minutes: jumps alone from the top of the apparatus. Five minutes after, falls on its side, its hind- quarters paralyzed; sensitivity much dulled. The front feet are in forced extension and quiver at each breath. July 27. Complete paraplegia of movement; muscles relaxed; tail and feet insensible, but with reflex movements of the tail. The anal sphincter is relaxed, but the introduction of a thermometer pro- vokes violent reflex movements; temperature 39.5°. Bladder para- lyzed; when the belly is pressed, the urine issues in jerky spurts; it overflows regularly; no sugar. August 1. The animal has remained lying on its right side; the paralysis has made ascending progress; the ribs are motionless, and the respiration is purely diaphragmatic; we then see clearly the lifting of the lower ribs by the diaphragm. On pinching the right hind foot, it draws away, as does the tail: no movement in the left hind foot. The left sciatic, when exposed and pinched vigorously, causes some slight movements in the flexor muscles of the leg, but the animal feels nothing. The right sciatic gives marked movements, and the animal shows pain when it is pinched. The muscles tested by electricity require for contraction a current a little stronger on the left than on the right, which is no doubt due to the different action of the nerves. The toes of the hind feet, when taken in the hands, are warmer than the toes of the front feet; the latter are sensitive and are drawn away when pinched. The anal sphincter contracts convulsively when touched; the rectal temper- Sudden Changes in Pressure 865 ature is 38°. The urine issues when the right sciatic nerve is stimu- lated: no sugar. I kill the animal, which is very sick, by opening the thorax. The left sciatic nerve is reddish, its vessels are bloodshot; in most of its fibers the myelin is a little turbid and is beginning to separate. The right sciatic nerve is intact. The spinal cord is softened in the region of the lumbar enlarge- ment. Transverse sections show the following changes. Below the enlargement, red dots in the gray matter; in the upper part of the enlargement, where section is possible, we find complete suffusion of the left posterior horn of the gray matter and suffusion in parts of the horn on the right side; the antero-lateral and posterior columns on the left are of a very marked yellowish-gray; all of it is very soft. Below the dorsal region, uniformly red appearance of all the gray matter, which is less soft, with coloration spreading into the posterior white matter, especially on the left; yellowish gray softening of the left antero-lateral column and the posterior column. The alteration lessens as it goes upward and ceases above the brachial enlargement; the cord there is firm, but a little suffused. Experiment DXXXV. August 3. Dog. At 8 atmospheres, the little apparatus, which supports the cannula for drawing blood (Fig. 34, E), is violently thrown forward: the pressure falls in 3 or 4 minutes. The dog comes out, runs a few steps, then falls and dies rapidly. Gas in abundance in the right heart, but not in the left heart. Experiment DXXXVI. August 5. Pregnant bitch taken to 9V4 atmospheres, bled of 375 cc. of blood (See Exp. CLXXXIV)1; decom- pressed rapidly: takes a few breaths and dies. Both sides of the heart are full of gases almost completely free: the stomach contains little gas. The hearts of the foetuses and their veins contain both gas and a very dark blood. In the allantoid liquid abundant bubbles are float- ing; the placenta is all torn by the gases; no gas in the amnion. Experiment DXXXV II. October 16. Dog which has already served for Experiments DLXXVII and DLXXVIII (10 atmospheres, slow decompression). From 1:10 to 1:45, taken to 7 atmospheres, decom- pressed at 1:55 in 2 Vz minutes. Taken from the apparatus, is lively and seems to feel no painful symptom. 7>Vz minutes after the decompression, raises its right front foot and seems to be in pain. After 5 minutes, struggles, wavers in its hindquarters, has an almost sudden erection. After 7 minutes, enormous convulsive stiffening of the hindquarters, which one can hardly bend. The tail moves and the front legs are not affected. The animal is recompressed to 7 atmospheres and decompressed very slowly. (See Exp. DLXXXVIII.) Dies the next day. Experiment DXXXV III. October 18. Dog. From 2:25 to 3:10 compressed to 7 atmospheres, and left 7 min- utes. Decompressed as rapidly as possible, in 2 minutes, from 3:17 to 3:19. Withdrawn from the apparatus, comes, goes, fawns; but at 3:21 ) Experiments is seized by paralysis of the hindquarters; he soon remains lying down, and his sufferings are shown by howls. Taken to 7 atmospheres again, and then to an extremely slow decompression. (See Exp. DLXXXVII.) Dies in the evening. Experiment DXXXIX. October 20. Dog. Subjected to 3% atmospheres. Arterial blood drawn under mer- cury in a test tube. Very small bubbles of gas are plainly escaping, and collecting at the upper part of the tube. Decompressed in 1 minute, shows no symptom; the heart sounds are normal. Experiment DXL. October 23. Same animal taken to 4% atmos- pheres, and left 10 minutes. Decompressed in 1V4 minutes, expe- riences no symptoms immediate or delayed. Experiment DXLI. October 25. Same animal taken to 5 atmos- pheres; left 10 minutes and decompressed in 1% minutes. Still no symptom. Experiment DXLII. October 31. Dog. Taken to 7% atmospheres. Decompressed in 1V4 minutes. Taken out at 2:07, without immediate symptoms. At 2:15, is found weak, staggering, has vomited several times. At 2:35, enormous gurglings heard in the heart, and the animal dies suddenly. Gas in the heart and the whole venous system, even the portal vein. Nothing in the left heart. Experiment DXLIII. October 31. Dog. Placed beside the former; has no immediate symptom. But at 2:15 is found lying on its side motionless; respiration is difficult, whistling, as if the animal were going to die soon. There are gurglings in the heart. He is made to inhale oxygen (See conclusion, Exp. DLXXXIX). He dies during the night. Experiment DXLIV. November 12. Dog. Taken to 7x/4 atmospheres. Decompressed in 2 minutes. Dies in about 25 minutes. Free gas in all the little veins; right heart full of foam; bubbles less numerous in the left heart. Experiment DXLV. November 12. Dog. Placed beside the former. Seized by symptoms of paralysis and dies after about 1% hours, after he has been given oxygen. (See Exp. DXC.) Experiment DXLVI. November 15. Dog. Taken to 6V2 atmospheres; decompressed in 4 ¥2 minutes. No symptom; no gas in the blood of the jugular vein, which I examined with the microscope to make more certain. Experiment DXLVII. November 25. Bitch. From 2:25 to 3 o'clock taken to 7Y2 atmospheres. At 3:14, decompressed in 2 V2 minutes. Sudden Changes in Pressure 867 At 3:23, is paralyzed in the hindquarters, then falls; in a few minutes, respiration stops, and the heart beats only 20 times per minute; loud gurgles heard in the heart; eye lacks sensitivity, pupils dilated. Oxygen administered, but the animal dies at 3:35. (See Exp DXCI.) Experiment DXLVIII. November 27. Very small poodle. Raised to 7 atmospheres from 3 o'clock to 3:53. Decompressed in 2J/4 minutes. Taken from the apparatus, seems gay for a few minutes, then, at 4:10, begins to limp, is paralyzed in the hindquarters, and sud- denly falls on its side. Very loud gurgles in the heart. Oxygen administered, but the animal dies at 4:27. (See Exp. DXCII.) Experiment DXLIX. December 6. Short-haired dog, very lively. Put under pressure from 2:30 to 4:20 and taken to 7% atmos- pheres. At 4:20, decompression in 2 minutes. Leaves the apparatus. At the end of 10 to 15 minutes, is paralyzed in the hindquarters, and seems quite ill with perhaps gurgling in the heart (?). Then recovers a little, but yet cannot stand on its hind legs, which have retained sensitivity. December 7. Is still paraplegic and can hardly stand on its front legs. Reflex movements, reflex sensitivity in the hind legs, which are warmer than the front legs. December 11. Scab on the left shoulder, on which it is lying; odor of urine; hyperesthesia in the front feet; dying. Experiment DL. December 6. Spaniel, placed beside the preced- ing animal. Remained in the apparatus from which it was removed para- plegic, with very loud gurgles in the heart. It was given inhalations of oxygen. (See the continuation of its history, Experiment DXCIII.) Experiment DLL December 22. Dog. Taken to 8V2 atmospheres. Decompressed in 2V2 minutes. Taken from the apparatus, is already limp, and dies in 5 or 6 minutes. Air in great quantity in the right heart and the veins. Some bubbles in the left heart. Gas in abundance in all the vessels of the lower region of the spinal cord. Experiment DLII. January 16. Bitch weighing 6.5 kilos, in bad state generally. Taken to 71/2 atmospheres, then decompressed suddenly. No symptom immediate or delayed. Experiment DLIIL January 23. Same animal. Taken again to IV2 atmospheres and decompressed suddenly. About 10 minutes afterwards, bites its hindquarters, as if it felt keen pains there; it then seems to have some trouble in locomotion, but this disappears quickly. 868 Experiments Experiment DLIV. January 25. Same animal. Taken to 8 atmospheres, and decompressed suddenly. No ap- parent effect. Experiment DLV. January 29. Same animal. Taken to 8V2 atmospheres, and decompressed suddenly. Experiences a little irregularity and difficulty in the hindquar- ters, but seems very gay, with no uneasiness; no gurgles in the heart; no gas observed in the jugular, which has been exposed. Experiment DLV I. February 11. Same animal. Compressed to 8 atmospheres and left under pressure 5 minutes, then decompressed in exactly 3 minutes. At the fifth minute, after the beginning of the decompression, blood is drawn from the carotid; no gas found in it. At the tenth minute, blood drawn from the right heart with a cannula: no gas there either. No symptom. Experiment DLVII. February 12. Sickly dog, very thin, weigh- ing 8 kilos. From 4:30 to 5:32, taken to 8 atmospheres; decompressed in 3 minutes. Placed on the floor, does not seem at all uneasy, and walks. At 5:42, the hindquarters become stiff and motionless. At 5:55, the forequarters are similarly affected; great respiratory distress. Dies at 6:05. Air in the veins. Experiment DLVIII. February 27. Poodle weighing 7 kilos. Placed in the apparatus at 8 o'clock in the morning, at 9:30 is at 10 atmospheres; the pump is stopped. At 10 o'clock, the pressure is only 9%. At 10:30, I look at the animal; it is well, and puts its nose against the porthole; the pressure is 9 ¥2 atmospheres. I enter the laboratory again, and immediately a violent explosion is heard. The porthole glass has burst and its fragments had enough force to cut a lead water pipe one meter away; the apparatus was lifted, torn from its supports by the recoil, and overthrown. I take the animal out with great difficulty, for it has become cylindrical, and is hard to pull through the door. General sub- cutaneous intra- and submuscular emphysema. I open the belly; the gas which distends it escapes whistling. The right heart is full of gas, as are all the veins, the pulmonary artery, and the pulmonary veins. But there is none in the left auricle or the aorta. There is gas in the anterior chamber of the eye, and in the cerebro-spinal liquid. The nerve fibres of the spinal cord are dissociated by bubbles of gas, which are not in the vessels. There is no hemorrhage in the brain or the cord; the lungs are a little congested: no blood in the trachea. I extract 50 cc. of gas from the right heart (there is much more of it) taking all precautions to prevent entrance of air. This gas con- tains per 100 parts: O, 1.9; CO, 15.1; N 83.0. Sudden Changes in Pressure 869 Experiment DLIX. May 6. Dog weighing 11 kilos. From 1 o'clock to 1:58, compressed to 7% atmospheres. I maintain a current of air under pressure until 7 o'clock, when I make the decompression in 3 minutes. On leaving the apparatus, the animal staggers, then stops, falls, and dies. There are abundant bubbles of air in the right heart and the veins, tiny bubbles in the left heart. No gas in the subcutaneous cellular tissue, except in the hollows of the armpits; gas is also found in small bubbles in the tissue of the epiploon. The intestines do not appear more swollen than under ordinary conditions. Experiment DLX. June 3. Bitch of Experiments DLII to DLVI. Well fed, has become fat and very well. From 3:05 to 4:05 was taken to 8 atmospheres and decompressed immediately in 1% minutes. Taken from the apparatus, it runs everywhere, apparently gay, and wagging its tail. But after 3 or 4 minutes, utters pitiful howls and tries to bite its hindquarters, which begin to be paralyzed. Auscultation of the heart shows considerable gurgling on the right, but not on the left. Two or three minutes later, the howls cease, the paralysis, both of sensibility and movement, is complete. It increases, affects the whole body, with rigors in the legs and neck. The respiration, which for a long time has been merely diaphragmatic, becomes very difficult; the heart slows down and the animal dies about 4:30. I find gas in the general venous system and the portal vein, but not in the arteries. There is emphysema in the subcutaneous tissue of the armpits; there are innumerable little bubbles in the fatty tissue under the muscles of the thorax, and in the sub-aponeurotic layer all along the back, in the epiploon, the mediastinum, the furrow of the heart, and the fatty tissue of the medullary canal. Index of air in the vessels of the medullary and cerebral pia- mater: nothing in the velum interpositum, or the cerebro-spinal liquid. No blood effusion in the brain; rather large dotting on the spinal cord. Lungs healthy, without congestion or emphysema; con- gestion of the spleen; little suffusions of the great epiploon. Experiment DLXI. July 21. Dog weighing 6.5 kilos. From 2:30 to 4 o'clock, taken to 8 atmospheres. At 4:10, decompressed in l1/* minutes. Dies at 4:22, with air in quantity in the whole venous system; small bubbles in the left heart. Lungs blood-shot, edematous. 870 Experiments Experiment DLXII. May 24. Large spaniel. (Experiment made before the Committee of the Academy of Sciences.) Compression raised to 8V2 atmospheres, and decompression made in 2 minutes. The dog appears gay and runs about wagging his tail. After a few minutes, he sits down and becomes sad. Some minutes later, he falters on his front legs and falls down. Gurgles can be heard in the right heart. The animal seems to be in great pain and bites violently at what- ever is held out to him. He soon dies. Gas in fine bubbles in the whole venous system; none in the arteries. Experiment DLXIII. June 4. Young dog in good health, weigh- ing 4.500 kilos. The jugular vein is exposed without being opened; the animal, fastened on the operating board, is carried to the compression ap- paratus, and rapidly taken to 6 atmospheres, and this pressure is maintained under a current of air for 3V2 hours. It howls a great deal. Decompression in 20 seconds. The animal is taken from the cylinder and unfastened. Complete paralysis of movement and of sensibility in the four legs; rapid pulse, accelerated respiration; no howls. Put back immediately on the operating table; 50 cc. of blood are drawn from the peripheral end of the jugular; no gas to be seen; blood is slowly ejected under water; no gas bubbles. A cannula is inserted into the right auricle; 50 cc. of blood is drawn and treated in the same way; no bubbles. The dog is attacked by diarrhea and involuntary urination. It dies during the night. The autopsy shows the presence of large bubbles of gas in the venous system (vena cava, azygos vein, mesenteric veins). Much is found in certain lobes of the liver and in the kidneys, a little in the spinal cord, no trace of it in the brain, the meninges, or the muscles. Experiment DLXIV. June 12. Young white dog of small size, in very good health. Placed in the large cylinder; brought rapidly to 5 ¥2 atmospheres of pressure. Maintained under this pressure with a current of air for 4 hours. The animal seems very quiet during all this time. Decompressed in 20 seconds. When taken from the apparatus, it runs away, and we have great difficulty in catching it. When the right jugular and femoral veins are exposed, we see passing a long series of gas bubbles which keep growing larger. After a few minutes, by means of a syringe, we draw from the peripheral end of the jugular a certain quantity of blood which is gently ejected under water: immediately numerous bubbles are seen escaping to the surface. Dog, kept under observation for several days, shows no delayed symptom. Sudden Changes in Pressure 871 I summarize in the following table the principal results fur- nished by the experiments just read. I have listed them here by increasing order of pressures. I have included in this table the results of experiments in which I attempted to save the animals, either by recompressing them or by administering oxygen. (See Subchapter IV.) Table XVIII Duration Gv Duration Experiment of a, 2 of number compression Decompression Sparrows DXV slow compr. 1 1 7 instan- taneous 1 | Dead in a quarter of an hour. I Two animals. DV 5 min. 8 a few sec. 1 No symptoms. DIX 2 min. 8 id. 1 id. DVI 2 hours 8 1 id. I Died in 10 min. Gas in the 1 blood. DVII 1 h. 35 min. 9V2 id. I No symptoms. DX a few min. 10 id. id. DXI id. 12 1 id. | Died almost immed. Gas in | abundance. DXII id. 14 id. | Died in few minutes. Gas | in abundance. DXIII | id. 14 | 1 id. | No immediate symptoms. | Dead next day. DXIV | 1 id. 15 I 1 id. | Died quickly. Gas in abun- | dance. DVIII 1 5 min. 16 1 1 id | Died in a few minutes. Gas: | convulsions from oxygen had | begun. Rats 1 DXVII | iy4 h. 5% | a few sec. 1 | No symptoms. DXVIII 1% h. 6V2| | id. DXVI | % h. 6% I a few sec. I No symptoms. DXIX 1 1 | 8V2 | I 1 2 min. | Two animals. Dead in a few | minutes. Gas in the blood. 1 Rabbits i DXXIII 1 1% h. 6V2 | 4V2 min. | No symptoms. DXXI a few min. | 7 2 to 3 min. | Two animals. DXX | 5 min. 8 id. I id. DXXII | ! | 1 8% I 1 id. | Two animals. 1 872 Experiments Table XVIII— Continued c£ Experiment Duration Duration of fn of Condition of animal compression 3 §• $ o Decompression Cats DXXVI 5 min. 8 2 to 3 min ! Paraplegia, dies in 4 days; medullary softening. Exp. 1 made at the same time ! as Exp. DXX. DXXV 9 min. 10 id. I Dies in 15 min. Gas in the I blood. DXXIV 10 id. I Killed next day. Medullary ! softening. 1 Dogs DXXXIX DXXVII DXL DXXIX DXLI DLXIV DXXXI DXXXIII DXXX DLXIII DXLVI DXXXIV DXXXVIII DXXXVII DXLVII DXL VIII 15 min. 30 min. 4 hours 30 min. 2 hours a few min. 3 h. 30 min. a few min. id. 7 min. 10 min. 15 min. a few min. I I 3 Vz I 1 to 2 min. | No symptom, yet tiny bubbles I of gas escape from the blood. 4 ! 2 to 3 min. | No symptoms. 4V2 I id. | id. Same animal as in | Exp. DXXXIX. 5 I id. |id. 5 id. | id. Same animal as in I Exp. DXL. 5V2 | 20 sec. | Gas in the veins; no i symptoms. 6 id. I id. Same dog as in I Exp. DXXIX. 6 id. [ id. Same dog as in ! Exp. DXXXI. 6 id. I Drags hind-quarters a little. ! Recovers. 6 I 20 sec. I Immediate paralysis; no gas. I Dies; gas everywhere. 6V2 I 4V2 min. | No symptoms. No gas in ! jugular blood. 7 I 2 min. | Paraplegia, medullary sof- | tening. Dies in a week. Same I dog as in Exp. DXXXIII. I Paraplegia; recompressed and I decompressed slowly. Dies in I the evening. (Paraplegia; recompressed and I decompressed slowly; dies I next day. No gas in blood. ! Small bloody spots in spinal ! marrow. I Paralyzed, much gas in heart; I dying. Oxygen inhaled; res- I piration restored; accident; I death. ! 2V4 min. | Paralyzed; oxygen inhaled; I dies. 7 I 2 min. I 7 I 2V2 min. I I 7V2 I 2 min. I I Sudden Changes in Pressure Table XVIII— Continued 873 Experiment number Duration of compression Ko in the air, there was 70 of it in the blood. Dif- ference 15. With 30 of COL, in the air, there was 82 of it in the blood. Dif- ference 12. Action of Carbonic Acid 919 With 40 of CO. in the air, there was 95 of it in the blood. Dif- ference 13. With 45 of CO, in the air, there was 114 of it in the blood. Dif- ference 19. We see that increases in the arterial blood which do not differ much correspond to equal increases in the respirable air; this re- sult conforms to the laws of physics. But we should not attribute to it too great an exactness, because important changes in the Fig. 77 — Death by carbonic acid; relation of the respiration and the circu- lation to the carbonic acid content of the blood. (Exp. DCXV.) respiratory rhythm may modify considerably the quantity of car- bonic acid contained in the arterial blood. Let us now drop these chemical considerations and discuss the changes which occurred in the various functions. The number of heartbeats decreases progressively; the tables summarizing Experiments DCXIV and DCXV show that clearly, and line P of Figure 76 still more clearly, at least for Experiment DCXV. If we draw up graphs with the results of this experiment, taking for abscissae, not the time elapsed since the beginning of 920 Experiments the experiment, as in Figure 76, but the quantity of carbonic acid contained in the blood (Fig. 77), we see that this decrease in the number of heartbeats follows quite regularly the increase in the carbonic acid of the blood. The detailed account of the different experiments shows that the heartbeats persist after the respiratory movements have ceased; in Experiment DCVI, the heart continued to beat for about ten minutes. On the other hand, we see that the blood pressure in the arteries is modified only very slowly by the accumulation of carbonic acid in the blood and the tissues. At the very beginning it seems in- creased a little (Exp. DCXV and DCXVI) ; but it is still from 12 to 14 cm. at a time when there is more than 90 volumes of carbonic acid in the blood (Exp. DCXIV) , and from 11 to 15 when there is 95 (Exp. DCXV), and even from 8 to 10 when there, are only 8 respirations to the minute, when the temperature has fallen to 28°, and when the arterial blood contains more than its own volume of carbonic acid (Exp. DCXV) . Fig. 78 — Death by carbonic acid; last respiratory movements. (Exp. DCXV.) So, in progressive poisoning by carbonic acid, the heart is the ultimum moriens (last to die), and its beating is the last sign of life which one can observe in the dying animal. The number of respiratory movements decreases equally; at the beginning of the experiment it often increases, but when the car- bonic acid of the blood reaches a proportion above 90 volumes, the slackening assumes considerable intensity. For Experiment DCXV, these phenomena are easy to study in the summarizing table and in the lines R of Figures 76 and 77. In Experiment DCXIV, during the last hour of life, there were only 2 to 4 respira- tions per minute; at the very end, there was only one every two or three minutes, and in Experiment DCVI, one every three or four minutes. At the end, their depth decreased like their number, Action of Carbonic Acid 921 and the tracing in Figure 78 which was made by the pneumograph (Exp. DCXV), shows that the cessation of the respiratory move- ments took place without a last sigh: this in itself as I proved elsewhere', indicates that carbonic acid is not a heart poison. During the whole duration of this progressive poisoning, the animals remain perfectly calm. At the beginning, only a few struggles, which soon are quieted. If the animal is unfastened when the arterial blood contains 60 or 70 volumes of CO., it makes no attempt to escape. Later, it becomes insensible to stimuli, to pinching, even to electrical stimulation of the sensory nerves: finally the eye itself becomes insensible. This curious anesthesia deserves our attention for a few minutes. Let us say first that insensibility to pinching occurs long before the animal is threatened by death. In Experiment DCVI, the eye was insensible two hours before death, when there were still 10 respirations, and 64 heart beats, the temperature having fallen to 30 degrees; in Experiment DCXIV, the paws became insensible more than four hours before death, and the eye two hours (respira- tions 20; pulse 43; temperature 27°); finally in Experiment DCXV, absolute insensibility of the paws was observed more than three hours before death, and the eye became insensible two hours before (respirations 20; pulse 48; temperature 29.5°). This insensibility is very complete; stimulation of the sciatic nerve by pinching or electric currents causes no general movement, no change in the respiratory rhythm (Exp. DCXV) , in the arterial pressure or the state of the pupils (Exp. DCXVI) , even when they still contract under the direct influence of light. The eye, as I have just said, keeps its sensitivity for a long time yet, and this sensi- tivity disappears last in the conjunctiva (Exp. DCXIII). Now when the eye has become absolutely insensible, the animal is by no means in danger. If it is taken from the altered medium and brought into the air, it always recovers (Exp. DCXII, DCXIII, DCXVI, DCXVII, DCXVIII, DCXIX), generally after displaying strange symptoms, to which I shall call attention presently. If we investigate the proportion of carbonic acid in the air and the arterial blood at which insensibility of the feet or of the eye occurred, this is the average we obtain: insensibility of the feet appeared when the air contained about 28% of carbonic acid, and insensibility of the eye when the proportion rose to 35%; for the blood, the extremes are much wider, since they vary from 72.3 (Exp. DCXII) to 95.4 (Exp. DCXV) . 922 Experiments This complete anesthesia of the limbs, when the eye is still sensitive, when the heart still beats frequently and strongly, and when the animal is still so far from serious danger, naturally in- spired the idea of a possible surgical application. But an important difficulty appeared. In the experiments which I have just reported, the animal itself forms the carbonic acid which it stores up in its blood and tissues; that requires a very long time. In Experiment DCXIII, insensibility of the paws was ob- served only after two hours; it took more than three hours in Ex- periments DCXIV and DCXV. Nothing would be less practical than this long preparation, which would be a long torture. On the other hand, and this is still more important from another point of view, in these long experiments the temperature had dropped sev- eral degrees at the time when insensibility of the paws appeared, and that might have serious consequences for the patients. I then asked myself whether I could obtain results similar to the preceding ones by making the animals breathe a more or less rich mixture of carbonic acid and oxygen early in the experiment. I did this in Experiments DCXVI, DCXVII, DCXVIII, and DCXIX. When the mixture to be breathed contained 207c of carbonic acid (Exp. DCXVII), insensibility appeared only after IV2 hours, at which time the temperature had dropped 4°, the respirations numbered 36, and the pulse rate was 100; the arterial blood then contained 77 volumes of CCX. But with 40% of C02 (Exp. DCXVI, DCXIX) insensibility occurred after 3 or 5 minutes, of course without a change in the temperature, the heart having singular strength, (19 to 23 cm., Exp. DCXVI; 18 to 20 cm., Exp. DCXIX) greater than in the normal state: the arterial blood contained 78.6 volumes (Exp. DCXIX) or 81.2 volumes (Exp. DCXVI) of carbonic acid. Finally, with a mixture containing 52.8% of C02, insensibility was almost instantaneous, and the arterial blood was laden with 98.4 volumes of CO, (Exp. DCXVIII) . These last results show that the surgical use of carbonic acid, in a proportion of about 40%, the rest of the gas being nearly pure oxygen, might give good results, and would not at all affect arterial pressure, as do the compounds of carbon and hydrogen and the chloro-carbon compounds of hydrogen. But this proportion of carbonic acid in the respirable medium must not be much exceeded. I showed in 18644 that if two new- born rats were placed, one in carbonic acid, the other in nitrogen, the heart of the latter continues to beat more than a quarter of an Action of Carbonic Acid 923 hour, whereas the heart of the former stops in 2 or 3 minutes. But these conditions are quite different from those of my present ex- periments. Here we are dealing with carbonic acid slowly formed by the organism itself, and not with a flood of acid reaching the blood of the left heart suddenly. There is one last point left to study. When the animal is brought back to free air, even though its blood and its tissues are laden with an enormous proportion of carbonic acid, it recovers. And so the dogs in Experiments DCVI, DCXII, DCXIII, survived, although their arterial blood contained 73.3, 82.8, and 87.2 volumes of C02, and the body temperature had dropped to 25° (Exp. DCXII) . They recover gradually; their respiration accelerates, as does the heart; their temperature rises, and strength returns with sen- sitivity, which reappears in 10 or 15 minutes. But very strange nervous symptoms always appear at this time; these are rigors with a few clonic convulsions, or slow and languid movements, like those of a hibernating animal which is warmed and which is awakening. That lasts a few minutes, during the phase in which insensibility still persists. One might think that these phenomena are due in part to the considerable loss in temperature of the experimental animals. That is not the case, for in Experiments DCXVI and DCXIX, in which insensibility was obtained early by respiration of supercarbonated air, and in which there was no loss of temperature, the same symp- toms appeared. They are therefore related to the elimination of excess carbonic acid; the return to its normal state of the anesthetized spinal cord is shown by disconnected stimuli which for some minutes cause convulsive symptoms. We know that, according to M. Brown-Sequard, carbonic acid is a poison which causes convulsions; the violent symptoms which mark the end of asphyxias and quick hemorrhages are explained, according to him, by the action of the carbonic acid accumulation in the tissues. Long ago I replied to this theory, which, I hope will not return for discussion today. But here, by a singular coincidence, these convulsions, which the carbonic acid was accused of pro- ducing, are absolutely the sign of its elimination. I do not think that these convulsive symptoms of the return to sensibility constitute a serious obstacle to the use of carbonic acid by surgeons. They are surely much less terrifying than the violent struggles which so often mark the beginning of the action of chloro- 924 Experiments form, and which have mistakenly been named the "period of exci- tation." And besides we might very probably avoid them by lessening the speed of the elimination of the carbonic acid. But while I call attention of the surgeons to this anesthetic, which has often been considered but which has never been studied with sufficient care, I am far from believing that the preceding researches are precise and detailed enough to authorize immediate application: an experimental table upon which a dog is fastened is one thing, and the bed of a patient is another. While trying to give myself a precise idea of the inner action of carbonic acid, I reach the following considerations: The excretion of the carbonic acid which is constantly being formed in the interior of the tissues is a necessary condition on account of the continued metabolic exchanges which give rise to it. Here, as in so many other chemical phenomena, the product of the reaction must be eliminated constantly so that this reaction may maintain its maximum activity. When, through respiration in closed vessels, under conditions specified above, the carbonic acid is stored up in the tissues, it delays all the oxidations there, as is proved by the rapid drop in the temperature. As for the nervous system, if it seems affected first, that is because it is the first to show the general effects which disturb the whole organism; and because the spinal cord fails in its reflex functions of sensitivity and respiration, just as it is the first to show the organic disturbances which occur when we bleed, diminish or increase the 02 of the blood, chill, or overheat an animal. But when the carbonic acid is artificially brought from outside, and when it is inhaled in a gaseous mixture, it is not the whole organism which is affected as in the first case. The carbonic acid, absorbed by the arterial blood in passing through the lungs, is immediately carried by it to the nervous center, the metabolic changes of which are therefore suddenly disturbed, delayed, and altered: hence the anesthesia. Finally, when the proportion is great enough in the respiratory mixture, the cardiac ganglia them- selves are immediately affected in their metabolism and the heart stops, paralyzed. 5. Action of Carbonic Acid upon the Lower Living Beings. The universality of action of carbonic acid upon all tissues is shown very clearly when we experiment upon lower animals. Long ago, for example, I showed in my courses that frogs or new-born mammals die sooner in carbonic acid than in carbon monoxide. Action of Carbonic Acid 925 And that is easily understood, I said: carbon monoxide acts like a simple hemorrhage or an asphyxia in nitrogen, by suppressing the oxygen of the blood, whereas carbonic acid poisons the tissues themselves. Only if the experiment is stopped before the animals are quite dead, the frog with the C02 recovers quite quickly, but the one with the CO dies, on the contrary, since it is definitely de- prived of its red corpuscles. It seemed to me interesting to try to determine the proportion of carbonic acid dissolved in the water, which would be incom- patible with the life of fishes. Here are the details of the experi- ment: Experiment DCXXXI. May 22. At 12:15. Golden carp of the same size are immersed in flasks with stoppers, full of a well aerated water to which have been added growing proportions of water saturated with carbonic acid so that A contained pure water (which holds in solution 4.4 volumes of CO. per 100 volumes of liquid) B contained water with 11% of C02 C contained water with 18% of CO, D contained water with 30% of C02 E contained water with 45% of C02. At 12:35, fish E was breathing very feebly, whereas B was breath- ing more strongly than A. 12:45. E is on its side, very sick; D is evidently sick too. 1:05. E is dead; D, very sick; C and B are breathing with diffi- culty; D dies about 10 o'clock in the evening. The next day, A, B, and C are still alive. The proportion of free C02 which is rapidly fatal is therefore in the neighborhood of 30%. That is much above the quantities which exist in all waters not charged with saline elements. Carbonic acid manifests its action not only on animals, but also on plants. In a medium with high C02 content, green plants die rapidly, when we prevent the light from permitting them to decompose the dangerous gas rapidly.5 Germination is delayed and checked, when the proportion of the gas is sufficient; the seeds themselves may be killed by it. As an example of these facts, I quote the two experiments following: Experiment DCXXXII. April 8. Sowed, under a large bell of 11 liters, a few seeds of barley and of cress upon well moistened paper. The bell is filled with a mixture containing: 02 16; CO, 20; N 64. May 2. Nothing has developed; the air of the bell contains: 02 12.9; C02 29. I leave the seeds in the open air; on May 7, some shoots appear, and on May 20 all has sprouted well; the barley already measures 12 cm. 926 Experiments Experiment DCXXXIII. March 30. A. 20 barley seeds are sowed on wet paper, under a bell of 11 liters containing 50% of carbonic acid and 50 of ordinary air. B. As controls, other seeds are sowed under a bell of 2.5 liters full of ordinary air. April 3. Evident germination in B. April 9. The shoots in B are 3 to 4 cm. high; nothing in A. On the seeds in B abundant mold has appeared; there is nothing in A. April 22. There are fine shoots in B, and its air contains C02 4.4; O, 13.6. No shoots in A, the air of which still contains 9.3 of oxygen. A, when left in the open air, does not sprout. And so, with 20 % to 30% of carbonic acid, there is merely sus- pension of germination; but with 50%, the seeds are killed. And what is true of seeds of barley is true of molds, as we see in the very experiment which has just been reported. It is not surprising then to see that putrefaction itself is greatly delayed and even checked in an atmosphere laden with carbonic acid. That is what happened in the following experiments: Experiment DCXXXIV. December 14. Fragments of muscles placed in bells filled: A, with air; B, with almost pure carbonic acid. January 8. A is foul, in full decay, covered with mold; B has no odor and no mold is apparent. Experiment DCXXXV. January 14. Fragments of muscles placed in bells filled: A, with air; B, with a mixture (O, 14.4; N 54.6; CO, 31%). January 17. The air of A now contains only 18.1 of oxygen, with 3 of CO,; it smells bad. The air of B has not changed its composition and has no odor. Experiment DCXXXVI. July 29. A thin slice of beef weighing 100 gm. is hung in the glass apparatus, under a pressure of 6 atmospheres, 5 of which are carbonic acid. August 10. Decompression. The meat has no odor; its color is rather dull. I cook it; it has no putrid odor or taste; but its flavor is disagreeable, insipid, sweetish, like that of meat kept in compressed oxygen. Finally, the muscular contractility is rapidly destroyed by car- bonic acid and very probably the same thing would be true of the other vital characteristics. Action of Carbonic Acid 9^7 Experiment DCXXXVII. June 4. Two feet of the same frog are hung each at the top of a test tube: A in air; B in almost pure carbonic acid. June 5. A, nerve not excitable; muscle very contractile; B, no muscular contractility. 6. Summary and Conclusions. We have now reached the end of this long study. It is sum- marized in the following propositions: A. When an animal breathes in a closed vessel, either in com- pressed air, or in a superoxygenated air, at normal pressure, so that it never lacks oxygen, the increasing tension of C02 in the air maintains an increasing proportion of the same gas in the blood, so that the carbonic acid produced within the tissues remains in these tissues. B. From this accumulation there results a progressive slacken- ing of the intra-organic oxidations, and consequently, a consider- able lowering of the body temperature. C. The central nervous system, in this general effect upon the organism, is the first to show that it is attacked, by the loss of the reflex transmissions, first in the limbs, then in the eye, finally in the respiratory center, from which death results. D. No struggle, no convulsive movement precedes death. The heart, though slackening its beats, retains its full strength for a very long time, and remains the ultimum moriens (last to die) . These two facts definitely disprove the theories which make of carbonic acid either a poison which causes convulsions or a poison of the heart. E. The anesthesia produced by carbonic acid apparently de- serves to attract the attention of surgeons again; it is complete at the moment when the life of the animal is far from being in danger. F. Plant life, germination, the development of molds, and putre- faction are slowed, suspended, and definitely checked by carbonic acid at a sufficient tension. G. Therefore, carbonic acid is a universal poison, which kills animals and plants, large or microscopic; which kills the anatomical elements, isolated or grouped in tissues. And that is not at all surprising because it is the product of universal excretion of all living cells; its presence hinders excretion, and consequently by interposing a terminal obstacle stops the whole series of the con- stituent chemical transformations of life, which begin with the absorption of oxygen and end with the discharge of carbonic acid. 928 Experiments Subchapter II ASPHYXIA The researches of which I have given an account in the pre- ceding chapters have naturally led me to the study of asphyxia in closed vessels, in ordinary air, at normal pressure. Here, at the moment of death, are very low oxygen tension and fairly high C02 tension; to which of the two influences is death due? Do both have an effect? I have already treated this question in my "Lessons on Respira- tion" (page 525) , and basing my belief exclusively on the chemical composition of the lethal air, I had arrived at the following conclusions: A. For warm-blooded animals, death occurs from lack of oxygen; B. For cold-blooded animals, from poisoning by carbonic acid. I was brought to consider this question from another point of view, upon observing the modifications undergone by the gases of the blood, and comparing them on one hand with those reported in Chapter II, Subchapter IV, and ok che other hand, with those which are the result of carbonic acid poisoning. The experiments were made by the same method as in the chapters mentioned: respiration with a hermetically closed muzzle, or by the trachea, in a bag containing a certain quantity of air. The report of a few experiments follows: Experiment DCXXXVIII. March 5. Spaniel weighing 12 kilos. 5:35. Drew 40 cc. of blood from the carotid .... A 5:37. Caused to breathe -through a muzzle in a rubber bag con- taining about 20 liters of air. 5:52. The animal, which has struggled a great deal, and which has lost air around the sides of the muzzle, is very sick. Took air from the bag .... a 5:55. Drew 33 cc. of very dark blood from the carotid . . . . B 6:15. The animal dies, without convulsions or rigor. With diffi- culty I draw from the left heart blood which is beginning to coagu- late . . . . C Air from the bag . . . . b Blood A (in the open air) contained 02 15.9; CO, 44.8 Blood B (air a: O, 4.8; CO, 12.1) contained O, 2.4; CO, 44.5. Blood C (lethal air b: O, 3; CO, 15.8) contained O, 0.8; CO, 39.9 Experiment DCXXXIX. March 7. Spaniel weighing 13 kilos. I expose the carotid and the trachea. 3 o'clock. Respirations 45; pulse 90; rectal temperature 38.5 D. Asphyxia 929 3:05. Drew 33 cc. of blood from the carotid, moderately red ... A 3:15. Placed a tube in the trachea. The respirations become extraordinarily rapid. 3:20. Respirations 124; temperature 38.5°; drew 33 cc. of blood from the carotid, redder than A .... B 3:22. Placed the trachea in communication with a rubber bag con- taining 60 liters of air. Much struggling; respirations very frequent. 3:43. Temperature 38°. 4 o'clock. Respirations 84; pulse 96; took air and 33 cc. of blood, not so red as A .... C and a 4:05. Very deep respirations, 56 per minute; pulse 96. 4:15. Temperature 36.5°. 4:35. Respirations 28; pulse 52, very irregular. Temperature 36°. Air from the bag . . . . b Cornea sensitive; drew 25 cc. of very dark blood . . . . D 4:40. Cornea without sensitivity; pupils dilated; respirations 16; pulse too weak to be felt; temperature 35.5°. The respirations become slower and slower, and the last takes place at 4:46; there is no convulsion. 4:48. The heart still pumps a little blood into the carotid, and with a cannula I succeed in extracting 40 cc. of very dark blood from the left heart . . . . E Then I take a sample of air from the bag . . . . c 4:55. I collect under water the gases of the lungs . . . . d The urine, treated with sulphuric acid in the pump, gives about 15 volumes per 100 of C02. Blood A (free air, respiration by natural channel) 02 19.8; C02 40.1 Blood B (free air, respiration very rapid, by the trachea) 02 21.5; CO 18.3 Blood C (air a: 02 9.3; CO, 7.0) O2 14.4; CO. 32.0 Blood D (air b: 02 1.8; CO, 12.0) O. 2.1; C02 54.3 Blood E (lethal air c: O* 1.5; CO. 12.6) O, 1.2; C02 42.5 The air from the lungs d contained; 02 0; C02 14.6. Experiment DCXL. March 10. Brach-hound, weighing 16 kilos. Rectal temperature 39.5°. 3:15. Placed a tube in the trachea; breathes calmly. 3:20. Caused to breathe in the bag, which contains 137 liters of air. 3:23. Respiration calm; drew 33 cc. of blood from the carotid, moderately red .... A 3:49. Deep respirations, 58; took air from the bag .... a 3:50. Drew 25 cc. of blood, not so red as A .... B 4:05. Deep respirations, agitated, 48; temperature 37.8°. 4:12. Violent struggling; temperature 37.5°. 4: 15. Air from the bag . . . . b 4: 16. Respirations ample, 52; drew 25 cc. of blood, considerably less red . . . . C 4:38. Air from the bag . . . . c 930 Experiments 4:40. Respirations, 48; temperature 35.5°; drew 25 cc. of dark blood . . . . D 5 o'clock. Respirations fairly deep, 40; pulse 36; temperature 35°. 5:03. Air from the bag . . . . d 5:07. Drew 25 cc. of very dark blood . . . . E 5:08. The eye, till then sensitive, becomes insensible; the pupil dilates. 5: 10. Respirations 6; pulse 30. 5: 15. Urine; the respirations become slower and slower and weaker and weaker; the heart also is failing. 5:20. Died without convulsions. Took air from the bag . . . . e Took blood from the left heart . . . . F The urine contains 18 cc. of C02 per 100 cc. of liquid. The sciatic nerve remains excitable by electricity until 6:40, that is, for 1 hour 20 minutes. Blood A (free air) contained 02 21.8; C02 42.9 Blood B (air a: 02 12.5; CO: 6.8) O2 21.0; C02 48.2 Blood C (air b: 02 7.6; C02 9.8) O. 15.4; CO. 57.8 Blood D (air c: O. 4.0; CO, 10.3) 02 6.9; CO, 58.3 Blood E (air d: