The Library of the Wellcome Institute for the History of Medicine MEDICAL SOCIETY OF LONDON DEPOSIT Accession Number Press Mark Med K4253 / \ -V ( \ »*!■. ( 1 ■ ( •'K f ^ I Digitized by the Internet Archive in 2016 https://archive.org/details/b28122951 THE CELL DOCTRINE. BV THE SAME AUTHOR. A GUIDE TO THE PRACTICAL EXAMINATION OF URINE. For the use of Physicians and Students. Illustratetl. Second edition, re\dsed and improved. Just ready. Price, 5t-25. AN INTRODUCTION TO THE STUDY OF PRACTICAL HIS- TOLOGY. For Beginners in Microscopy. Price, $i.oo; inter- leaved, $1.50. AV r REPARA TIOX. A TREATISE ON DISEASES OF THE KIDNEYS, with especial reference to Pathology anti Therapeutics. J W ,» • 1 Middle layer. Oldest layer. 111 matter iu Epithelial cells, Irom section through layer ot Epithelium Youngest layer. Production of formed material from germiu: coveriug papilluj of tue tougue. X 700. formation of pus. To illustrate the chansre in germinal matter of an Enithelial cell, resulting from increased nutrition, showing the manner in which the geniiinal matter ot a normal cell, if supplied freely with pabulum, may ?ne rise to pus. Fig. H. Pia- ^2- ^*3- ELASTIC TISSUE. The arrow shows the direction in which germinal matter is supposed to be moving. Fia. iS. ^.r., ta NERVE. Development of young, dark -bordered ne^e fibres, at an early period, showing germinal matter and formed material of elementary parts. X 1800. Fig. 17. New centre or nucleolus. Oldest part of formeil material. Youngest part of formed material. Germinal matter(nucleus). Fig. IS. >M®BA. Pure germinal matter. X5000. A'oung. Fully forir~I. TENDON. Young. Fully formed. CARTILAGE. Course of pabulum. PLATE ILLUSTRATING DR. BEALE’S VIEWS, -if H. He. c FHE CELL DO ITS HISTORY AND PRESENT STATE. FOR THE USE OF STUDENTS IN MEDICINE AND DENTISTRY. ALSO, A COPIOUS BIBLIOGRAPHY OF THE SUBJECT. By JAMES TYSON, M.D., PROFESSOR OF GENERAL PATHOLOGY AND MORBID ANATOMY IN THE UNIVER- SITY OF PENNSYLVANIA; ONE OF THE VICE-PRESIDENTS OF THE PATHOLOGICAL SOCIETY OF PHILADELPHIA; ONE OF THE VISITING PHYSICIANS TO THE PHILADELPHIA HOSPITAL; FELLOW OF THE COLLEGE OF PHY'SICIANS, PHILADELPHIA ; V ETC., ETC,, ETC. SECOND EDITION, , REVISED, CORRECTED, AND ENLARGED. ILL DS TEA TED. s PHILADELPHIA : LINDSAY & BLAKISTON. 18 78. Entered according to Act of Congress, in the year 1878, By LINDSAY & BLAKISTON, In the Office of the Librarian of Congress, at Washington, D. C, CAXTON PRESS OF SHERMAN & CO., PHILADELPHIA. 0^ TO THE MEDICAL CLASS OF THE UNIVERSITY OF PENNSYLVANIA, Cittle llolumc IS RESPECTFULLY INSCRIBED, BY THE AUTHOR. PREFACE TO THE SECOND EDITION. The highly favorable and quite iinexpeeted reeeption aecorded the first edition of this book has stimulated my interest in the subjeet, and in preparing a second, I have sought to improve it as much as possible. In doing so, many of the original sources of my information have been re-examined, and from them some additions made ’ and inaccuracies corrected. The section on the Present State of the Cell Doctrine, incorporating my own views, has been entirely rewritten, as was necessitated by the very important and numerous contributions to the subject since the first edition a^^peared. The bibliography has been increased by the addition of over three hundred and fifty new references, mostly to pajiers contributed directly on the subject since the first edition was issued. To make room for these, many of the references included in the bibliography of the first edition have been omitted where there did not seem to be a sufficiently close bearing on the subject. Vlll PREFACE TO THE SECOND EDITION. The suggestion of one of the reviewers of the first edi- tion, that the bibliography should be chronologically in- stead of alphabetically arranged was carefully considered', and at one time I had concluded to adopt it, but when I attempted to do so, I found that the inconvenience resulting from the wide separation of several papers by a single author, more than offset the advantages of a chronological arrangement. I therefore adhered to the original plan. For valuable assistance in collecting references and examination of papers I am greatly indebted to my as- sistant, Dr. H. F. Formad. 1506 Spruce Street, October 1st, 1878. PKEF ACE TO THE FIEST EDITIOI^. The author has become convincecl, by several years’ intimate intercourse with students of medicine, that their acquaintance with the subjects he has endeavored to in- clude in this little volume would be facilitated, if the views, which are now taught and scattered throughout the often expensive works of their authors, were collected in a convenient form for study and reference. Taking it for granted that a knowledge of this subject is of fun- damental importance in its bearing upon the study of physiology and pathology, and stimulated by the frequent inquiries of students for an appropriate source of infor- mation, he has prepared what he now submits to them. He has sought to obtain a continuous historv of the o evolution of the cell doctrine ” up to its present state, without embarrassing his pages with a large number of isolated facts. He has attempted, however, to secure a completeness, and to make 'the work useful to physicians X PREFACE TO THE FIRST EDITION. and others engaged in research, by careful references, and the addition of a bibliography, which lie has sought to make accurate and extended. Some authors may have been overlooked ; such the writer cordially invites to send him references to their own papers, or to those of others they believe to have a bearing upon the subject. ILLUSTRATIONS. Plate. — Illustrating Dr. Beale’s Views. Figs. Figs, Fig. Fig. Fig. Fig. Fig. Fig. Fig. 1 to 7. Production of formed material from germinal matter in epithelial cells, from section through layer of epithelium covering papillae of tongue. 7 to 11. Formation of Pus. u ct (( a 11. 12. 13. 14. 15. 16. Amoeba. 17. Illustrating Nutrition of Cell. (( u (( (( “ Tendon. Cartilage. Muscle. Elastic Tissue. “ Nerve. Intercalated. Fig. 1. Illustrating Globular Theory. After Virchow. Fig. 2. Cellular Tissue from the Embryo Sac of Chamaedorea Schie- deana in the act of formation. After Schleiden. Fig. 3. From the Point of a Branchial Cartilage of Bana Esculenta. After Schwann. Figs. 4 to 12. Formation of Nuclei and Cells from Molecules, accord- ing to Bennett. Xll ILLUSTRATIONS. Fig. 12. Diagram of tlie Investment Theory. From Virchow. Fig. 13. Formation of Pus from subcutaneous connective tissue. From Virchow. Fig. 14. Formation of Pus from interstitial connective tissue of mus- cle. From Virchow. Fig. 15. Development of Cancer from connective tissue. From Vir- chow. Fig. 16. Connective Tissue Corpuscles anastomosing one with the other. From Virchow. Fig. 17. Formation of Elastic Tissue, according to Virchow. Fig. 18. Formation of Connective Tissue, according to Schwann and Henle. From Virchow. Fig. 19. Formation of Connective Tissue, according to Virchow. From Virchow. THE CELL The idea that animals and plants, however com- plex their organization, are really composed of a limited variety of elementary parts, constantly re- curring, was appreciated by Aristotle, who was born 38d years before Christ, while it appears to have been little more clearly conceived by the acknowl- edged father of medical science, Galen, who lived 400 years later. Aristotle distinguished as ‘‘ partes similares,” those structures, such as bone, cartilage, fat, flesh, blood, lymph, nerve, ligament, tendon, membrane, vessels, nails, hairs, and skin, which were not confined to one part of the body, but distributed throughout it generally. He applied the term ‘‘ partes dissimilares ” to the regions of the head, neck, trunk, and extremities. Fallopius of Modena, 1523-1562, to whom we are indebted for our knowledge of the conceptions of Galen in regard to these “ partes similares ’’ or ‘‘ simplices,” has fur- ther developed the subject of general anatomy in his “ Lectiones de Partibus Similaribus Humani Corpo- ris.” These, however, plainly do not correspond with the “ elementary parts ” or “ cells ” of the pres- ent day. As' Prof. Huxley says in his valuable essay 2 0 14 THE CELL DOCTRINE. on “ The Cell Theory,” they were ultimate to Fallo- pius, because he could go no further, “ though it is, of course, a very different matter whether we are stopped by the imperfection of our instruments of analysis, as these older observers were, or by having really arrived at parts no longer analyzable.”* These “ partes similares ” really correspond to the “ tissues” of the present day, which are collections of elementary parts. The conceptions of these older writers with regard to the vital endowment ” or “ independent vitality ” of their similar parts or tissues, were sin- gularly correct, and correspond almost identically with those held by the majority of physiologists of the present day. Further than this, however, the anatomists of the period of Fallopius could not go — not because, as we now well know, they had arrived at parts no longer analyzable, but because of their imperfect means of analysis. It is probable that the magnifying properties of lenses were known to the Egyptians, as well as tlie Greeks and Eomans, over 2000 years ago ; since a table of refractive powers is introduced into his ‘‘Optics” by Ptolemy, since Aristophanes, the Athenian poet (B.C. 500), speaks of “burning spheres ” of glass as sold in the grocers’ shops of Athens, and since both Pliny and Seneca refer to lenses and their magnifying properties ; while lenses themselves have been found in the ruins of Xineveh, * The Cell Theory — a Keview, by T. H. Huxley ; Br. and For- eign Med. Chir. Kev. for October 1853, No. xxiv. THE CELL DOCTRINE. 15 Herculaneum, and Pompeii. But it is quite certain, also, that they did not become available as com- pound microscopes until about 1590, when the Jan- sens, father and son, of Holland, are said to have in- vented the compound microscope. Fontana, in 1646, writes that he had invented the microscope in 1618. Galileo, as early as 1612, is said to have sent a micro- scope to King Sigismund of Poland, though whether it was his own invention, or made after the pattern of atiother, is not easily determined.' In 1685, Stelluti published a description of the parts of a bee he liad examined with the microscope, and although George Hufnagle is said to have published in Frank- fort, in 1592, a work uj>on insects, illustrated by lifty copper plates, it is highly probable that these, as well as very many most important observations made after the invention of the compound microscope, were made with the simple instrument.* It is impossible to estimate the assistance the microscope has been to us in opening up the ndnute structure of animals and vegetables, and in thus af- fordino; a reliable basis on which to build a doctrine of organization. Prof. Huxley further says, “ The intluence of this mighty instrument of research upon biology, can only be compared to that of the galvanic battery, in the hands of Davy , upon chemistry. It has enabled proximate analysis to be ulti\iicder\ But it is more than this. Since, as he correctly states, it * For interesting and exhaustive liistory of the invention of tlie comj>ound microscope, see Das Mikroskop, Theorii*, G(‘braucb, Geseliichte und gegenwiirtiger Zustand desselben. Von P Harting. In drei Handen, Braunschweig, 1866. Dritter Band, ss. 1-35. f Huxley, loc. citat., p. 290. 16 THE CELL DOCTRINE. has enabled iwoximate physical analysis to become ultimate, it corresponds, not to the galvanic battery alone, but to all the appliances made use of in ulti- mate chemical analysis. The time prior to the invention of the compound microscope may be considered as the first j)eriod in histology ; that between this date and that of the ob- servations of Scbleiden and Schwann (1838), inclu- sive, the second loeriod ; while the time subsequent to these observations becomes appropriately the third period. ^Tot withstanding the imperfect state of in- struments during quite two hundred years after the invention of the compound microscope, a flood of facts was added to our knowledge of the minute structure of living things Borellus, of Pisa, seems first to have used the mi- croscope in the examination of the higher animal structures, about the year 1656, but his observations were grossly misinterpreted in his attempt to adapt them to the prevailing idea of the day, that diseases were caused by animalcul?e in the blood and tissues. Asa result, he describes pus-corpuscles as animalcules, and even says he has seen them delivering their eggs. According to Boerhaave, Swammerdam had recog- nized the blood-corpuscle in the frog in 1658. Malpighi,* between 1661 and 1665, had seen the blood-corpuscle in the hedge-hog, had witnessed the circulation of the blood, and had published observa- tions upon the minute structure of the lungs, which he had even compared to a racemose gland,t of the * Malpighi, Opera Omnia. London, 1686. I Fort, Anatomie et Physiologie dn Pounion, considere com me THE CELL DOCTRINE. 17 kidneys, spleen, liver, and membranes of the brain, and with some of these structures his name has become inseparably associated. In 1667, Robert Ilooke'^ |)ointed out the celltdar structure of plants, and Mali>igliit further elaborated the same subject with considerable accuracy in his “ Anatome Planta- ruin,” in 1670. lie showed that the walls of the “ cells ” or ‘‘ vesicles,” were separable, that they could be isolated, and gave to each the name utriculus^^ believing also the '‘cell,” or ‘‘ utriculus,” to be an inde|)endent entity. The latter observer:}: also recog- nized the blood corpuscle. Leeuwenhoek, in 1673, § described these corpuscles with considerable accuracy, not only in man, but also in the lower animals. He also demonstrated the capillaries, examined most of the tissues, and made the discovery of the sperma- tozoids, which he conceived to be spermatozoa or sperm animals, and of different sexes. Theory of Hallei\ 1757. — No attempt, however, seems to have been intelligently made at building up the tissues by an ultimate physical element, to cor- respond with the '' atom ” of the inorganic chemist, prior to that of Haller. He resolved the solid parts of animals and vegetables into the ’'’'fibre ” (fibra)^ un organe de Secretion. Paris, 1867, Preface; or a notice of Dr, Fort’s book, by the writer, in American Journal of Medical Sciences, October, 1869. * Hooke, Rob., Micrograpbia. London, 1667. f Malpighi, Anatome Plantarum. London, 1670. t Malpighi, Opera Posthuma. London, 1697. ^ Leeuwenhoek, Opera Omnia seu Arcana Naturae detecta. Tom. ii, p 421. Leyden, 1687. Yel Opera Omnia, etc., Lugd. Batav., 1722. 2* 18 THE CELL DOCTRINE. and an ‘‘ organized concrete.!^ To the former he as- signs the most important position, asserting that it is to the physiologist what the line is to the geome- trician ; that a ‘‘ fibre,” in general, may he con- sidered as resembling a line made up of points, having a moderate breadth, or rather as a slender cylinder.* «/ Tlie second elementary substance of the human body according to Haller, the “ organized concrete,” must not he lost sight of, as appears to have been the case with many eminent authorities who have attempted to give his views. This, he says, is a mere glue, evasated and concreted, not within the fibres, but in the spaces betwixt them, in illustration of which it is stated, that cartilages seem to be scarcely anything else besides this glue concreted. But these views of Haller were clearly not based upon microscopic observation, though the microscope had been for some time in use. For Haller himself tells us that the fibre is invisible, and to be distinguished only by the “mind’s eye,” — invisihilis est ea jibr a ^ sold mentis acie distinguirnus.\ Ho allusion to the cell beyond the imperfect description of the blood- * Haller, Elementa Pbysiologise, vol. i, lib. i, sec. i. Lausan., Helvet , 1757. f A singular discrepancy exists between these words of Haller and those found in both the Latin and English editions of the “ elegant compend ” of Haller’s works printed in Edinburgh, the former in 1766, and the latter (an edition in the possession of the writer), in 1779, under the inspection of William Cullen, M.D. In the latter, we have the following : “ The solid parts of animals and vegetables have this fabric in common, that their elements, or THE CELL DOCTKINE. 19 corpuscles and spermatozoids appears to liave been made by Haller. Theory of Wolffs 1759-74. — Better founded, in being based upon observation, was the theory of Wolff, and it contained many of the elements of truth. For an available exposition of these views, physiologists are much indebted to Prof. Huxley, who ill the able review already cited, has pre- sented them as agreeing partially, also, with his own. The doctrine of Wolff, as given by Prof. Huxley, is as follows : ‘‘Every organ is composed, at first, of a mass of clear viscous, nutritive fluid, which possesses no organization of any kind, but is at most composed of globules. In this semifluid mass, cavi- ties (Blaschen, Zellen) are now developed ; these, if they remain rounded or polygonal, become the sub- sequent cells, if they elongate, the vessels ; and the process is identically the same, whether it is ex- amined in the vegetating point of a plant, or in the young budding organs of an animal. Both cells and vessels may subsequently be thickened by deposits from the ‘ solidescible ’ nutritive fluid. In the plant, the cells at first communicate, but subsequently be- come separated from one another ; in the animal, they always remain in communication. In each ease they are mere cavities and not independent entities ; or- ganization is not effected by them, hut they are the visible residts of the action of the organizing power inherent in the smallest parts we can see hy the finest microscope^ fiVQ either fibres or an organized concrete. ^ First Lines of Physiology. By the celebrated Baron Albertus Haller, M.D. Translated from the correct Latin edition, and printed under the insiiection of William Cullen, M.D. Edinburgh, 1779. 20 THE CELL DOCTRINE. the living mass, or what Wolff calls the vis essevtialis. For him, however, this vis essentialis is no ArcJuEus, but simply a convenient name for two facts which he takes a great deal of trouble to demonstrate ; the first, the existence in living tissues (before any pas- sages are developed in them^ of currents of the nu- tritious fluid determined to particular parts by some power which is independent of all external influence ; and the second, the peculiar changes of form and composition, which take place in the same manner.”* Two points are here particularly to be observed as cardinal, — first, the non-independence of cells, either anatomically or physiologically ; that they are effects, 'passive i^esalts, and not causes of a vitalizing or or- ganizing force ; second, that organization takes place from the “ differentiation ” of the homogeneous living mass in these parts, through the agency of the vis essentialis or inherent vital force. The radical difference between these principles of development and those generally held at the present day, will be better appreciated when these latter have been worked out. An acknowledged error may, however, be pointed out, — the probable result of the inferiority of the instruments of that day — that of supposing the cells of plants and animals in all instances to communicate when in their youngest state, and in the latter to continue thus in communication through- out life. It will be observed, also, that this theory involved the spontaneous origin of the cell, that is, independent of any previously existing cell. * Huxley, loc. citat., p. 293-4. Wolff, C. F., Theoria Genera- tionis, 1759. Ed. Nova, Halae, 1774. THE CELL DOCTRINE. 21 The theory of Wolff, however, full as it was of origi- nal conception, and based on actual observation , seemed to claim little attention, and would have been still less known but for the labors of Prof. Huxley. The ‘‘ fibre ” theory of Plaller was still further expanded, and that fibres were the groundwork of nearly all the tissues, continued the prevailing view, until the latter part of the eighteenth century, and there are few of the older Physiologies even of a later date, which do not contain an account of it. ^N’aturally, it maintained itself longest in the case of the fibrous tissues, since the appearances of these tissues, when examined by the highest powers, are those of struc- tures apparently composed of fibres. Oken^ 1808. — The first clear expression with regard to the cellular or vesicular composition of animal or- ganisms as well as vegetable, comes from the ph^^sical school in the language of Oken, who, as early as 1805, in his work on Generation,’’ refers to elemen- tary parts as “vesicles;” and who says in his “ Pro- gramm iiber das Universum ” in 1808, “ The first transition of the inoro^anic to the ororanic is the con- version into a vesicle (Blaschen), which I, in my theory of generation, have called infusorium. Ani- mals and plants are throughout nothing else than mani- foldly divided, or repeating vesicles^ as I shall prove anatomically at the proper time.” This most ex- plicit statement seems also to have been overlooked. The Globular Theory^ 1779-1842. — The reaction which took place at the date referred to against the “ fibre ” theory, culminated in the “ globular ” theory, due less to speculation than erroneous methods of oh- 99 THE CELL DOCTRINE. servation and imperfect instruments. Leeuwenhoek* (1687) earl}^ announced the ‘‘globular” structure of the ])rimitive tissues of the body, but the “ globule” apparently attracted little notice until this period of reaction against the “ fibre,” when it claimed the attention of Prochaskaf (1779), Fontana:}; (1778), the brothers Wenzelg (1812), Treviranus|| (1816), Bauer"[ (1818 and 1828), Heusinger'^* (1822), MM. Prevost and Dumas, tt Milne- Edwards:}::}; (1828), Hodg- king§ (1829), Baurngartneiil| (1830-42), Frederick * Leeuwenhoek, op. citat. •j- Proehaska, De Structura Nervorum. Yind., 1779. Opera min., Pars i. I Fontana, Sur les Poisons, 1787, ii, 18; Abhandlung liber das Yiperngift, das Amerikanische Gift, u. s. w. Aus dem Italien. Berlin, 1787. ^ Wenzel, Joseph and Charles. De structura cerebri. Tubmg., 1812. II Treviranus, Yermischte Schriften, Anatom, und Physiolog. Inhalts Bd. i. Gottingen, 1816. ^ Bauer, Philosoph. Transac. for 1818, and SirE. Home’s Lec- tures on Comparative Anatomy, vol. iii, Lect. iii. London, 1823. Heiisiiiger, System der Histologie. Thl. i Eisenach, 1822-4 ft M:M. Prev(»st and Dumas, Bibliotheque Universelle des Sci- ences et Arts, T. xvii. tt M ilne-Ed wards, IMemoire sur la Structure Elementaire des Principaux Tissues Orgauiques des Animaux. Paris, 1823. Also, liecherches Microscoj)iques sur la Structure Intime des Tissues Or- ganiques des Animaux, in Ann. des Sci. ivTit. December, 1826. Hodgkin, in Grainger’s Elements of General Anatomy. Lon- don, 1829. Also Hodgkin and Fisher’s translation of 31. Edwards “ Sur les Agens Physiques.” London, 1832. Hodgkin’s Lectures on the Morbid AnaUmiy of the Serous and 31ucous Membranes. London, 1836, p. 26. Am. Ed., Philadelphia, 1838, vol. i, pp. 17-18. nil Baumgartner, K. H., Beobachtungen iiber die Nerven und das Blut in ihrem gesunden und Krankhatten Zustande, February, THE CELL DOCTRINE. 23 Arnold* * (1836), Dutrochetf (1837), Kaspail;}; (1839); all except Hodgkin admitting in greater or less de- gree the importance of the globule as an ultimate phys- ical element ; while it is evident, also, that there was much confusion in the use of terms, the words globule^ granule^ and molecule,^ being often indiscrimi- nately used, and the word globule sometimes used to indicate what is now clearly recognized as the ^‘cell.” 1830. His views are further elaborated in liis Beitrlige zur Phy- siologie und Anatomie. Aus der Lehre von der Gegensazen in den Kraften in lebenden thierschen Korper, ein Grundriss zur Physiologie und zur allgemeinen Pathologie und Tberapie, 2te Auflage, besonders abgedruokt. Stuttgart, 1842. * Arnold, Friedreich, Lehrbuch der Ph3'siologie des Menschen. Erst. Theil, Zurich, 1836. f Dutrochet, Memoires pour servir a PHistoire Anatomique et Physiologique des Vegetaux et des Animaux, t. ii, Atlas. Paris, 1837. J Raspail, Recherch sur la struct, et ledevelopm. de la feuille et du tronc, et sur la struct., etdevel. des tissus Animale, Paris, 1837. ^ The German authors of this period, and even more recent times (Henle, 1841, Virchow, 1858), at least in speaking of the development of histology, seem to use indiscriminatelv^ the terms granule or molecule and globule^ whereas they are morphologically something distinct. A globule is usually held to be a body which, under the microscope, is more or less spherical in form, possessing a bright centre, and dark outline, — the width of this outline being directly as the difference between the refracting power of the globule itself and that of the menstruum in which it floats. Thus, the dark outline of a globule of oil floating in water is wider than that of the same globule floating in gU'cerin. A granule or molecule^ on the other hand, is indeterminate in size and shape, and appears as a mere dot under tlie highest powers of the microscope. It is true that what appears as a granule under a low power, may appear as a globule under a higher. 24 THE CELL DOCTRINE. Prochaska,^ in 1779, described the brain as made np of globules eight times smaller than blood-glob- ules. In the year 1801, the philosophic mind of Bichat elaborated his excellent classification, but he seems to have made no orii^inal investio;ations in minute structure, or to have adopted any special theory of an ultimate physical element. The bro- thers, Joseph and Charles Wenzel,f in 1812, de- scribed the brain as composed of globules of small size. Among the earliest histologists worthy of mention, is Treviranus,:}: whose elements, according to Ilenle, were first, a homogeneous, formless matter; second, lib res ; third, globules (kugelchen). Mr. Bauer, § quoted as a most experienced microscopic observer by Sir Everard Home, in 1818, and again in 1823, described the ultimate globules of the brain and of muscular fibre as of the size of a globule of blood when deprived of its coloring matter, or about of an inch in diameter. The fibre was excluded as an ultimate element of organization by Heusinger|| in 1822-4, who started all tissues from the globule^ still, however, retaining the formless material of Haller and Treviranus. Heusinger formed the fibre by the linear apposition of his globular elementary parts, and even explained how canals and vessels were formed by a similar arrangement of vesicles which had originated from the globules. The ac- count given by HenleT[ of the method in which Heu- * Proschaska, Opera Minora, Part I, p. 342 f Wenzel, op. citat., p. 24. % Treviranus, op. citat. I Bauer, op. citat. || Heusinger, op. citat., p. 112. ^ Henle, Allgeraeine Anatomic. Leipzig, 1841, p. 128. THE CELL DOCTRINE. 25 singer built up his fibres and vessels is interesting and important, since there is in these views an ap- proximation to the truth. “As the result of an equal contest between contraction and expansion, there arises the globule^ of which all organisms, all organic parts, are originally composed. By a stron- ger exercise (Spannung, tension) of power, there originates from the often more homogeneous globule, the vesicle. Where in an organism globules and a formless mass are present, the globules arrange them- selves according to chemical(?) laws and form fibres. Where vesicles arrange themselves, there arise and vessels.'^ In the latter sentence one cannot fail to note a close approximation to the truth, though the facts upon which the theory was based are partly false and partly misinterpreted. Eut the observations and w’ritings of Milne Ed- wards* may be looked upon as having given, more than those of any other author, position and popular- ity to the “globular theory.” lie examined all the principal tissues, and announced that the fibres of the then so-called cellular (fibrous) tissues, membranes composed of these fibres, muscle and nerve, were • composed of globules of about the same size, from 5oW TsVir diameter ; whence he concluded that these spherical corpuscles, by their aggregation, constituted all organic textures, vege- table or animal, and whatsoever their properties or functions. There is little doubt but that many of these so-called globules described by Edwards were * Edwards, loc. citat. 3 ' 26 THE CELL DOCTRINE. really cells, seen with indifterent instruments, and further distorted by the glare of direct sunlight. Similar, as regards the element of organization, were the views of Baumgartner* and Arnold,! who were joint observers. They considered^ the fundamental elements of or- ganization to be the formative globule (BildungskugeB, and the molecular granule (Molecular-kugelchen). The first is primarily formed by a simple aggrega- tion of smaller granules first represented by the gran- ules of the yolk united by a formless material. The ^‘molecular granule ” arises from a breaking up of the “ formative globule.” A modification of the “ formative globule ” out of an ao;o-reo:ation of which the entire embryo is first formed, is the haematoid body (Hamatoidkorper). This is a nucleated dis- coid body with a distinct ring-like border (geringtes Korperkern ndt einem Ringe). Further, “Out of these two kinds of globules and out of formless material,” says Baumgartner, “all tissues are formed, namely, the tissue-fibres (threads) out of the molecular granules, and the haematoid bodies out of the formative globules and newly- formed tissue-fibres. The molecular form is not everywhere equally expressed, which is owing in the first place to the fact that often the molecular gran- * Baumgartner, loc. citat. ; also, Virchow, Cellular Patholog}', Am. Ed. of Chance’s Translation. Philadelphia, 1863, p. 63. t Arnold, loc. citat. ; also, Virchow, Cellular Pathology, Am. Ed. of Chance’s Translation. Philadelphia, 1863, p. 53. J Baumgartner, Beitrage zur Physiologie und Anatomic, 1842, THE CELL DOCTRINE. 27 ules more or less fuse together, and second, that formless material surrounds the molecular granules and makes their outline indistinct. The theory here brought forward of the fundamental form of organi- zation in animals may well be called the globular theory.^’’ P. 88. It is evident that the “ formative globule,” or at least the modification of it called the Ilcematoidkbr- ye)\ is nothing more nor less than the nucleated cell, which, however, Baumgartner did not admit, contend- ing as late as 1842 against the cell doctrine ; asserting also (p. 40, op. citai.) that in the development of tissues the formative globule never divides to form two, in other words, that there is no such thing as cell di- vision.* Arnold also says thatf all fluid and solid parts of the human body are resolvable first into a fluid or half fluid material of no determinate form, and sec- ond, into granules Avhich are more or less completely spherical, and in all solid structures appear for the most part as minute globules. The granules, which are the second more important element, occur not only in all fluids and solid parts of the completely formed human organism, but thev are also the origi- nal and essential constituents of the human embryo. Out of these by their aggregation are formed the most complex tissues of the organism. * To tlie student desiring to pursue further this very interesting subject, with the argument against the cell theory by Baumgart- ner, I would recommend the perusal of the very interesting “ Bei- triige zur Anatomic und Physiologic” alluded to. f Lehrbuch der Physiologic des Menschen, 1836, p. 82. 28 THE CELL DOCTRINE. The error of these and other observers seems to have been clearly pointed out by ])r. Hodgkin,* though much importance was still attached to the A, Fibre, composed of elementary granules (molecular granules), drawn up in a line. B, Cell, with spherically arranged granules. (After Virchow, slightly modified.) globule as an element of organization (but perhaps from this time forward, more in the stricter sense of the term granule), which has continued, in this latter sense, to the present day. It should be mentioned that in 1828 Ddllingert announced that the tissues of the body are built up of blood-corpuscles, which move in wall-less (wandlos) channels in these tissues. From the foregoing facts it is evident that for some time prior to the year 1838, the cell had come to he quite universally recognized as a constantly re- curring element in vegetable and animal tissues, though as yet little importance had been attached to it as an element of organization, nor had its charac- ters been clearly determined. As stages in its grow- ing importance may be mentioned, the demonstration of the cellular structure of plants by Eobert Hooke, Fig. 1. 0 Illustrating the Globular Theory. * IlodgUin, loc. citat. t Dollinger, Ignaz, Yom Kreislaufe des Blutes, 18*28. THE CELL DOCTRINE. 29 in 16G7, the further elaboration of this subject by Malpighi, and his statement that each “ ntricnlus was an independent entity , the very clear statement of Oken in 1808 with regard to the cellular composition of animals and vegetables, the description of Hensin- ger,in 1822, of the mode of formation of vessels by the apposition of vesicles^ already referred to, and the an- nouncement, though erroneous, of Dollinger, in 1828, that the body is built up of blood-corpuscles which move in wall-less (wandlos) channels in the tissues. Baspail^ 1837. — Singularly near the truth did Ras- pail* approach, in 1837, when he tells us that in the condition of development there are vesicles or cells, endowed with life and the property, almost unlimited, of producing out of themselves other cells of the same structure and similar endowments, of spherical form, and capable of taking up oxygen when exposed to the atmosphere ; that the cell membrane in its fresh state is structureless. Yet he considers the organic cell as made up of granules or atoms, spirally ar- ranged about an ideal axis, comparing the cell with the crystal, and speaks of organization as crystalliza- tion in vesicles (crystallization vesicidaire). Datrochet^ 1837. — Similar was the view of Dutro- chet,t who divided the component parts of the body into solids jla.id. The solids were formed by the aggregation of cells of a certain degree of firmness; the liquids^ as the blood, are also made up of cells, which, however, fioat freely among each other, and there are also tissues in which the cells are so feebly * Kaspail, op. citat. 3* f Dutrochet, op, citat. 30 THE CELL DOCTRINE. united, that one can scarcely tell in what class to place them. The contents of the cell may he more or less solid, but the highest degree of vitality is only compatible with liquid cell contents. Muscular fibres^ and the remaining animal fibres^ are cells much elongated. And. he considers the same general 'plan to prevail in the animal and vegetable.' The approach of both of these observers to the truth is strikins:. Both, however, either failed to detect the nucleus or to attach any importance to it. They failed also to lay down a law of organic development, and their views were soon forgotten. Discovery of the Nucleus., 1833. — A most important contribution to the anatomy of the cell was made be- fore this, however, in the discovery of the “nucleus,'’ by Dr. Bobert Brown, of Edinburgh, whose paper, “ Organs and Mode of Fecundation in Orchide^e and Asclepiadese,” appeared in the Transactions of the Linnean Society of London, in 1833. He failed, how- ever, to appreciate its importance, though its dis- covery was another fact added to those necessary to complete the data on which has been founded the so-called “ cell theory.” Aleyen., 1836. — Meyen* sought to establish the opinion that the cell is formed of spiral fibres which lie closely upon one another, founding his view upon his own observation. Since the discovery of the nucleus, by Dr. Eohert Brown, in the vegetable cell, it had been recognized by many observers in various pathological, as well as * Meyen, Pflanzenphysiologie, Bd. i, 183G. THE CELL DOCTRINE. 31 liealtliv animal cells, and in the s;erm cell or ovule of birds, as early as in 1825, by Purkinje ;* * * § while Pur- kinje,t Yalentin,^ and Turpin, § bad actually called attention to the relations of the animal and vegetable cell to each other. The pre-existence of the nucleus, and the gradual development of the cell about it, Valentin had at- tempted to demonstrate in the case of pigment cells, C. II. Schultzl in the blood-corpuscle, Rudolph Wag- ner in the egg, and Ilenle in epithelium, all before the work of Schleiden had appeared. Muller had also insisted on the analoo^y between the cells of the chorda dorsalis and vegetable cells. ^ Valentin, too, had said, when describing the nucleus of epidermic cells, which he was the first to point out, that they reminded him of the nucleus of the cells of vege- table tissues.'^* Rot only this, but Arniand de Quia- trefagesft and Dumortier;];:}; had actually observed the origin of young cells from the full grown, in the * Purkinje, J., Ev^ Symbolse ad ovi avium historiam ante incu- bationern, cum duobus lithographs. Yratis., 1825. f Purkinje and Rascbkow, Meletemata circa Mammalium Den- tium Evolutionem. Diss. Inaug. Vratis., 1835, p. 12. t Valentin, Ueber den Verlauf und die Enden der Nerven, aus den Nov. Act. Nat. Curios., vol. xvii ; besonders abgedruckt. Bonn, 1836. § Turpin, Ann. d. Sci. Nat., 2 ser. vii, 207. II Schultz, C. H., Muller’s Archiv fur Anatomie, Physiologic und AVissenschaft. Med., p. cvii, 1837. ^ Strieker, Manual of Human and Comparative Histology, New. Syd. Soc. Translat., 1870, p. 1. » *5^ Valentin, Nov. Act., N. C. xvii, pt. I, p. 96. If Quatrefages, Annales des Sci. Nat., 2 ser. ii, p. 114. ++ Dumortier, Annales des Sci. Nat., 2 ser. vii, p. 129. 32 THE CELL DOCTRINE. embryo of the freshwater snail, while Valentin had famished examples of the development of fibres out of cells in the muscular fibres, and in the sub- stance of tlie crystalline lens. In fact, as stated by Dr. AValdo J. Burnett, in his admirable paper,* Val- entin “ perceived the true physiological relations of cells as far as he well could without apprehending the grand fact that the nucleated cell is the funda- mental expression of organic forms.” Virchow had also compared the whole organism to a free state containing individuals endowed with equal privileges if not with equal powers.f SCHLEIDEN AND SCHWANN, 1838. It was reserved for Schwann to accomplish this mas- terstroke in observation and generalization, through the intermediate results of Schleiden, without whose observations on vegetable structures, the true position of the cell would probably have remained undetected for some time longer. Schleiden, in 1838, clearly pointed out the formation of cells in vegetable struc- tures, according to a single and uniform method, and elaborated the theory of development of which the cell was the unit, and which Schwann immediately extended to animal tissues. * Burnett, W. J., The Cell; its Physiolos^y, Pathology, and Philosophy, as deduced from original investigations. To which is added its History and Criticism. A prize essay, read before the American Medical Association, and published in vol. vi of its Transactions. Philadelphia, 1853. f Strieker, op. citat., p. 2. THE CELL DOCTRINE. 33 A formidable obstacle for some time in tlie way of a law of development, applicable to animal and vege- table tissues, was the opinion, long entertained, that the scrowth of animals, whose tissues are furnished with vessels, is essentially different from that of plants ; an independent vitality being ascribed to the elemen- tary particles of vegetables growing Avithout vessels. So firnd}' Avas this believed, that the ovum, Avhich exhibited undoubted evidences of an actual vitality at one period of its groAvth,Avas said by all phj^siolo- gists to haA^e had a plant-like groAvth. This obstacle Avas removed in 1837, by Henle,* Avho shoAved that an actual groAvth of the elementary parts of epithe- lium took place Avithout vessels. Taking up the nucleus as discovered by Robert BroAvn, 8chleiden,f in reference to its function, ap- plies the name cytoblast [xoro^, a cell, a bud or sprout), or “ cell bud,” and in a careful study of its anatomy, discovers that “ in very large and beau- tifully developed cytoblasts, there is observed a small, sharply defined body, Avhich, judging from the shadow Avhicli it casts, appears to represent a thick ring, or thick-Avalled holloAv globule. One, tAvo, three, and even four of these may be present. AVithout fur- ther present comment than that these characters, as * Henle, Symbolce ad Anatomiam vill. intest. Berol., 1837. t Sehleiden, Beitriige zur Phylogenesis, Muller’s Archiv, 1838, p. ii ; Contributions to Phytogenesis, Sydenham Soc. Transl., p. Zoo. t The term nucleolus or nucleus-corpuscle (Kernkorperchen), seems to have been first applied by Schwann. (See Introduction to Schwann’s Researches, Syd. Society’s Translation.) 34 THE CELL DOCTRINE. given by Sclileiden, are by no means constant, it is plain that wbat is commonly known as tbe nucleolus is here intended, to tbe discovery of wliicli we are therefore indebted to him, though Valentin also claims its discovery at an earlier period.* He far- ther states that the observations he has made upon all plants, lead him to the conclusion that these small bodies are found earlier than the cytoblasts. According to Schleiden, when starch, which is superfluous nutritive material deposited for future use, is to be employed in new formations, it becomes dissolved into sugar or gum, which are convertible into one another. The sugar appears as a perfectly transparent fluid, not rendered turbid by alcohol, and receiving from tincture of iodine only so much color as corresponds to the strength of the solution. The gum is somewhat yellowish, more consistent, less transparent, and coagulated into granules b}" tincture of iodine, assuming a pale yellow color, which is permanent. In further progress of organi- zation, in which the o^um is alwavs the last immedi- ately preceding fluid, a quantity of exceedingly mi- nute granules appears in it, most of which, from their exceeding minuteness, appearing as black points. It is in this mass that organization takes place, though the youngest structures are con) posed of another distinct, homogeneous, perfectly transparent substance — so transparent as to be invisible when * Valentin, “ Outline of the Development of Animal Tissues,” in Wagner’s Elements of Physiology, translated by Dr. Willis, London, 1844, p. 214; Leipzig, 1839; where he refers to Valen- tin’s Kepertorium, vol. i, p. 143. THE CELL DOCTRINE. 35 not surrounded by opaque or colored bodies, — and continuing thus after pressure. This substance, which frequently occurs in plants, 8chleiden calls vegetable gelatin, and considers as slight modifications, pectin, the basis of gum tragacanth, and many of the sub- stances usually enumerated under the term vegetable mucus. It is this gelatin which is ultimately, through the agency of the nucleus, converted into the actual cell-wall, or structures which consist of it in a thickened state, and into the matter of vege- table fibre. There are two situations in the plant in which new organization may be observed most easily and clearly, in consequence of there being cavities closed by a simple membrane, 1st, in the large cell, which subsequently contains the albumen of the seed, the embryonal sac^ and 2d, in the extremity of the j^oUen tabe^ from which the embryo itself is developed. The embryonal sac never contains starch originally, but probably in most instances the saccharine solution or gum. The jpollen always contains starch, or repre- senting it, a semi-granulous substance identical with the small granules in the gum above alluded to, which Schleiden calls mucus. In both of these situations the above-mentioned minute 'mz/ci<5-granules are very soon developed in the gum, upon which the solution, previously homo- geneous, becomes clouded and more or less opaque. Single, larger, more sharply defined granules next become apparent, A, Fig. 2, constituting the nucleoli, and soon after the cytoblasts or nuclei, B, appear, look- ing like granulous coagulations about the granules. 36 THE CELL DOCTRINE. The cy toblasts then grow considerably in the free state, C, but so soon as they have attained their full size, a delicate transparent vesicle rises upon their surface, assuming the relation of the watch-crvstal to a watch, D, E. This is the young cell, which at first Fig. 2. o O B © Cellular Tissue, from the embryo sac of Chama*clorea Schiedeana, in the act of formation. A, Formative substance, gum, mucus-granules, nu- clei of cytoblasts (nucleoli). B, Cytoblasts. C, Single and free cytoblast, more highly magni- fied. D, Cytoblast with cell forming in it. E, Same, more highly magnified. F, Cytoblast isolated after destruction of cell. From Schleiden’s “Beitriige zur Phytogenesis.” represents a very flat segment of a sphere, the plane side of which is formed by the cytoblast, and the convex side by the young cell, wdiich is placed upon it somewhat like a watch-glass of a watch. In a natural medium it is distinguished almost by this circumstance alone, that the space between its con- vexity and the cytoblast is perfectly clear and trans- parent, and probably filled with a watery fluid, and is bounded by the surrounding mucus-granules, which have been aggregated at its first formation, and are pressed back by its expansion, as shown in 13, E. But if these young cells be isolated, the mucus-granules may be almost entirely removed by shaking the stage. Tliey cannot, however, be absent for any length of time, for in a few minutes they become THE CELL DOCTRINE. 37 completely dissolved in distilled water, leaving only the cytoblasts behind. The vesicle gradually ex- pands and becomes more consistent, and with the exception of the cytoblast, which always forms a portion of it, the wall now consists of gelatin. The entire cell then increases beyond the margin of the cytoblast, and quickly becomes so large that the latter at least merely appears as a small body inclosed in one of the side-walls in such a manner that the wall of the cell splits into two laminae, one of which passes exterior aud the other interior to the cytoblast. That upon the inner side is generally the more delicate, and in most instances only gelatinous, and is also absorbed simultaneously with the cytoblast. Within these cells, again, new cytoblasts arise, grow, and form young cells, which grow and fill up the mother cells, and finally cause the latter to disappear. This is endogen- ous cell formation^ while the formation of cells external to other cells constitutes exogenous cell formation. But according to Schleiden “ the entire growth of the plant consists only of a formation of cells within cells. ^so other method of formation of new cells seems to have been conceived bv him. For althoimh the multiplication of cells, by fissiparous division of previously existing cells,- had been demonstrated by Mirbel,t confirmed by Yon Mohl,:|; and the seg- * Loc. citat., p. 257. f Mirbel, Recherches sur la Marchantia, 1833. Schleiden, how- ever, says distinctly (op. cit. p. 232), “Mirbel does not make any allusion to the process of cell formation.” :|; Von Mohl, Entwicklung und Ban der Sporen der Kryptogam. Gew., Flor., 1833. 4 38 THE CELL DOCTRINE. mentation of the egg had been observed even earlier (1824) by Prevost and Dumas, all before the inves- tigations of Scbleiden bad been made, the latter author considered the apparent growing across of the partition walls an illusion, and that the young cells escape observation in consequence of their transpar- ency, until, at a late stage, their line of contact is re- garded as the partition wall of the parent cell ; while even Schwann states somewhat hesitatingly what is now so generally admitted.* This is the cell theory of Scbleiden, which he assumes to be the universal law for the formation of vegetable cellular tissue in the phanerogamia. At that time the cryptogamia had not been examined, and Scbleiden had not then ex- pressed his views in reference to the cambium. The merit of Schwann consisted in applying this theory to animal tissues, his conclusions being based upon the study of the formation of the chorda dor- salis and cartilage, and a comparison of their cells with those of vegetable tissues. Thus, in a cyto- blastema, either structureless or minutely granulous, ‘‘a nucleolus is first formed; around this a stratum of substance is deposited, usually minutely granulous, but not yet sharply defined on the outside. .As new molecules are constantly being deposited in this stra- tum between those already present, and as this takes place within a precise distance of the nucleolus only, the stratum becomes defined externally, and a cell nucleus, having a more or less sharp contour, is formed. The nucleus grows by a continuous deposition of new * Schwann, op. citat, Introduction, p. 4. THE CELL DOCTRINE. 39 molecules between those already existing, that is by intussusception. (See Fig. 3, e.) If this go on equally throuo;hout the entire thickness of the stratum, the Fig. 3. From the point of a Branchial Cartilage of Rana esculenta. (From Schwann.) , nucleus may remain solid ; but if it go on more vigor- ously in the external part, the latter will become more dense, and may become hardened into a mem- brane, and such are the hollow nuclei.”* When the nucleus has reached a certain stage of development, the cell is formed around it. The fol- lowing is the process by which this takes place : ‘‘ A stratum of substance, which differs from the cyto- hlastema^ is deposited upon the exterior of the nu- cleus. (See Fig. 3, d.) In the first instance, this stratum is not sharply defined externally, but be- comes so in consequence of the progressive deposition of new molecules. The stratum is more or less thick, sometimes homogeneous, sometimes granulous: the latter is most frequently the case in the thick strata which occur in the formation of the majority of ani- * Schwann, op. citat., p. 175. 40 THE CELL DOCTRINE. Inal cells. We cannot, at this period, distinguish a cell cavity and cell wall. The deposition of new molecules, between those already existing, proceeds, however, and is so effected that when the stratum is thin, the entire layer, and when it is thick, only the external portion, becomes graduaily consolidated into a membrane. The external portion of the layer may become consolidated soon after it is defined on the outside ; but, generally, the membrane does not be- come perceptible until a later period, when it is thicker and more defined internallj^ ; many cells, however, do not exhibit any appearance of the for- mation of a cell membrane, but they seem to be solid, and all that can be remarked is that the external por- tion of the layer is somewhat more compact.* “ Immediately that the cell membrane has become consolidated, its expansion proceeds as the result of the progressive reception of new molecules between the existing ones ; that is to say, by virtue of a growth by intussusception, while at the same time it becomes separated from the cell nucleus The inter- space between the cell membrane and the cell nu- cleus is at the same time filled with fiuid, and this constitutes the cell contents. During this expansion the nucleus remains attached to a spot on the internal surface of the cell mend)rane.” Though, according to Schwann, in animal cells the nucleus is never covered by a lamella passing over its inner surface, as is the case with the vegetable cell according to Schleiden. * Schwann, op. citat., p. 176. Strieker also informs us (Syden- ham Soc. translation, p. 5) that the corpuscles of mucus and pus, even in the eyes of Schwann, had no cell-wall. THE CELL DOCTRINE. 41 Thus is formed the animal cell according to Schwann, and although its method is very similar to that of Sclileiden, both as to endogenous and exoge- nous cell formation (for Schwann did not restrict cell genesis to endogenous cell formation), we have ([noted his own paper because he is plainly fuller and more precise in his descriptions. The object of each observer was, however, the same with regard to the tissues studied ; the additional object of Schwann being to show that all organisms^ whether animal or vegetable^ are formed on a common iirinciple^ and that this principle is origin from cells^ — that the various tissues of the plant and animal, however simple or complicated, are all combinations of these cells, modi- fied in adaptation to the special peculiarities of tis- sues. The conception of Schleiden was truly original, though its application was less difficult in conse- quence of the simplicity of vegetable tissues. The conception of Schwann was easier, in being the re- flection of that of Schleiden, w.hile its application was more difficult, in consequence of the great diver- sity of animal tissues ; so difficult that be acknowl- edged that “ there are some exceptions, or at least differences, which are as yet unexplained.^’ This need not surprise us when we recollect that one of theablest modern exponents of the cell theory admits the diffi- culty of its application to some of the so-called higher tissues.* Indeed, the careful reader of Schwann’s * Virchow, Cellular Pathology, Chance’s Translation. Am. Edit., Philadelphia, 1863, p. 78. 4* 42 THE CELL DOCTRINE. researches cannot but be surprised at the accuracy of the observations of this histologist, nor can be fail to realize how comparatively few have been the changes necessitated in bis descriptions, or the method of ap- plication of bis theory to the formation of the differ- ent tissues ; while the portion of the theory of Schleiden and Schwann which does not accord with the latest expression of the cell doctrine, is not so much that which pertains to the formation of tissues from existing cells as that which relates to the method in which they supposed the cells to origi- nate; which, it will he recollected, was by a species of spontaneous generation of the essential parts of the cell, in a homogeneous cytoblastema. A difference in the anatomy of the cell as given hj^ Schwann and physiologists of the present day, is seen in the location of the nucleus by the former, who places it not merely eccentrically^ hut actually “separated from the surface only by the thickness of the assumed cell-wall.’^* At the present day, the situation of the nucleus, though usually central, is known to he not unvarying. Again, the primary and absolutely essential presence of the nucleolus^ as well as the universal presence of the cell-wall^ may he considered characteristics of Schleiden and Schwann’s idea of the cell, which are now no longer insisted upon. As already stated (p. 38), Schwann would seem to have admitted also, the formation of cells by di- vision, though with some hesitation. Thus he writes :t * Schwann, op. citat., p. 37, a. f. f vSchwann, op. citat., Introduction, p. 4. THE CELL DOCTRINE. 43 ‘‘ A mode of formation of new cells, different from the above described, is exhibited in the multiplica- tion of cells by division of the existing ones ; in this case, partition walls grow across the old cell, if, as Schleiden supposes, this be not an illusion, inasmuch as the young cells might escape observation in con- sequence of their transparency, and at a later stage, their line of contact would be regarded as the parti- tion wall of the parent cell.” Schwann believed that the cell-wall was the most active constituent of the cell, that it possessed the power not onlj^ of producing physical and chemical changes in its own substance and the cell contents, but of secretino: materials from the surrounding sub- stance, and depositing them in its interior, explain- ing in this manner the secretions of glands, the for- mation of fat in some cells, pigment in others, etc. It would be easy to point out other defects in the theory of Schleiden and Schwann, when it is tested by comparison Avith the more accurate observation of the last twenty-live years, none of which should be permitted to detract from the credit which at- taches to the originators of this conception. It must not be forgotten, that it is no less true of science than of art, that great and important truths in their en- tirety are gradually developed, and that no single mind is capable of elaborating them from their in- cipiency to their complete expression. And as many clever people had daily noticed the rising of steam from the boiling kettle without thinking of utilizing its principles of expansion, so also, many careful ob- servers had time and again Avitnessed the cellular or 44 THE CELL DOCTRINE. vesicular composition of plants, and vet failed to ap- preciate the importance of the nucleated cell, and to deduce from it a law of development applicable to all organic forms. Again, as the engine of Watt was far different from the beautiful and powerful crea- tion of the mechanic of the present day, so the cell theory, as developed by Schleiden and Schwann, has been further evolved by later histologists. We may therefore truthfully reiterate, with Prof. Hux- ley, that “ w^hatever cavillers may say, it is certain that histology before 1838, and histology since then, are two different sciences — in scope, in purpose, and in dignity — and the eminent men to whom we allude, may safely answer all detraction by a proud ^ circum- spice. According to these observers, then, a perfectly formed cell would be defined as a dosed veside^ with certain contents, among which were essentially a nu- cleolus and nucleus. HENLE, EEROM ANN, REICHERT, AND OTHERS, 1840-46. It is not consistent with our object to include all of the numerous observations which were multiplied after this period, incited by the researches of Schlei- den and Schwann. It is simply to point out the salient features of those results which point towards and have culminated in accepted views. It has been stated that previous to Schleiden’s researches, in 1838, the formation of cells by division had been as- serted as one mode of origin, that Schleiden had de- clared this an error of observation, and that Schwann * Huxley, op. citat., p. 290. THE CELL DOCTRINE. 45 had hesitatingly, if at all, accepted it as a rare method of cell formation. ITenle,* who, in general, adopted the view of Schwann as to the primary origin of cells, though he made exception to its universality of application, says that cells multiply in three ways: 1. I3y budding (durch Sprossen), as in certain lower plants. 2. By endogenous cell development (durch endo- gene Zeugung), where the cell contents of the mother cell become the cytoblastema of the daughter cells, as originally given by Schleiden and Schwann. 3. By division or segmentation (durch Theilung), of which he says, however, no examples are found among animals ; though he also states in the para- graphf immediately following, We would, with Schwann, consider cell formation in the yolk, by ‘ furrowing,’ an analogous process, if we may con- sider the yolk as a simple cell.” He then proceeds to describe how, by a constriction of the surface, the yolk is divided into two equal parts, these into four, and so on until the entire yolk becomes a mulberry mass, made up of little round bodies. This segmen- tation of the ovum already observed in the yolks of frogs, fish, molluscs, and medusae, ITenle says at this time (1841), has perhaps merely escaped notice:}; in the case of the higher animals, as plausibly sus- pected by Bergmann,§ a suspicion which* we need * Henle, Allgeineine Anatomie. Leipzig, 1841, p. 112 et seq. t Ilenle, op. cit., p. 17G. % Henle, op. cit., p. 177. I Bergmann, Muller’s Archiv, 1841. Bergmann also in this paper objected to the existence of a cell membrane, and correctly 46 THE CELL DOCTRINE. scarcely say was amply confirmed a little later. Eat Henle also states, in the same connection, that certain cases arise in which perfect cells are developed in a cytoblastema, in a manner which is inexplicable, and that from these cells tissues are finally developed.* * Whence the undetermined state of the question at that time may be easily inferred. IS’or is mention here made by Henle of the nucleus of the cell as the primary seat of the segmentation. The surface of the cell is said to be constricted ” or “ furrowed,” deeper and deeper, until the division takes place. This de- scription is still adhered to by many phj^siologists of the present day, who consider that there is a simple disappearance of the germinal vesicle or nucleus of the ovum after fecundation, rather than a division of it into two, and substitution of these for the original one. While endeavoring to trace out the steps by which the present most generally accepted views with regard to the origin of cells were arrived at, it must not be for- gotten that other dissenting views were also ad- vanced, though tending difierently from those incor- porated in the text, where it is desired more particu- larly to trace those culminating in existing doctrines. Thus did Reichertf early (1840), dissent from Schwann, since he failed to find the nucleus universally present in the yolk, and he was the first to defend the view maintained that the spheres of segmentation are cells which are at first destitute of a cell membrane, though they become invested by one at a subsequent period. * Henle, op. cit., p. 177. f Reichert, Das Entwickelungsleben im "VVirbelthierreich. Ber- lin, 1840, pp. 6, 93. THE CELL DOCTRINE. 47 that the segments into which the egg breaks up are cells. Karsten* (1843), published a dissertation upon the cell, in which he stated that cells originate with- out a pre-existing nucleus, and by the expansion of amorphous granules of organic matter ; and more recently (1863), the same author practically reiterates this view, since he says that all ‘‘ cells of vegetables originate as minute free vesicles in the fluid contents of previously existing cells,” and regards the nucleus as a ‘‘small tertiary cell, retarded in its develop- ment.”f Again, “when the nucleus is present, the origin of new cells is quite independent of it.”:J: In addition to the statement already given, Henle also (1843), alleged that some of the so-called fibrous tis- sues were “ formed by the aggregation of granules in a certain way without the intervention of true nucleated cells.”§ Kblliker,|| one of the foremost exponents of the cell doctrine of the present day, in 1844 expressed his dissent from the idea of unity in the mode of cell formation, and states that if there is a single method of cell formation which is in- variable, it remains to be discovered, although he interpreted the segmentation of the germ of ce- phalopods in the same manner as Bergmann. Mr. * Karsten, De Celia vitale Dissertatio. Berlin, 1843. I Karsten, Ann. and Mag. of Nat. History, vol. xiii, p. 268. London, 1864. t Karsten, Ann. and Mag. Nat. History, vol. xiii, p. 281. I Henle, Traite d’Anatomie G^nerale. Trad. d’Allemand, par A. J., Jourdan, 2 vol., Paris, 1843, tom. 1, p. 374. II Kolliker, Entwickelungsgeschichte der Cephalapoden. Zurich, 1844. 48 THE CELL DOCTRINE. Paget,* SO well known from his Lectures on Surgical Pathology, suggested in 1846, that a cell might arise in some other way than from a nucleus, since he had met morbid growths composed entirely of fibres, in which not a nucleated cell was present. Most of these statements are, however, reconciled by the informa- tion which has since been added to our knowledo;e of the subject. MARTIN BARRY, 1840. It was in his first series of embryological researches, published in Part II of the ‘‘ Philosophical Transac- tions” of the Eoyal Society of London, for 1838, p. 310, that Dr. Martin Barry declared “that the ger- minal vesicle (which he regarded as the nucleus), and its contents constitute throughout the animal king- dom the most primitive portion of the ovum.” In his second series. Part II, 1839, in stating that the ger- minal vesicle returns to the centre of the cell, jjost coitum^ he first pointed out that the nucleus does not always accompany the cell through the whole vital ]3rocess at the joeriphery (the original position accord- ing to Schleiden and Schwann), but that it also passes to the centre, as we now well know. Here, also, he declares, but in his third series. Part IT, 1840, he demonstrates^ that there arise in the parent vesicle, two or more infant vesicles, the parent vesicle disappear- ing by liquefaction. And in his third series, p. 529, he says, “The germinal vesicle does not burst, or dis- solve away, or become flattened, on or before the fecun- * Paget, Keport on the Progress of Anatomy and Physiology, Br. and For. Med. Rev., July, 1846. THE CELL DOCTRINE. 49 elation of the ovum as hitherto supposed. It ceases to be pellucid. And on page 531, “The germinal vesicle fills with cells, and these become tilled with the foundations of other cells ; so that the germinal vesicle is gradually rendered opaque.” lie also describes in this series, in great detail, the mode in which these cells are produced from the germinal spot^ which he considers in the light of a nucleus to the germinal vesicle. Part II, 1839, p. 360. And though the minute details may not pre- cisely accord with those of the most recent “observa- tions, the correct idea is clearly grasped. In fact, it may be said that in minuteness of detail alone does he differ from later observers, and had he simply stated that the young cells arise from the nucleus or nucleolus of the parent cell, he would accord pre- cisely with the most recent observers. But he is, if possible, even more explicit when he says, “ The pro- cess inherited from the germinal vesicle by its off- spring, reappears in the descendants of these. Every cell, whatever its minuteness, if its interior be dis- ceined, is filled with the foundations of new cells, into which its nucleus has been resolved.” Again he says,* “ Schleiden has seen the nucleus undergoing such changes (division), but failed to recognize them.” And finally, in “ Philosophical Transactions ” for 1841, pp. 207-8, we have the following striking paragraphs, which would seem also to correct some previous errors : ‘‘ § 77. I am very much inclined to believe, that * Barry, Philosophical Transac., 1840, p. 348, I 385. 5 I 50 THE CELL DOCTRINE. in the many instances in which authors on ^cells’ have described and figured more than one nucleolus in a nucleus, there has been either an incipient divi- sion of the nucleus into discs, or the nucleus has consisted of two or more discs ; the nucleoli of those authors having been the minute and highly refract- ing cavities or depressions in the discs. If this has really been the case, it affords additional evidence, I think, that the I'eproduction of cells by the process I have described — namely^ division of the nucleus of the parent cell — is universal — so numerous have been the in- stances in question. I may refer to the figures givmn by Schwann, who examined nearly every tissue, and to those of Schleiden, whose observations have been so extensive on plants. I think, indeed, that many of the figures of Schwann afford evidence of the division in question having taken place. It is to be recognized in his delineation of the cells of cartilage, cellular tissue, middle coat of the aorta, muscle, ten- don, feather, etc. The same remark is applicable to a figure given by Reichert of ciliated epithelium cells. Dr. Henle found that in the layers of his ‘ pilaster-epithelium ’ cells, the nucleus, very distinct in the lower cells, had almost disappeared in those situated in the upper part. From this observation, and from the presence of two nucleoli in some of the nuclei figured by this observer, as well as from the nucleus becoming more granular,! think it extremely probable that these cells (including those of the epi- dermis), are reproduced by the process just referred to, — division of the nucleus ; additions being no doubt continuously made at the lower part of the layer, hy ‘ which cells previously there are pushed fartlier out.’ THE CELL DOCTRINE. 51 “ § 83. The nuclei which various observers have found lying among the fibres of various- tissues, have been considered by them as the ‘ remains of cells.’ This may have been the case, but so far from think- ing with those observers, that the nuclei in question were ‘ destined to be absorbed,’ I am disposed to con- sider that they were sources from which there would have arisen new cells.” Without doubt, we can say, as did Goodsir,* in the above by Martin Barry, we have the “ first consistent account of the development of cells from a parent centre, and more especially of the appearance of centres within the original sphere.” N^othing more definite, or directly to the point, could be desired, and we think it may be justly said of Barry, that he completed the expression of the cell theory in- augurated by Schleiden and Schwann, in modifying the mode of origin to conform to most recent obser- vation. PROF. JOHN GOODSIR, 1845. In 1845, Prof. John Goodsir published his paper on “Centres of ISTutrition,”! in “ Anatomical and Patho- logical Observations,” in which he clearly grasped the two important principles of the modern Cellular Pa- thology ; firsts the activity oi these centres (nuclei), their power “ to draw from the capillary vessels, or from other sources, the materials of nutrition, and to distrib- ute them by development to each organ or texture after its kind ; ” second^ the origin of such centres or nuclei * Goodsir, Turner’s Edition of Anatomical Memoirs. Edin- burgh, 1868. Note on p. 390. t Goodsir, op. citat., p, 389. 52 THE CELL DOCTRINE. from previously existing nuclei. In this short paper of three pages, are contained, as stated, the essentials of the cell doctrine of Virchow, .and as it has recentl^^ as- sumed additional interest on controversial* o;rounds, it may be well to introduce as much as bears directl}^ upon the subject. “ The centre of nutrition with which we are most familiar, is that from which the wdiole organism derives its origin, — tlie germinal spot of the ovum. From this, all the other centres are derived, either mediately or immediately; and in directions, numbers, and arrangements, Avhich induce the configuration and structure of the being. As the entire organism is formed at first, not by si- multaneous formation of its parts, but by the suc- cessive development of these from one centre, so the various parts arise each from its own centre, this bein^ the orio:inal source of all the centres with which the part is ultimately supplied. ‘‘From this it follows, not only that the entire or- ganism, as has been stated by the authors of the cellular theory, consists of simple or developed cells, each having a peculiar independant vitality, but that there is in addition, a division of the whole into departments^ each containing a certain number of de- veloped cells, all of which hold certain relations to one central or capital cell^ around which they are grouped. It would appear that from this central cell, all the other cells of its department derive their origin. It is the mother of all those within its own territorv. 4/ * Edinburgh Monthly Medical Journal, February and April, 1869, pp. 766 and 959. THE CELL DOCTRINE. 53 It lias absorbed materials of noarishment for them while in a state of development, and has passed them oft' after they have been fully formed, or have arrived at a stage of growth when they can be de- veloped by their own powers. Centres of nutrition are of two kinds, — those which are peculiar to the textures, and those which belong to the organs. The nutritive centres of the textures are in general permanent. Those of the organs are in most instances peculiar to their em- bryonic stage, and either disappear ultimately or break up into the various centres of the textures of which the organs are composed. “ A nutritive centre^ anatomically considered^ is merely a cell^ the nucleus of which is the permanent source of successive broods of young cells^ which from time to time fill the cavity of their parent, pass off in certain directions and under various forms, according to the texture or organ of which their parent forms a part.” Prof. Goodsir does not fail to state in the first para- graph of his paper, that with many of these centres anatomists have been for some time familiar, but • further remarks, that with few exceptions they have looked upon them as embryonic structures. He al- ludes in a note to the observations of Bowman and Barry, the former on Muscle,” and the latter “On the C^orpuscles of the Blood,” in Philosophical Trans- actions, respectively, of 1840 and 1841, and states in a second note that “ for the first consistent account of the development of cells from a parent centre, and more especially the appearance of new centres within the original sphere, we are indebted to Martin 5* 54 THE CELL DOCTRINE. Barry.”* * * § We have carefully read the references in each instance. In Bowman’s paperf we can recog- nize a brief reference to a possible influence of the cell upon nutrition, but none as to its origin, in the following sentence: ‘‘It is, however, not impossible, that in all these cases, there may be during develop- ment, and subsequently, a further and successive de- posit of corpuscles (nuclei) from which both growth and nutrition may take their source.” That Dr. Barry’s paper is more explicit has been shown. REMAK, 1853-55. Remak:}: defended most effectually the view that cells originate from previously existing cells hy divi- sion., and that at least in the early stages of the de- velopment of the embryo, no other mode of cell devel- opment occurs than by division. Rernak also con- tended for, and according to Strieker, § established the same law in respect to the pathological develop- ment of cells, although Strieker admits also that Virchow played an important part in the extension of our knowledge in this direction. HUXLEY, 1853.11 Allusion has already been made to Prof. Huxley * Goodsir, Anatomical Memoirs, vol. ii, p. 389, and note on pp. 390-91. I Bowman, “ Muscle,” Philos. Transac., 1840, pt. i, p. 485. J Remak, Untersuchung iiber die Entwickelung der AVirtel- tliiere. Berlin, 1852-55. § Strieker, Manual of Human and Corporative Histology. New Syd. Soc. Transl., 1870, p, 34. Ij We presume it will scarcely be inferred by any reader, that THE CELL DOCTRINE. 55 in connection with WolfF, of whose theory he has been the able exponent. In the same pa[)er* he has given us his own views — ‘‘conceived in the spirit, and not unfreqnently borrowing the phraseology, of AVolff and Von Baer.” AVe present them, as far as may be consistent with brevity, in his own words : “ A^itality, the faculty, that is, of exhibiting defi- nite cycles of change in form and composition, is a property inherent in certain kinds of matter.. There is a condition of all kinds of livino- matter in which O it is an amorphous germ — that is, in which its exter- nal form depends merely on ordinary physical laws, and in Avhich it possesses no internal structure. Vow, according to the nature of certain previous condi- tions, the character of the changes undergone, or the different states exhibited — or, in other words, the successive differentiations of the amorphous mass will be different. “ The morphological differentiation may be of two the A^ews of Prof. Huxley here presented are brought forward as those now entertained by him, and with which the public have been made so generally familiar through his lecture on “Proto- plasm,” or the “ Physical Basis of Life,” delivered at Edinburgh, November 18th, 1868, and originally published in the “ Fort- nightly Review” for February, 1869; but also largely republished in numerous English and American periodicals, as well as in a separate pamphlet, to be had of the publishers of the Yale College Courant, New Haven, Conn. To one closely observing, however, we think that these latter views will appear to be foreshadowed in the theory here given, and which we think of sufficient his- torical importance to justify its presentation here. * Huxley, Review of the Cell Theory. Br. and For. Med. Chir. Rev., October, 1853, p. 305. I 56 THE CELL DOCTRINE. kinds. In the lowest animals and plants, — the so- called unicellular organisms — it may be said to be ex- ternal^ the changes of form being essentially confined to the outward shape of the germ, and being unac- companied by the development of any internal struc- ture. ‘‘ But in all other animals and plants, an internal morphological differentiation precedes or accompa- nies the external, and the homogeneous germ becomes separated into a certain central portion, which we have called the endojplast^ and a peripheral portion, the periplast. Inasmuch as the separate existence of the former necessarily implies a cavity in which it lies, the germ in this state constitutes a vesicle with a central particle., or a ‘ nucleated cell.’ There is no evidence whatever that the molecular forces of the liv- ing matter (the ‘ vis essentialis ’ of Wolff, or the vital forces of the moderns), are by this act of differentia- tion localized in the endoplast to the exclusion of the periplast, or vice versa. Neither is there any evi- dence that any attraction or other influence is exercised hy the one over the other ; the changes which each sub- sequently undergoes, though they are in harmony, having no causal connection with one another., but each proceeding, as it would seem in accordance with the general determining laws of the organism. On the other hand, the ‘ vis essentialis ’ appears to have es- sentially different and independent ends in view, in thus separating the endoplast from the periplast. “ The endoplast (nucleus) grows and divides ; but, except in a few more or less doubtful cases, it would seem to undergo no other morphological change. It THE CELL DOCTRINE. 57 frequently disappears altogether ; but as a rule it undergoes neither chemical nor morphological meta- morphosis. So far from being the centre of activity of the vital actions, it would appear much rather to be the less important histological element. “ Tlie periplast^ on the other hand, which has hitherto passed under the name of cell-wall, contents and intercellular substance,, is the subject of all the most important metamorphic processes, whether mor- phological or chemical, in the animal and plant. By its differentiation, every variety of tissue is pro- duced ; and this differentiation is the result, not of any metabolic action of the endojylast^ which has fre- quently disappeared before the metamorphosis begins, but the intimate molecular chamres in its substance, which take place under the guidance of the ‘ vis essentialis,’ or, to use a strictly positive phrase, occur in a definite order, we know not why. “ The metamorphoses of the periplastic substance are twofold, — chemical and structural. The former {chemical)., ma}^ be of the nature either of conversion, — change of cellulose into xylogen, intercellular sub- stance, etc., of the indifferent tissues of embryos, into collagen, chondrin, etc., — or of deposit, — as of silica in plants, of calcareous salts in animals. The structural metamorphoses, again, are of two kinds, vacuolation or the formation of cavities, as in the intercellular passages of plants, the first vascular canals of animals; and fibrillation, or the develop- ment ot a tendency to break up in certain definite lines rather than in others.’’ Ihese views he illustrates by examples from vege- 58 THE CELL DOCTRINE. table life in the sphagnum leaf, and from animal life in connective tissue and striped muscle. As characteristic and distinguishing features of this theoiy, we desire to point out, first, the substi- tution of the term ‘‘ endoplast ” for “ nucleus ; ” that of periplast for “ cell-wall,” and ‘‘ intercellular,” “ substance.” Second, the absolutely passive nature of the “ endoplast,” which is neither itself the author of changes nor the subject of changes. Third, the passive nature as well of the “periplast,” so far as it is the author of changes, though it is pre-emi- nently t\\Q subject of changes, the seat in which changes take place. And herein, we believe Huxley to have been misinterpreted by some who have presented his views elsewhere, as Dr. Beale,* who repre- sents him as believing the periplast active, that it is the efficient agent, that it sends in partitions, etc. But that Prof. Huxley considered it passive we be- lieve may be legitimately inferred from his text. As the seat of change, however, accomplished not as “ the result of any metabolic action of the endoplast, but of intimate molecular changes in its substance, which take place under the guidance of the vis essen- tialis.^^ i\iQ periplastic differentiated into every variety of tissue. Finally, we have the distinct admission, as seen in the sentence last quoted, and also through- out the entire expression of the theory, of a con- trolling, guiding principle, through which the differ- * Beale, Microscope in Medicine. Tliird Edition. London, 1867, page 147. Beale, Structure and Growth of the Tissues, London, 1865, pp. 9, 10. THE CELL DOCTRINE. 59 entiation isaccomplislied. This principle, which is here referred to as the “ vis essentiaiis,” is elsewhere in- cluded under the expressions “ vitality,” and “ general deterniinino; laws of the organism.” Though this ad- mission is seemingly so at variance with the views of the same observer in 1870, when, in common with other physicists, he emphatically denied the exist- ence of “ vital force,” or even such a thing as life itself, yet, as already intimated, we deem it possible to detect a foreshadowing of his more modern views, in the following paragraph of the paper whence we have derived our information ; We have therefore maintained the broad doctrine established by Wolff, that the vital phenomena are not necessarily preceded by organization, nor are in any way the result or effect of formed parts, but that the faculty of manifesting them resides in the matter of which living bodies are composed, as such ; or, to use the language of the day, that the vital forces are molecular forces. Huxley moreover says that the three botanical data upon which Schwann’s theory was based, viz. : 1. The anatomical independence of the vegetable cell as a separate entity. 2. His conception of the structure of the vege- table cell, and 3. Its mode of development, were all erroneous. Since first, he (Huxley) considers that the fact that by certain chemical or mechanical means, a plant may be broken up into vesicles, corresponding * Huxley, loc. citat., p. 314. 60 THE CELL DOCTRINE. with the cavities which previously existed in it, is of no more value in proving the independence of these vesicles, than the fact that a rhombohedron of spar, broken up with the hammer, into minute rhombohe- drons, is evidence that those minuter ones were once independent, and formed the larger by their coales- cence. Second, Schwann’s view of the anatomy of the cell was incorrect, since he regarded the nucleus as in- variably present, whereas in certain vegetable cells (as in Ilydrodictyon, Vaucheria, Caulerpa, Sphag- num), it is indubitably absent ; and since he did not include the nitrogenous primordial utricle, discov- ered by Mohl, in 1844,* as one of the elements of the cell. Finally, Schwann’s mode of cell-development is erronous, having ‘‘ been long since set aside by the common consent of all observers;” cell-development always occurring by division^ except in the embryo sac of the Phanerogamia, the sporangia of Lichens, and of some Algre and Fungi ; and even the free cell-development of the latter is quite different from that of Schleiden and Schwann, being by the develop- ment of a cellulose membrane (periplast) around a mass of nitrogenous substance (endoplast), which may or may not contain a nucleus. The difference between the views of Schwann and Huxley are best expressed by the latter in the con- trast he draws between those of Schwann and Wolff : * The existence of the primordial utricle is denied by many botanists of the present day. THE CELL DOCTRINE. 61 “ For ScLwami, the organism is a beeliive, its action and forces resulting from the separate but harmo- nious action of all its parts. For Wolff* (and Hux- ley), it is a mosaic, every portion of which expresses only the conditions under which the formative power acted, and the tendencies by which it was guided.” The statements of Prof. Huxley with regard to cell-development entirely accord with the most recent observations on the subject, and are quite important to us in tracing out the present state of the cell doctrine. J. HUGHES BENNETT, 1855.* I)r. Bennett, of Edinburgh, considered that ‘Hhe ultimate parts of organization are not cells nor nu- clei, but the minute molecules from which these are formed They possess independent physical and vital properties, which enable them to unite and arrano’e themselves so as to produce higher forms. Among these are nuclei, cells, fibres, and membranes, all of which may be produced directly from molecules. The development and growth of organic tissues is owing to the successive formation of histoo-enetic and hystolytic molecules. The breaking down of one substance is often the necessary step to the for- mation of another; so that the histolytic or disin- * Bennett’s Practice of Medicine. Am. Ed. of William Wood & Co., N. Y., 1866, p. 118. I rof. Bennett has further elaborated his views in the Edinburgh Medical Journal, March, 1868, and The Popular Science Review, January, 1869, but his conclusions are substantially the same as quoted. 6 62 THE CELL DOCTRINE. tegrative molecules of one period become the bisto- genetic or formative molecules of another.” Again : “ As to development, the molecular is the basis of all the tissues. The first step in the process of organic formation is the production of an organic fluid ; the second, the precipitation in it of organic molecules, from which, according to the molecular law of growth, all other textures are derived either directly or indirectly.”* Figs. 4, 5, 6, 7, illustrate these views amply. Fig. 4, Molecular structure of the scum on its first appearance, in a clear ani- mal infusion. Fig. 5, Molecular structure of the same six hours afterwards. The molecules are separated, and the long ones (so-called vibriones) in active movement. Fig. 6, The same on the second day. Fig. 7, Filaments (so-called spirilla) formed by aggregation of the molecules, in the same scum on the third and fourth days, all in rapid motion. 800 diam. linear. (From Bennett’s Prac- tice.) Prof. Bennett contends, also, that morbid growths may easily be shown to originate in a molecular blastema, though not to the exclusion of pre-existing cells. The accompanying figures are sufliciently ex- planatory. It should be stated also that this author, in com- mon with others not accepting the cell doctrine in its entirety, admits the production of cells by buds, division or proliferation, without a new act of gen- eration, and that “ this fact comprehends most of the admitted observations having reference to the cell doctrine.”t Fig. 4. Fig. 5. Fig. 6. Fig. 7. * Op. citat., p. 119. I Op. citat., p. 123. THE CELL DOCTRINE. 63 We have in the expression of this theory, a prac- tical admission of the spontaneous origin of animal life, of which Dr. Bennett, in the paper referred to in the Popular Science Review^ for January, 1869, Fig. 8. Fig. 9. Fig. 10. Fig. 11. Fig. 8, Nuclei imbedded in a molecular blastema. Fig. 9, Young fibre-cells formed by the aggregation of molecules around the nuclei of Fig. 8. Fig. 10, Cancer cells, one with a double nucleus. Fig. 11, Histolytic or so-called granule- cells, breaking down from fatty degeneration. 250 diam. linear. (From Ben- nett’s Practice.) openly declares himself the advocate, while the views are in no way essentially different from those of Schwann. Closely allied to this theory is the so-called in- vestment or cluster theory (Umhiillungs-theorie), de- scribed by Virchow on page 53 of Cellular Pathology (Am. Ed. of Chance’s Translation) : according to which ‘‘ originally a number of elementary globules Fig. 12. Diagram of the Investment (cluster) theory, a. Separate elementary granules. 5, Heap of granules (cluster), c, Granule-cell, with membrane and nucleus. existed scattered throughout a fluid, but that under certain circumstances they gathered together, not in the form of vesicular membranes, but so as to consti- tute a compact heap, a globe (mass, cluster — Kliimp- chen), and that this globe was the starting-point of 64 THE CELL DOCTRINE. all further development, a membrane being formed outside and a nucleus inside, by the differentiation of the mass, by apposition, or intussusception.” TODD AND BOWMAN, 1856. Notwithstanding earlier approximations to the truth, we find free cell formation still admitted by the eminent authorities, Todd and Bowman, as one mode of origin of cells, so late ‘as December, 1856, though the spontaneous origin of organs is spoken of as ex- ceedingly doubtful. After describing the elements of the ovum, considered in its entirety as a nucleated cell, and referring to the period after fecundation, it is stated, “At this period the embryo consists of an aggregate of cells, and its further growth takes place by the development of new ones. This may be ac- complished in two ways: first, by the development of new cells within the old, through the subdivision of the nucleus into two or more segments, and the formation of a cell around each, which then becomes the nucleus of a new cell, and may in its turn be the parent of other nuclei ; and, secondly, by the forma- tion of a granular deposit between the cells, in which the development of the new cells takes place. The granules cohere to each other in separate groups^ here and there^ to form nuclei^ and around each of these a delicate membrane is formed^ ivhich is the cell membrane. The nuclei have been named cytoblasts, because they appear to form the cells ; and the granular deposit in which these changes take place is called the cytohlastema. “ In every part of the embryo the formation of nuclei and of cells ^oes on in one or both of the wavs TEIE CELL DOCTRINE. 65 above mentioned, and, by and by, ulterior changes take place, for the production of the elementary parts of the tissues.”* Thus did physiologists adhere to the original free cell formation of Schleiden and Schwann. Sinni- larly, Dr. Carpenter,t who expressly states, in his Manual of Physiology, edition of 1865, that he has been led to the view of Professor Beale by compari- son of the results of the recent inquiries of several British and Continental histologists wuth those of his own studies, says, a few pages further on (p. 150), “Xew cells may originate in one of two principal modes; either directly from a previously existing cell, or by an entirely new process in the midst of an organizable blastema.” He then proceeds to give the two methods iu detail, without in any way deny- ing the latter. VIRCHOW, 1858. I^ess than two years later, August 20th, 1858, Prof. Virchow published his “ Cellular Pathology, as based upon Physiological and Pathological His- tology.” According to him, the cell is the only possible starting-point for all biological doctrines. Ihis cell can only originate from a previously exist- ing cell, taking its primary origin from the ovum, and the Ilarveian maxim oinuc vivuui. ex ovo, becomes in its special application, omnis cellida e celluld. This N * Todd and Bowman, The Physiological Anatomy and Physi- ology of 31an. Am. Edit., Philadelphia, 1857, p. 63. f Carpenter, Manual of Physiology. London, 1865. Note on p. 14. 6* 66 THE CELL DOCTRINE. is true of all physiological and pathological processes in the vegetable and animal. In all editions of “Cellular Pathology” which we have met, the typical cell is described as consisting essentially of “cell-wall,” “cell contents,” and “nucleus;” the “ nucleolus,” thougji usually met in fully developed older forms, is not considered an essential constit- uent of the cell. The object of the “ nucleus,” ac- cording to Virchow, is entirely connected with the life of the cell, that which maintains it as an element and which insures its reproduction. While to the “ cell contents ” over and above the nucleus, that is the “ residual cell contents,” is due the f unction of the cell, that to which is due the contractility of muscle, the neurility and sensation of nerve, and the secretory office of the gland cell.’^ To secure the universal application of the cell doctrine, it becomes necessary to eliminate from the vegetable cell, the external non-nitrogenous mem- brane known as cellulose, and restrict it to the nitro- genized portion comprised in the finmordial utricle as the proper cell-wall^ and in the protoplasmic con- tents of the cavity as the proper cell contents, which contain also the nucleus. “ It is only when we ad- here to this view of the matter, when we separate from the cell all that has been added to it as an after- development, that we obtain a simple, homogeneous, * Virchow, Cellular Pathology, as based upon Physiological and Pathological Histology. Second Edition. Translated by Frank Chance, M.B., etc. Am. Edition, Philadelphia, 1863, p. 37. THE CELL DOCTRINE. 67 extremely monotonous structure, recurring with ex- traordinary frequency in living organisms.”* More recently, however, Virchow is reported as not regarding the ‘‘ cell-wall ” as an essential part of the cell, as stated in Cellular Pathology ; but that a nucleus surrounded by a molecular blastema teas suffi- cient to constitute a cell ; then he says that the outer part of this cell blastema consolidates and forms a cell-wall as Beale has shown, and that this takes place in the amoeba when placed in water. f As thus defined, the cell is the seat of pathologi- cal and physiological processes rather than the blood, or the nerves. The cell is active — the ultimate mor- phological element in which there is any manifesta- tion of life, and beyond which the seat of real ac- tion cannot be removed. Hence the term Cellular Pathology rather than humoral, or neural, or solid- istic. The so-called exudations are not such in the strict sense of the term, and the cells which they contain, whether of pus or organizable lymph, are the result of proliferation of previously existing cells. Even “ fibrin, wherever it occurs in the body exter- nal to the blood, is not to he regarded as an excre- tion from the blood, but as a local production,” re- sulting from the activity of the cells of the tissue in which it is found, and conveyed to the surface by the transudation of the serous fluids alone. :j; In the * Op. cit., pp. 31, 34. f Letter from Berlin, in Edinburgh Medical Journal, February, 1865. J Virchow, op. cit., pp. 435-6, 68 THE CELL DOCTRINE. above statements we have the first distinctive feature of Virchow’s theory. Again, since every organized body is usually made up of a number of these cells, each independent in itself, yet combined and arranged for the attainment of a special end, and therefore mutually dependent, there result certain communities or cell territories into which the body is portioned out by Virchow. But not only is the relation of these cells to each and to the central cell whence they took their origin mutually dependent, but in many animal tissues, at least, we have the so-called intercellalar substance^ in a certain definite manner dependent upon the cell or cells which it surrounds, so that certain districts belono; to one cell and certain others to another.” Especially is this the case in pathological processes, where sharp boundaries may often be drawn between cell territories. Herein have we the second dis- tinguishing character of Virchow’s theory. There are also a third and fourth distinctive fea- tures. It has already been explained that the prin- ciple of the theory of Schleiden and Schwann lay in this, that every tissue, healthy or morbid, results from the apposition of cells, and that this principle is still observed as correct, the mode of origin of the primary cell being alone the object of dispute. Ac- cording to Virchow, however, it is a special cell which becomes the starting-point of physiological and pathological processes, and by its various meta- morphoses constitutes the healthy or morbid tissue, excepting epithelial formations. This cell is the so- called connective tissue corpuscle^ or cell of the con- THE CELL DOCTRINE. 69 nective tissue, which, according to Virchow, is a cell with all its essential constituents (cell- wall, cell con- tents, and nucleus), and not a nucleus alone, as origi- nally described Schwann, and later by Ilenle* and Landois.f From the well-known universal preva- lence of connective tissue, this view receives support. Thus, it is from the connective tissue corpuscles of the soft, silk-like connective tissue, so universally present in muscle, that the muscular fasciculi are primarily developed. It is from these that nerve- Fig. 13. Fig. 14. Fig. 13. Purulent granulation from the subcutaneous tissue of a rabbit, round about a ligature, a, Connective tissue corpuscles. 6, Enlargement of the cor- puscles with division of the nuclei, c, Division of the cells (granulations), d, Development of the pus-corpuscles. X300. (From Virchow.) Fig. 14. Interstitial purulent inflammation of muscle in a puerperal woman, m m, Primitive muscular fibres, i i, Development of pus-corpuseles by means of the proliferation of the corpuscles of the interstitial connective tissue. X280. (From Virchow.) fibres take their origin. It is by the rapid prolifera- tion of tlmse corpuscles that pus is formed (Figs. 13 and 14) ; it is from the perverted growth and cle- * Henle, Bericht uber die Fortschritte d. Physiol., 1859 ; 1866 p. 41. ’ f Landois, Zeits. f. wiss. Zool., Bd. xvi, p. 1. 70 THE CELL DOCTRINE. velopment of these that tubercle and cancer arise (Fig. 15), and similarly all pathological new forma- ■ tions. ISTone of these products are exudations from Fig. 15. Development of cancer from connective tissue in carcinoma of the breast, a, Connective tissue corpuscles, b, Division of the nuclei, c, Division of the cells. d, Accumulation of the cells in rows, e, Enlargement of the young cells and formation of the groups of cells (foci, Zellenheerde), which fill the alveoli of cancer. /, Further enlargement of cells and groups, g, The same development seen in transverse section. (From Virchow.) the blood, according to Yirchow. They are entirely local in their origin. In these views he is supported by the majority of German observers. Another mode of formation of pus is however ad- mitted by ATrchow, in the growth and development of new cells in epithelium^ whether in cuticle or mu- cous membranes. Whether forms of suppuration exist which may be referred to muscular, nervous, and capillary elements, he considers doubtful. K fourth and final distinctive feature of Virchow’s views, concerning which there is less unanimity, even among German histologists, is his peculiar system of canals or tubes, produced by the anastomosis of one * Virchow, op. citat. , p. 76. f Virchow, op. citat., p. 133, a. f. X Donders, Siebold und Kolliker’s Zeitschrift, Bd. iii. THE CELL DOCTRINE. cell with another, and which he considers must be classed with the great canalicular system of the body, as forming a supplement to the blood and lymphatic vessels, and as filling up the vacancy left by the old vasa serosa, which do not exist.* (See Fig. 16.) Of Fig. 16. Connective: tissue from the embryo of a pig after long-continued boiling. Large spindle-shaped cells, connective tissue corpuscles (Bindegewebeskorper- chen), some isolated and some still imbedded in their basis substance, and anas- tomosing one with the other. Large nuclei with their membrane detached; cell contents in some cases shrunken. X350. (From Virchow.) this system he also considers the cordlike fibres of yellow elastic tissue as forming a part.f These he considers, with Ilonders,:]; as originating by a trans- 72 THE CELL DOCTRINE. formation of the connective tissue corpuscles them- selves. lie says, The transformation of these latter into the former, can gradually he traced with such distinctness, that there remains no doubt, that even the coarser elastic iibres directlv result from a chemi- cal change and condensation of the walls them- selves.* Where originally there lay a cell, provided with a delicate membrane and elongated processes, there we see the membrane gradually increasing in Fig. 17. Elastic networks and fibres from the subcutaneous tissue of the abdomen of a woman, a a, Large elastic bodies (cell bodies), with numerous anastomosing processes, h b, Dense elastic bands of fibres on the border of larger meshes. c c, Moderately thick fibres spirally coiled up at tlie end. d d, Finer elastic fibres, at e with more minute spiral coils. X300. (From Virchow.) thickness and refractin«: the light more strongly, whilst the proper cell contents continually decrease and finally disappear. ‘‘ The whole structure becomes in this way more * Virchow, op. ciUit., p. 133. THE CELL DOCTRINE. 73 homoG^eneoiis, and to a certain extent sclerotic, and acquires an incredible power of resisting the influ- ence of reagents, so that it is only after long-con- tinned action that even the strongest caustic sub- stances are able to destroy it, whilst it completely resists the caustic alkalies and acids in the des’ree of concentration usually employed in microscopical in- vestigation. The farther this change advances, the more does the elasticity of the parts increase, and in sections we usually find these fibres, not straight or elongated, but tortuous, curled up, spirally coiled, or forming little zigzags (Fig. 17, c, e). These are the elements which by virtue of their great elasticity, cause retraction in those parts in which they are found in considerable quantity, as, for example, in the arteries. The fine elastic fibres, which are those which possess the greatest extensibility, are usually distinguished from the broader ones, which certainly do not present themselves in tortuous forms. As re- gards their origin, however, there seems to be no difference between the two kinds: both are derived from thevconnective tissue cells, and their subsequent arrangement is only a reproduction of the original plan. In the place of a tissue consisting of a basis substance and anastomosing reticulated cells, there afterward arises a tissue with its basis substance mapped out by long elastic networks with extremely compact and tough fibres.’’ This may be looked upon as the least well determined of the important points of \irchow’s doctrine, though most German histologists also favor it. Among these may be 74 THE CELL DOCTRINE. classed Kolliker,* * * § C. 0. Weber, f Fried- reich,§ His, II Donders,T Wittich,** * * * *** Bottcher,tt Bill- roth,and Strieker. They are opposed by Schwann, Reichert, and Henle, and find little favor among English and American histoloo’ists. A part of this system, also, according to Virchow, are the so-called dentinal tubules, the lacunae and canaliculi of bone, even the continuity traced by Gerlach,§§ between the ciliated cells of the aqueduct of Fallopius; that by Heidenhain|||| and Brucke\*[ between the lacteals and cylinder epithelium of the intestinal villi of the rabbit, by means of corpuscles of connective tissue ; in the epithelium of the endo- cardium bv Luschka;**^ and the results of similar * Kolliker, Manual of Human Microscopic Anatomy, p. 41, 1860. Also recent paper, in which be completely assents to Vir- chow’s views, according to N, Y. Quart. J. Pschy. Med., July, 1869. f Weber, C. O., Virchow’s Archiv, End. xiii-xv. t Le^'dig, Handbuch der Histologic, 1856. § Friedreich, Virchow’s Archiv, Bd. xv. . II His, Beitriige zur Normalen und Pathol. Histol. d. Cornea. Basel, 1856. ^ Do riders, loc. citat. ** Wittich, Virchow’s Archiv, Bd. ix. ff Bottcher, Virchow’s Archiv, Bd. xiii. Billroth, in Beitriige zur Pathol. Histol., 1858, admits all but the tubular nature of the processes. Gerlach, Mikrosk. Studien, 1858. III! Heidenhaiii; Moleschott’s Untersuchungen, Bd. iv, 1858, p. 251. Briicke, Moleschott’s Untersuchungen, Bd. viii, 1862, p. 495. *** Luschka, Virchow’s Archiv, Bd. ix, p. 569. THE CE^L DOCTRINE. 75 observations by Eckbart,* Eillrotb,f and Fried- reich. The other fibrous element of areolar or connective tissue, which forms the mass of its bulk, the jywre ichite fibrous or waving, does not, according to Vir- chow, have its origin in cells, but is a modification of a previously homogeneous intercellular substance, deposited between the cells, a view which in its glar- ing departure from the primary proposition that the cell is the starting-point, and that every tissue is composed of cells or some modification of cell forms, presents one of the few inconsistencies traceable in the theory of Virchow. AVe think it proper, in a historical memoir of this kind, to refer to some severe critical remarks which appeared in the Edinburgh Mediccd Journal^ of Feb- ruary and April, 1869, in which Prof. Virchow is ac- cused of appropriating the observations of Prof. Goodsir as his own. That there are points in com- mon, it will be recollected, and, also, that these are 1st, the invariable origin of cells from previously ex- isting cells, and 2d, the division of the tissues into cell territories. !Now on the one hand we deem that the dedication of Virchow’s volume to Prof. Goodsir is as handsome an accredit as could possibly be given for whatever of common there may be in the writings of the two authors, and on the other hand we have seen that Martin Barry is acknowledged even by * Eckhart, Beitrage Anat. und Physiol., 1855. t Billroth, Muller’s Archiv, 1858. t Friedreich, loc. eitat., p. 538. 76 THE CELL DOCTRINE. Good sir, to be the author of the “first consistent account of the development of cells from a parent centre.” The idea of cell territories seems, however, to have originated with Goodsir, nor do we believe, for the reason stated, that Virchow intended to usurp his prerogative. The merit of Virchow consists in his application by actual demonstration of the first ^ of these points to so large a variety of physiological and pathological processes, to which is added original conception in the prominence given to the connec- tive tissue corpuscle and the canalicular system, whatever may be the truth with regard to either. SARCODE or DUJARDIN — PROTOPLASM OF MAX SCIIULTZE. 1835-61. Dujardin* had, in 1835, discovered in the lower animals a living, moving, contractile substance, which he called sarcode. The peculiar appearances of this substance attracted the attention of many ob- servers, among whom were Kiihne, Reichert, Ecker, Ilenle, Meyen, Huxley, Max Schultze, John M tiller, and others. It was thought peculiar to the lower animals, and there was assigned to it a property of “irritability without nerves.”f The observation of Siebold,:}: that the yolk glob- ules (vitelline spheres of the egg) of Planaria exhibit contractions and expansions, which with suitable care continue for hours, and the discoveries which fol- * Dujardin, Ann. d. Sciences Nat., tom. iii et v. f Schultze, INIax, Organis. d. Polythalamien, 1854. t Siebold, Froriep’s Notizen, Nr. 380, p. 85. THE CELL DOCTRINE. 77 lowed of similar movements and changes in form, in colorless blood-corpuscles, pigment cells, and else- where, led Ivolliker* to express the conjecture that the contents of all cells are contractile. Virchowf attributed the ciliary movement to a contractile sub- stance. Leydig:]; and Ecker considered the move- .ments of the yolk spherules as phenomena of life, and Ivlihne§ had studied physiologically and chemi- cally, sarcode and muscular tissue, and pointed out the similarity of the phenomena presented in the act of dying, by both. But all considered sarcode as something different from the animal cell, as a body sid generis. According to Haeckel || the protoplasm or sarcode theory, that is, the theory that the albuminous con- tents of animal and vegetable ceils as well as the treely moving sarcode of Rhizopoda, Myxomycetae, etc., are identical, and that in both cases this albu- minous material is the original active substratum of all vital phenomena, was brought forward in its ele- mentary form by F. Cohr^ in 1850, and by Unger in 1855.** Haeckel says also that it may be considered one of the greatest achievements in modern biology and one of the richest in results. It was further de- * Kolliker, Wurzb. Verb., Bd. viii. t Virchow, Archiv, Band v., 1853. X Leydig, Handbuch der Histologic, 1856. ^ Kuhne, Miill. Arcbiv, 1859, p. 817. II Quart. .J. Mic. Sc. July, 1869, 'p. 223. ^ F. Cobn, Nachtrage zur Naturgeschicbte des protococcus plu- vialis. Nova Acta Ac. Leop. Carol., vol. xxii, pars. 2, 1850, p. 605. ** Unger, Anatomic und Physiologic d. Pflanzcn, 1855. 7* 78 THE CELL DOCTRINE. veloped by Max Schultze in 1858, and finally’ estal)- lisbed by him in 1861.* He first showed the anal- ogy between sarcode and the contents of the animal cell, and that the entire infusorial world, simple or compound, is made up of cells, thus extending the tj^pical formative element of Schwann to the entire organized creation. The comparison between sarcode and the proto- plasm of plants on the one hand, and that of animal cells on the other, was also made by Pringsheim,f E. Briicke,! E. Haeckel, § and W. Kuhne,!| and by their efforts, together with those of Max Schultze, Unger, and Cohn, our knowledge of the indepen- dent life of the cell was extended, in a very short space of time, further than in the twenty years pre- vious.T The name jyrotoplasm for a portion of the contents of the animal cell had already been brought into use by Remak, who extended it from the layer which bore that name in the veo;etable cell to the analoo;ous element in the animal cell.** * Schultze, Max, Miill. Archiv, 1861, p. 17. f Pringsheim, Untersuchungon iiber d. Ban. a. d. Bildung d. Pflanzenzellen, 1854. I Briicke, E., Elementar-organismen, Wien. Sitzungsb., 1861. I Haeckel, E., Die Radiolaren, 1862. |j Kiihne, W., Protoplasm und die Contractilitat. Lpzg., 1864. ^ Strieker, S., Handbuch der Lehre von den Geweben des Menschen und der Thiere. Leipzig, 1868, p. 3, German Ed. ** Sterling, J. H., As regards Protoplasm in relation to Prof. Huxley’s Essay on the Physical Basis of Life. Edinburgh, 1869, p. 14. Conf, also McNab, Monthly Microsc. J., No. xvii, vol. iii, 1870, p. 33. THE CELL DOCTRINE. 79 Prill o'sbcirn licid also shown, in 1854, tluit no such membrane as a primordial utricle existed, but that all within the cellulose wall of the living vegetable cell was 'protopi asm and cell fluid, however complex its composition. He admitted that in the cortical layer of the pro- toplasma a distinct arrangement into layers often occurred, and these be distinguished as the cutaneous and granular layers of the protoplasma, but be de- nied that the primordial utricle could be differen- tiated as a membrane from the subjacent protoplasm. If, in animal cells, partly from their relatively small size, and partly from their greater average wealth in protoplasma, it is more rarely possible to make a sharp demarcation between a cortical layer of pro- toplasm and a cell fluid, there nevertheless exists a difference in the constitution of the former, such that a cutaneous layer, destitute of or scantily sup- plied with granules, incloses the remaining more granular material. The white blood cell may serve as an example. This is, however, very different from a proper membrane.”* Ungerf (1855), had been struck with the close similarity of the mobile phenomena of the Polytha- lamiie with those of the processes of protoplasm stretched across the cavity of many vegetable cells. Although he had not personally investigated the for- mer, he became convinced from Schultze’s description that a resemblance amounting to identity existed * Duffin, A. B,, On Protoplasm. Quart. Jour. Mic. Sci., N. S., vol. iii, 1863, p. 252. t Unger, op. citat., p. 280. 80 THE CELL DOCTRINE. between their movements and the protoplasm streams of veo;etable cells.* * * § Leydig,f in 1856, claimed for the contents of the cell a higher dignity than for the membrane or cell- wall. He claimed that a cell was hut 'protoplasm (klumpchen-substanz) indosing a nucleus. The cell membrane, according to him, was simply the hard- ened periphery of the substance of the cell. To Max Schultze, however, as already stated, be- longs the credit of having fully overturned the vesic- ular idea of cells In 1861,:}; he insisted upon some modification of prevailing views, respecting the rela- tion of cell-wall to cell contents, and contended for a higher position for that part of the cell correspond- ing to the protoplasm of Von Mold (that within the so-called primordial utricle), and showed how a care- ful study of the phenomena presented by the pseudo- podia, extended by the various Rhizopods, might aid in clearing up the life of the elements of the cell. He also' defined the cell as protoplasm surround- ing a nudeusd The importance of this definition, as stated by Stricker,§ lay not so much in the fact that many cells were denied a cell-wall, as that the so-called cell contents could now be made to har- monize with the animal primordial substance or sar- code. Schultze illustrates his definition by the em- * Duffin, A. B., loc. citat., p. 252. f Leydig, op. citat. I Schultze, Max, Ueber Muskelkorperchen, in Reichert and Du- bois Ileymond’s Archiv, 1861. § Strieker, op, citat., 5. (German Ed.) THE CELL DOCTRINE. 81 biyo cells resulting from the segmentation of the ovum, as typical cells, which are thus composed of proto- plasm surrounding a nucleus, which nucleus, as well as protoplasm, are products of like constituent parts of another similar cell. “The cell leads in itself an independent life, of which the protoplasm is espe- cially the seat, although to the nucleus also undoubt- edly falls a most important, though not yet precisely determined role. Protoplasm is for the most part no further distinct than that it will not comming:le with the surrounding medium, and in the peculiarity that with the nucleus it forms a unit. Upon the surface of the protoplasm, there may form a mem- brane, which, although derived from may he chemi- cally different^ and the assertion that it is the begin- ning of a retrogression may be defended. A cell with a membrane cannot divide itself, unless the proto- plasm within the membrane divides itself. A cell within a membrane chemically different from proto- plasm, is like an encysted infusorium.”* Briicket went even further in his definition, and said that it was not shown that the nucleus even is an essential element of the cell. In proof of which he adduces the cells of cryptogams and says; “We have no positive knowledge either of the origin or function of the nucleus, and, indeed, the constancy of its occurrence seems subject to certain limitations if we take into consideration the cells of cryptogams, '■ Schultze, Max, Protopl. cl. Khizopoden. Leipzig, 1863. f Briicke, E., Die Elementar-organismen, p. 18-22. 1861. 82 THE CELL BOCTRINE. and do not start out with the belief that the nucleus is there even though do not see it.” Facts in justification of Briicke’s doubt are adduced hy Strieker* in the discovery by Max Schultze,t in the Adriatic Sea, of a non-nucleated amoeba (Amoeba por recta), by Hseckel,:}; in the Mediterranean, of a non-nucleated protozoon (Protogenes primordialis), and by Cienkowsky§ of two non-nucleated monads, namely, Monas amyli and Protomonas amyli. Haec- kel says of his Ih’otogenes primordialis that it mul- tiplies by division. Stricker’s|| own observations on the fecundated egg of the frog, which confirm those of Von Baer, incline him to adopt the view of Briicke, and to omit the nucleus in a theory of elementary organization. ®|[ Such is the history of and such the properties of the substance known as protoplasm.” But of late * Strieker, op. citat., p. 6. (German Ed.) f Sehultze, Max, Organis. d. Polythalam. 1854. t Haeckel, Zeitschr. f. w. Zoolog., 1865, Bd. xv. ^ Cienkowsky, Max Schultze’s Arehiv, 1865. II Strieker, op. citat., New Sydenham Society's Translation, vol. i, p. 8, London, 1870. See also Strieker’s paper On the De- velopment of the Simple Tissues, in vol. iii, London, 1873. ^ HaeckeU also considers that by no phenomena is the correct- ness of the “ protoplasm theory ” so thoroughly proved, and at the same time in so simple and unassailable a manner, as by the vital phenomena of the Monera, by the processes of their nourishment and reproduction, sensitiveness and motion, which entirely pro- ceed from one and the same very simple substance, a true “ primi- tive slime.” * Heeckel, Ernst, Monograpli on the INIonera, and Remarks on the Protoplasm Theory. Q. Jour. Mic. Sci., N. S. vol. ix, 1869. THE CELL DOCTRINE. 83 years another meaning has been given to the term, an anatomical one, in which the original general ap- 23lication has been altogether ignored, and that is that part of the cell outside of the nucleus without re- gard to the properties of the matter, corresponding to the “cell contents ” in cells wliich have a cell-wall. Thus we speak of the protoplasm of the colorless corpuscle or the liver-cell, or of the squamous epithe- lial cell, whereas the properties of the substance thus named are vastly ditferent. In the former two in- stances living growing matter is meant, in the latter dead formless material, incapable of growth and re- production through its own inherent properties. These differences should be always remembered. With these general considerations in the history of “ protoplasm,” we are the better prepared to take up the theory of DR. BEALE, 1861- In April and May, 1861, Prof. Lionel S. Beale de- livered the lectures before the Royal College of Phy- sicians of London, in which he promulgated the views which have since been further elaborated and become permanently associated with his name. These views were published in part, in Beale’s “ Archives of Medicine,” and in September, 1861, in a volume “ On the Structure of the Simple Tissues of the Human Body,” in the preface to which he says, “ he thinks it right to state that the conclusions which have now assumed a definite form have gradually grown upon him during the course of observations 84 THE CELL DOCTRINE. extending over a period of several years. In fact some of the drawings in this volume, and others which have been published elsewhere, equally favor- able to this view, were made long before any specific theory had been arrived at.” The ‘‘ cell^^ or “ elementary part^^ as Dr. Beale pre- fers to call it, is composed of matter in two states, matter which forming^ and matter which is formed ; matter which has the power of growing by produc- ing matter like itself out of p>^-^^ulum or food, and matter which possesses no such power, but results from the death of the forming matter. The former is known as germinal or living matter, the latter as formed matter. The former, in varying quantity in ditferent cells, is central in its situation (see frontis- piece, Fig. 17), and includes what has been called by others nucleus, cell contents, protoplasm, endoplast. The latter, also present in ditterent quantity in difter- ent cells, is peripheral (frontispiece. Fig. 17), and in- cludes what is known as cell-wall, periplast, inter- cellular substance, and products of secretion. In its structural characters, germinal matter is 50/?, transparent^ colorless^ and as far as can be determined by the highest powers, structureless^ being visible only through its ditierence in refracting power as compared with the menstruum in which it fioats, or by the granular matter it may entangle ; and these characters are the same at every period of its exist- ence.' In the simplest vegetables they may be studied, in the thallus of the sugar fungus, among the lowest animals, in the amoeba (frontispiece. Fig. 16), and in higher animals in the mucus-, pus-, or white blood-cor- THE CELL DOCTRINE. 85 puscles (frontispiece, Fig. 10), all of which are com- posed almost purely of germinal matter; the very thin periphery of formed material being scarcely appreci- able or distinguishable from the diffraction band. In its endowments and jjrojwrties, germinal matter is acting^ living^ growing^ and moving ^ through some inherent power of its own. It alone, as stated, is capable of producing material like itself out of pabu- lum, and of multiplying by division, or dropping off of a portion of itself, which portion immediately assumes an independent existence, and grows, main- tains, and reproduces itself like the parent germinal matter. It is also capable of being stained by an ammoniacal solution of carmine, and the younger it is, or more recently formed, the deeper is the stain it assumes. And since the latest formed always ap- pears in the centre of the mass, successive tints, or zones of color, will often be produced in the staining process, growing deeper from without inward, as seen in Fig. 17 of the frontispiece. It has been stated that what is called nucleus by V irchow and others, is included in germinal matter. Ihis is true, though the nucleus is not always the whole of the germinal matter. There may be other older germinal matter beyond the nucleus, on its way to conversion into formed material, but still germinal matter, which assumes a tint with carmine, but not so deep as the nucleus. Thus, the entire mass of the pus-corpuscle (frontispiece. Fig. 10), except, perhaps, its extreme periphery, is germinal matter, yet there is within this another younger portion of germinal matter, taking a deeper tint with carmine, 8 86 THE CELL DOCTRINE. but which alone of the elements of this cell we are in the habit of calling “ nucleus.” The ‘‘ nucleus^'' then, is nothing but a neiD centre of germinal matter, and the “ nucleolus ” is a younger centre. And there may even be within this a still younger portion of living matter, taking even a deeper stain, which might be called a nucieoleohis.^^ By this staining process may we distinguish the nucleolus from a minute oil-drop often mistaken for it, and which will not admit of being stained. On the other hand, germinal matter in a compar- atively quiescent state is often quite destitute of nuclei. But let the mass be freely supplied with nu- trient matter, and nuclei and nucleoli rapidly make their appearance. So with ‘regard to the “ cell contents ” over and above the nucleus, although they may all be germinal matter, yet this is not necessarily the case. Thus in the white blood-corpuscle and mucus-corpuscles, what Virchow would consider cell contents is all ger- minal matter ; but the superficial epithelial cell lining the interior of the mouth has its nucleus alone com- posed of germinal matter, and much that has been described as cell contents is really formed matter. (Figs. 5 and 6 of frontispiece.) More nearly does the germinal matter of Beale* correspond with the ‘^proto- plasm” of Max Schultze, with which, indeed, it seems identical, except that the latter observer seems some- what at a loss how to dispose of the nucleus, of * Beale, Protoplasm; or, Life, Force, and Matter. London, 1870, p. 38. THE CELL DOCTRINE. 87 which he does not speak as a new or young centre of protoplasm. Formed material^ instead of being active^ so far as the vital acts described as characteristic of germinal matter are concerned, is 'passive^ non-acting^ dead^ and can only increase at the expense and death of the germinal matter, on the periphery of which it is formed. It differs widely in its appearance, and is often ‘‘structured” as in muscle and nerve, but not necessarily so, as is seen in the intercellular sub- stance of hyaline cartilage. It possesses also cer- tain properties, different in different situations, and widely different also from those of germinal matter. Thus it is contractile in the sarcous tissue of muscle, exhibits neurility in the nerve, is protective in epi- thelium, is diffluent as the formed material of the milk-cell (milk), and in the formed material of the liver-cell (bile). Again, it is hard and elastic in the intercellular substance of cartilage and epidermis, horn and nails. It does not become stained on being: soaked in weak solution of carmine in ammonia, and if by reason of the strength of the solution it should happen to be stained, the color will wash out on soaking in glycerin, which is not the case with the coloring of the germinal matter. The cause of this permanent staining of the ger- minal matter by an ammoniacal solution of carmine, is thought by Dr. Beale to be due to an acid reaction of this matter, in consequence of which the carmine is precipitated from its alkaline solution. This view would seem to be confirmed by the researches of Ranke on the Reaction of the Tissues. 88 THE CELL DOCTRINE. The size of the elementaiy part, as thus composed, is extremely various. The smallest particles of ger- minal matter, measured by Dr. Beale, are less than TooVoo inch in diameter, and would not be called cells in the ordinary sense of the word, yet they are functionally such ; that is, they grow, multi- ply by division, and under appropriate circumstances assume the characters of fully formed cells. On the other hand, the largest epithelial cells, including their germinal matter and formed material, are often as large as the of an inch in diameter, or larger ; cells of morbid growths are sometimes ^ while the human ovum, which is a typical cell, varies from the 2 7 o' T2o inch. Pure germinal matter is rarely seen in masses as large as the - of an inch in diameter, without breaking up into smaller par- ticles of germinal matter, and as constituting the nuclei of fully formed cells, is usually from guw of an inch in diameter. The m.ethod of production of formed material is best studied in the epithelial structures, particularly in the epithelium lining mucous cavities, of which sec- tions may be easily made down to the vessels whence their nourishment is obtained. In the deep layers, next the nutrient surface, the cells will be found to consist of almost pure germinal matter (frontispiece, Fig. 1), imbedded in a soft, mucus-like,yet continuous formed matter. These masses of germinal matter divide and subdivide, pushing the older masses to- wards the surhice, to make up for those which are constantly exfoliated. While this is going on, how- ever, the germinal matter keeps increasing in size THE CELL DOCTRINE. 89 9 until the cells arrive half way towards the surface, by ahsorptiou of nutrient pabulum, which has to dif- fuse itself through any formed material already ex- isting. At the same time, a portion of the germinal matter is being converted into formed material, which accumulates on its surface, within that already formed, stretching it, and becoming more or less in- corporated with it. lyius, both constituents of the cell increase up to a certain pointy the cells constantly groiring in consequence. As new cells are, however, produced from below, the older ones are removed farther and farther away, the formed matter becoming more and more impervious to nutrient pabulum. At length a point is attained when the entire ceH ceases to in- crease in size, since no pabulum reaches the masses of germinal matter, though the latter is still being converted into formed material. Hence, the masses of germinal matter actually grow smaller as the cell increases in age ; and when the periphery is reached, there remains but a small nucleus of germinal matter, with a large quantity of formed material. Thus, we are enabled to judge of the age of the cell by the relative quantity of germinal matter and formed material ; if the former be large, and the latter small, the cell is young, whereas, if the opposite relation exists, the cell is old and almost ready to exfoliate. But exfoliation in health probably does not take place until the last particle of germinal matter dies, and the entire cell becomes a mass of passive, life- less, formed material. The production of formed material from germinal matter may also be studied in the conversion of the 8* 90 THE CELL DOCTRINE. white blood-corpuscle into the red. In the spring of the year many white corpuscles can be found in the blood of the frog and newt, undergoing conversion into formed material at their edges, where the usual granular appearance is being substituted by the smooth aud slightly colored. This goes on until all except the nucleus is thus converted. In mammalia this change goes on until the whole white corpuscle is thus converted into the red. Secondary Formed Material. — There are certain kinds of formed material to which this term is ap- plied by Dr. Beale. These are the oil of the fat-cell or vesicle and the starch-granule of the vegetable cell. It results, as does all formed material, by a con- version of the germinal matter into this special form. The young fat-cell, as all young cells, is almost pure germinal matter ; as it grows older, however, and is exposed to oxidizing influences, the conversion of germinal matter takes place, partly into the cell-wall proper of the fat- vesicle, and partly into the second- ary formed material or oil, until finally it becomes a mere dot on the inner surface of the cell-wall, or dis- appears altogether. The increase of cells ^ according to Beale, takes place in several waj^s ; every cell coming from a. pre-existing cell., but the germinal matter is always the portion in which it originates. There is not generally a symmetrical division of the nucleus into two, and these into four, as is so often described, and as is often seen in the vegetable cell, hut there is rather a budding, aud subsequent dropping off of tlie portions of germinal matter THE CELL DOCTRINE. 91 wliicli is to produce the new cell, and which almost always assumes the spherical form when allowed to float freely. (See Figure 10 of frontispiece.) Tlie formed material is never active, according to Beale, but entirely passive in the process of cell multiplica- tion. Nutrition of Cells. — So, too, in the nutrition of the cell, the germinal matter is the sole active agent. The formed material may act as a Alter to the nu- trient matter, but is quite passive. The pabulum, which is coursing through the bloodvessels, becomes converted into germinal matter, which in turn be- comes formed material, and so long as this is kept up, the cell continues to grow. The course taken by the pabulum, and the order of conversion, is shown by the arrows, in Figure 17, of frontispiece, and will he readily understood by reference to the explanation. Occasionally, and especially in disease, the formed material may become the pabulum for rapidly mul- tiplying cells, and thus be consumed. Inter cell idar substance has already been spoken of as formed material. We have it most strikingly present in the white fibrous tissue, or tissue of ten- dons, and in hyaline cartilage. If the former be stained by carmine, and examined in thin section under the microscope, it will be found composed of beautiful bands of gently waving fibrous tissue, or tissue exhibiting a fibrous appearance, at varying in- tervals in which are noted nuclear masses of germinal matter, which have assumed the tint of carmine. Or, if dilute acetic acid be added to the specimen, the fibrous appearance will at once become homogeneous, 92 THE CELL DOCTRINE. while the nuclei will he rendered distinct, and clearly visible. In young tendon (frontispiece, Fig. 11), the masses of germinal matter will be found very abun- dant, and the intercellular fibrous substance in smaller quantity than in old tendon where the masses of ger- minal matter occur only at long intervals. These masses of germinal matter, or connective tissue cor- puscles, it will be recollected, are considered by Vir- chow as perfect cells, presenting cell-wall, cell con- tents, and nucleus, and the fibrous intercellular sub- stance as a subsequent modification of a homogene- ous matrix, deposited between the cells by the blood- vessels. These connective tissue corpuscles are re- garded by Beale as simple masses of germinal matter, the conversion of which into formed material pro- duces the fibrous intercellular substance, as seen in Fig. 11, frontispiece, and between which and the intercellular substance immediately adjoining, there is no line of separation, constituting a cell-wall. As the tendon grows older, the masses of germinal matter become less abundant, because a larger num- ber have been totally converted into formed material ; and the bands of indestructible material which some- times join them, and wdiich are considered by Virchow as a part of his canalicular system, are, according to Beale, nothing hut imiperfedly converted formed material, or rather germinal matter, wdiich has not been con- verted. While the twisted and curling cord-like fibres of the so-called yellow elastic tissue, also con- sidered by Virchow as a part of his canalicular sys- tem, are thought by Beale to be composed in part of true yellow elastic tissue, such as is found in the THE CELL DOCTRINE. 93 ligamentum niichae, and likewise formed from nuclei (frontispiece, Fig. 14), but in part also of the remains of nerves and vessels, which were active at an earlier period of life * So, also, with hyaline cartilage. According to Beale, the intercellular substance of cartila2:e results from O the conversion of the so-called cartilage-corpuscles or cells into formed material, and here also the germinal matter is directl}^ continuous with the matrix, no proper cell-w’all intervening. Cartilage is not to be considered as a distinct class of tissue from epithelium, nor can the latter, in all cases, be distinguished from cartilage by the exist- ence of separate cells, since in many forms of epi- thelium, at an early period of existence, the formed material corresponding to the masses of germinal matter is continuous throughout, and presents no indication of division into cells. f A ‘‘cell,” or “ele- mentary part,” then, of fully formed tendon or carti- lage, would consist of a portion of germinal matter, with a proportion of formed material about it, ex- tending to a line midway between that mass of ger- minal matter and the masses immediately adjacent, of which the cartilage or tendon is composed ; and such a line would correspond to the outer part of the surface of an epithelial cell.;}; In very young car- tilages, as in very young epithelium, the cells consist * Beale, On the Structure and Growth of the Tissues, and on Life. London, 1865, pp. 95, 96, and 101. f Beale, Protoplasm ; or, Life, Force, and Matter. London, 1870, p. 51. t Beale, Protoplasm, pp. 51-2. 94 THE CELL DOCTRINE. of germiDal matter only, with a small quantity of soft formed material intervening ; and to understand the true relation of the cells to the intercellular sub- stance, the tissue should be studied at different pe- riods of its growth. So, too, a “ cell ” or elementary part of muscle or nerve, would consist of a mass of germinal matter (the so-called nucleus), with a portion of muscular or nervous tissue corresponding with it, and with which it is uninterruptedly continuous. In the formation of the contractile tissue or muscle^ the germinal matter seems to move onward, under- going conversion at its posterior part, into the mus- cular tissue, while it maintains itself by absorbing and converting pabulum. This will be understood by reference to Fig. 13, of frontispiece. The fibres of yellow elastic tissue are formed in precisely the same manner. (See frontispiece. Fig. 14.) Nerve fibres^ which in their completed state consist almost wholly of formed material, are siniilarly produced. In the young state, the fibre is composed of masses of germi- nal matter, linearly arranged, and in close proximity. As the conversion takes place and the fibre is pro- duced, these become more widely separated, and the tissue resulting from such conversion is nerve (fron- tispiece, Fig. 15). The ‘‘ Cell ” or ‘‘ Elementary Part ” in Disease. Here, as in normal nutrition, the germinal matter is alone active. It is impossible to state precisely every instance, but it is probable that in the majority I THE CELL DOCTRINE. 95 of cases of disease, the morbid state consists essen- tially in a modiiication of the healthy nutrition of the cell, that is, the cell is made to grow more or less rapidly, or is perverted in its mode of growth, though it is likely that within certain limits, the conditions under which cells ordinarily live may he moditied without deviation from health. But in m- Jiaminatory processes attended by local products, as pus or lymph^ and in the production of tubercle and cancer we see the results of excessive multiplication and perversion of germinal matter consequent upon the appropriation of an excess of nutrient pabulum. In other instances, as cirrhosis, where there is shrink- ing, and hardening, and wasting, we see the effects of a diminished sup[)ly of pabulum, either through a diminution in the quantity supplied, or an imper- meability in the septum through which it is com- ])elled to pass. An increased supply of pabulum maybe admitted to germinal matter, either in consequence of the removal of barriers through which it is ordinarily compelled to pass, or in consequence of the nature of the fluids by which it is bathed. A simple illus- tration is seen in suppuration in epithelium, or the germinal matter of any tissue ; for, according to Beale, suppuration and morbid processes generally, are not restricted to any one kind of germinal matter, as the connective tissue corpuscle, but may occur in all germinal matter to which the conditions are supplied. Using epithelium by way of illustration, as the result of the increased supply of pabulum, the germinal matter first grows, as seen in the frontispiece, 96 THE CELL DOCTRINE. Figs. 7 and 8, then in the luxuriance of its growth, even at the expense of the formed matter, sends out buds or processes, which soon drop otf and become separate pus-corpuscles. (Figs. 9 and 10.) These are produced so rapidly that there is not time for formed material to form upon their surface in any quantity, and they have not time, therefore, to pass on into epithelium. Hence pus-corpuscles are almost pure germinal matter. So soon as the process ceases, in consequence of the supply of pabulum being di- minished, the germinal matter multiplies less rapidly ; opportunity is permitted for the production of formed material on its periphery, and the cell now passes through the different grades of epithelium, as de- scribed on pages 88, 89, and 90. The pus-corpuscles are analogous to the deepest layers of epithelial cells there referred to, which deep cells are iu fact the “ mucus-corpuscles,” so-called, well known to be mor- phologically identical with pus-corpuscles ; the for- mer being simply the young epithelial cell on its way to become perfect epithelium, while the latter is the same also, though never allowed to pass into the perfectly formed state. Again, in jmeurnonia^ and here we note where the paths of Virchow and Feale separate more widely, the so-called “ exudation,” or product which tills up the vesicular portion of the lung, is regarded by Beale as the result of a proliferation of minute particles of germinal matter (very much smaller than white blood- corpuscles), which have passed out through the capil- lary walls with the liquor sanguinis. In all inflammatory processes and fevers, this is THE CELL DOCTRINE. 97 believed by Dr. Beale to take place to a greater or less extent, the little masses of germinal matter or nuclei in the capillary walls also taking part, often increasing in size to such degree that they materi- ally obstruct the passage of the blood, and by drop- ping off portions give rise to bodies floating in the blood precisely similar to white blood-corpuscles, or pus-corpuscles; indeed. Dr. Beale considers that this may be one of the sources of origin of the white blood-corpuscle.^^ So, also, tubercle is believed by Dr. Beale to result either from the multiplication of masses of germinal matter which have passed through the capillary walls from the blood, or from the masses of oferminal matter usually termed nuclei, in connection with the capillary Avails. He says, in illustration : ‘‘ In a case of tubercle, which was very rapidly de\mloped upon the surface of the pia mater, in a man of tuber- cular constitution, I proved most distinctly that the tubercles were connected with the Avascular Avails, and that if the nuclei had not given origin to them, they Avere certainly implicated. My oavm opinion is, that these nuclei gave origin to the tubercle-cor- puscles, in consequence of receiving from the blood peculiar nutrient matter. In the lung I have seen appearances Avhich point to a similar conclusion. ould not these vfe\A"s arise from appearances pre- * Beale, Microscope in Clinical Medicine, third ed. London 1867,p. 16G. ’ t 3Iicroscope in Clinical Medicine, third ed., 1867, p. 205. 9 98 THE CELL DOCTRINE. cisely analogous to those represented as giving sup- port to the view, that tubercle originates in the perivascular sheaths of bloodvessels? The views of Eeale, H. Charlton Bastian,^ and Cornil,f would then constitute simply different modes of expression of the same truths. ROBIN,:}: 1867. Eobin, who may be considered the mouthpiece of the French school of histologists, reduces the human body to elementary parts, usually microscopic, which he calls anatomical elements. The forms he makes threefold,— tithes^ and cells. The fibres are generally of considerable length, sometimes extending from the lower part of the spinal cord to the extremity of the foot. Their di- ameter is, however, small, often not exceeding .001 millimeter, or .00003987 of an inch. The tubes offer as objects of study the walls and the cavity. * Bastian, H. 0., Tiiberc. Meningitis, Edinb. 3led Jour., 1867, p. 875. f Cornil, Tubercle in Connection with the Vessels,^\.rchiv. de Phys. Norm, et Path., Jan. et Fev., 1868. J Our information with regard to M. Robin’s views, is derived from an admirable exposition of them published in vol. iv, 1867, of the New York Medical Journal, by Dr. William T. Lusk, who there states that he has them mainly from a course of familiar and private instruction, furnished to him by IM. C. H. Georges Pouchet, assistant to M. Robin, Lecturer upon Anatomy and His- tology to the Ecole Pratique, author of “ Un Precis d’Histologie,” etc., and son of the eminent physiologist, Prof. F. A. Pouchet ; so that they may be said to be the views also of the elder Pouchet. THE CELL DOCTRINE. 99 The cells of vegetxihles have a wall, a cavitj", and contents (air, oil, etc.). The cells of animals, on the contrary, are, as a rule, homogeneous. Animal cells containing a cavity are only found exceptionallj^ The substance of cells is ordinarilj^ granular. Most cells contain an ovoid nucleus more granular than the substance itself. Jn all cells the nuclei afford different chemical reactions from those of the substance of the element. Each cell is an independent organism, passing through various stages of development, from birth to death. The birth (origin) of the elements takes place by 1st, segmentation; 2d, genesis; 3d, epigenesis ; 4th, germination. 1st. Segmentation. — The human ovum is a small hollow sphere, containing in its interior the vitellus or yolk, which consists of granular matter in a hya- line substance. At the end of a certain time par- ticles of the granular matter approximate , unite, and form a nucleus in the vitellus. Next, the nucleus elongates, takes an hour-glass form (biscuit), then divides. The division of the yolk occurs simulta- neously. In the same way, the division takes place into 4, 8, 16, and more parts. These divisions of the vitellus have received the name vitelline nlobules. Their mode of formation is called segmentation. 2d. Genesis. — When the vitelline globes have be- come very small by successive segmentation (diame- ter .008 millimeter, .00031396 of an inch), these little bodies take the name of embryonic cells. According to M. Robin, these cells dissolve. From the fusion results a blastema, in the midst of which 100 THE CELL DOCTRINE. nuclei make their appearance. This is known as genesis. It is the second and most frequent mode of the formation of anatomical elements. It is char- acterized by the appearance of an anatomical ele- ment in a fluid termed blastema, in which the element did not previously exist. 3d. Epigenesis. — When the embryonic cells dis- solve, the emhrj’o -plastic nuclei are produced by genesis in the blastema which results from their fusion. Then little cone-like prolongations of trans- parent matter are observed at the extremities of the nuclei, giving rise to the fasifonn bodies, which are the connective tissue corpuscles. This mode of forma- tion by growth upon another element is known as epigenesis,^ and is the mode in which connective' tissue is developed. The prolongations of these fusiform bodies constitute the non-elastic fibres or white fibrous tissue element of connective tissue. Some- times the substance deposited by epigenesis upon the nucleus has several prolongations, forming a stellate cell or connective tissue corpuscle. These fusiform and stellate cells are likewise known as embryo- plastic or jibro-plastic bodies,, and this latter term is a most common one in French histology. The elastic fibres of connective tissue are likewise formed by epigenesis, but upon special nuclei, and the prolongations are insoluble in acetic acid. There is an early period of fmtal life, previous to the formation of connective tissue, in which we find only embryo-plastic nuclei and fusiform bodies in amorphous matter. This is called embryo-plastic tissue. Growth at this epoch is most rapid, the THE CELL DOCTRINE. 101 f(Btus reaching in a short space of time the dimen- sion of .080 millimeter (.0118 of an inch). 4th. Germination. — This is very frequent in vege- tables, but in animals only one example is known, viz., at a period previous to the fecundation of the ovum. Before segmentation takes place the vitellus is observed to retract. The hyaline substance pushes out a prolongation, which becomes round, separates, and constitutes an independent anatomical element exterior to the vitellus, and bearing no part in the future development of the ovum. The following account of certain special elements illustrates and further explains the views of M. Robin. Red blood-globules (hematies), diameter, .007 millimeter (35’ou of an inch); thickness .002 milli- meter (yoT52 of an inch). Blood-globules are elastic, —a property enabling them to elongate, and pass through capillaries which have a calibre less than the diameter of the blood-globule. They are homo- geneous throughout— i. e., have no cell-wall. Blood- globules arv formed by genesis in the blood 'plasma. In the foetus they make their appearance before the white blood-globules (leucocytes). In man there are two kinds of red blood-globules, viz. : first, embry- onic ; second, normal. The embryonic blood-globules are double the size of the normal ones. They have a slightly granular nucleus, situated nearly in the centre, which is insoluble in acetic acid. The nor- mal blood-globules are not a transformation of the embryonic. They appear by genesis in the midst of the blastema of the blood. After the fourth month, the embryonic globules cease to form, and as the 9^ 102 THE CELL DOCTRINE. mass of the blood increases, the proportionate num- ber diminishes with great rapidity. Ijeucocytes^ or white blood-globules, are found in many tissues, in the blood, on the surface of mucous membranes ; in a word they are the j>us-corpuscles. In form, they are round, with pale, well-deh‘ned bor- ders, and contain extremely fine gray granules. They possess a very thin envelope, and a granular cell con- tents. The normal diameter is .008 millimeter (soVtt inch). On the addition of water, the leucocytes swell, the granular particles are agitated by a peculiar movement (first observed by Brown), and finally, a considerable number of these particles unite^ so as to form txoo or three little masses, that have been mistaken for nuclei. Upon the addition of acetic acid the same reaction follows, but with greater rapidity. The mode of production may be followed, step by step, upon the surface of wounds, especially little ones. At first a hyaline liquid appears. At the end of a couple of hours, this liquid becomes finely gran- ular, and then all at once, in the midst of the granu- lations, we perceive small granular bodies analogous to leucocytes, offering the same chemical reactions, but measuring only .003 millimeter (.000118 of an inch) in diameter. They are, in fact, leucocytes of young growth. When leucocytes are retained in the economy, as in shut sacs, they increase in size, and reach a diameter of .012 millimeter {odoo inch). Then they fill with fat-granules, and are known as corpuscles of inflammation (exudation corpuscles, com- pound granule-cells). Finally the substance and in- THE CELL DOCTRINE. 103 vesting membrane of the leucocytes disappear, the granules dissolve and are reabsorbed. Capillaries. — The finest capillaries are anatomical elements of tubular form, with transparent resistant walls which measure .001 mm. (.00003987 of an inch) in diameter. These walls contain erranular ovoid nuclei, which project, sometimes exteriorly, some- times upon the inner surface of the tubes. These nuclei measure .006 mm. (.00028622 of an inch) in the transverse, and .008 mm. (.00031596 of an inch) in the long diameter. Their long axis is parallel to that of the vessel. The finest capillaries have a diameter of .007 mm. (.0003756 of an inch), leaving a calibre (after deducting the walls) of .005 mm. (.00019685 of an inch), or .002 mm. (.00007874 of an inch) less than the average diameter of the blood- globules which traverse them. They are formed as follows: 1st. In new tissues, hollow projections push out from contiguous capil- laries, which meet and unite together. 2d. A solid filament forms, in which nuclei make their appear- ance. Subsequently, the filament becomes hollow, and its nuclei remain the nuclei of the capillary. A single perusal of these views as thus illustrated, will convince the reader that spontaneous formation is ’ the prevailing mode of origin of the elements of tissues, according to the French school. Such pe- rusal cannot fail to convince the reader also of the accuracy of description of the fully formed elements described by Robin. 104 THE CELL DOCTRINE. PROF. HUXLEY,* 1869. There is one kind of matter wliicli is common to all living beings, and that matter is ^‘protoplasm” the scientific name for ‘‘ the physical basis of life.” In illustration from vegetable life, each stinging needle or hair of the common nettle consists of a very delicate outer case of wood, closely applied to the inner surface of which is a layer of semitluid mat- ter, full of innumerable granules of extreme minute- ness. 77iis semifluid lining is protoplasm^ which thus constitutes a kind of bag, full of a limpid fluid, and roughly corresponding in form with the interior of the hair which it fills. When viewed with a suffi- ciently high magnifying power, the protoplasmic layer of the nettle hair is seen to be in a condition of unceasing activity. Local contractions of the whole thickness of its substance pass slowly and gradually from point to point, and give rise to the appearance of progressive waves, just as the bending of successive stalks of wheat by a breeze produces the a|3parent billows in a wheat-field. But in addition to these movements, and inde- pendently of them, the granules are driven, in rela- tively rapid streams, through channels in the proto- plasm which seem to have a considerable amount of persistence. The currents in adjacent parts com- monly take similar directions, coursing in a general stream up one side of the hair and down the other, * Protoplasm ; or, The Physical Basis of Life. A Lecture by Prof. Huxley, delivered in Edinburgh, November 18th, 1868. THE CELL DOCTRINE. 105 though partial currents also exist which take differ- ent routes ; so that sometimes trains of granules may be seen coursing swiftly in opposite directions, within a twenty-thousandth of an inch of each other; and occasionally opposite streams come in direct col- lision, and after a longer or shorter struggle one pre- dominates. The cause of these currents seems to lie in contractions of the protoplasm which bounds the channels in which they how, but which are so minute that the best microscopes show only their effects and not themselves. Among the lower plants it is the rule rather than the exception, that contractility should he still more openly manifested at some periods of their existence. The protoplasm of Algre and Fungi becomes, under many circumstances, partially or completely freed from its woody case, and exhibits movements of its whole mass, or is propelled by the contractility of one or more vibratile cilia. In illustration of animal protoplasm* Prof. Huxley adduces the colorless corpuscles of the blood, which, under the microscope, at the temperature of the body, exhibit a marvellous activity, changing their forms with great rapidity, drawing in and thrusting out prolongations of their substance, and creeping about as if they were independent organisms. ‘‘ The sub- stance which is thus active is a mass of protoplasm, and its activity differs in detail rather than in prin- ciple from that of the protoplasm of tlie nettle. Under sundry circumstances the corpuscle dies, and becomes distended into a round mass, in the midst of which is seen a smaller spherical body, wliich existed, but 106 THE CELL DOCTRINE. was more or less hidden, in the living corpuscle, and is called its nucleus. Corpuscles of essentially similar structure are to be found in the skin, in the lining of the mouth, and scattered through the whole frame- work of the body. Nay, more, in the earliest condi- tion of the human organism, in that state in which it has just become distinguishable from the egg in which it arises, it is nothino; but an ao;2:reo;ation of such corpuscles, and every organ of the body was, once, no more than such an aggregation. Thus a nucleated mass of protoplasm- turns out to he what may he termed the structural unit of the human body. As a matter of fact, the body, in its earliest state, is a mere multiple of such units ; and, in its perfect con- dition, it is a multiple of such units, variously modi- fied.” The formula which expresses the essential structural character of the highest animal, very nearly covers all the rest, as the statement of its powers and faculties covered that of all others. ‘‘Beast and fowl, reptile and fish, mollusk, worm, and polype, are all composed of structural units of the same character, namely, masses of protoplasm with a nucleus. There are sundry very low animals, each of which, structurally, is a mere colorless blood- corpuscle, leading an independent life. But, at the very bottom of the animal scale, even this simplicity becomes simplified, and all the phenomena of life are manifested by a particle of protoplasm ivithout a nucleus. “ What has been said of the animal world is no less true of plants. Imbedded in the protoplasm at the broad, or attached end of the nettle hair, there lies a spheroidal nucleus. Careful examination further THE CELL DOCTRINE. 107 proves that the whole substance of the nettle is made up of a repetition of such masses of nucleated proto- plasm, each contained in a wooden case, which is modified in form, sometimes into a woody fibre, sometimes into a duct or spiral vessel, sometimes into a pollen grain, or an ovule. Traced back to its earliest state, the nettle arises as the man does, in a particle of nucleated protoplasm. And in the lowest plants, as in the lowest animals, a single mass of such protoplasm may constitute the whole plant, or the protoplasm may exist without a nucleus. Under these circumstances it may well be asked, how is one mass of non-nucleated protoplasm to be distinguished from another ? why call one ‘ plant,’ and the other ‘ animal ?’ The only reply is that, so far as form is concerned, plants and animals are not separable, and that, in many cases, it is a mere matter of conven- tion whether we call a given organism an animal or a plant.” The researches of the chemist have also shown a like uniformity of chemical composition in “ proto- plasm ” or living matter, proving that whatever its source, it contains carbon, hydrogen, oxygen, and nitrogen, producing in their combination a complex substance, which in our ignorance of its more exact nature, we call proteinaceous or albuminoid 'matter. Further, the matter of life is composed of ordi- nary matter, and again resolved into ordinary matter when its work is done. Waste is constantly going on, which must be supplied by food, which is con- verted into protoplasm. A solution of smelling salts in water, with an infinitesimal proportion of some 108 THE CELL DOCTRINE. other saline matters, contains all the elementary bodies which enter into protoplasm, yet an animal cannot make protoplasm out of these. And this is characteristic. It must take it ready made from some other animal or some plant, the animal’s highest feat of constructive chemistry being to convert dead protoplasm into the living matter of life, which is appropriate to itself. Therefore, in seeking for the origin of protoplasm, we must eventually turn to the vegetable world. The plant, however, takes carbonic acid, water, and ammonia, and converts it to the same stage of living protoplasm with itself, though some of the fungi need higher compounds to start with ; and no plant can live on the uncompounded elements of protoplasm, and the absence of anj^ one of the elements renders the plant unable to manufac- ture protoplasm. These elements, carbon, hydrogen, oxygen, and nitrogen, are related to the protoplasm of the plant as the protoplasm of the plant to the animal. Thus far it is plain that the views of Prof. Huxley accord with those of many eminent histologists and physiologists, the result of whose observations have been embodied in these pages, and his descriptions will be accepted as undoubtedly accurate. More widely, in common with the school of so-called physicists,” of which he is one, does he ditier in his views as to the phenomena exhibited by protoplasm. According to Huxley, protoplasm once produced., all the phenomena exhibited by it are simply its properties., just as the jihenomena exhibited by water in its various states are properties. They do not take place through THE CELL DOCTRINE. 109 the guidance of any principle called vitality,” any more than the phenomena of water take place by virtue of “ aquosity.” Prof. Huxley can discover no halting-place between the admission that protoplasm of one animal or vegetable is essentially identical with and readily converted into another, and the further concession that all vital action may, with equal propriety, be said to be the result of the molecu- lar forces of the ^protoplasm which displays it. The thoughts to which we give utterance are the expression of molecular changes in protoplasm. These are admit- tedly so-called materialistic terms. Yet Prof. Huxley says: ‘‘Nevertheless, two things are certain : the one, that I hold the statement (above) to be substantially correct ; the other, that I, individually, am no material- ist, but on the contrary believe materialism to involve grave philosophical errors.” Such union of materialis- tic terminology with the repudiation of materialistic philosophy, he believes to be “ not onlj^ consistent with, but necessitated by sound logic.” This he pro- ceeds to show in this manner : If it be supposed that knowledge is absolute, that we know more of cause and eftect than a certain definite order of succession of facts, and that we have a knowledge of the ne- cessity of that succession, then there is no escape from utter materialism and necessarianism. But it is impossible to prove that anything whatever may not be the efiect of a material and necessary cause, and no act is really spontaneous, since a really spon- taneous act is one which has no cause. Yet any one familiar with the history of science will admit that its object has always meant, and means the exten- 10 110 THE CELL DOCTRINE. sion of tlie province of matter and causation, and the concomitant gradual banishment from all regions of human thought, of what we call spirit and sponta- neity,— that is, the object of all science has been and is to lind out the causes of all phenomena ; and there is no ditterence between the conception of life as the product of a certain disposition of material molecules, and the old notion of an Archseus o-overnino; and di- renting blind matter within each living body, except that here, as elsewhere, matter and law have devoured spirit and spontaneity. And moreover, the physiology of the future will gradually so extend the realm of matter and law, until it is coextensive with knowl- edge, with feeling, and with action. It is this }orog- ress of Jawidedge^ according to Ih’of. Huxley, which so many of the best minds conceive to be the j^i'ogress of m£iterudism^ which they watch with such fear and powerless anger as a savage feels, when, during an eclipse, the great shadow creeps over the face of the sun. AVe know nothing of this terrible matter,’’ except as the name for the unknown and hypotheti- cal cause of states of our own consciousness, and as little of that “ spirit,” except that it is also a name for an unknown and hypothetical cause of states of consciousness, that is, matter and spirit are both names for the imaginary substrata of groups of natu- ral phenomena. Hire necessity and iron ” law are gratuitously invented bugbears. If there be an “ iron ” law, it is that of gravitation, and if there be a physi- cal necessity, it is that a stone unsupported will fall to the ground. AVe know nothing more of this latter phenomenon, except that stones always have fallen THE CELL DOCTRINE. Ill to the ground under these conditions, and that they will continue to fall to tlie ground thus unsupported. It is simply convenient to indicate that all the con- ditions of belief in this case have been fulfilled, by calling the statement that unsupported stones will fall to the earth a “law of nature.’’ But when for will we exchange must^ we introduce an idea of neces- sity which does not lie in the observed facts, and is not warranted by anything that is discovered else- \ where. And with regard to which Prof. Huxley says ; “ For my part, 1 utterly repudiate and anathe- matize the intruder. Fact I know, and Law I know ; but what is tliis necessity, save an empty shadow of my own mind’s throwing? But, if it is certain that we can have no knowledge of the nature of either matter or spirit, and that the notion of necessity is something illegitimately thrust into the perfectly legitimate conception of law, the materialistic position that there is nothing in the world hut matter^ force^ and necessity^ is as utterly devoid, of justification as the most baseless of theological dogmas. “ Tlie fundamental doctrine of materialism, like those of spiritualism, and most other ‘ isms,’ lie out- side ‘ the limits of philosophical inquiry,’ and David Hume’s great service to humanity is his irrefragable demonstration of what these limits are. llurne called himself a skeptic, and therefore otliers cannot be blamed if they apply the same title to him ; but that does not alter the fact that the name, with its existing implications, does him gross injustice. If a man asks me what the politics of the inhabitants of the moon are, and I reply that I do not know ; 112 THE CELL DOCTRINE. that neither I nor any one else have any means of knowing ; and that, under these circumstances, I de- cline to trouble myself about the subject at all, I do not think he has any right to call me a skeptic. On the contrary, in replying thus, I conceive that I am simply honest and truthful, and show a proper regard for the economy of time. So Hume’s strong and subtle intellect takes up a great many problems about which we are naturally curious, and shows us that they are essentially questions of lunar politics, in their essence incapable of being answered, and therefore not worth the attention of men who have work to do in the world.” .... “ If w^e find that the ascertainment of the order of nature is facilitated bv usino; one terminoloo^v, or one set of symbols, rather than another, it is our clear duty to use the former,, and no harm can accrue so long as we bear in mind that we are dealing merely with terms and svnibols. In itself it is of little mo- ment whether we express the phenomena of matter in terms of spirit, or the phenomena of spirit in terms of matter ; matter may be regarded as a form of thought, thought may be regarded as a property of matter — each statement has a certain relative truth. But with a view to the progress of science, the materialistic terminology is in every way to be preferred. For it connects thought with the other phenomena of the universe, and suggests inquiry into the nature of those physical conditions, or con- comitants of thought, which are more or less acces- sible to us, and a knowledge of which may, in future, help us to exercise the same kind of control over the THE CELL DOCTRINE. 113 world of thought as we already possess in respect to the material world ; whereas/ the alternative, or spiritualistic terminology is utterly barren, and leads to nothing but obscurity and confusion of ideas. Thus, there can he little doubt that the further science advances, the more extensively and consist- ently will all the phenomena of nature he represented by materialistic formulBe and symbols. But the man of science, who, forgetting the limits of philosophical inquiry, slides from these formuliB and symbols into what is commonly understood by materialism, seems to me to place himself on a level with the mathema- tician, who should mistake the x's and ys^ with which he works his problems, for real entities, and with this further disadvantage, as compared with the mathematician : that the blunders of the latter are of no practical consequence, while the errors of sys- tematic materialism may paralyze the energies and destro\^ the beauty of a life.” These are the views of the “ physicists,” so-called, a school represented by Prof. Huxley, Prof. Owen, Herbert Spencer, Mr. Grove, Prof. Tyndall, and others. Prof. Owen, in the last pages of vol iii of The Anatomy of the Vertebrates^ declares himself the champion of spontaneous generation, and he main- tains, also, that the formation of livins; beina;s out of inanimate matter by the conversion of physical and chemical into vital modes of force, is a matter of daily and hourly occurrence. Mr. Grove says that “ in a voltaic battery and its effects we have the nearest approach man has made to an experimental organism,” and that in the human body we hav^e 10* 114 THE CELL DOCTRINE. chemical action, electricity, magnetism, heat, light, motion, and possibly other forces “ contributing, in the most complex manner, to sustain that result of combined action we call life.” ADDISON, WALLER, COHNHEIM (1842, 1846, 1867). At the annual meeting of the Provincial Medical and Surgical Association of England, held at Exeter, August 3d and 4th, 1842, AYilliam Addison read a paper entitled “ Experimental and Practical Re- searches on the Structure and Function of Blood-cor- puscles, on Inflammation, and on the Origin and R^a- ture of Tubercles in the Lungs.” In the section “ On Pus-corpuscles,” he says ; The colorless blood-cor- puscles appear to form pus-corpuscles.” In the section on “ Inflammation,” we find the following ; “ The cir- culation in the web of a frog’s foot was watched at intervals for half an hour, and only a few lymph-glob- ules were seen. A crystal of salt was applied, and the examination continued : its first effect was to quicken the rate of the circulation ; this soon ceased, and ■ the blood became stationary, the vessels being red and congested. In the capillaries contiguous to the congested vessels, the blood was oscillating to and fro ; a little further oft*, the circulation was very quick. In half an hour the number of lymph-globules had increased considerably, and the circulation in the congested vessels was resumed ; but the corpuscles passing through them sometimes oscillated to and fro, sometimes retrograded, and at others hurried oi: darted through the vessels with the utmost velocity. THE CELL DOCTRINE. 115 The current of the red corpuscles in some of the veins appeared to be confined to the centre of the vessel, and not to touch the circumference, which was occupied by a great many lymph-globules. On the following morning the whole interior of the inflamed vessels a[>peared to be lined with lymph-globules. By gently altering the focus of the microscope they were seen below the red current, and many of them appeared to lie externally to the boundary of the vessels.^’’ Again, page 258:* “ During some of these experi- ments the islets of tissue between the capillaries be- came distinctly cellular, and appeared as if over- spread with irregular-shaped l3unph-globules.” These various statements, while they permit the inference that Addison first conceived that the col- orless blood-corpuscle becomes the pus-corpuscle in inflammation, do not allow us to infer that he actu- ally observed its migration through the walls of vessels. Indeed, he says, page 259: “ The phenomena observed in the foregoing experiments corroborate the views of those distinguished physiologists who entertain the opinion that the capillary distribution of the blood is situated in the channels of the tissue, and not in vessels with a distinct membranous coat.^f In 1846 Waller:]; more correctly appreciated this migration, but it was not until Cohnheim published his famous paper on “ Inflammation and Suppura- * The Transactions of the Provincial Medical and Surgical Association, vol. xi. London, 1843. t Mailer’s Physiology, vol. i, p. 229. X London, Dublin, and Edinburgh Philosophical Magazine, vol. xxix, pp. 271 and 398. 116 THE CELL DOCTRINE. tion,”* in 1867, that the observation attracted the attention it deserved. Since then it has been con- firmed again and again, and most conclusively lately by Arnold, of Heidelberg. f The theory which grew out of Cohnheim’s obser- vation was, that it is the colorless corpuscle of the bloody rather than the connective tissue corpuscle, which is the starting-point of all new formations, healthy and morbid. It is the accumulation of these corpuscles outside of the bloodvessels, in the interspaces of the fibrillar connective tissue, which forms the headlike rows of cells figured by Virchow and others. It is these which, accumulated in larger numbers, forms the pus of an abscess. It is these which, perverted in the direction of their development, produce the tissue of tubercle, cancer, sarcoma, and other forms of morbid growth. It is these, also, which become the medium of repair of all injured or destroyed tissues which are capable of regeneration, whatever their complexity or simplicity^ That the colorless corpuscle plays a most important role in the production of new formations, healthy and morbid, few now deny; but that it is the sole morphological element, exclusive of the connective tissue corpuscle, thus active, many will not admit. Conspicuous among those who have combated this exclusive view are Strieker and ATorris,;}; whose ob- * Ueber Entzundung und Eiterung, Virchow’s Archiv, JBd. xl, 1867, p. 1. f Ueber Diapedesis, Virchow’s Archiv, vol. 68, 1873. J Yersuche iiher Hornhaiit Entzundung, Studien aus dem In- stitute fiir Experimentelle Pathologie in Wien, aus dem Jahro 1869. THE CELL DOCTRINE. 117 servations and experiments in the production of inflammation in the corneai of frogs and rabbits have attracted mucb attention. Their object was to show that the connective tissue corpuscles (the corneal cor- puscles here) shared in the formation of the products of inflammation by their proliferation, and that the colorless corpuscles themselves, after their migration beyond the walls of the bloodvessels, also underwent cell division, and thus contributed in a second man- ner to the formation of pus. They argued, also, that the enormous accumulations of pus in large abscesses could not be reasonably accounted for on the ground that the only source of the pus-corpuscle is the wan- dered-out colorless corpuscle. These observations of Strieker and Norris are gen- erally acknowledged as having settled the question in favor of the view, that there are two elements of organization, — the colorless corpuscle am/ the connec- tive tissue corpuscle, either of which may also become the starting-point ot pathological new formations. NEW VIEWS ON THE STRUCTURE OF CELLS AND NUCLEI. — 1877-78. As early as 1867, C. Frommann* published a pam- phlet on the “Normal and Pathological Anatomy of the Spinal Cord,” in which he states that the pres- ence of fibrils in the nuclei and nucleoli of cells, first observed in ganglion-cells, was demonstrated by him also in the cells of connective tissue, cartilage, and * Untersuchungen iiber die normale und pathologische Anato- mie des liuckenmarks, 2 Theil. Jena, 4. Mit 6 Taf. p. 17. For abstract of, see Henle and Meissner’s Bericht iiber die Forschritto der Anatomie und Physiologie, in Jahre 1867, Leipzig, 1868. 118 THE CELL DOCTRINE. bone-cells, and in the epithelium of the mouth and capillary vessels. He observed clear shining fibrils pro- ceeding from the nucleolus joining themselves to others proceeding from the nucleus and protoplasm. From the nucleoli of connective tissue arise one, two, and, more seldom, three fibrils. These sometimes dwindle away in the nucleus itself ; at others, after a straight or curved course, leave the cell and lose themselves in the neighborhood. Repeatedly was observed the entrance of a nucleolus-fibre into a cell process, and if two cells were united by a process from each, the nucleolus-fibre was seen to pass from one cell to another. So also fibres originating in the nucleus, sometimes as many as six in number, could be fol- lowed into the protoplasm, and more seldom beyond the cell. Certain fibres appear to cease in the nu- cleus by a free extremity, as though cut ofi‘. Others have attached to them glistening granules, which in fresh, as well as hardened preparations, are con- tained in variable number in the nucleus. F rommann believes that the granules of the nucleus and proto- plasm are the nodal points of a very fine fibrous net- work, from which fibrils go oft* and leave the cell. These are found in the cells of all the tissues named above. In consequence of this complicated structure of the nucleus, Frommann thinks it improbable that it multiplies by division ; he believes in a free new formation of the nucleus in the protoplasm, where, alongside of nuclei of ordinary appearance, smaller homogeneous ones make their appearance. In 1873,'^ Ileitzmann asserted that the substance * Untersiichungen iiber das Protoplusma, Sitziingsber., d. k. Akad. d. Wiss. zu Wien, Bd. Ixvii und Ixviii, Abth. iii, 1873. THE CELL DOCTRINE. 119 of various cells, amoebae, blood-corpuscles, cartilage- cells, bone-cells, epithelial cells, etc., contain net- works of minute fibrils, into which pass fibrils radi- atino-froni the interior of the nuclei of these cells. O In 1875, Fromrnaim* * again described, in accordance with Ileitzmann, a minute network of fibrils in the nuclei of blood-corpuscles of Astacus Jiuviatilis^ which passed through the nuclear membrane into a similar network in the substance of the blood-corpuscles. Schwalbe,t in 1875, found the nucleoli in the nuclei of ganglion-cells in the retina often possessed of mi- nute filamentous prolongations, and the nuclear membrane showing prominences on its inner surface. Schwalbe designates as nucleolarsubstanz,” the nu- cleolus and filaments, nuclear membrane and its prominences, to distinguish it from the rest of nu- clear matter, which he calls “ kernsaft ” or ‘‘ nuclear juice. Ivupfier,:j; in 1875, maintained that the substance of the lower cells of the frog, the odontoblasts, the epithelial cells of the salivary gland of Periplaneta orientalis^ is composed of a hyaline (non-fluid) ground See also a paper by Heitzmann on the same subject, in the New York Medical Journal for 1877. For the historical facts from this date in the development of these new views, 1 am indebted to the very valuable paper of Dr. Klein in the Quarterly Journal of Mi- croscopical Science for July, 1878. * Frommann, Zur Lehre von der Structur der Zellen, Jenaische Zeitschrift f. Naturw., J3d. ix, 1875, p. 280. f Bemerkungen iiber d. Kerne d. Ganglionzellen, Jenaische Zeitschrift f. Naturw., Bd. x, 1875, p. 25. J Ueber Ditterenzirung d. Proto})lasma an den Zellen thierescher Gew., Schriften des Naturw. Vereins f. Schleswig-Holstein, Heft iii; and Beitr. z. Anat. u. Physiol., Festgabo f. Carl Ludwig, 1875. 120 THE CELL DOCTRINE. substance, “ Paraplasma,” and of a granular fibrillar contractile “ Protoplasma,” imbedded in the former. The relation and distribution of the protoplasmic fibrillar substance varies in cells of different kinds. Strassburger,* in 1876, observed that in developing cells of Phaseolus multijiorus^ a network of fibrils is ' present radiating from the nucleolus, and permeating the interior of the nucleus in connection with a simi- lar network of the cell substance. In 1876, Biitschlif observed in the nuclei of colored blood-corpuscles of the frog and newt, minute fibres with granular thickenings, but no nucleolus as as- serted by Panvier. Moyzel,:}: in 1875, found in the epithelium of the cornea of the frog, rabbit, and cat, during regenera- tion, large round nuclei, in which he observed filamen- tous masses, either convoluted or radiating from a central point. He regarded these forms as due to a particular stage of division, as described by Biitschli and Strassburger. 0. Ilertwig,§ in 1876, also distinguished a “ nuclear substance,” from a ‘‘ nuclear juice,” and Biitschli, || in the same year, a “ nuclear matter ” from a “ nuclear fluid.” The “ nuclear matter ” of the latter com- * Ueber Zellbildung und Zelltheilung, Jena, 1875. Abstract in Quart. Jour. Mic. Sci., vol. xvi, 1876, p. 138. t Studien iiber die ersten Entwickelungserscbeinungen der Eizelle, Abhandl. d. Senkenbergischen Naturf. Gesellsch., Bd. x, 1876. J Ueber eigenthumliche Vorgange bei der Theilung der Kerne in Epithelialzellen, Centralbl. f. Medic. AVissensch., No. 50, 1875. I Beitriige zu einer einheitlichen Autfassung der verschiedenen Kernformen, Morphol. Jahrbucb, 1876, Bd. 2, II. 1, 1876, p. 73. II Loc. citat., vol. x. THE CELL DOCTRINE. 121 prises the nuclear membrane, the nucleolus, and a librillar stroma, which latter, in some instances, ex- tends in a radial manner from the nucleolus. E. Van Beneden* saw a tine protoplasmic reticu- lum in the large axial entoderm cell of Dicjema, which (reticulum) exhibited slow spontaneous move- ments. In the nucleus of the ripe ovum of Astero- canthion rubens he also observed within the nuclear membrane and beside the nucleolus a delicate net- work of tinely granular substance, which he calls “nucleoplasma,” including several “ pseudo-nucleoli.” According to him the germinal vesicle of the ripe ovum of the rabbit also contains a minute network. Arndt, t in 1876, distinguished in the nucleus a homogeneous ground substance and elementary glob- ules ; the tormer *possesses a vesicular structure, and incloses in its meshes the latter. AV. Flemming,:}: in observations on the structure of nuclei found in the membrane of the urinary blad- der of A^alainandra maculata^ in 1876, saw a very deli- cate and dense network of fibres uniformly pervading the interior of the nucleus, and attached to the nuclear membrane. This network, ‘‘ Geriistformige * La maturation de I’oeuf, la fecondation et les premieres phases du developpement embryonaire des Mammif^res. Bui. de PAcad. Koyale de Belgique, 2 Ser., t. 40, 1875; also Contributions a Phis- toire de la vesicule gerrninative et du premier noyau embryonaire, in the same journal, January, 1876. t liber den Zellkern, Sitzungsb., d. Medicin. Vereins zu Greifs- wald, Nov., 1876. X Beobachtungen liber die Beschaffenheit des Zellkerns, Archiv fUr Mikrosk. Anat., Bd. xiii, 1876, p. 693, and following. 11 122 THE CELL DOCTRINE. Strnctnr,” was seen by Flemming in the nucleus of all cellular elements of the bladder of Salamandra^ epithelial cells, connective tissue cells, migratory cells, unstriped muscle-cells, nerve-cells, endothelial cells, and blood-corpuscles. With regard to Flem- ming’s observations, Klein* says their clearness and extent leave no doubt that the network in the nu- cleus represents a definite and pre-existing structure. This has been to a certain extent questioned by Lang- hanst as regards the fresh cells of the human decidua serotina, but, Klein again observes, ‘‘ Flemming’s assertions cannot be in the least shaken, considering that he observed the above structure, not onlv after the use of reagents, e. g., acetic acid, chromate of potash, alcohol, chromic acid, with or without sub- sequent staining in carmine or h^ematoxylin, but also in the absolutely uninjured bladder, i. ^., while this organ was being observed in the living curarized animal.” And, in a later note, Flemming:j: states that he observed the same network in the nuclei of various cells, also in the living and perfectly unin- jured larva of Salamandra. Eberth§ noticed nuclei containing anastomosing ^ O O filaments in their interior in the epithelium of the cornea and the endothelium of the membrana Des- cemeti under normal conditions, lie regards them * Loc. citat. f Zur Lehre von Zusammensetz. des Kerns, Central blatt f. Medic. Wissenschaft, 1876, N. 50. I Zur Kenntniss des Zellkerns, in Centralbl. f. Medic. Wiss., 1877, No. 20. ^ Ueber Kern und Zelltheilung, Virchow’s Archiv, Bd. 67, 1876. THE CELL DOCTRINE. 123 as peculiar forms in the development and division of nuclei. Eiiner* found in numerous nuclei that the gran- ules of the “granular zone” surrounding his “hya- loid ” are due to protoplasmic filaments, which per- meate the interior of the nucleus, and anastomose with each other so as to form a network, which ex- tends to the membrane of the nucleus, and also sends radiating fibrils through the hyaloid into the nu- cleus. The network of fibrils of the nucleus is, in some instances, also in connection with fibrils and networks of the same belonging to the cell substance itself. The most recent contribution on this subject is the valuable paper by Dr. E. Klein, already alluded to, and published in the Quarterly Journal of MicroscojJical l^cience^ for July, 1878. In this paper Klein shows by observations! on the ordinary freshly killed newt * Weitere Nuchrichten iiber den Bau des Zellkerns, etc., Archiv f. Mikrosk. Anat., Bd.xiv, 1877, p. 94. Also, “Notes and Mem- oranda” of the April number of the Quart. Jour. Microsc Sci 1878. ” t The following is the method pursued by Klein : The stomach of a freshly killed newt is cut open and placed into a 5 per cent, solution of chromate of ammonia in a closed vessel, where it is kept for about twenty-four hours. It is then washed in water for about half an hour, and placed after this in a dilute solution of picro- carmine, where it is left till it assumes a deep pinkish-yellow tint. It is now washed in water, and microscopic specimens are pre- pared in this manner. The mucous surface of the organ is scraped with a small scalpel, whereby smaller or larger flakes may be easily removed ; they are placed in a very tiny droplet of glycerin on a glass slide ; by slight knocking with the rounded or flat top of any thin rod or needle-holder these flakes are broken up into micro- 124 THE CELL DOCTRINE. {Triton cristatus)^ that the statements of Flemming are correct, and presents in addition several observa- tions he has made with reference to the cell-sub- stance itself, and the relation of it to the intranuclear network. Dr. Klein examined gland-cells, surface epithelial cells, endothelium, unstriped muscle-fibres, connec- tive tissue corpuscles, and nervm-fibres. And every where the nuclei showed an extremely beautiful net- work of fibrils. This he desio-nates as the intra- nuclear network, which is imbedded in a homoge- neous ground-substance. The network does not in all instances extend up to the nuclear membrane, but leaves a narrower or broader zone next to the mem- brane unoccupied. But in all instances the network is in connection with the limiting membrane by nu- merous fibrils. The spaces formed by their anasto- moses are not uniform, being sometimes larger in the peripheral parts than in the central, and sometimes the reverse. All forms are found between a network with fibrils as in a net, and a honeycomb of mem- branous structure as in a sponge. In almost all in- stances are observed a smaller or greater number of scopic fragments, a drop of glycerin is placed on a covering-glass, and this is inverted over the above specimen. Examined under a moderately high power, say Hartnack’s 7 or 8, or Zeiss’s D or E, we recognize easily innumerable isolated cells or groups of epithelial cells, and a great many isolated nuclei or fragments of nuclei. If the scalpel has been drawn over the sur- face of the mucous membrane with a little energy, the preparation contains great numbers of gland-cells, isolated and in continuous masses, and also other elements belonging to the tissue of the mucosa. THE CELL DOCTRINE. 125 Tinimte bright spots, which are shown by careful focussing to be fibrils of the network seen in optical transverse section or at the points of anastomosis. In some nuclei, according to Klein, the more irregu- larly shaped dots are due to a thickening of fibrils from place to place, although Flemming attributes them altogether to the former cause (transverse sec- tions of fibrils). Whence it is clear, the more shrunk the intranuclear network, or the more twisted and convoluted the fibrils, the more does the nucleus present the appearance of being granular. The nucleolus receives an entirely peculiar expla- nation at the hands of Klein, in which he seems to be sustained by the observations of Van Beneden, 0. Ilertwig, Flemming himself, Auerbach, Eimer, and especially of Strassburger, Schwalbe, and Langhans. With regard to it Klein first says with undoubted truth: “Kow, to every experienced student of his- tology, it must have become apparent that if there is one thing unsatisfactory, unreliable, puzzling, and inconstant about the nucleus of vast numbers of cells, it is this very nucleolus.” Second, that after a very prolonged examination he has arrived at the conclusion that these large particles (nucleoli) are due to one of two things : in some instances they are distinctly thickenings of the network, in others they appear to be merely due to the shrivelling up and intimate fusion of a part of the network. The in- constancy as regards size, shape, and number of the so-called nucleoli seem to him to point very strongly in the above direction. The assertions "which have been made as regards 11* 126 THE CELL DOCTRINE. spontaneous movements of nucleoli by Auerbach, Brandt, Eimer, Kidd, and others, be regards as quite compatible with the above view, for Van Beneden has observed movements in the intranuclear network, and it is quite possible that the above assertions might refer to such movements. AVith regard to the nuclear membrane alreadv men- tinned, Klein says that it is composed of an outer thicker portion, which is Xh^limiting membrane proper and closely connected with it, an innei\ more or less incomplete layer, which is a peripheral condensation of the intranuclear network^ with which it is connected bp longer or shorter threads. The clear space some- times observed between the membrane of the nucleus and the intranuclear netwmrk is due to a retraction of the latter from the former. Klein has also demonstrated a network of fibrils in the substance of cells outside of the nucleus, which he designates as the intracellular network, in contra- distinction to intranuclear^ in the meshes of which again is the interfibrillar or ground-substance, which in the case; of the columnar epithelial cells on mucus- surfaces, known as goblet-cells, is mucus,* but finds them also in the endothelium of the surface, in un- striped muscle-fibres, connective tissue corpuscles, and nerve-fibres. Klein further traces a direct connection of the fibrils * They are best seen on the slender goblet-cells of the stomach of the newt, kept for twenty-four hours in Muller’s fluid, placed then for half an hour in a mixture of two parts chromic acid per cent.), and one part methylated alcohol, washed after this in water, and stained with picro-carmine. THE CELL DOCTRINE. 127 of the intracellular uith those of the intranuclear network^ and along with Eberth, Marchi, and Eimer, traces in tlie epithelial cells of the foregut of the newt, the cilia in direct continuation through the cell-cover with the fibrils of the intracellular network. The intracellular network is less conspicuous than the intranuclear, but possesses the same general characters. The importance of this subject has seemed so great that I have added at the end of the volume the essen- tial portions of the plate from the Quart. Jour, of ]\lic7ws. for July, 1878, which, with its descrip- tion, will give a very accurate notion of these new views as confirmed by Dr. Klein, than whom, of modern observers, I consider none more reliable. SUMMARY — PRESENT STATE OF THE CELL DOCTRINE — author’s VIEAVS. ]\Iinute analysis of the solids of the organism has long been an object of the histologist and physiolo- gist, which, resulting first in the j)artes similares of Aristotle and Galen, has finally reached the so-called “ cell ” or “ elementary part ” as the ultimate physi- cal element of organization, out of which all tissues, healthy or diseased, are formed. Our ideas as to the exact physical constitution of this elementary part have undergone considerable change since the first announcement by Schleiden and Schwann, in 1838, of its exact physiological position. The most impor- tant modifications of the original conception of a cell is that which removes altogether its vesicular char- 128 THE CELL DOCTRINE. acter. So that the term cell *’ is reallv no lontrer a correct one, since the object to which it is applied is, in its youngest, most active state, at least, a solid mass or “clump ” of living matter without the ves- tige of a wall or envelope about it. The word has, how^ever, become so intimatelv associated with his- tology that it is doubtful whether it will ever fall into disuse, nor does it much matter, so long as cor- rect notions of the elementary part are obtained. This latter term, “ elementary part,” is, however, to be preferred. Consistently with the latest determined facts, the cell or elementary yart is best defined as the smallest mass of living matter possessing the essential life projo- erties of reproduction^ nutrition^ growth^ and develop- ment. To such substance the terms “ sarcode,” “ pro- toplasm,” “germinal matter,” and “bioplasm” have been applied, the first by Dujardin, the second by Max Schultze and Eemak, and the third and fourth by Beale. The term “ sarcode ” has nearly gone out of use, and “ protoplasm ” has come to be largely used for that part of the cell outside of the nucleus, without regard to its living properties. The term “ bioplasm,” on the other hand, has not yet received such exten- sion of meaning, while it also etymologically defines the substance it represents, and is therefore much to be preferred. The Nucleus of the Cell. — In the interior of most cells are found one or more difierentiated masses ot bioplasm, usually round or nearly so, and more grah- ular or darker in hue by transmitted light than the THE CELL DOCTRINE. 129 remainder of the cell, wliich are called nuclei. These nuclei, although strikingly constant, are not invari- ably present, as pointed out by Briicke,* in 1861, in the cells of cryptogams, and confirmed hy the earlier discovery in 1854, of a non-nucleated amoeba (Amoeba porrecta) by Max Schultze,f in the Adriatic Sea ; also later by IIreckel:J: and Cienkowski§ in their dis- coveries in 1865, hy the former of a non-nucleated protozoon (Protogenes primordialis) in the Mediterra- nean, and by the latter of two non-nucleated monads (Monas amyli and Protomonas amyli). Stricker’sl observations on the fecundated egg of the frog in- cline him to adopt the view of Briicke, and omit the nucleus in a theory of elementary organiza- tion. Such facts as these prove erroneous the defini- tion of a cell proposed by Leydig and Max Schultze, “ protoplasm surrounding a nucleus,” and the defini- tion more recently accepted by Virchow,^ that a cell is “ a nucleus surrounded by a molecular blastema;” though if we restrict ourselves to the cells concerned in the organization of the higher animals, the latter may be anatomically correct, but the former involves the confusion already referred to in the use of the word “ protoplasm,” which is here applied to some- * Briicke, E.,Die Elementar-organismen, p. 18-22, 18G1. t Schultze Max, Organis. d. Folythalam., 1854. X Hjeckel, Zeitschr. f. w. Zoolog., 1865, Bd. xv. ^ Cienkowsky, Max Scliultze’s Archiv, 1865. II Strieker, S., in vol. i, p. 8, Strieker’s Histology, New Syden- ham Society’s Translation, London, 1870; also p. 504, vol. iii, London, 1873. ^ Letter from Berlin, in Edinburgh Medical Journal, Febru- ary, 1865. 130 THE CELL DOCTRINE. thing outside of the nucleus to the exdusion of the latter, to which, if to anything, should be assigned the term. For the nucleus possesses pre-eminently three of the properties of bioplasm named, nutrition, reproduc- tion, and growth, and in it usually take place the first steps towards the production of new cells, in, first, its increase of size through nutrition, and second, by fission, which subsequently extends to the remainder of the cell. Indeed the chief function of the nucleus has been heretofore considered as that of the reproduction of the cell. But this is by no means invariably the case, as indeed it is clear should not be, when we recall the properties of bioplasm or germinal matter. For although the nucleus is a sep- arate differentiated portion of bioplasm, it does not in every cell comprise the whole of the bioplasm of that cell. This is perhaps best illustrated by the pus-cell and colorless blood-corpuscle, which are pure bioplasm, but which still contain within them sepa- rate centres of germinal matter or nuclei. Consist- ently with this fact, the pus-cells or white blood-cells multiply not necessarily through a primary fission of the nucleus, but often by separating a portion of the external bioplasm, which becomes an independent cell with the endowments of its predecessor. See Fig. 7, 8, 9, 10, of frontispiece. This fact has further a very important illustration in the fecundated germ or ovum of sexual generation. It is now universallv admitted that the non-fecundated germ is a distinctly nucleated cell, and it is almost as generally acknowl- edged that immediately after fecundation the nu- THE CELL DOCTRINE. 131 cleus disappears, to be replaced, however, by a new one, under favorable conditions, which appears to take no part in the subsequent cleavage processes.* Recent descriptions of the nucleus include in its anatomy a nuclear membrane^ which is described by Auerbach as a somewhat thick, highly retractile, doubly contoured membrane, whic^i appears to be less distinctly separated from the cell protoplasm than from the exterior of the nucleus. This mem- brane is regarded by Auerbach as having been formed about the original droplike nucleus by the differ- entiation of the inmost layer of the protoplasm into a species of interior cell membrane. According to Klein, it is composed of an outer thicker portion, which is the limiting membrane proper, and closely connected with it an inner more or less incom- plete layer, which is a 'perii:>heral condensation of the intranuclear network^ with which it is connected by longer or shorter threads. According to Auer- bach, the nuclei first appear as clear spaces, vacuoles * According to Prof. Strieker (“Development of the Simple Tissues,” in vol. iii, of “ Human and Comparative Histology,” New Syd. Soc. Ed.), precise statement to the effect that the germi- nal vesicle is persistent and becomes transformed into the nucleus of the cleavage cells, has only been made by Johann Muller in the case of Entoconcha rnirabilis (Monatsberichte der Berliner Akade- mie, September, 1851). But in recording this fact Strieker seems, as many more recent writers have done, to have entirely overlooked the much earlier observation of Martin Barry, who distinctly as- serts (Philosophical Transactions, London, 1840, p. 529), that “ the germinal vesicle does not burst, or dissolve away, or become flat- tened, on or before the fecundation of the ovum, as hitherto sup- posed.” 132 THE CELL DOCTRINE. filled with a tenacious fluid mass possessing no dis- tinct wall. Each droplet then acquires a membrane by differentiation of the inmost layer of cell proto- plasm and nuclei, and intermediaiy granules after- wards make their appearance. Once differentiated, the nuclear membrane is an integral part of the nu- cleus, constituting the latter a true vesicle, isolable as a whole by mechanical means.* The Nucleolus. — Very commonly also, though not invariahlj’ attending it, a second differentiated mass of matter is found within the nucleus, to which the term nucleolus is applied. According to Beale, it is possessed of like endowments, and is supposed to be the most recently formed bioplasm, the non-vitalized circulatino; albumen of the blood beino; converted through the agency of pre-existing bioplasm into the latter substance. If the cell normally develop, the nucleolus growing becomes the nucleus, the lat- ter being gradually oxidized upon its exterior and converted into the cell-contents and cell-wall, while a younger centre of germinal matter takes the place of the original nucleolus. This living matter exhibits the important property of being stained by weak so- lutions of various coloring matters, as carmine, anilin, etc., the younger matter taking on the deeper stain, and by these means its demonstration is rendered strikingly easy. In rapidly growing cells, a still younger centre of bioplasm may sometimes be demon- strated within the nucleolus, while the nucleus re- mains a distinctly ditierentiated mass capable of also * Auerbach, Organologische Studien, Breslau, 1873-4. THE CELL DOCTRINE. 133 being stained. To this youngest centre of bioplasm, the term ‘‘ nucleoleolus ” might not be inappropriately applied. Klein has announced in his recent paper “ On the Structure of Cells and Kuclei” (Quart. Journ. Mi- croscop. Sci., July, 1878), that after very prolonged examination he has arrived at the conclusion that these large particles (nucleoli) are due to one of two things : in some instances they are distinctly thick- enings of the nuclear network of librillaB demonstra- ted by Frommann and Heitzmann, and confirmed by Flemming, Ilertwig, E. Van Beneden, Klein himself, and others, or they are merely due to the shrivelling up and intimate fusion of a part of this network. Auerbach supposes that the nucleolus is formed by the aggregation about a centre, of nucleolar sub- stance, which is derived either from the periphery of the nucleus itself or from the inmost layer of cell protoplasm. According to him, nucleoli may also multiply by fission. This division is associated with a movement of the new nucleoli through the nu- clear ground-substance, ‘the cause of which is not understood. The reverse, or the fusion of several nucleoli into one, also occurs. Auerbach says also that many facts speak for the identity of nucleolar substance and cell protoplasm. In o]3tical appearance, nucleoli and the substance of young cells agree, and vacuolation may occur in either, large nucleoli being seldom free from clear spaces. Both are amoeboid, the movements in nucleoli having been described by many observers. Lastly, nucleoli have, as Auerbach himself shows, that characteristic of vital protoplasm, 12 134 THE CELL DOCTRINE. the power of multiplication hy division. That is, nucleoli have all the capabilities of elementary or- ganisms, and are in truth cytodes. Eegarded in this light, they are real daughter cells, which have arisen hy an endogenous process, and the nucleus is the chamber in which they develop. It is now m^erely necessary for them to find a way out through the body of the mother cell, in order to begin life as independent beings. That this method of increase has become obsolete in the cases of a majority of cells of higher adult animals, or perhaps only occurs in pathological processes, may be quite true, according to Auerbach, without offering any obstacle in the way of such a hypothesis. In the specialization of function which appears as we ascend the animal senes new means of gaining the same end present themselves, while the old vanish or are made use of for other purposes. The phases in the act of propaga- tion of a unicellular organism may be less significant, and have a far different outcome in a unit cell of a more complex creature.* The fact of the total or partial disappearance of the nucleus or germinal vesicle shortly before or im- mediately after fecundation, has been amply con- firmed by recent observers, although there are some slight differences in the exact mode of its acceptance. The »most important recent contributions on the sub- * Auerbach, Organologische Studien, Breslau, 1873-4, or see abstract of Auerbach’s paper, by Priestley, in vol. xvi, Quart. Jour. Microsc. Sci., 1876, whence I have obtained the .above views of Auerbach with regard to nuclei and nucleoli. THE CELL DOCTRINE. 135 jeet have been by Anerbacb,* ** Strassburger,f ITert- wig,:}; and Yan Beneden,§ to whom may be added Bntsebli,l| Oellacber,^ Ivleinenberg,^-'^ and Balfour. ft Under the influence of the fertilizino- act the ovum O again becomes nucleated, the nucleus arising in a fusion of pronuclear bodies, one of which may pos- sibly be derived from the fertilizing element (sper- matozoid). The nucleus then begins series of changes, about which most observers are agreed, but for the details of which the reader is referred to the sources named in the footnote. * Organolocjische Studien. Breslau, 1873-4. f Ueber Zellbildung und Zelltheilung, Jena, 1875, t Beitrage zur Kenntniss der Bildung, Befruchtung, und Thei- lung des thierescben Eies, Morpholog. Jahrbuch, 1, 1875. I La Maturation de I’oeuf, la Fecondation et les Premieres Phases du Developpement Embryonaire des Mammiferes, d’apres des Recherches faites chez le Lapin. Bruxelles, 1875. Excellent abstracts of these four papers, by John Priestly, are found in the Quart. Jour, of Microsc. Sci., for July, 1878, vol. xvi, new series. In the same number will be found an oriirinal paper by Van Beneden, entitled “ Contributions to the History of the Germinal Vesicle, and of the first Embryonic Nucleus,” in which he compares the views of Hertwig with his own. II yorlaufige Mittheilung fiber Untersuchungen betreffend die Ersten Entwickelungsvorgange in Befruchteton Ei von Nemato- den und Schnecken, Zeitsch. ffir Wiss. Zoologie, Bd. xxv ; and “ Vorlaufige Mittheilung Einiger Resultate von Studien fiber die Conjugation der Infusorien und die Zelltheilung, Zeitsch. ffir Wiss. Zoologie, Bd. xxv, 1875. ][ Beitrage zur Geschichte des Keimblaschens im Wirbelthierei, Archiv ffir Mikrosk. Anat., Bd. viii, 1872. ** On the Anatomy and Development of the Fresh- water Hydra. Leipzig, 1872. ff Baltour, Developmental History of Elasmobranch Fishes, in the Journal of Anatomy and Physiology, January, 1876. 136 THE CELL DOCTRINE. As already stated, previous to the researches of Muller alluded to, no one doubted the disappearance of the germinal vesicle after fecundation. This was thought to have been established by Purkinje* ** and Yon Baer.f But immediately after Muller made his announcement, others followed in its confirmation. Among these were Leydig,:j;Gegenbauer,§ Fol,]| Leuc- kart,^ Pagenstecher,*"^ Mecznikow,ff Haeckel Ivol- liker,§§ and Van Beneden,l|ll as the result of his earlier researches. Still later, however, of the above-named * Purkinje, Symbolse ad ovi avium historiam ante incuba- tionem, 1825. f Baer, C. E. v., Untersuch. u. die Entwicklungsgesch. der Fische, 1835; and Untersuch. u. die Entwicklungsgesch. der Thiere, Bd. ii, Konigsberg, 1828. t Ley dig, Ueber den Bau und die Systematische Stellung der Roderthiere, Zeit. fiir Wiss. Zook, Bd. vi, p. 102, 1856. ^ Gegenbauer, Beitrage zur Naheren Kenntniss der Siphono- phoren, Zeit. fiir Wiss. Zook, Bd. v ; Zur Lehre vom Genera- tionswechsel bei Medusen und Polypen, p. 24; Untersuch. iiber Pteropoden und Heteropoden, Leipzig, 1855. Ueber die Ent- wickelung der Sagitta, Halle, 1856. II Fol, Die erste Entwickelung des Geryonideneies, Jenaischi Zeitsch., Bd. vii, 1873, p. 474. ^ Leuckart, Die Menschlichen Parasiten, Bd. ii, 2te Lief. p. 322, 1863. ** Pagenstecher, Die Wochenen, Leipzig, 1865. ft Mecznikow, Embryologische Studien an Insecten Zeitsch. fiir Wiss. Zoologie, Bd. xvi, p. 484, 1866. Hfeckel, Zur Entvvickelungsgeschichte der Siphonophoren, Utrecht, 1869. II Kolliker, Die Sch winimpolypen von Messina, Leipzig, 1853. III! Van Beneden, Becherches sur la Composition et la Significa- tion de I’oeuf basees sur PEtude de son mode de Formation et des Premieres Phenomenes Embryonaires, Mem. Couronne de PAcad. Boy. de Belgique, 1. xxxiv. THE CELL DOCTRINE. 137 more recent observers, Auerbach, Strassbiirger, Oellacber, Kleinenberg, Butsclili, Balfonr, and Van Beneden, in accordance with fresh researches made on account of the doubts which those of Oellacher and Ivleinenberg had created in his mind, all agreed that the germinal vesicle disappeared entirely either before or during fertilization. Hertwig and Van Beneden both furnish a carefully detailed account of the steps in the destruction of the germinal vesicle, the former in the unripe ova of Toxopneustes lividus^ and the latter in the ovum of the rabbit. While agreeing in many particulars, they differ in their ac- count of the final dissolution. According to Hert- wig, the whole structure, after having become periph- eral, disappears, leaving behind, of its contents, the germinal spot, or nucleolus, which becomes the nucleus of the ovum ready for the changes of fertilization. Van Beneden, on the other hand, believes that all the constituents of the germinal spot disappear in toto. It seems also that the view of Hertwug, that a part of the germinal vesicle remains to form the nucleus of the ovum, was previously suggested by Derbes and Von Baer. The former, in 1847,* described the ovarian ova as consisting of three zones, the germi- nal spot, the germinal vesicle, and the yolk, of which the middle one only disappears. Von Baerf also states that in the case of echinoderms, the germinal * Derbes, Observ. sur le Mecanisme et le Phen. qui accomp, la Formation de TEmbryon chez I’Oursin Comestible, Ann. des Sc. Nat., Zoologie, 1847, vol. viii. t C. E. V. J3aer, Neue Untersuch., iiber die Entwickel. der Thiere, Froriep’s Neue Notizen, vol. xxxix, 1846. 12^ 138 THE CELL DOCTRINE. spot remains as a nucleus of the ovum when the ger- minal vesicle is no lono;er seen. Similar statements were made Leydig,* and Bischoffjt the former with regard to Piscicola, and the latter in the case of mammals. The Cell-contents and Cell-wall. — As cells grow older and are farther removed from the bloodvessels which nourish them, there is found to be, exterior to the nucleus, a portion which no longer admits of staining by carmine solutions of the strength which will tinge the nucleus. Further, the extreme periphery of this is often found condensed so as to present under the microscope a double contour, and to form an actual limitary membrane to the cell. To the former the name cell-contents ” has come to be applied, and to the latter, ‘‘ cell-wall.” With regard to the “ cell-contents,” it is plain that a strict adherence* to the term would require to be included the nucleus and nucleolus when present, and such was the original scope of the term when a cell was defined as a “ closed vesicle or bag with cer- tain ‘ contents/ among which is essentially a nu- cleus,” a definition now very properly rejected. It is to this portion of the cell also, that the German histologists of the present day apply the term 'plasrn^^ instead of to the nucleus and nucleolus, which in many cells, at least, alone possess the endowments suggested by the word protoplasm (j^poru'^ first, -hiapa, * Leydig, Ziir Anatomie von Piscicola Geometrica, Zeitscb. f. Wiss. Zoologie, vol. i, 1849. t Bischolf, Entwickelungsgeschiclite des Kaninchen eies, 1842. THE CELL DOCTRINE. 139 a tiling formed). It is for this reason that I would prefer to reject the term altogether, but it has come to be so closely associated with this portion of the cell, that such omission w^ould now seem impossible. It is at least probable that this ‘‘ protoplasm ” or cell- contents, the portion of the cell exterior to the nu- cleus, is derived from the latter by a change in its structure and composition, a change which in the absence of more accurate knowledge we may char- acterize as of the nature of oxidation. But what- ever this change is, its effect is to alter entirely the properties of the matter in which it has taken place. So that it no longer possesses the power of growth through active efforts of nutrition, that is, by con- verting the pabulum of the blood into material like itself, but continues to grow at the expense of the nucleus or bioplasm, which is gradually converted into it. It is this to which Beale has applied the name of “dead” or “formed” material, but for which I prefer the term non-germinal^ since this ac- curately marks the property which it has lost, and it is not always lifeless in any other sense, because in it still reside properties which are inconsistent with the state known as death. Thus the function of the tissue of which the cell forms a part commonly resides in the cell-contents or non-germinal matter, as that of “contractility” in muscle and “ neu- ridity ” in nervous tissues. In some situations it is truly dead, as where it becomes the secretion of glands, as milk and bile. It has already been stated that the “ cell-wall ” when present is simply condensed periphery of cell- 140 THE CELL DOCTRINE. contents, and is therefore a part of the formed or non germinal matter, and is in no way essential to the constitution of the cell. In structure the cell-wall when present is usually homogeneous, transparent, in a word structureless. Recent observations have, however, shown this to he not invariable. Thus, it is not difficult to demon- strate with the higher powers certain lines or stride in the outer thickened edge of the columnar cells capping the villi of the small intestine, which are perhaps correctly interpreted by Funke, Kolliker, and others, as porous canals in the cell-wall, through which the tine particles of the emulsitied fats are absorbed. These may at least be discovered occupy- ing corresponding situations with great distinctness. Schroen has also described similar markings in the thickened cell-wall of the rete 31alpighii of the human skin. Intercellular Substance. — Closely allied to the cell- wall is the so-called intercellular substance of tissues. Althoua;h it is true that all tissues oris^inate from cells, yet there are comparatively few which in their perfect, state are composed purely of cells, hut the latter are more or less separated by a substance be- tween them. Thus cartilage or gristle ” is com- posed of cells and an intercellular substance, which is either hyaline or tibrous, and all the connective tissues, under which are included bone, cartilage, already alluded to, white fibrous tissue, yellow elastic tissue, and even teeth, are similarly composed of cellular elements, and a something between them, which is either homogeneous or structured. THE CELL DOCTRINE. 141 The mode of origin of this intercellular substance has given rise to considerable discussion. Schwann assumed that there originally existed spindle-cells, the caudate corpuscles, and that out of these cells, fas- ciculi of connective tissue were developed by split- ting up of the body of the cell. Fig. 18. A, Bundle of common, wavy, connective tissue (intercellular substance) split- ting at its end into fine fibrils. B, Diagram of the development of connective tissue, according to Schwann, a, Spindle-shaped cell (caudate corpuscle, fibro- plastic corpuscle of Lebert), with nucleus and nucleolus, d, Cleavage of the body of the cell into fibrils. C, Diagram of the development of connective tissue, according to Henle. a, Hyaline matrix (blastema) with nucleolated nuclei regu- larly distributed through it. b, Fibrillation of blastema (direct formation of fibrils), and transformation of the nuclei into nucleus-fibres. Henle thought that originally there Avere no cells, but nuclei only Avere developed in the blastema at certain intervals, while the fibres which afterwards appeared Avere produced by a direct fibrillation of the blastema, and that while the intermediate sub- stance Avas thus being differentiated into fibres, the nuclei gradually became elongated, so as at length to 142 THE CELL DOCTRINE. ruD into one another, and thus give rise to peculiar longitudinal fibres {nadeits-Jihres or kernfasern). Reichert contended that there were cells in great abundance between which was deposited intercellular substance, with which the membrane of the cells be- came subsequently blended, reaching thus a stage in which there was no longer any boundary between the cells and the intermediate substance. The nuclei he thought also disappeared in some instances. The intercellular fibres he said were a false interpretation of an optical image. Virchow, with Schwann and against Henle, be- Fig. 19. Diagram of the development of connective tissue, according to Yircjiow’s in- vestigations. A, Earliest stage, hyaline basis (intercellular) substance, with largish cells (connective tissue corpuscles); the latter drawn up in rows at regular intervals ; at first, separated, spindle-shaped and simple ; at a later j»eriod, anas- tomosing and branched. B, More advanced stage ; at a, the basis-substance which has become striated (fibrillared) presents a fasciculated appearance on account of the cells imbedded in it in rows, the cells becoming narrower and smaller; at b, the striation of the basis-substance has disappeared under the influence of acetic acid, and the fine and long-anastomosing fibre-cells (connective tissue corpuscles), still retaining their nuclei, are seen. lieves that spindle-shaped cells indisputably exist, and with Henle and Reichert and ai^ainst Schwann, THE CELL DOCTRINE. 143 a splitting up of the cells into fibres does not occur, but that a previously homogeneous intercellular sub- stance becomes fibrillated, and that the cells them- selves preserve their integrity. In young connective tissue, cells undoubtedly exist, with at least their more important parts as nuclei and protoplasm, but in fully formed fibrous tissue the only portion of the cell which I have been able to satisfy myself, in an almost daily study of healthy and diseased struc- tures, is constantly present, is the nucleus. Max Schultze, in Germany, Beale, in England, and Leidy, in this country, believe the intercellular sub- stance to orio;inate as the cell-contents and cell-wall by a conversion of the nucleus or bioplasm at its periphery, and a pushing off* of this converted matter by the deposition of new bioplasm within the nucleus. In fact, according to them, the intercellu- lar substance is simply the oldest cell-wall or formed material, under which term Beale consistently in- cludes all intercellular substance. See Figs. II, 12, frontispiece. This view seems to me also to be most consistent with observation, and until something more reason- able is off'ered I shall adopt it. One of the most potent arguments in its favor is the fact that the cell-wall and intercellular substance are often so closely continuous that they cannot be separated, either visually or by dissection. On this account Beale has also described a “ cell ” or ‘‘ elementary part ” of cartilage and similar structures, as includ- ing in its formed material the intercellular substance extending to a point midway between it and its neighbor. 144 THE CELL DOCTRINE. The Structure of Cells. — As to structure, cells have been heretofore described as structureless, or vari- ously granular, and with powers not exceeding 250 diameters, they may still be so described. Few cells even with these powers are structureless, while on the other hand, a highly granular condition of a cell is considered indicative of some pathological change, except in the case of nerve-cells, which in many situations are admittedly highly granular in the normal state. The same may be said of the nucleus. Occasionally, however, even previous to 1867, certain nerve-cells were described as striated in appearance. Examples of structureless cells are most striking in the unicellular organism, as the amoeba (Fig. 16, front- ispiece), in which we have a structureless nucleated mass, which owes whatever of structure it possesses to foreign particles, which it takes up as food. So far as the structure of the elementary part of the more complex organisms, however, is concerned, the recent discoveries, already described (see p. 11 7) as discernible by a power as low as 300 diameters, demand a total change in the description of the structure of cells. Henceforward we must describe not only the nucleus but also the cellular substance (protoplasm) as fibrillar in structure, made up of a network of delicate fibres the meshes of which are filled with an interfibril- lar ” or ground substance,” which is structureless, and that the fibrillae of the intracellular and intra- nuclear networks are continuous. And if Klein be correct we must define the nucleoli as merely local thickenings, natural or artificial, of the intranuclear network. The intranuclear networks are much more THE CELL DOCTRINE. 145 distinct than the ini r acellular. See plate at end of volume. Ike Sharpe of Cells. — The shape of cells is extremely varied. In its fully developed state each tissue is com- posed of cells which may be said to he characteristic of it. First, the typical form of a cell may be said to be spherical, and this is the shape of all young cells in whatever situation found. See Fig. 10, frontispiece. Second, in glandular tissue, where perhaps cells are dianging more rapidly than in any other situation in health, their deviation from the round shape is only such as results from mutual compression, forming more or less polygonal cells, as seen in Fig. 3, p. 39. Third, in epithelial structures we have upon the ex- treme periphery either fiat scales containing a small proportion of bioplasm (nucleus) in proportion to the non-germinal matter (cell-contents), and of irregular outline, forming the so-called squamous epithelium. Figs. 3, 4, 5, 6, frontispiece ; or fourth, similar scales, of regular outline, many-sided and with their edges so adapted as to form a pavement-like structure, forming tessellated epithelium ; ov fifth, elongated nu- cleated cells, which from their shape are called colum- nar cells. Sixth, in certain situations, as the respira- tory passages, these columnar cells are further provid- ed with hairlike prolongations, known as cilia, which in health exhibit a constant waving motion, whence the cells aie called ciliated cells. Wherever columnar cells are present in successive layers (as is usually the case), they lose their characteristic shape and ap- proach more and more the sj^herical outline as we recede from the surface, until the deepest and there- 13 U6 THE CELL DOCTRINE. fore youngest cells are again spherical. Seventh^ in nervous tissues again, we meet cells which from their prolongations, which may be one or many, are called jjolai^ cells, and unipolar, bipolar, or multipolar, ac- cordii]g to the number of processes they possess. Eighth^ in the so-called connective tissue again, we have a variety in the shape of the cells. Thus in areolar tissue or connective tissue proper, we have young round cells composed almost wholly of germi- nal matter, exhibiting amoeboid movements and all the characters of the leucocyte or colorless corpuscle (Fig. 10, frontispiece), as well as the elongated spin- dle shaped nucleated cell, so characteristic as to have long ago received the name connective tissue corpuscle (Fig. 10, frontispiece. Fig. 18, B.). These latter cells also possess prolongations, which unite with those extending from adjacent cells, and being hollow thus form a canalicular sj^stem, of exceeding fineness, which is believed to he capable of conveying nutrient juices in the absence of bloodvessels of sufficient size to conduct the corpuscles of the blood. The appear- ance of this system is shown in Figs. IG and 19, from A'irchow’s Cellular Pathology. Ninth, the cells of striated muscular tissue exhibit a prolonged oval shape, sometimes resembling that of the connective tissue corpuscle, while the cells of unstriped muscular tissue are typical spmdle-cells, with bellied centres and staff-shaped nuclei. A^ain, in cartilage we have cells exhibiting various modifications of the spherical shape, while the cells of bone give us a tenth form. These are contained in correspondingly irregular cavities in its substance, THE CELL DOCTRINE. 147 and are almost fantastic in their irrei^ularitv, ex- hibiting also prolongations which unite with those of neighboring bone-cells, and with the Haversian canals which conduct the bloodvessels throuorh bone. The shape of the cells through whose agency the teeth are formed is also seen to be peculiar, those whence the dentine is developed being provided with a single long process, giving an eleventh form of cell. Those producii^’ the enamel are columnar, while the crusta petrosa^ or portion of bone-like substance cover- ing the fang, contains cells similar to those of bone. Finally, the cells of adipose or fatty tissue require allusion, dliey are spherical or compressed vesicles or sacs of considerable size, are filled with oil, and exhibit in consequence a brilliant, highly refracting character, under the microscope, indicated by a broad dark border and a transparent centre. In the begin- ning they are in no way different from other young cells, but, according to Beale, their bioplasm, instead of being converted into the ordinary non-germinal matter of albuminous composition, undergoes a fatty conversion, in the course of which it gradually di- minishes in size and is thrust towards the wall of the cell, where it may sometimes be demonstrated by staining as a small flattened nucleus. The oil thus produced is termed by Beale secondary formed material, to distinguish it from the albuminous non- germinal matter. The same term is applied by him to the secondary product, starchy found in the shape of concentrically laminated granules in many vegeta- ble cells. According to most other histoloo;ists, how- ever, the fatty contents of the /a/l-vesicles are an infil- 148 THE CELL DOCTRINE. tration of fat from the blood, su peradded to the pro- toplasm or cell-contents, pushing the latter with the nucleus to one side, without substituting it or beina: derived directly from it as is alleged by Beale. In pathological formations all the different forms of cells here alluded to are met with, and there is now no special type of cell which is known by its shape to have a pathological impression. It is rather by the rapidity of growth of cells, their arrangement and relation to the intercellular substance, as well as peculiarities in the latter substance itself, that we know a structure to be a pathological formation. The “ cancer-cell,” which was so long an object of wonder and fear, and eagerly sought for as such, is no longer acknowledged to be anything peculiar as to form. At the same time, when cells from a sus- pected growth are observed to be very large, to con- tain numerous nuclei or centres of bioplasm, and to exhibit great variety in shape, we have evidences of that rapidity of growth which is more or less char- acteristic of malio:nant formations. The Size of Cells. — This is likewise extremely vari- ous. They may be particles of such extreme minute- ness as to be recognized as mere dots by the highest powers of the microscope, the smallest particles of germinal matter measured by Dr. Beale being less than the toVo-qo (.000024 mm.) in diame- ter, while the largest epithelial scales are o j of an inch (.1 mm.) in diameter, and the cells of morbid growths often reach the of an inch (.127 mm.\ The human ovum, which may be regarded as a typi- cal cell, with nucleus, nucleolus, and contents, varies THE CELL DOCTRINE. 149 from the o^-q to inch (.105 mm. to .21 mm.). The smallest particles of germinar matter above alluded to would not be called cells in the or- dinary sense of the word, but they are such consist- ently with our definition, and it must moreover be remembered that the term is only applied to such particles of matter endowed with the life properties of reproduction, nutrition, growth, and development. hTo particle of oil, inorganic or other matter, which does not possess these properties can be characterized as a living cell, whatever its size. Pure germinal matter is rarely seen in masses as large as the ^ J ^ of an inch (.05 mrn.), since it usually breaks up into smaller masses to form independent cells before it reaches this size. As constitutino: the nuclei of fully formed cells, it is usually from the eVoT inch (004. mm. to 008. mrn.) in diameter. While nuclei exhibit less variation in size than do the cells, they are also more constant in shape, being generally round or oval. Sometimes, however, they also exhibit a stellate shape. The Origin of Cells. — It is to be regretted that this most important question as to the exact origin of cells is not yet definitely settled. A very short time ago the proposition omnis cellula e cellidd was thought to have been abundantly proven, and that all living things come from previously existing things, was generally admitted. But although this view has been, in the conception of some, shaken by more recent ex- periment, it still remains the only law of cell forma- tion in the minds of most physiologists, and I be- lieve there are none who deny that it forms in all 13* 150 THE CELL DOCTRINE. the liio;her forms of animal and vegetable life the only method of cell genesis which is constantly before us, while the phenomena of spontaneous generation are confined to the creation of the lowest vegetable and animal organisms, so that the proposition omnis cellula e celluld may be now considered as generally accepted. Prof. II. Charlton Bastian remains the most eminent English supporter of the doctrine of spontaneous generation, against whom Huxley, Kob- erts, Tyndall, Beale and others have directed arti- cles and experiments. In the division of cells to produce }mung cells, it is usually in the nucleus that the segmentation first begins, extending thence to the protoplasm outside of it, although this is not invariable. For any portion of the bioplasm of a cell may grow, separate and form a young cell. It is the bioplasm or germinal matter alone, however, which can give rise to the cell, and never the non-germinal matter or formed material. It is seldom, also, that we see in the animal cell, ex- cept in the segmentation of the fecundated ovum, that symmetrical division of the nucleus into two, these into four, these into eight, and so on, as is con- stantly seen in the vegetable cell, but it is rather a budding and subsequent dropping oti* of portions of bioplasm which become young cells, and which al- most always assume the spherical form when allowed to float freely (see Fig. 10, of frontispiece). Strassburger,^^ in his recent work on Cell Formation and Cell Division^ admits three methods of increase * Ueber Zellbildung und Zelltheilung, Jena, 1875. THE CELL DOCTRINE. 151 of cells, — cell division, free cell formation, and re- newal (vollzellbildnng) of cells. He says that in the animal kingdom cell division seems to be the only authenticated mode of increase of cells. Of methods of free cell formation, only a few instances are re- corded in vegetables. The last method, renewal or rejuvenescence, has reference rather to the complete formation or development of cells than to their orio^in. Nutrition of Cells. — In the nutrition of the cell, the pabulum comes to it from the periphery, being strained through the formed material. The new germinal matter takes its place in or near the centre of the original mass, constituting, according to Beale, a new centre of germinal matter, which may be the nucleus, if no other circumscribed centre be present, or the nucleolus, if it be deposited within such a centre. Other new" centres, according to him, may again take position within these, and assume the relation of nu- cleolus to the original nucleolus, wdiich now" becomes the nucleus, an older centre of germinal matter ; Avhile the original nucleus has probably been con- verted into the second constituent of the cell, the formed material. If the nucleolus be w"hat Klein con- siders it, a mere tliickening of the intranuclear net- w"ork referred to, this order of succession in the for- mation of differentiated centres of germinal matter is of course impossible, and it can only be said that the new" matter takes its position tow"ards the centre of the cell mass. Amoeboid Movement {Diaimiesis). — Germinal mat- ter, w"hen free and living, exhibits a pow"er of move- 152 THE CELL DOCTRINE. raent, both in j')ortions of its substance, producing changes in shape, and in its entire mass^ resulting in changes of position. The former, and probably, also, the latter, may have for its object the ob- taining of pabulum, as is seen in the amoeba, when it embraces bj^ its protrusions a particle of nutri- tive matter. These movements are less decided in the cells of the higher animals, yet they are of con- stant occurrence, as in pus and white corpuscles, and when thus occurring they are spoken of as amoeboid movements."’ Allied or identical with this second class of movements, are those of undoubted occur- rence in white blood-corpuscles, first observed by Addison,* Waller,t and Cohnheim,:}; whereby these cells have been seen mii^ratino: from the bloodvessels. * Addison, Physiological Researches, London, 1841. f Waller, London, Dublin and Edinburgh Philosophical Maga- zine, vol. xxix, 1846, pp. 271 and 398. t Cohnheini, Ueber Entzundung, und Eiterung, Yirch. Arch. Bd. xl, 1867, p. 1. BIBLIOGEAPHY. Abiogenesis, article in Encyclopsedia Britannica, vol. i, 9th ed. 1878. Addison^ Experiaiental and Practical Besearches on the Structure and Functions of Bed Blood-Corpuscles ; on inflammation, and on the origin and nature of tubercles in the lungs. Transactions of the Pro- vincial Medical and Surgical Association, vol. xi. London : 1842. “ Physiological Besearches. London : 1841. Amici^ Movement of Protoplasm, in Ann. d. Sc. Nat. Bot., 1 serie, 1830, p. 329. Arndt B., Ueber eine bemerkenswerthe Art des Zerfalles der Eiterkorperchen, Berk kl. Wochenschr., No. 19, 1876. “ Ueber den Zellkern, Sitsungsb. der med. Vereins zu Greifswald, November, 1876. “ Eine Bemerkung liber weisse Blutkorperchen, Ber- liner klinische Wochenschr., No. 29, 1876. Arnold, F., Lehrbuch der Physiologie des Menschen. Zurich : 1836. Arnold, F. und J. W., Die Erscheinungen und Gesetze des lebenden menschlichen Ktirpers im gesunden und kranken Zustande. Bd. i, Thl. i. Zurich : 1836-.39. Arnold, J., Ueber das Verbal ten des Indigocarmins in den lebenden Geweben, Med. Centralbl. No. 41, 1875. “ Ueber die Kittsubstanz der Epithelien, Virchow’s Arch. Bd. 64, 1875, and Bd. 66, 1876 (with two plates). “ Zur Kenntniss der Saftbahnen des Bindegewebes, Virchow’s Arch., Bd. 68, 1876 (with two plates). “ Ueber Diapedesis, Virchow’s Archiv, vol. 58, 1873. 154 THE CELL DOCTRINE. Arnold^ Ueber das Yerhalten der lYandungeii der Bliitge- fasse, bei der Emigration der weissen Blutkorper, Virchow’s Arcbiv, vol. 6*2, 1875 (with plate). Asc/?, Diss. de natura spermatis, observat. microscop, indi- gato. G()tt. : 1756. AscAerson, Muller’s Arcbiv, 1840. Auerbach, Ueber die Einzelligkeit der Amoeben, Zeitschr. fur IViss. Zook, 1856, vol. vii, p. 412. Auerbach, L., Organologische Studien. Zur Cbaracteristik imd Lebensgeschichte der Zellkerne. Breslau : 1874. ‘‘ Zelle mid Zellkern, Beitrage zur Biologie der Plianzen, herausgegeb. v. Cohn, Bd. ii, 1876. “ Zur Lebre von der Vermebrung der Zellkerne, Med. Centralbk, No. 1, 1876. “ Ueber die streifige Spindelfigar bei der Vermebrung der Zellkerne, Bericbt liber die mlincbener Naturforscber- versammlung, 1877. Baer, C. E. v., Untersucbungen liber die Entwicklungsge- scbicbte derTbiere., vol. ii. “ Unters. ii. d. Entwicklungsgescb. der Eiscbe, 1835. “ Neue Unters. ii. d. Entwicklung der Tbiere, Froriep’s neue Notizen, vol. 39. Bagge, Diss. inaug. de Evolutione Strongyli, etc., Erlangen : 1841. Balbani, Surles pbenom^nes de la division du noyau cellulaire, Gazette Medic., 1876, p. 565. “ Zeitscbrift f. rat. Medicin, xxvii, 1865. Balfour, E. Al., A preliminary account of tbe Development of tbe Elasmobrancb Fisbes, Quart. Jour. Micr. Sci., Oct., 1814. “ Journal of Anatomy and Pb3^siolog}’, Januaiy, 1876. Barry, Alartin, Pbilosopb. Transac. , London : 1838-39-40-41. Papers on Embryology and tbe Blood. Barclay, John, An inquiry into tbe opinions, ancient and modern, on life and organization. London : 1822. Barthez, F. J., De principio bominis vitali, oratio acad. INIont- pellier, 1777. BIBLIOGRAPHY. 155 Barthez^ P. J., ^^'ova doctriua cle fimctionibus naturae humanae. Montpellier : 1774. “ Nouveaux elements de la science de I’homme. Mont- pellier: 1778, 2e. edit. Paris, 1806. Bastian, II. Cliarltan., Spontaneous Generation, in “Nature” for June 30th, July 7th and 14th, 1870. “ Facts and Reasonings concerning the Heterogeneous Evolutions of Living Things. “ Nature,” vol. ii, p. 170, et seq.^ 1870. “ The Modes of Origin of Lowest Organisms ; including a discussion of the experiments of Pasteur, and a reply to some statements by Professors Huxley and . Tyndall. London : 1871. “ Bibliographical notice of the above volume in Pop. Science Rev. for October, 1871. “ Bibliographical notice of the above volume in Atlantic Monthly, January, 1872. “ Beginning of Life. London : 1872. “ Some Heterogeneous Modes of Origin of Flagellated Monads, Fungus germs, and Ciliated Infusoria. Read at Royal Society, London, March 21st, 1872 ; abstract published in Quar. Jour. Mic. Sci., July, 1872, p. 302. Bauer, Philosoph. Transac. for 1818, and Sir E. Home’s Lec- tures on Compar. Anatomy, vol. iii, lect. 3. Lon- don : 1823. Baumgartner., K. iL, Beobachtungen liber die Nerven und das Blut in ihrem gesunden und krankhaften Zustande. Freib : 1830. “ Beitrage zur Physiologie und Anatomie, aus den Grundzligen zur Physiologie und zur allgemeinen Krankheits-und Heilungslehre, 2te Auflage, besonders abgedruckt. Stuttgart : 1842. Baur., Entw. d. Bindesubstanz. 1858, p. 28. ^ Beale., Lionel >S., On the Structure of the Simple Tissues of the Human Bod}\ With some observations on their development, growth, nutrition, decay, and on certain 156 THE CELL DOCTRINE. changes occurring in disease. A course of Lectures delivered at the Royal College of Physicians of Lon- don, 18G1. Also published in Beale’s Archives of Medi- cine, vols. ii and iii. Beetle^ Lionel S., On the Structure and Growth of the Tis- sues, and on Life. Ten Lectures delivered at King’s College. London : 1865. ‘‘ Microscope in Medicine, p. 146, 3d ed. London : 1867. “ Kew Views upon the Structure, Pormation and Growth of the Tissues, and on Life ; p. 308, et seq. of Beale’s How to 'Work with the Microscope, 4th ed. Lon- don : 1868. ‘‘ Introductory chap, to new ed. of Todd and Bowman’s Physiolog. Anatomy. London : 1867. “ Protoplasm ; or Life, Porce, and Matter. London : 1870. “ Protoplasm ; or Life, Matter, and Mind. 2d ed., much enlarged. London : 1870. ‘‘ Prof. Owen’s Views on Magnetic and Vital Porce, Med. Times and Gazette, vol. i, 1869. “ Bioplasm and its Degradation ; with observations on the origin of Contagious Diseases, Quar. Jour. Mic. Sci. K. S., vol. X, July, 1870. “ Disease Germs ; their supposed nature ; an original in- vestigation, with critical remarks. London: 1870. “ On the Real Kature of Disease Germs, IMonthly INlic. Jour., vol. iii, Ko. 22, October, 1870. “ Disease Germs : their real nature ; an original investi- gation. London : 1870. “ Bioplasm : An Introduction to the Study of Physiology and Medicine. AVith numerous illustrations. Lon- don : 1872. BSchamj^ et Estor^ Du role des microzymas pendant le devel- oppement embryonnaire, Compt. rendu, t. 75, p. 962, 1872. Beneden^ Edouard van, Recherches sur la Composition et la Signification de I’oeuf basees sur I’Etude de son mode BIBLIOGRAPHY. 157 (le Formation et des Premiere Phenomhies Embryon- naires. Presented to the Royal Academy of Belginm, August 1st, 18G8. Abstract in Q. J. Mic. Sci., S., vol. X, p. 406, Oct., 1870. Beneden^ Edouard van^ Remarks on the Structure of the Gregariiiffi, Quart. Journ. of Micr. Science, vol. xii (with plate), 1872. “ Contributions a I’histoire de la vesicule germinative, etc. Bulletins de I’Academie Royal Belgique, t. 41, 1876 (with plate). English in Quart. Journ. Micr. Sc., 1876, p. 153. “ La maturation de I’oeuf, la fecondation et les premieres phase du developp. embryonnaire des mammif^res, etc. Bruxelles : 1875. “ Sur line nouvelle espece de gregarine, etc. Bull. Acad. Roy. de Belg., vol. xxviii. See also translation of the same in Quarterly Journ. Micr. Sc., vol. xvi, 1876. BenediH^ J/., Zur Lehre der entzUndl. Kernwurcherung, Med. Central blatt, No. 13, 1874. Bennett, J. Hughes, Treatise on Inflammation. Edinburgh : 1844. “ Practice of Medicine (Am edit.). New York : 1866. ‘‘ Edinburgh Monthly Med. Jour., May, 1852. ‘‘ Report to* British Association for the Advancement of Science, 1855. “ Proceedings of the Royal Society of Edinburgh, April 1st, 1861. ‘‘ Lectures on Molecular Physiology, in London Lancet, 1863. ‘‘ Edinburgh Monthly Med. Jour., March, 1868. “ Popular Science Rev. London, elan., 1869. Bergeret, Composition du pus et mode de formation des leu- cocytes du pus. Robin, Journ. d’Anatomie, etc., page 334, 1875. Bergmann, Muller’s Archiv, 1841. Bernhardt, Symbolse ad ovi mammalium historian!. Diss. in- aug. Wratisl. : 1834. 14 158 THE CELL DOCTRINE. Bichat^ Xavier^ Reclierches physiologiques sur la vie et la mort. Paris : 1800, 1802, 1805, avec notes de Ma- gendie. Ibid., 1822. “ Anatomie gene rale ; Considerations generates, t. I. Paris : 1801. Billroth^ Beitrage zur Path. Hist. Berlin : 1858. Bischojf] 111. L. TP., Entwickelungsgeschichte des Hunde-Eies. Braunschweig : 1845. “ Entwickelungsgeschichte des Kaninchen-Eies. Braun- schweig : 1842. “ Ueber Missbilduugen nebst einer Einleitung liber die Literatur der Entwickelungsgeschichte. Beprinted fr. Wagner’s Handworterbuch der Physiologie. Braun- schweig : 1850. Bizzozero, 6r., Beitrage zur Kenntniss der sogenannten endo- genen Zellbildung, Wiener inedicinische Jahrbiicher, 1872- “ Ueber Entwickelung des secundaren Gliom der Leber, Moleschott’s Untersuchungen, etc., Bd. xi, p. 50-53, 1872, with plate. “ Ueber den Bau der gesch. Plattenepithelien, Mole- schott’s Untersuch., Bd. xi, p. 30-35, with plate, 1872. “ Ueber den Bau des Sehnengewebes, Moleschott’s JJn- tersuch., Bd. xi, 1, p. 36-49, 1872. • “ Zur BindegeAvebsfrage, Med. Centralblatt, Xo. 51, 1872. Blach^ Jas. /., The Ketrospective Address delivered at the Tenth Anniversary Meeting of the Provincial ^ledi- cal and Surgical Association, held at Exeter, England, August 3d and 4th, 1842. Bowditch, II. P., The lymph-spaces in fosciie, etc. Proceed- ino-s of the Ainer. Acad, of Arts and Sciences, 1873 (with plate), and Quarterly Jour, of Micr. Sciences, 1874. Boll, F., Structure and development of tissue. Arch. f. mikr. Anat., vii and viii, 1871. Bonnet, C/ms., Considerations sur les corps organisee. Am- sterdam : 1762, 2 vol.. Ibid., 1768. BIBLIOGRAPHY. 159 Bory^ Saint Vincent, Article “Matifere” dii Diet, classique d’hist. naturelle, t. x. Paris : 182G. Bottcher, A., ^^’eue Untersuchungen liber die rothen Blut- korperchen, Memoires de I’Academie imper. de Sci- ences de St. Petersbourg, vii, t. 22, No. 11, 1876 (witli two plates). “ Ueber die feineren Structur-Verhaltnisse der rothen Blntkorpercben, Arebiv flir Micr. Anat. xiv, 1877, p. 73 (with plate). English in Quart. Journ. of Micr. Sc. 1877, p. 377. “ Virchow’s Archiv, Bd. xiii. “ Ueber d. Zusammenhang sog. Molecularen mit dem Leben des Protoplasma, Yirch. Arch., Bd. xv. Boicman, Paper on Muscle, in Philosophical Transactions. London : 1840. Part i, p. 485. “ Art. “Muscle,” Cyclopedia of Anatomy and Physi- ology. London : 4839-47. Bowman and Todd, Physiolog. Anatomy and Physiology of Man. Philadelphia: 1857. Braidwood, Development of Striped Muscular Eibre (from cytoblasts, or nuclei in a molecular blastema). Br. and For. Med. Chir. Rev., Ap., 1866. Braun, A., De Algis nnicelinlar. nonnullis. novis vel minus cogn. Berol : 1855. Brandt, A., Bermerkungen liber die Kerne der rothen Blnt- korperchen. Arch. f. Mikr. Anat., Bd. xiii, 1876, p. 391. “ Ueber active Formveranderung am Kernkorperchen, Arch. f. Mikr. Anatomic, Bd. x, 1873. Briicke, E., Denkschriften der Wiener Akad., Bd. iv, p. 203, Bd. vi. “ Moleschott’s Untersuchungen, Bd. viii, 1862, p. 495. “ Elementar-Organismen, WTen. Sitznngsb., 1861. “ Die sog. Molecularen, Wien. Sitzb., 1862. “ Das Verhalten d. sogenannten Protoplasmastrome in den Brennhaaren von Urtica Urens, etc., in Kais. Akad. d. Wiss., zu Wien, Bd. xlvi, June 20, 1862. 160 THE CELL DOCTRINE. Buffon G. L. Leclerc de^ Discours sur la nature des animaux, et Ilistoire naturelle de I’homine. Editions multiplees. Buchanan^ Andrew^ On the Fibrin contained in the Animal Fluids and Transformations which it undergoes. (Contains views on the Formation of Cells. ) Proceed- ings of the Philosophical Society of Glasgow. No. 7. Abridged account in the Lond. and Edinb. Mo. Jour, of Med. Sci., vol. iv, 1844, p. 9G4. Bur don- Sanderson, The Origin and Distribution of Micro- zymes (Bacteria) in Water, and the Circumstances which determine their existence in the tissues and liquids of the living Body. lieprinted in the Quar- terly Journal of Microscopic Science, for October, 1871 (vol. xliv, p. 323), from the author’s second “Report of Researches concerning the intimate pa- thology of contagion,” in the Appendix to tlie 13th Report of the Medical Officer of the Privy Council, 1871. “ On the Intimate Pathology of Contagion. Reports to Her Majesty’s Privy Council. London : 18G8-70. Burdach, G., Beitnige zur Mikroskopischen Anatomie der Nerven. Konigsb. : 1837. Burdach, E., Observationes nonnullse microscopicte de inflam- matione. Diss. Inaug. Regiomont : 182G. Brims, T., Lehrbuch der Allgemeinen Anatomie des Men- schen, nach eigenen Untersuchungen. Braunsch- weig, 1841. Burnett, Waldo J., of Boston, Mass. The Cell: its Physi- ology, Pathology, and Philosophy ^ as deduced from original investigation. To which is added its Ilis- tory and Criticism. A prize essay read before the American Medical Association, and published in vol. vi of its Transactions. Philadelphia : 1853. Butc/ili, O., Yorhiufige Mittheilung einiger Result, von Stu- dien liber die Conjugation von Infusorien uiid die Zelltheilung, Zeitsch. f. Wiss. Zook, xxv, 1875. “ Studien liber die ersten Entwickelungen, etc. Abhandl. BIBLIOGRAPHY. 161 cl. Seiikenb. ISTatiirforscliergesellschaft, Bd. x, 187G (with 15 plates). Biitchli, 0., Zur Kenntniss des Theiliingsprocesses der Knor- pelzellen, Zeitsch. fur Wiss. Zoologie, Bd. 20, 1877 (with plate). Ca(jnard-Latoni\ Mode of multiplication of Yeast Corpuscles, Aimales de Chemie et de Physiologic, t. lxviii,1838. Calori^ Luigi^ On the Glohular Composition of Yervous Struc- tures, in Bulletino delle Scienza Medich. di Bologna, Sett. 1836, p. 152. Calvert, Crace, Putrefaction and Permentation, Brit. Assoc. for Advancement of Science, 1870. Carmalt, TP. iJ. , Bemerkungen zur Lehre von der Entwick- lung der Carcinome nehst Beohachtungen llher spon- . tane Bewegungsfahigkeit von Geschwulstzellen, Vir- chow’s Arch., 1872, Bd. 55, p. 481-487. Carpenter, W. B., Manual of Physiology. London : 1865. “ The ISIicroscope, 4th edition, pp. 689-602. London- 1868. “ On the Mutual Belation of the Vital and Physical Forces, Phil. Trans. London : 1850. “ Principles of Human Physiology, 7th edition. Lon- don : 1867. “ Vegetable Physiology. Ed. by II. Lankester. Lon- don : 1858. Chafford, Em., The Idea of Life, as deduced from contempo- rary Pliysiology. ViRCiiow, Claude Bernard. Translated from “ Le Correspondent,” of October 25th, 1868, for the Y. Y. Quar. Journal of Psycho- logical Medicine and Medical Jurisprudence, for July 1869, by E. S. Dunster, M.D. Cherest et Bouvaist, Des fibres elementaires animales Paris * 1840. Child, Gilbert W., On Protoplasm and the Germ Theories, British Association for Advancement of Science 1870. Chiaje, Belle, Osservazione sullas struttura dell’ epidermide umana. Yapoli : 1827. 14* 162 THE CELL DOCTRINE. “ Cell,” Various opinions on the nature of; Eev. of Turner’s Edit, of Goodsir, Q. J. Mic. Sci., April, 1869. “ Article on, in Micographic Dictionary. “ Article on, in Cyclopedia of Anatomy and Physiology, 1839-47. Cell Doctrine, The ; a review of Beale, Tyson, Iluxle}^ Schleiden and Schwann, The I^ational Quarterly Beview for December, 1870. Cieiikowsky ^ Beitrage zur Kenntniss der Monaden, Max Schultze’s Archiv f. Mikr. Anat , vol. i, 1865. “ Das Plasmodium, Pringsheim’s Jahrb., Bd. iii, 1863, p. 400. Zur Entwickelungsgeschichte der Myxomyceten, l^ringsheim’s Jahrb., Bd. iii, 1863, p. 325. “ Zur Genesis eines einzell. Organismus. Petersh. :,1856. “ ‘ Ueber contractile Gewebe im Pdanzenreich. Bresl. : 1861. Clarke^ J. Lockhart^ Development of Muse. Eibre in Man, Mammalia, and Birds, Quart. Jour. Mic. Sci., E". S., vol. ii and iii, 1861-2. Claparede et Lacliman^ Etudes sur les Infusiores et les Bhizo- podes, 2 tom. Paris : 1858. Clemenceau^ G., De la Generation des Elements Anatomiques, preside d’une Introduction par M. Ch. Bohin*. Paris : 1867 ; Or Beview of, in Biclim. and Louisville Med. Jour., ISfovember, 1868, p. 560. Cleland^ S'., On Cell Theories, Quart. Jour. Micr. Science, 1873, p. 255. Colvn, Ferdinand, Classification and General Physiology of ' Bacteria, in Beitrage zur Biologie der Pfianzen, Xo. 2, p. 127. “ Organismen in der Pockenlymphe, Archiv fur Patholog. Anatomie und Ph^^siologie, pp. 55, 229. “ Vegetable nature and Structural relation of Bacteria, Nova Acta nat. cur. Lib. xxiv. “ Beitriige zur Biologie der Pfianzen, Zweites Heft, Breslau : 1872. “ Nachtrage zur Naturgeschichte des Protococcus plu- BIBLIOGRAPHY. 163 vialis, in Xova Acta Ac. Leop. Carol., tom. xxii, pars. ii. Colin^ Ferdinand^ I^ov. Act. Leop. Carol., tom. xxiv. “ Contractile Gewebe im Pllanzenreich. Breslau : 1801. Cohnheim^ Ueber EntzUndung imd Eiternng, Yirch. Archiv, Bd. xl, p. 1, 1807. “ Yirchow’s Archiv, Bd. xlix, p. 333. “ Nene Untersnclmngen liber die EntzUndung. Berlin: 1873. CooA’c, Introduction to the Study of Microscopic Fungi. Lon- don : 1870. Coste^ M. Victoi% Kecherches sur la Generation des Mammifferes. Paris : 1830. “ Embryogenie comparee. Tom i,et Atlas. Paris: 1837. Dalton^ Chap, on Generation in Human Physiology, 5th edition. Philadelphia : 1807. Fanforth, The theories of cell development. Monthly Micr. Journal, viii, p. 121-128, 1872. Darwin^ Er., Zoonomia, or the laws of organized life. Lon- don : 1794-90. 3d ed. Ibid., 1801. Translated into French by J. F. Kluyskens, Gant : 1810-11. “ G/o, Origin of Species, 0th edition. New York, 1870. Derbcs, Observ. sur le mecanisme et les Phen. qui accom- pagnent la Formation de I’Embryon, etc., Ann. des Sc. nati Zoologie, 1847, vol. 8. Dippel, D.,Beitrage z. Ilistologie d. Pflanzen. Bonn: 1804. “ Entstehung der wandstand. Protoplasmastromchen in den Pllanzellen und dessen YerhUltn. zu den Yerdick- ungsschichten. Bonn: 1807. “ Die Intercellularsubstanz u. deren Entstehung. Eot- terd. : 1808. Yegetabilische Zellenbildung. 1858. Dictionnaire de Medecine, Art. “Organization,” tom. xxii, p. 428. Paris : 1840. Bohrowolshj^ 0., Contributions to the Histology of the Mar- row of Jlone, Jour, for norm, and patholog Histology, by M. Ptudneff, St. Petersburg, p. 408,* 1870 (with plate). Bussian. 164 THE CELL DOCTRINE. Donders, Siebold and Kolliker’s Zeitschrift, Bd. iii. “ Zeitschrift fUr Wissen. Zoologie, Bd. iii, p. .348. Donn^^ Du lait et en particulier de celui nourrices. Paris : 1837. Nouvelles experiences sur les animalcules spermatiques. Paris : 1837. “ Becherches microscopiques sur la nature des mucus et de la matifere des ecoulemens. Paris : 1837. Drysdale^ J. , The Protoplasmic Theory of Life. London : 1874. Duffin^ A. B., Cellular Pathology ; Analysis of Yirchow. Beale’s Archives of Medicine, vol. ii, p. 112. “ Protoplasm and the part it plays in the Actions of Living Beings, Quarterly Jour, of Microscopic Science, vol. iii, N. S., 1863, p. 251. Dujardin^ “ Sarcode ” in Ann. d. Sciences Kat., tom. iii et V, 1835, et seq. Dumortier ^ Besearches into the Development of the Ova of Snails, Ann. des Sci. Nat., viii, p. 129. Dutrooliet^ Mernoires pour servir a I’histoire anatomique et physiologique des vegetaux et des animaux, t. i, ii. Atlas. Paris : 1837. “ Becherches sur la nature intime des animaux et des veg6taux. Paris : 1824. Duncan^ Wiener Sitzungsberichte, 1867. W. T. ThiseJton^ On Spontaneous Generation and Evolu- tion, Quart. Journ. Micr. Science, vol. x, p. 333, 1870. Eherth^ C. /., Zur Entwickelungeschichte der Muskeln, in Arch, fur Mikr. Anatomic, ii, p. 504, 1866. “ TJeber Kern und Zelltheilung, Yirchow’s Arch., vol. Ixvii, 1876 (with two plates). “ Yirchow’s Archiv. Bd. li, s. 36. Ehle^ Die Lehre von den Haaren in der gesammten organ- ischen Natur. Bd. i, ii. ITien : 1831. Ecl'hardt. Beitrilge zur Anat. und Physiol, 1855. Edinburgh Medical Journal, Eebruary and April, 1869. Ewald^ A., and Kuhne TY, Die Yerdauung als histologische Methode, Yerh. d. Naturf. Med. Yereins zu Hei- delberg, I, Ileft 5, 1876. BIBLIOGR A PIIY. 165 Edwards^ II. Milne., Legons sur la Pliysiologie et I’Anatomie, I , etc. T. 9, 2me partie, Generation. Paris : 1870. “ De 1’ Influence des agens physiques de la vie. Paris : [. 1824. Eichorst., 17., Ueber die Entwicklung des mensclil. PUcken- marks und seiner Formelemente. Arbeiten der St. Petersburger Gesellscli. der Naturforsclier, Bd. YI. St. Petersburg : 1875. Elmer., Th., On the Structure of the Cellular nucleus, Arch, f. mikr. Anatoiuie, viii, 1871, p. 141. “ Ueber amoboide Bewegungeu des Ivernkorperchens, Archiv. f. mikr. Auat., Bd. xii, 1875. “ Weitere l^achrichteii liber den Ban d. Zellkerus, Ar- chiv f. mikr. Anatomic, xiv, 1877, with plate See also Quarterly Jour, of Micr. Sc., April, 1878. Ehreyihercj, Die Infusionsthierchen als vollkommene Organis- men. Ein Blick in das tiefere organische Leben der Natur. Leipzig : 1838. Engelmann, Th. IE., Mikrosk. Untersuchungen liber die quergestreifte Muskelssubstanz, Pfluger’s Arch., Bd. vii, 1873 (with two plates). “ Ueber die Hornhaut. Leipzig : 1867. “ BeitrUge zur Physiologic des Protoplasma, in Archiv. f. Physiol., II, 6, p. 307. Ercolani, On Connective Tissues. Memoire dell’ Acad, delle Scienza di Bologna, tom. iv, Ser. ii,' 1866. Eidenherg, De tela elastica. Diss. inaug. Berol : 1836. Eojetsky, Th. U., Ueber das Endothel der Membrana Des- cemeti. Untersuchungen aus dem pathol. Inst, zu Zurich, III Heft, 1875 (with two plates). FaivreE., Sur I’ovule et sa nature morphologique. Lyon: 1870. Fallopius, G., Tractatus quinque de partibus similaribus. Francof. : 1600. “ Lectiones de partibus similaribus humani corporis ex diversis exemplaribus a Yolchero Coitero Collectse. Xorimb. : 1775. Originally written anterior to 1562, though the date is uncertain. 166 THE CELL DOCTRINE. Flemming^ TF., Ueber das Subcutane Bindegewebe uiid sein Yerhalten an EntzlindUngsherden, Virchow’s Ar- chiv, Bd. 50, 187*2. “ Ueber die ersten Entwickelungsersheinungen am Ei O O der Teichmuschel, Archiv. f. milir. Anat., Bd. x, 1873 (with plate). “ Studien Uber die Entwicklungsgesch. der iSTajaden, Sitzimgsber. der Wiener Academic, Bd. 71, III Abth., 1875 (with 4 plates). “ Beobachtungen Uber die Beschaffenheit des Zellkerns, Arch. f. Mikr. Anat., xiii, 1876 (with plate). “ Beitrlige z. Anatomic und Physiol, des Bindegewebes, Archiv. f. micr. Anat. , xiii, 1876. “ Beobachtungen uber Eettgewebe, Arch. f. mikr. Anat., xiii, 1876 (with 2 plates). “ Zur Kenntniss des Zellkerns, Med. Centralblatt, No. 20, 1877. “ Ueber Bindes'ubstanz und Gefasswandung im Schwell- gewebe der Muscheln, Archiv. f. mikr. Anatomic, xiii, 1876 (with 3 plates). Flower^ W. iP., Introductory Lecture to course of comp. Anat., delivered at the Royal Col. of Surgeons, Feb. 4th, 1870. London. id)?, il., Sur les phenomfenes intimes de la division cellulaire. Comptes rend us, t. 83, No. 14, 1876. Die erste Entwicklung des Geryonideneies, Jenaische Zeitschrift, f. Med. und Naturwiss., vol. vii, 1873. Fontana^ Abhandlung liber das Yiperngift, das American- ische Gift, u. s. w. Aus dem Italien. Berlin : 1787. Forster^ A. , Ilandbuch der Pathologischen Anatomic, Bd. i, 2te Autlage und Atlas. Leipzig : 1865. Foulis, L, On the Dev. of the Ova and the Structure of the Ovary in man and other mammals. Quart. Journ. Micr. Science, New S., XYI, 1876, with 3 plates. Fourcaud^ A., Lois de I’organisme vivant, on application des lois physiquo-chemiques i\ la physiologic, precedees de recherches sur les causes physiques des phtmo- BIBLIOGKAPHY. 167 ni^nes d ’attraction et de repulsion, considerees dans les molecules et dans les masses de la mati^re. Paris : 1829. Pox, ^Y^lson^ Development of Striated Muscular Fibre. Phil- osoph. Transac. London : 18G5-G6. Frank, Ueber die anatomische Bedeutuimund die Entsteliuno- des vegetabilisclien Schleims. Jena : 18G7. See also Pringsheim’s Jalirbucli fur Wiss. Botanik, Bd. V, 18G7, p. IGl. Freke, Henry, Reflections on Organization ; or. Suggestions for the Construction of an Organic Atomic Theory. Dublin : 1848. Friedreich, Yirchow’s Archiv, Bd. xv. Frey, Ilandbuch der Histologie und Histochemie des Men- schen. Leipzig : 18G7. Frommann, C., Untersuchungen liber die normale und patho- logische Anatomie des RUckenmarks. 2t Th., p. 17, Jena : 18G7 (with G plates). “ Untersuchungen liber die normale und pathol. His- tologie des centralenNerven-Systems. 4 plates. Jena : / 187G. “ Zur Lehre von der Structur der Zellen, Jenaische Zeitsch. fur Naturwissensch. Bd. ix. 1875 (with 2 plates). Gabriel, Be Cucullaris Elegantis Evolutione. Berolin : 1853. Ganeau, Memoiie sur la protoplasma vegetal. Compt. rendus t. 79, 1874. ’ Gardner, Rep. British Assoc. Ad. Sci., 1850. Gasc, J. P., Reflexions generales sur la vie et sur le syst^me des molecules organiques, etc. Paris : 1822. Gavarret, J., Les Phenomenes Physiques de la vie. Paris * 18G9. Gegenhauer, Zur Lehre vom Oenerationswechsel u. der Fort- pflanzung bei Medusen und Poly pen. Untersuch. liber Pteropoden und Heteropoden. “ Ueber d. Entwickl. der Sagitta. Halle, 185G. Gerber, Ilandbuch der Allgemeinen Anatomie des Menschen und der Haussaiigethiere. Grosstentheils nach eigener 168 THE CELL DOCTRINE. Untersuchungen. Bern unci Chur : 1840. English Transl. London : 1841. Gerlach^ Ilandbucli der Allgeineinen und Speciellen Ge- webelehre des menschlichen Korpers. Mainz : 1800. “ Mikrosk. Studien., 1858. Gluge^ Anatomisch-mikroskopische Untersuchungen zur all- gemeinen und speciellen Pathologie. Heft i. Min- den : 1839. “ Observationes nonnullge microscopicse fila quse dicunt primitiva in inflammatione spectantes. Diss. inaug. Berol : 1835. Golubew^ Sitzungsber. d. Wiener. Acad., 16 April, 1868. Archiv fur Mikrosk. Anatomic, Bd. v, 1869, p. 133. Goodsir^ Anatomical and Patholog. Observations. Xos. 1 and 5. Edinburgh : 1845. “ ‘‘Centres of Nutrition,” and “ Secreting Structures,” in Anatomical Memoirs, by Turner. Edinburgh : 1868. Grimm^ 0. A. ,Ueber die niederste Thierform (Die Proto- zoen), Arbeiten der St. Petersburgher Gesellsch. der Naturf., Bd. vii. St. Petersburg: 1876. Grore, Br. 'Med. Jour., May 29, 1869, p. 486. Gruby^ Observationes microscopicce ad morphologicam patho- logicam spectantes. Yindob. : 1839. Grwahagen^ A., Notiz liber die Ranvierschen Sehnenkorper, Arch. f. Mikr. Anat., ix, 1872. Ilceckel^ U., Zur Entwicklungsgesch. der Siphonophoren. Utrecht : 1869. “ Die Kalkschwamme, Bd. i, p. 104-100. Berlin: 1872. “ Zur Morphologic d. Infusorien, Jenaische Zeitsch. f. Med. u. Naturw., Bd. vii, 1873 (with plates). “ Biologische Studien. Studien liber Protisten. 1 Ileft, 1870. Review of in Quart. Journ. of Micr. Sc., 1871, p. 60. , “ Naturliche Schopfungsgeschichte, 4te Auflage. Ber- lin : 1873. “ Die Radiolaren. Berlin : 1802. “ Protogenes primordialis ; in Zeitschr. f. w. Zoolog., Bd. X, 1865. BIBLIOGRAPHY. 169 llc^cl-el., X, Ueber den Sarcodkorper der Ehizopoden ; in Zeitsclir. fUr Wiss. Zook, Bd. xv, 1865. “ Generelle Morpliologie der Organismen. Zwei BUnde. 1866. “ Monograph on Monerre ; in Quart. Jonrn. Micr. Sci- ence, for April, July, and Oc|;Ober, 1869. “ Remarks on the Protoplasm Theory ; in Q. J. Mic. Sci., July, 1869, p. 222. “ Anthropogenie oder Entwicklungeschichte des Men- chen. Leipzig : 1874. Haller^ Disputantes anatomicse selectee, vol. i-vii. Gutting. : 1750-52. “ Elementa physiologiee corporis humani, t. i, lib. i. Lau- sanne : 1757-78. “ First lines of Physiology ; by Cullen. Edinburgh : 1779 Hammond^ 11. TP., Observation on the structure of the red blood-corpuscle of a young trout. JMonthly Micr. Journ., June, 1877, p. 282. “ Observation on the structure of the red blood-corpuscle of living pyreneematous vertebrates. Monthly Micr. Journal, September, 1877, p. 147. llartig^ Th.^ Neue Theorie der Befruchtung der Pflanzeu. o f Braunschweig. Harting, P., Botanische Zeitung, 1846, p. 46. Recherch. Micrometrique sur le developpment des Tis- sus. Utrecht : 1845. Hartley, Experiments Concerning the Evolution of Life from Lifeless Matter. Proceedings of the Royal Soc., vol. XX, December 7th, 1871. Hassall, A. 11., The Microscopic Anatomy of the Human Body. London : 1846-49. American Edition by Yanarsdale. E'ew York : 1851. llausmann, Ueber die Zeugung und Entstehung des wahren weiblichen Eies. Hannover : 1840. llaie') s, Clopton, Osteologia nova, or some new observations on the bones, and the parts belonging to them. Lon- don : 1691. llayeiii et llenocgue. On 4he Amoeboid Movements of the 15 170 THE CELL DOCTRINE. Blood, etc. ; in Archives de Medecine, Ser. G, Tom. ii et viii, June, 18GG. Heiberg^ Wiener medic. JahrbUcher, 1871. lieidenliain^ Moleschott’s Untersuchungen, Bd. iv, 1858, p. 251. Studien, physiol. Inst., Breslau, 1861. Heitzmann^ (7., Untersuchungen Uher das Protoplasma. I. Bau des trotoplasmas. II. Das Yerhaltniss zw. Protoplasma und Grundsubstanz im Thierkurper. III. Die Lehensphasen des Protoplasmas. lY. Die Entwicklung der Beinhaut des Knochen und des Knorpels. Sitzungsberichte d. k. Acad. d. IVissensch. zu AVien. Ill Abth. April- July, 1873. “ Ueber die Entwicklung und d. Bau der Knorpel, AViener med. AYochensch. , 4 January, 1873. “ Ueber die BUck-und Neubildung von BlutgefUssen im Knochen und Knorpel, Wiener medic. JahrbUcher, 1873 (with 2 plates). “ Die Lehensphasen d. Protoplasma, AA'iener medic. Presse, xv, p. 1874. Die Entwicklung d. typischen Eormen des Bindege- webes, AViener med. Presse xv, 1874. “ Kew York Med. Journal, 1877. Ilenfrey^ A., On Yegetable Cell-formation, in Ann. and Alag. Kat. Hist., 1856, p. 42. “ On Multiplication of Yegetable Cells by Division ; in Ann. and Mag. Kat. Hist., 1848, p. 36. Hcnle^ Symbolse ad anatomiam villorum intestinalium im- primis eoruni epithelii et vasorum lacteorum. Berol. : 1837. u u a c ( Ueber Schleim und Eiterbildung und ihr AYrhUll niss zur Oberhaut. Berl. : 1838. Pathologische Untersuchungen. Berlin : 1840. Allgemeine Anatomie, Lehre von den Alischungs — und Eormbestandtheilen des menschlichen Korpers. I.eip- zig : 1841. French translation by Joiirdain. Paris: 1843. ITandbuch der Eingeweidelehre. Braunschweig : 1866 BIBLIOGRAPHY. 171 being the 2d vol. of Ilandbuch der systematisclien Anatoniie des Meusclien, in drei Biinden. IlenJe^ Yearly Eeports in Canstatt’s Jabresberichte, especially 1845, vol. i, p. 55, and 1847, vol. i, p. 44. “ Bericht ilber die Fortscbritte d. Physiol. 1859 ; 18G1, p. 41. Ihring^ Wiener medic. Sitziuigsber., 1868. Hertwig^ O., Beitrage zur Kenntnissder Bildung, Befrucbtung und Tlieilung d. thierischen Eies, Morphol. Jahrbuch i, 1875 (with 4 plates). “ Beitrage zur Kenntniss der Bildung, Befrucht. und Theilung d. thierischen Eies, Morphologische Jahr- bticher iii, 1877 (with 5 plates). Hertivig, i?., Beitrage zur Kenntniss der Acineten, Morphol. Jahrbuch i, 1875. ‘‘ Beitrage zur einheitlichen Auffassung der verschiede- nen Kernformen, Morphol. JahrbUcher ii, 1876 (with plate). Ilesslmg^ Th. r.. Atlas der Allgemeinen Thierischen Gewe- belehre. Kach der Natur photographirt von J. Al- bert. 2 Lieferungen. Leipzig : 1860-1. “ System der Histologie. Thl. i. Eisenach: 1824. “ Ueber anomale Kohlen — und Pigmentbilduna: in deni o O menschlichen Kcirper. Jena : 1823. “ Ueber Schleim und Eiterbildung und ihr Yerhaltniss zur Oberhaut. Berl. : 1838. Heusmger, L, Progr. de Organogenia, Particulal, De materia organica amorpha. Jena : 1822. Ilicl-s, J. B., Observations on Vegetable Amoeboid Bodies. Quart. Jour. Micr. Science, vol. ii, K. S., p. 96. IBs, Wilh., Beitrage zur normalen und pathol. Ilistol. d. Cornea. Basil : 1856. “ Leber die Bedeutung der Entwicklungsgesch. f. die Aufassung d. org. Katurs. Leipzig : 1870. Hodgkin, in Hodgkin and Fisher’s translation of M. Edward’s “ Sur les Agens Physiques.” London : 1832. “ Lectures on the Morbid Anatomy of the Serous and 172 THE CELL DOCTRINE. Mucous Membranes. London : 1836. American edition. Philadelphia : 1838. Hoffman^ F. A., Virchow’s Archiv, Bd. liv, p. 506. Hoffman., C. iT., Sur I’anatomie des Asterides, Extrait des Archives Neerlandaises, vol. ix. Hoffman., Virchow’s Archiv, Bd. li, p. 373. “ Ueber Eiterbildung in der Cornea, Virch. Archiv, vol. xlii, 1867, p. 204. Hofmeister, Wilhelm., Die Lehre von der Pfianzelle. Leip- zig : 1867. “ Entstehung d. Embryo, d. Phanerog. Leipzig : 1849. “ Vergleich. Unters. Lpzg. : 1851. “ Neuere Beobachtimgen liber Embry obildungen des Phanerog, Pringsheim’s Jahrb., Bd. i, 1857. Hogg., e7., The Fungoid Origin of Disease and Spontaneous Generation, Monthly Journal of Micr. Science, September, 1871. Hollis, W. A., Tissue metabolism, or the artif. induction of structural changes in living organisms. Journal of Anat. and Physiology, 1872, vol. vi (with plate). See also vol. viii, pp. 120-126, 1874. Home, Sir Everard, Philos. Transac. for 1821, and Lectures on Comparative Anatomy, vol. iii. I^ondon : 1823. Hoohe, Eohert, Micrographia. I^ondon : 1667. Hoyer, H, ^7ew Contributions to the Histology of the Mar- row of Bones, ‘‘ Pamjatnik,” Pt. 3, Warsaw : 1873. (Polish.) Hunter, J., Treatise on the Blood and Inflammation. Lon- don. Hiiter, C., Ueber die Veranderung. der roth. Blutkorperch. durch Sepsis und durch Sept. Infection, Berliner klin. Wochensch., U. 31, 1873. Huxley, Review of the Cell Theory, Br. and For. Med. Chir. Rev., vol. xii, October, 1853, p. 285. “ On the Development of the Teeth, and on the Xatui-e and Import of Nasmyth’s “Persistent Capsule,*’ Quar. Jour. Mic. Sci., No. iii, 1853. u “Protoplasm,” or the Physical Basis of Life. Alec- BIBLIOGRAPHY. 173 ture delivered in Edinburgh, jS'ovember 18tb, 1868, published in the “ Fortnightly Ke view ” for February, I860, and republished in pamphlet by publishers of ‘‘Yale College Courant,” New Haven, Conn., 1869. Huxley^ On Some Organisms from great Depths in the North Atlantic Ocean, Quart. Jour, of Micros. Sci., Octo- ber, 1868, p. 206. “ Anatomy of the Invertebrated Animals, chap, on the Protozoa. New York, 1878. “ Generation of Living Organisms. Inaugural Address at Meeting of British Association for Advancement of Science, 1870. Published in Med. Times and Ga- zette, September 17th, 1870. “ Belations of Penicilium, Torula, and Bacterium. Ad- dress in Biolog. section of British Assoc., September 13th, 1870. lluxUy^ Bastian, Tyndall and others. Discussion on the Spon- taneous Generation Theory. British Association for Advancement of Science, 1870. Jdger, Gustav^ .Ueber Erzeugung u. Befruchtung, Ztschr. f. Zool. xix, 4, p. 479. “ Jahresberichte, liber die Fortschritte der Anatomie und Physiologie. Edited by Prof. Fr. Hoffmann and Prof. G. Schwalbe, vol. i-vi. Literature, 1872-1877. Johnson, Metcalfe, A few experiments bearing on spontaneous generation. Mo. Journ. Micr. Science, April, 1871. “ Ptemarks on Dr. Bastian’s paper on spon. generat., Mo. Journ. Micr. Science, November, 1870. Karsten, De Celia, vitale Dissertatio. Berlin : 1843. (See also, a Translation by the Boyal Society. ) “ Abhandl. der Berlin Akad., 1847, p. 111. “ Botan. Zeitung, 1857, p. 314. “ Poggendorf’s Annalen, 1860, No. 4. “ On some Phenomena of the Development of the Or- ganic Cell. Translated by Dr. Arlidge for “The Annals and Magazine of Natural History,” for July, 1863 (vol. xii, 3d series), from Poggendorff’s An- nalen, vol. cxviii. Berlin : 1863. 15* 174 THE CELL DOCTRINE. Karsten^ Histological llesearclies on the Formation, Develop- ment and Structure of the Vegetable Cell. Trans- lated by Dr. Arlidge, for “ The Annals and Maga- zine of a^atnral History,” for April, May, June, 1864 (vol. xiii), July, August, Sept., 1864 (vol. xiv). Kaster, IF., Ueb?r d. Bildung von Eiern in den Ovarien der SUuirethiere, u. iiber d. Verhalten d. Ovarium zum Bauchfell. Verslagen en mededeclingen d. konikl. O o Akad. V. Wetensch. Afd. Natuurk. 2, Eeeks. 3, Deel, p. 141, 1870. Keher^ F., XJeber die Befruchtung des Flussmuschel-Eies, Arch. f. Anat., Phj^siol. und Med. IVissenschaft, 3, p. 284. “ Elements d’llistologie Humaine. Paris: 1856. Keferstein^ Beitrage zur Anatomie und Entwicklungggesch. einiger Seeplanarien. Grcittingen : 1868. Key, Axel, Virchow’s Archiv, Bd. Iv, S. 296. Key, A., and Retzius, Studier i nervsystemets anatomie, Nord. Med. Archiv, vol. iv, Ko. 21 and 25. German, in M. Schultze’s Archiv, Bd. ix, 1872. “ Studien in der Anatomie des Nervensystems und des Bindegewebes. Erste ITalfte (with 39 plates), 1875. “ ■ Oin senornas bygnad. Xordiskt Medic. Arkiv, vii, 1875 (with 2 plates). “ Studien in der Anatomie, etc., zweite H'alfte. Stock- holm : 1876 (with 36 plates). Kidd, P., Observations on spontaneous movement of nucleoli. Quart. Journ. ofMicr. Science, p. 133, 1875. Kistiol^oiDsky, Wiener Medic. Sitzungsb., 1865. Klein, E., and Bunion- Sanderson, Zur Kenntniss der Anato- mie der serlisen Haute, etc., Med. Centralblatt, Xo. 2, 3, and 4. English in Quart. Journ. of Micr. Sc. xii, p. 142-154. 1872. “ The Anatom}^ of the Lymphatic S^’stem. The Serous IMembranes. London : 1873 (with 10 plates). The Lungs. London : 1875. “ Observations on the structure of cells and nuclei (with BIBLIOGRAPHY. 175 plate). Quart. Joum. of Micr. Science, No. 71. July, 1878. Klein, E., Contributions to the minute anatomy of the omen- tum, Quart. Journ. of Micr. Sc.,p. 235-244, 1877 (with plate). Kieinenherg, Hydra, Leipzig : 1872. Kollmann, S., IlUutchenzellen und Bindegewebe, Med. Cen- tralbl.. No. 25, 1876. Structurlose Membranen, etc., Sitzungsber. d. math, phys. Klasse d. k. bairisch. Acad. d. Wiss., 1876, Heft. ii. “ Bindesubstanz der Acephalen, Arch. f. Mikr. Anat., xiii, 1876. “ Hautchenzellen und Myxom., Virchow’s Arch., Bd. 68, 1876 (with plate). ‘ KdlUker, A., Die Verbreitung und Bedeutung der vielkorni- sen Zellen der Knochen und Zliline, Verhandl. d. Wiirzb. ph. med. Gesellsch. N. F., 2 Band, 1872. “ Dritter Beitrag zur Lehre von der Entwicklung d. Knochen, Verh. d. Wiirzb. ph. med. gesellsch. Bd. iv, 1873. “ Muller’s Archiv, 1843. “ Die Schwimmpolypen von Messina. Leipzig : 1853. “ leones Histologies, Erstes Heft. Leipzig : 1864. “ Neue XJntersuch ungen liber die Entwicklung des Bin- degewebes. Wurzburg: 1861. “ Wurzburg Verb., Bd. viii. “ On Cell Division ; in Wiegm. Archiv, Jahrg. xiii, Bd. i, p. 19. “ Entwicklungsgeschichte der Cephalopoden. Zurich : 1844. “ Die Lehre von der thierischen Zelle ; Schleiden und Nageli’s Zeitschrift fiir Wiss. Botanik, Heft ii. “ Handbuch der Gewebelehre. Wiirzburg : 1852. 5te And., Lpzg. : 1867. “ Mikroskopische Anatomie oder Gewebelehre des Men- schen. 1850-54. English translation by Geo. Busk 176 THE CELL DOCTRINE. and Thomas II. Huxley, for Sydenham Soc. Lon- don : 1853. French translation. Paris : 1858. Kowalewshj^ Mem. de I’Academie imp. de St. Petersburg, tome X. Krause^ TF. , Allgemeine und mikroskopische Anatomic. Han- over : 1876. Krohn^ TJeher die Entwick. d. Asciden, Arch. f. Anat. u. Phys., 1852. Ktlhne^ IF., Untersuchungen liber das Protoplasma und die Contractilitat. Leipzig : 1864. “ Muller’s Archiv, 1859, p. 817. Kiqjffer^ G., Hie Stammesverwandschaft zwischen Asciden u. Wirbelthieren, Arch. f. Mikr. Anat., vol. vi, 1870. “ TJber Hitferenzirung des Protoplasma an den Zellen thierischer Gewebe, Schriften d. naturw. Vereins f. Schleswig-Holstein. Heft iii, 1875, und Beitrage zur Anat. und Phys. Festsch. f. C. Ludwig, 1875. “ Ueber Sternzellen der Leber, Archiv f. Mikr. Anat., Bd. xii, 1875. La VaUette^ St. George, Tiber d. Keimfleck u. die Deutung der Eitheile, Max Schultze’s Archiv, vol. ii, 1866. Langlians.! Th.., Zur Lehre von der Zusammensetz. des Kerns, Med. Centralbl., No. 50, 1876. Langenhaus., Yirchow’s Archiv, Bd. xliii, p. 314. Lamarcl^ J. B. P., Ant. de Becherches sur I’organization des corps vivans, particuliferement sur leur origine, sur le cause de leur developpement, des progr^s de leur composition, et celle qui amtine la mort. Paris: 1808. ‘‘ Philosophic zoologique. Paris: 1809. La Metlierie., J. Cl. de, Yues Physiologiques sur I’organiza- tion animale et vegetale. Paris : 1780. “ Considerations sur les corps organises, Paris : 1804. Langenbeek, Mikroskopisch-anatomische Abbildungen, Lief, i-iv. Gottingen : 1846-51. Landois, Zeits. fUr IViss. f. Zook, Bd. xvi, p. 1. Lehertj //., Physiologic Pathologique. Paris : 1845. “ Hevelopment of Muse. Fibre in A'ertebrate Animals, Annales d. Sci. Nat., 1849-50. BIBLIOGRAPHY. 177 Lehert, IT., Atlas d’Anatomie Pathologique. Paris : 1857. Leemccnhoel-. Anton i\, Anatomia interiora rerum. Plates. London : 1687. “ Philosophical Transactions : London. “ Opera omnia. Lugd. Patav. : 17*22. “ Arcana natui'se detecta. Delph: 1795. “ Continuatio arcanorum naturae detector urn. Lugd. Bat. : 1722, etc. LegdUois, J. J. Cesar, Experiences sur le principe de la vie, etc. Paris : 1812. Lddii, Joseph, Intimate Structure and History of the Articu- lar Cartilages, Am. Jour. Med. Sciences, April, 1845 ; p. 277. Lieherluhn, JS\, XJeher Bewegungserscheinungen der Zellen. Marburg : 1870. Leuclart, Die menschl. Parasiten., vol. ii, p. 322. “ Article “Zeugung,” in Wagner’s Handworterb. d. Phys., p. 922. Ley dig, F., Lehrbuch der Histologie des Menschen und der Thiere. Berlin : 1857. “ Heber den Ban und die Systematische Stellung der B6- derthiere, Zeitschr. f. wiss. Zool., Bd. vi. “ Zur Anatomie von Piscicola Geometrica, Zeitsch. f. Wiss. Zool., Bd. i. Liegeois, Th., Traite de Physiologie appliquee a la Medecine et h la Chirurgie. I part. : Yie, Organisation, Genera- tion. Paris : 1869. Lott, G., Ueber d. feinern Ban und d. phys, Eegeneration d. Epitbelian, etc. Untersucb, ausd. Institute f. Phys. und TIistol. in Graz, berausgegeben von Bollett. 3 Heft, 1873. Lowe, B. T., On the so-called Spontaneous Generation, Mo. Jour. Micr. Science, December, 1870, p. 32. Lowe, L., BeitrUge zur Histologie d. Bindegewebes, Med. Centralblatt, Ko. 10, 1874. “ Zur Histologie des Bindegewebes, Wiener Med. Jabr- bucber, 1874, p. 303. 178 THE CELL DOCTRINE. Xotue, X., Zur Kemitniss d. Bindegewebeg, Arch, fur Anat. und Phys., 1877, p. 63 (with plate). Xwca6, S, (7., Grimdriss der Entwicklungsgeschichte des mensclilichen Korpers. Marburg : 1819. Luschka^ Hub. v. Ueher die Furchung des Protoplasma bei der Zellenbildung, in Yircliow’s Archiv., Bd. xlvii, 1869, 2, p. 310. “ Yircliow’s Archiv, Bd. ix. Lyons., Bohert X., Besearclies on the Primary Stages of His- togenesis and Histolysis. From Proceedings of the Iloyal Irisli Academy^ vol. v, pt. hi. Dublin : 1853, p. 16. McCarthy., 8., Some Bemarks on the Spinal Ganglia and Kerve Fibres, Quart. Jour, of Micr. Sc., p. 377, 1875 (with plate). Magendie., Legons sur les Phenomenes Physiques de la vie, re- cueillies par G. Funel. Paris : 1836-37. 4 vol. Malynghii., MarcelU, Anatome Plantarum. 1670. “ Opera omnia, in tom. ii, comprehensa. London : 1686. “ Opera posthuma. London : 1697. Mandl, X. , Anatomie microscopique. Paris: 1838-48. “ Traite Pract. du microscope, et de son emploi dans I’etude des corps organises, suivi de recherches sur I’organisat. des animaux infusoires, par D.C. Ehren- berg. Paris : 1839. Marchand., Leon, De la reproduction des animaux infusoires (6tude medico-zoologique). Paris : 1870. Martyn, S., On Connective Tissue, Beale’s Archives of Med., vol. ii, p. 99. Mayer, C., Die Elementarorganization des Seelenorganes. Bonn: 1838. Die Metamorphose der Monaden. Bonn : 1849. 3layer, S., Zur Lehre von der Structur d. Spinal Ganglien, und d. peripherischen Nerven, IViener Acad. An- zeiger. No. 8-10, 1873. “ Die peripherische Nervenzelle, etc., Archiv. f. Psy- chiatric, Bd. vi, 1876 (with plate). Mayzel, IF., Further Contributions to the Stud}^ of the Phe- BIBLIOGRAPHY. 179 nomena of the Division of the Cell-nucleus ; Medic. Gazette, vol. xxii, No. 27, 1876, and vol. xxiii. No. 26, 1877. Warsaw. (Polish.) Mayzel, TF., Uebereigenthumliche YorgUnge bei der Theilung der Kerne in Epithelialzellen, Medic. Centralblatt, No. 50, 1875. il/ecA-auer, De Penitiori cartilaginum struetura symbolse. Diss. inaug. Wratisl., 1836. Mentschikoff\ Virchow’s Archiv, vol. xli, 1867. “ Embry ologische Studien an Insecten, Zeitsch. f. Wiss. Zool.', Bd. xvi, p. 484. 3ferA:eZ, F.^ Der quergestreifte Muskel. I., Arch, fur mikr. Anat. , Bd. viii, 1871. “ Der quergestreifte Muskel. II., Arch. f. mikr. Anat., Bd. ix, 1872. Meyen. Neues Svstem der Pflanzen physiologic. Bd. i-iii. Berlin: 1836-39. Miescher. F.^ Die Spermatozoen einiger Wirbelthiere., Yerh. d. Baseler naturf. Ges. vi, 1874. JSRrhel^ Recherches sur la Marchantia Polymorpha ; in An- nales de Mus6e, i, 55. Paris : 1839. “ Traite d’Anat. et de Physiol. Yeg. Paris : 1802. Milne-Fdwards^ A., Memoire sur la structure elementaire des principaux tissus des animaux ; in Archives Ge- nerates de Medecine- Paris : 1823. “ Recherches microscopiques sur la structure intime des tissus organiques des animaux ; in Annales des Sciences Naturelles, 1821. Tom. ix, p. 362. 3/q/on, R., Observazione sulle leggi fisiologische. Geneva : 1816. 3d ed., Milan : 1821. Tr. into French by Baron Michel. Paris : 1821. Montgomery^ R., Formation of Cells in Animal Bodies. Lon- don : 1867 ; or, A Review of this pamphlet by the Author, in Am. Jour, of Med. Sciences, Jan. 1868. J/o/i?, Hugo r., GrundzUge der Anatomic und Physiologic der Yegetabilischen Zelle. Reprinted from Wagner’s Ilandworterbuch. Braunschweig : 1850. 180 THE CELL DOCTRINE. 3Iohl, Hiigov., The Vegetable Cell, Translated by Heiifrey. London : 1852. “ TJeber die Yerbindung der Pflanzenzellen. 1835. “ Yermehrung der Pflanzenzellen durch Theilung. Tu- bingen : 1835. “ Yermischte Scbriften, 1845. “ ErUiuterinig und Yertheidigung meiner Ansicht von der Structur der Pflanzensubstanzen. Tubingen : 1836. “ Entwicklimg und Bau der Sporen der Kryptogam. Gew., Elora, 1833. “ Einige Beobachtungen iib. den Bau der vegetabil. Zelle, in Bot. Zeitung, 1844, p. 273. J/oreZ, C., Traite elementaire d’histologie bumaine, normale et pathologique, precede d’un expose des moyens d’observer au microscope, accompagne d’un Atlas, etc. Deuxieine edition. Paris : 1864. 3Iorgan, Th. Ch. Philosophical essay on the phenomena of life. London: 1818, Transl. into Erench. Paris: 1819. 3[iilleVj Jo/o, Ueber die Erzeugung yon Schnecken u. Holo- thurien. Arch. f. Anat. und Phys., 1852. “ Handbuch der Physiologie des Menschen fur Yorles- ungen. 4te. verb. Aufl. Coblenz : 1846. “ Elements of Physiology. Translated by AVilliam Baily, M.D., and edited by John Bell, M.D. Philadelphia : 1844. “ Ueber den feinen Bau und die Formen derkrankhaften Geschwlilste. Lief. i. Berlin : 1838. “ On the Nature and Structural Characteristics of Can- cer. Translated by Dr. West. London : 1839. “ De Glandularum secernentium structura penitiori ea- rumque prima formatione in homine atque animali- bus. Lips. : 1830. “ Jahrbuch, 1839. 3Iidler^ II. , Bau der INIolen. Ncigeli^ Ueber Entwickelung des Pollens. Zurich : 1842. BIBLIOGRAPHY. 181 Xdgeli, Zellkerne, Zellbildmig unci Zellenwachsthiim ; in Zeit- schr. f. w. Bofc., i, 1844, p. 34. “ TJeber die Pflanzenzelle, Schleidcn nnd ISTUgeli’s Zeit- schrift, fur Wiss. Botanik., Heft ii, iii, und iv, 1846. Ndgeli und Cramer^ Pflanzenph3^siol. Unters. , i, p. 13. “ Gattungen einzelliger Algen. iSTeucliatel : 1849. o o o Nelson^ Division of the original nucleus (germinal vesicle) of the ovum, in the development of Molluscs. Philos Transac. London : 1852, p. 580. Nedsvetzki^ Zur Histologic d. IVlenschenblatts, Med. Central- blatt, No. 10, 1873. JS'eumaim, Ueber d. Zusammenhang. sog. Molecularen mit dem Leben des Protoplasma, Du Bois Peymond und Peichert’s Archiv, 1867. Keumann^ E.^ Ueber tlimmernde Eiterzellen, Medic. Central- blatt. No. 24, 1876. “ Knochenmark und Blutkorperchen, Arcbiv f. mikr. Anat., xii, 1875. Norris^ W. F. and Strieker^ S., Yersuche iiber die Hornhau- tentzlindung. Wien : 1869. JS'ykamjj, A., Beitriig. zur Kenntniss der Structur des Knor- pels. Arch. f. Mikr. Anatomie, xiv, 1877 (with plate). Ohersteiner, Beitriig. zur Kenntniss vom Ban der Kleinhirn- rinde, Sitzungsber. d. K. K. Acad. d. IViss. , Bd. 40, IVien. Oberliauser^ Die Bindegewel)e, Sitzungsb. d. Akad. zu Wien. Bd. i, vi, 1867, p. 162. Onunus, Experiments on the Genesis of Leucocytes and on Spontaneous Generation ; in Pobin’s Journal de 1 ’Anatomic. January and February, 1867. Otto, Lehrbuch der Pathologischen Anatomie des Menschen und der Tiiiere. Berlin : 1830. “ Anatomy of Vertebrata. Mammals. Yol. iii, 1869. Peviews of, in Jour. Anat. and Phys., 2d series. No. iv. May, 1869, p. 446, and Popular Sci. Pev. , Janu- ary, 1869. IG 182 THE CELL DOCTRINE. Otto, Monthly Microscopical Jour., ^^^o. v, May 1st, 1809. Oweyi, On Art. vi, No. iii (Beale’s reply to Owen), Mo. Micro- scopical Journal, vol. i, 1809 ; in the same journal, vol. i, p. 294. Oken, lYork on Generation, 1805. Ahriss des Systems der Biologie d. Isis und Programm liber das llniversum, 1808. Farjit, Edward, Experiments on Spontaneous Generation, in ]Mo. Micros. Jour., vol, ii, 1809. FagenstecJier, Die Trichine n, Leipzig : 1805. “ Wiener Sitzungsbe., 1S§8. Paget, Report on the Progress of Anatomy and Physiolog}^ in Br. and For. Med.-Chir. Rev., July, 1840. “ Lectures on Surgical Pathology. Edited by Turner. London : 1803. Pasteur, L., Recherches sur la putrefaction. Comptes ren- dus, Ivi, pp. 1189-1194. Peremescliko, Wiener Sitzungsh., 1808. Pennetier, Georges, L’Origine de la Vie. Preface par F. A. Pouchet, Troisieme Edition. Paris : 1870. Polotehnow, On the Origin and Development of Bacteria, Nature, vol. ii, p. 171, 1870. Pouchet, F. A., The Universe : or the Infinitely Great and the Infinitely Little. Transl. from the French. Lon- don : 1870. Pouchet, Gh., Theorie positive d. I’ovulation spontanee et de la fecundation des mammiferes et de I’espece humaiue, basee sur I’observation de toute la serie animale ; avec atlas. Paris : 1847. “ Ileterogenie, on Traite de la generation spontanee has^e sur de nouvelles experiences. Paris : 1859. Pouchet, C. II. G., Un Precis d’llistologie humaiue. Paris : 1804. Priestly, 8., Recent researches on the nuclei of animal and vegetable cells, and especially of ova. Quart. Journ^ of Micr. Science, pp. 131-152, 1870. Pringsheim, W., Ueb. Befruchtung, Keimung u. Genorations- wechsel d. Algen., 3 Abtheil. Berlin ; 1855-57. BIBLIOGRAPHY. 183 rringsheim, N., Ziir Morpbologie und Systematik der Algen, Priiigsbeim’s Jabrb. Bd. i, ii. “ Bail und Bildung d. Pflaiizenzellen. 1854. “ Ueber Embryobildimg d. Gefass. Kryptogamen u. d. Wacbstbum v. Salvinia ^^'atans. Berlin : 1863. Frochas'ka^ De came muscnlare tractatus anatomico-pbysi- olou'icns. Vienn. : 1778. “ De strnctnra nervorum. Vind. : 1779. ‘ ‘ Disquisitio anatomico-pbysiologica organismi corp. bn- mani ejnsqne processus vitalis. Vienn. : 1812. Institntionum pbysiologioe bumance in usum snarum prielectionnm conscript, vol. i, ii. Vienn. : 1805. Purldnje, Symbolic ad ovi avium bistoriam ante incubationem. 1825. ' Purkinje et Rasclikow, Meletemata circa Mammalium Dentium Evolutionem. Wratisl. : 1835. Purkinje et Valentin^ De Pbienomeno generali et fundamentali motus vibratorii continui in membranis animalium, etc. Wratisl. : 1835. Queckett, Lectures on Histology, delivered at tbe Poyal Col- lege of Surgeons, England. 2 vols. London: 1850- 54. Bajeivitsch^ On tbe form-elements of tendons. St. Peters- burg : 1874 (Kussian). Banvier^ L., Cell Elements of tbe Tendons and Areolar Tissue, in Archives de Pbysiol., Ho. 4, 1809, and Amer. Jour. Med. Sciences, January, 1870, p. 227. “ On tbe Importance of tbe Vesicular Transformation of Hucleoli (Soc. de Biol.), Gaz. de Paris, 23, p. 314, 1869. “ Sur les elements conjontifs de la moelle epini^re, Comptes rendus, t. 77, Ho. 22, 1873. “ Quelques faits relatifs au developpement du tissu osseux, Comptes rendus, t. 77, 1873. “ De la regeneration des nerfs sectionnes, Comptes ren- dus, f. 76, 1873. “ Houvelles recbercbes sur la structure et dWeloppement des tendons, Arcb. de Pbysiologie, 1874, p. 181-202. 184 THE CELL DOCTRINE. Banvier, X., De quelques faits relatifs a I’histologie et de la physiol, de muscles stries, Arch, de physiologie, 1874, with plate. “ Traite technique d’llistologie. Paris: 1875. “ Pecherches sur les elements du sang, Arch.de ph^^sioh, t. ii, 1875 (with plate). “ Article “Epithelium,” in ISTouveau Dictionnaire de Medecine et Chirurgie, vol. xiii, p. 675, 1870. Bansom^ On the Ovum of Osseous Pishes. Phil. Trans,, pt. ii, 1867. Basjmil, F. P., Pech. s. la struct, et le developpm. de la feuille et du tronc, et de la struc. et devel. des tissus animal. Paris : 1837. “ Premier mOiioire sur la structure intime des tissus de nature animal., in Pepert. GenO\ d’Anatomie, t. iv. Paris : 1827. Batlike^ B. XT., Abhandlungen zur Bildungs-und Entwickl- ungsgeschichte des Menschen und der Thiere. Thl. i, ii. Leipzig : 1832. Benaut^ M. 8., Sur les cellules fixes, etc. Comptes rendus, t. 83, Xo. 24, 1876. BecMinghausen, Die Wanderfahigkeit d. Zellen, Yirch. Ar- chiv, Bd. xxviii, 1863. Beichert^ BeitrUge zur vergleichenden P’aturforschung, etc. Dorpat : 1845. “ Das Entwicklungslehen im Wirbelthierreich. Berlin : 1840. “ Ueber das Bindegewebe, 1845. “ Yearly Peports in Muller’s Archiv, 1844-53. “ Der Furchungsprozess und die sogenannte Zellenbild- ting um Inhaltsportionen, in Muller’s Archiv, 1846. “ Monatschrift d. Akad. d. IViss. zu Berlin, pp. 406-426, 1862. “ Studien des Physiologischen Instituts zu Breslau. Leip- zig : 1858. “ Ueber den Sarcodekorper der Phizopoden, in Zeitschr. fur wissensch. Zook. Bd. xv, 1865, p. 342. BIBLIOGRAPHY. 185 Beichert, Ueber die contractile Substanz, in Monatschrift der Berlin. Akad., 1805, p. 491. “ Ueber die contractile Substanz (Sarcode, Protoplasma) imd ihre Bewegungs-Ersclieinungen, in Abhandl. der Berlin. Akad., 1867, pp. 151, 293. Beil^ Exercitationum anatomicarum fasciculus, de structura nervorum. IIal?e : 1790. Beil^ J. C., Abhandlimg Ueber die Lebenskraft, in Beil’s Ar- chiv fur Physiol., Bd. i, 1795. Beinhardt^ Ueber d. Form. d. Eiterkorperchen im verdlinten IMedium, Yircliow’s Arch., Bd. i. Bernal', Boh., The Embryological Basis of the Cell Theory, Q. Jour. Mic. Sci., N. S., vol. ii, p. 277. Transl. fr. Eeichart and Du Bois Keymond’s Archiv, 1862, No. ii, p. 230. “ Observationes anatomic® et microscopic® de systematis nervosi structura. Berol. : 1838. “ Cell Division in the Blood-Corpuscles of Embryos, Med. Yerein, 1841, No. 27; Schmidt, Jhrb. , 1841, p. 145. “ Untersuchungen liber die Entwicklung der Wirbel- thiere. Berlin : 1855. “ Yalentin’s Bepertor., vol. iii. “ Ueber den Eurchungsprozess im Eroschei, in Muller’s Archiv, 1851. “ Ueber extra-cellulare Entstehung thierischer Zellen, Muller’s Archiv, 1852. ‘‘ Entstehung des Bindegewebes und Knorpels, Mull. Archiv, 1852. Bichardson, J. Gr., On the Structure of the white Blood-Cor- puscles, ISIonthly Micr. Jour., vol. ix, p. 69, from Transact, of the Am. Med. Association, 1873. Bindfleisch, Lehrbuch der patholog. Gewebelehre, 4th ed., 1875. Bohin, Cli., Histological Doctrines of. By W. T. Lusk, INI.D. , in N. Y. Med. Jour., vol. iv, p. 241, 1867. “ Programme du cours d’histologie professG a la Faculte IG* 186 THE CELL DOCTRINE. de medecine pendent les anii6es 18G2-C3, et 18G3-64. Paris : 18G4. i Mobin^ Ch., Legons siir les humenrs normales et morbides du corps de I’homme profess^es a la Faculte de mede- cine de Paris. Paris : 18G7. “ Du microscope et des injections dans leurs applications a I’anatomie et a la pathologie, suivi d’une classidca- tion des sciences fundamentales, de celle de la biologie et d. I’anatomie en particulier. Paris : 1869. “ Tableaux d’anatomie, comprenant l’expos6 de tontes les parties a etudies dans I’organisme de I’liomme et dans celui des animaux. Paris : 1851. “ Legons sur les substances amorphes et blasthnes. Paris : 18G6. “ Hist, natur. des v^getaux parasites qui croissent s. I’homme et s. les animaux viv. Paris : 1853. “ Anatomie et physiologie cellulaires. Paris : 1873. “ Hote : Anat. et phys. cellulaires, Comptes rendus, 7G, No. 22, 1873. “ “ Cellule.” Diet, encycl. des Sc. med. xiii,2 partie, 1873. “ Note sur la constitution de tissu fibreux. Journal de 1’ Anatomie, etc., 1876, p. 611. “ Traite du Microscope. Paris: 1871. Hohinet^ J. J>., Traite de la nature, liv. iv. Consid. pliilos. sur la gradation naturelle des formes de I’ette. Amstd. : 1768. Hokitansky^ Carl, Die Solidarifat alles Thierlebens, "\"ortrag., gehalten in der feierl. Sitz der k. Akadeinie der IViss., am 31 Mai, 1869. Wien : Gerold’s Solin. “ Ilandbucli d. allgem. Pathology. Wien : 1866. Bolando, L., Ilumani corporis tabriem acfunctionum analysis adumbrata. Turin : 1817. Rollett, A., Ueber d. Entwickelungd. fibrillUren Bindegewebes. Untersuch. aus d. Institute f. Phys. und llistol. in Graz. 3 Heft, 1873. “ Yersuche am Blute, IViener Sitzungsberichte, 1863. liosanojf, Zur Kenntniss des Baues und der Entwickelungs- BIBLIOGRAPHY. 187 geschichte des Pollen der Mimosen. Jena : 18GG ; also in Pringsheim’s Jahrb., Bd. iv, 18G5-GG, p. 441. liosanoff^ Morphorlogiscli-einbiyologische Stndien, Pring- sheim’s Jahrb., Bd. v, 18G7, p. 72. De forinatione granulosa. Diss. inaug. Wratisl. : 1839. Hou(j€% Ch.^ Note siir line organism particnlifere du proto- plasma, etc.. Arch, de physiol., p. G3G-G37. Benj.^ Three lectures on animal life. Philada., 1799. SamueJsoyi^ On the Source of Living Organisms, Quart. Jour. Micro. Sci. , vol. i, p. 598. Samuehon, James^ Controversy on Spontaneous Greneration (favors biogenesis). British Association for Ad- vancement of Science, 1870. Satterthwaite^ TIi. On the Structure and development of Connective Substances, Monthly Micr. Journ., xvi, 18G7 (with 4 plates). Savory, On the Development of Striated Muscular Fibre in Mammalia; in Phil. Transac., London. Pt. ii, 1855. Scarpa, De penitiori ossium structura commentarius. Lips. : 1799. Schacht, Hermann, Die Pllanzenzelle. Berlin : 1852. “ Ueber Plianzenbefruchtung, Pringsheim’s Jahrb., Bd. i, 1857. “ Die Spermazoiden im Pflanzenreich. Braunschweio; : 18GG. Schafer, A., On the structure of striped muscular fibre, Pro- ceedings of the Boyal Society, vol. xxi, and British Med. Journ., April, 1873. “ The intracellular development of blood-corpuscles in mammals. Monthly Micr. Journ., xi, 1874. Sclileiden, Observations counter to those of Mirbel on ‘‘ Mar- chantia,” Muller’s Archiv, 1838, p. IGl. “ Beitrage zur Phytogenesis, Muller’s Archiv, 1838, lift. ii. “ Researches, Syd. Society’s Translation, by Henry Smith. London ; 1847. Schmidt, J. C., Ueber die Blutkurper. Wurzb. : 1823. 188 THE CELL DOCTRINE. Schmidt, II. D., Synopsis of the principal facts elicited from a series of microsc. researches upon the nervous tis- sues, Monthly Micr. Journ., xii, 1874. “ On the construction of dark or double-bordered nerve- fibres, Monthly Micr. Journ., xi (with 3 plates). ‘‘ On the structure of nervous tissue, etc. Transactions of the American Neurological Association for 1875. New York : p. 71. “ On the development of nerve tissue in the human em- bryo, Chicago Journ. of Nervous Diseases, iv, 1877. “ On the origin and development of colored blood-cor- puscles in man. Monthly Micr. Jour., xi, 1871 (with plate). Schulze, F. E., Rhizopodenstudien, Arch. f. Mikrosk. Anat- omic, xiii, 187(3 (with 2 plates). Schultz, C. II,, Das System der Circulation in seiner Ent- wicklung durch die Thierreihe. Stuttg. : 1836. Ab- stract of, in Muller’s Archiv fUr Anat. Physiol., und Wissenschaftl. Med., 1837, p. cvii. Sckultze, Max, Neue Untersuchungen liber d. Entwick. d, Bindegewebe, Muller’s Archiv, 1861. “ Organis. d. Polythalamien. Leipzig : 1851. “ Ueber innere Bewea'un^s-Erscheinun^en bei Diato- meen, Midler’s Archiv, 1858, p. 330. “ Ueber Cornupira, Archiv fUr Naturgesch, 1860, p. 287. Reichert und die Gromien ; in Archiv fiir Mikrosk. Anat., 1866, vol. ii, p. 110. “ Muller’s Archiv, 18(31, p. 17. ‘ ‘ Das Protoplas. d. Rhizopoden und der Pflanzenzellen. Lpzg. : 1863. “ Ueber Muskelkurperchen und das was man eine Zelle zu nennen habe, Reichert u. Du Bois Reym. Archiv, 1861, S. 1. Schultze, C. A. S., Mikroskopische Untersuchungen liber R. Brown’s Entdeckung lebender Theilchen in alien KUr- pern, und uber Erzeugung der Monaden. Carlsruhe : 1821. Schwalbe, G., Beitriige zur Kenntniss des Glatten ]Muskelfi\- BIBLIOGRAPHY. 189 sern, Arch. f. Anat. Physiol., und Wiss. Med., 1SG3, p. 21. Schwalbe^ (?., Bemerkimgen liber die Kerne der Ganglienzellen, Jeiiaische Zeitschr. f. Katurwissensch., x, 1875. “ BeitrUge zur Kenntiiiss der elastischen Gewebe , Zeitschr. f. Anatomic, etc., ii, 1S7G. Schwann^ Froriep’s Keue Kotizen, Hft. i, 1838. “ Mikroskopische Untersuch ungen liber die Ueberein- stinmumg in der Structiir und dem Wachsthuni der Thiere und Pdanzen. Berlin : 1839. “ Kesearches. Sydenham Society’s Translation, by Henry Smith. London : 1847. Siebold^ C. T/i. von^ BeitrUge zur Katurgeschichte der Wir- bellosen Thiere. Danzig : 1839. “ Froriep’s Kotizen, Ko. 380, p. 85. Sharpey^ Introduction to Quain’s Anatomy, 4th edition. London : 18G7. Smadezki, A., Theorie des organischen Wesen. Kiirnberg: 1821. Spallanzani^ Dissertations relative to the Katural History of Animals and Vegetables. Translated from the Ita- lian. 2 yols. London : 1784. Spencer^ J/., Principles of Biology. Am. ed. K. Y. : 18GG. Spina, A., ITntersuchungen liber den Bau der Sehnen, Wiener Med. Jahrblich., iii, 1873. “ Weitere BeitrUge z. Histologic d. Sehnen, Wiener Medic. Jahrblicher 1875, p. 345 (with plate). St. Hilaire, G., On the principle of unity of organic compo- sition, 1828. Strassbiirger, E., Ueber Zellbildung und Zelltheilung, Jena, 1875 (with 7 plates). (See abstract of this work with plate, by J. Priestley, in Quarterly Journ. of Micr. Science, vol. xvi, p. 138, 187G.) “ Studien liber das Protoplasma, Jenaische Zeitschrift f. Katurwiss. x, 187G (with 2 plates). “ IJeber Befruchtung und Zelltheilung, Jenaische Zeit- schrift d. Katurwiss, xi, 1877 (with 9 plates). Sterling, J. H., As regards Protoplasm in relation to Prof. 190 THE CELL DOCTRINE. Huxley’s Essay on the Physical Basis of Life. Edin- burgh : 1809. Steinruecl'^ De nervorum regeneratione. Diss. inaug. Berol. : 1838. Stricl-ei% S. , ITandbueh der Lehre von den Geweben des Men- schen und der Thiere. Leipzig : 1868-09-70. “ Ueber selbstandige Bewegung. Wiener Sitzungsbe- richte, 1864. Ueber contractile Korper in der Milch. Wiener Sitz- ungsber., 1800. “ Sitzungsb. , 1807. “ Development of the Simple Tissues, in last part of Strieker’s “ ITandbueh.” Leipzig: 1871. “ Studien aus dem Institute fdr Experimentelle Patholo- gic in Wien, aus dem Jahre., 1809. I. Ueber den jetzigen Zustand der Entzundungslehre (Eine Einleitung zu den folgenden Aufsutzen). Von S. Strieker. II. Yersuche uber IIornhaut-EntzUn- dung. Yon William E. ISTorris und S. Strieker. III. Ueber die Zelltheilung in Entz’dndeten Geweben, Yon S. Strieker. YI. Untersuehungen uber die Furchung und BlUtterbildung im Ildhnereie Yon Dr. Josef Oellacher aus Innsbruck. YII. Ueber Endo- gene Bildung von Eiterkdrperehen an der Conjunc- tiva des Kaninchens, Yon Dr. L. Oser. YIII. LYber die Entzdndlichen Yeranderungen der Muskelfasern von Dr. Janovitsch Tschainski aus Petersburg. X. Ueber das Yerhalten der tixen Zellen des Eroschlar- venschwanzes nach meehaniseher Eeizung desselben, von E. Klein und II. Kundrat. IX. Ueber Entzdn- dung. Ein Resume aus den vorangestellten Abhand- lungen, von S. Strieker. “ Beobaehtungen uber die Entstehung ^les Zellkerns. Sitzimgsber. d. Wiener Acad, iii, 1877. “ Yorlesungen dber allgemeine und experimentelle Pa- thologic. 4Vien : 1878. T'aruffi^ Ce.s., Ueber die Kerne d. Lymphzellen. Revist clinic, vi, 5, 1870. BIBLIOGRAPHY. 191 Tiedemann, Anatomic der Robren-IIolothiirie, etc. 1816, p. 42. Thanhauffer, X., Ueber den Ban der Spinalen Ganglienzellen, Medic. Centralbl. No. 20, 1875. lliin, G., A Contribution to tbe Anatomy of connective tis- sue, nerve, and muscle, etc. Proceedings of tbe Koyal Society, No. 155, 1874 (with 4 plates). “ On tbe Minute Anatomy of Muscle and Tendons, etc. , Edinburgh Med. Jour., September, 1874 (with 3 plates). ‘‘ On tbe Anatomy of Connective Tissues. Proceedings of tbe Boyal Society, No. 158, 1875. “ On tbe Structure of Hyaline Cartilage, Quart. Journ. of Micr. Science, p. i, 22, 1876 (with 2 plates). Thierfelder^ A. , Ueber die Bedeutung der provisoriscb. Knor- pelverkalkung, Arch. d. Heilkunde, 16. Jabrgang, p. 441 (with plate). Todd, Tbe Cyclopaedia of Anatomy and Physiology. Lon- don : 1836-59. Todd and Bowman^ Physiological Anatomy and Physiology of Man. Philadelphia: 1857. Tojnes, Dental Tissues; in Tomes’s Dental Surgery. Am. ed. Philadelphia : 1859. “ Dental Physiology and Surgery. A course of Lectures at Middlesex IIosp. Med. School. Am. ed. Philadel- phia . 1853. Tomes and Be Morgan^ On Ossification. Philosophical Trans- actions, London : 1853. Torre^ G. 31. Bella., Nuove Osservazione Microscopiche. Na- poli : 1776. Tourneux^ Becherches sur I’epith. des Sereuses, Journal de 1’ Anatomic et de la Phys., Jan. and Eebr. 1874. Toynbee., Memoir on the Non- vascular Tissues. Philosophical Transactions, 1841. Treviranus., L. C. , Entwick. d. Embryo im Pflanzenei. Ber- lin : 1815. Treeiranus., G. Fr.., Beitrage zur AufklUrung der Erscheinun- 192 THE CELL DOCTRINE. gen und Gesetze des organischen Lebens. Bd. i, Heft i-iv. Brem. : 1831-3. Treviranus, G. Fr. and L. O. , Yermischte Scbriften anatom. n. physiologiscben Inlialts. Bd. i. Gotting. : 1816. Treviraniis^ G. Fr.^ Biologie oder Philosopbie der lebenden Natnr. Gottingen : 1802-22. “ Snr les eleinens organiques du corps animal, in Journ. Compi. du Diet, des 8c. Med., t. xxi, p. 109, 1825. Trichinse^ Ueber den Ban des Eicbens der Mollusken. Acade- mia di Bologna, Sednta 4. 1877. Troxler. Fin. P. Y., Yersuclie in der organischen Phvsik. Jena: 1804. “ Ueber das Lebenund sein Problem. Gottingen : 1806. “ Elemente der Biosopbie. Augsburg : 1808. Trueman. E. B., On the Development of the Ovum of the Pike, in Mo. Microscopical Journal, vol. ii, 1869. Turner., W. B. , Section on “The Cell,” in article “Anato- my,” in Encyclopsedia Britannica, vol. i, 9th ed., 1878. Turpin P. B, Ann. d. sc. nat., 2 ser., vii, p. 207. “ Sur quelques vegetaux microsc. Paris : 1827. Tyson., B, The Micr. Stud}^ of Blood and Epithelium, Phil. Med. Times, March 1st, 1873. Tyndall., John., On Dust and Disease. Boyal Institution. London : 1870. Unger., Pflanze im Momente der Thierwerdung. Wien : 1843. “ Ueber merismatisebe Zellenbildung bei Entwick. des Pollens. 1844. “ Aphorismen znr Anatomie und Physiol, der Pflanzen. Wien : 1838. Valentin, Ilistoriai Evolutionis Systematis muscularis prolu- sio. Diss. inaug. lYratisl. : 1832. Ilandbucb der Entwickhmgsgeschicbte des Menschen. Berlin : 1835. “ “Ueber den Yerlauf und die Enden der Xerven,” aus den Xov. Act. Nat. Curios., vol. xviii, pt. i, p. 96, besonders abgedruckt. Bonn : 1836. “ Principal Features in the Development of the Animal BIBLIOGRAPHY. 193 Tissues ; in Wagner’s Physiology, trans. by Willis. London : 1844, p. 214. Valentin^ Ammon’s Zeitschrift, vol. iii, 1838, p. 330. “ llepertor., i, p. 87. ^ i, p. 143. “ “ i, p. 175, 281. “ “ i,p. 245. “ Muller’s Archiv, 1836. “ “ 1838, p. 196. “ “ ‘‘ 1839. Velten^ IF., Die Physicalische Beshaffenlieit des pflanzl. Protoplasma. SitzUngsber. der Wiener Acad., Bd. 73, 1876 (with 2 plates). “ Einwirkimg strUmender ElectricitUt auf die Beweg. des Protoplasma, etc. Sitzimgsb. d. Wiener Acad. 73, 1876. “ TJeber die Einwirkung d. Temperatur auf die Proto- plasma-Bewegungen. Regensb. Flora, No. 12-14, 1876. Tirey^ J. J.^ De la puissance vitale, considere dans ses func- tions physiologiques, etc. Paris : 1823. “ Philosophie de I’Histoire Naturelle, ou Phenom^nes de I’Organisation des Aniinaux et desMegetaux. Paris : 1833. TTco, D’A^yr, Exposition des caract^res qui distinguent les corps vivans. In Discours sur I’Anat. CEuvr. , t. iv, p. 229. Virchow, if., Ueber Bildung und Umbildung des Knochenge- webes, Berliner Klinische Wochenschr., pt. No. 1 und 2, 1875. ‘‘ Wurzburger Verhandl., vol. ii, p. 154 and 314. “ Gesammelte Abhandlungen, vol. ii, p. 27. Cellularpathologie in ihrer JlegrUndung auf physiolo- gische und pathologische Gewebelehre. 3te Auflage. Berlin : 1871. “ Cellular Pathology as based upon Physiological and Pa- thological Histology. Twenty Lectures, during Eeb- 17 194 THE CELL DOCTRINE. ruary, March, and April, 1858. Translated by Frank Chance, B. A. Philadelphia : 1863. Virchow^ J?., Die Krankhaften Geschwlilste. 30 Yorlesungen. Berlin : 1863-65. 2 Bande. “ Letter concerning his Yiews, Edinburgh Med. Jour., Feb. , 1865. “ Archiv, Bd. V. “ The Mechanical Conception of Life. A discourse de- livered at the “ Congress of German Naturalists.” “ Atom and Individual. A public Lecture at Berlin, 1866. Vogel., Ji, Physiologisch-pathologische Untersuchungen liber Eiter, Eiterung, etc. Erlangen : 1838. “ Anleitung zum Gebrauche des Mikroskops und zur zoochemischen Analyse. Leipzig : 1841. “ Pathologische Anatomie des Menschlichen Korpers. Leipzig : 1845. Wagener., G. B. , Die Entwicklung der Muskelfaser. mit 3 Taf. in Kuperst. Marburg : 1869. “ Ueher die Entwicklung u. den Ban der quergestreiften u. glatten Muskelfasern. Sitz. Ber. d. Ges. Zur Beford. d. ges. nat. Wiss. zu Marburg, No. 10, August, 1867, Wagner, B., leones PhysiologicEe, tahulEe physiologiam et geneseas historiam illustrantes. Ease, i, iii. Leip- zig : 1839. Second edition by A. Ecker. Leipzig : 1851-59. “ Partium Elementarium organorum qua3 sunt in homine atque animalibus mensiones micrometricse. Leip- zig : 1834. “ Prodromus bistoriae generationis bominis atque ani- nialium : Leipzig : 1836, fob ‘‘ Zur vergleicbenden Pbysiologie des Blutes. Leipzig: 1833. Beitriigezur Yergleicbenden Pbysiologie, lift, ii. Ebendas. : 1838. “ Lebrbucb der speziell Pbysiologie. 3te Aufl. Leip- zig : 1845. ‘‘ Elements of Physiology. Translated from the German, with additions, by Robert Willis. I^ondon : 1844. BIBLIOGRAPHY. 195 Wagner^ JR. , Beitrage zur Gesclnchte der Zeugung und Entwick- lung. Erster Beitrag Sitzmigsbericlite der Matlie- matisch-physikaliscben Klasse der Konigl. Baier- schen Akad. der Wissenscliaften in Mlinchen. “ Ilandworterbucli der Physiologie. Braunschweig : 1849. TEa/de^er, TE., Ueber Bindegewebszellen, Arch. f. Mikrosk. Anat., xi, 1874 (with plate). TEfddeyer, Yirchow’s Archiv, Bd. Iv, pp. 83, 485. TEcddeyer, Van Beneden., ITis., Bamkke., and others. A review of their observations and writings on ‘ ‘ The Develop- ment of the Egg,” Archives des Sciences, Xo. 152, 1870. I Wake, C. Stanislaus.^ On Animals in ]\Iineral Infusions, Mo. ISIicroscopical Journal, 1870. WaUich., G. 0., The Yital Eunctions of the Deep-sea Pro- tozoa, Mo. Micros. Jour., vol. i, 1809. WaJther, Amceboid movements in sections of a frozen frog’s brain ; in Ilenle’s Bericht liber die Eortscliritte der Anat. u. Phys., im Jalire 1808, p. 00. Waller, Microscopical Examination of some of the Principal Tissues of the Animal Frame, as observed in the Tongue of the Living Erog, Toad, etc., Ijondou, Dublin and Edinburgh Philosophical Magazine, vol. xxix, 1840, pp. 271 and 398. Watters, J. II., Theory of Life advanced in his thesis written for the degree of Doctor of Medicine, 1851. “ Doctrines of Life. Reply to London Lancet and closing remarks, St. Louis Med. and Surg. Jour., November 10th, 1809. Weher, E. II., Canstatt’s Jahrb., 1847, p. 59. Weher, C. 0., Yirchow’s Archiv, Bd. xiii-xv. Wedl, (7., Grundzlige der pathologischen Histologic. lYien : 1853. TEeiss, G., Ueber die Bildung und Bedelitung der Riesen- zellen, etc., Yirchow’s Arch., Bd. 08, 1870 (with plate). TEem, Die PHanzenhaare. Berlin : 1807. 196 THE CELL DOCTRINE. Weissmann^ Entwicklung der Diptera. Wien : 1864. Wendt^ J-., De Epidermide humana. Diss. inaug. W^ratisl. : 1833. Wenzel^ Jos, et Chas.,, Ee Structura Cerebri. Tubingen : 1812. W/iytt, Boh.,, An essay on the vital and other involuntary motions of animals. Edinburgh: 1751. Williamson,, W. C., What is Bathybius ? Pop. Sci. Kev., vol. viii, No. 33, October, 1869, p. 350. “ The Amoeba, its Structure, Development and Habits. Pop. Sci. Bev. ,vol. v, p. 188. Wilso7i Philips,, A. P., An Experimental Inquiry into the laws of the vital functions. London : 1818. Winhler, F. W., Textur, Structur und Zelleben in den Ad- nexen des menschlichen Eies. Jena : 1870. Winslow., Anatomical Exposition of the Structure of the Human Body. Paris : 1732. Wittich, Yirchow’s Archiv, Bd. ix. Wolf, Casper P., Theoria Generationis. 1759. “ Theorie von der Generation. 1764. “ Theoria Generationis, Ed. Nova. Haloe, 1774. Zielonko, S., IJeber d. Eiitstehung und Proliferation von Epithelien und Endothelien, Med. Centralbl. No. 56, 1873, und Arch. fur. Mikr. Anat., Bd. x, 1873 (with 3 plates). Ziegler, E., Experimentelle Erzeugung von Kiesenzellen aus farblosen Blutkorperchen, Med. Centralblatt,No. 51, 1874. “ Experimentelle Hntersuchungen liber die Herkunft der Tuberkelelemeijte, etc. AVUrzburg : 1875. “ Untersuchungen liber patholog. Bindegewebs-und Ge- fass-Neubildung. AVlirzburg : 1876 (with 7 plates). INDEX. A. Addison, 114 Amoeba, 144 Amoeboid movement, 151 Aristotle, 13 Arndt, 121 Arnold, 26 Auerbach, 133 Author’s views, 127 B. Baumgartner, 26 Barry, Martin, 48 Beale, 83 Beneden, Van, 121 Bennett, 61 Bergmann, 44 Bibliography, 152 Bioplasm or Germinal Matter, 84 Borellus, 16 Bowman, 64 Bril eke, 81 Biitschli, 120 C. Cell, Leydig’s definition of, 80 !M. vSchultze’s “ “ 80 Virchow’s “ ‘‘ 67 author’s “ “ 128 Cell doctrine, present state of, 127 formation, 150 division, 150 nutrition of, 151 contents, 138 wall, 138 structure of, 140 Cell, or elementary part in dis- ease, 94 Cells, structure of, 144 shape of, 145 size of, 148 in pathological formations, 148 origin of, 149 and nuclei, new views on the structure of, 117 polygonal, 145 young, 145 ciliated epithelial, 145 columnar “ 145 squamous “ 145 tessellated “ 145 of adipose tissue, 147 of bone, 146 of connective tissues, 146 of nervous tissue, 146 of striated muscular tissue, 146 of unstriped muscular tissue, 146 Cohnheim, 114 Compound microscope, invention of, 15 198 INDEX. D. Diapedesis, 151 Dujardin, 76 Dutrocliet, 29 E. Ebertli, 122 Eimer, 123 Elastic tissue, yellow, 71, 92 F. Fallopius, 13 Flemming, 121 Formed material, 87 “ secondary, 90 Frommann, 118 G. Galen, 13 Germinal matter, 84 Globular theory, the, 21 Goodsir, 51 H. Haeckel, 77 Haller, 17 Heitzmann, 118 Ilenle, 44 Hertwig, 120 Hodgkin, 28 Home, Sir Everard, 25 Hooke, 17 Huxley, 54 and 104 I. Illustrations, list of, xi Intercellular substance, 91, 140 K. Klein, 123 Kupfer, 119 L. Leeuwenhoek, 17 M. Malpighi, 16 Mayzel, 120 Meyen, 30 Milne, Edwards, 25 K. Network, intracellular, 144 intranuclear, 131 and 144 Norris, 116 Nucleus, 128 discovery of, 30 Nucleolus, 132 “ new explanation of, 12 Nucleus fibre, 142 Nuclear membrane, 131 O. Oken, 21 P. Plate, description of, 201 Preface to second edition, vii to first “ ix Prochaska, 24 Protoplasm, 138 of M. Schultze, 76 R. Raspall, 29 Reichert, 44 Remak, 54 Robin, 98 w INDEX. 199 s. Sarcode of Diijardin, 76 Schleiden, 32 Schwalbe, 119 Schwann, 32 Strassburger, 120 Strieker, 116 Swammerdam, 16 T. Tissues, formation of, 91 Todd, 64 Tubercle, 97 V. Virchow, 65 W. Waller, 114 Wolff, 19 ,1/ 1% > . * ** ' ' ' * Vi EXPLANATION OF PLATE. 201 EXPLANATION OF PLATE, ILLUSTRATING DR. KLEIN’S PAPER, “ OBSERVATIONS ON THE STRUCTURE OF CELLS AND NUCLEI.” (From the Quarterly Journal of Microscopical Science, for July, 1878.) Figures 1-11 (incl.) refer to preparations of stomach, 12-20 to those of mesentery of newt. For method of preparing see text. All figures are represented as seen on Hartnack’s small stand with eye-piece III, and Zeiss’s objective F. Fig. 1 represents a goblet cell ; the intranuclear network is well shown, and also the fibrils passing from this into the upper and lower part of the cell. Fig. 2. — The intranuclear network separated from the membrane of the nucleus. Fig. 3. — A goblet-cell (like that of 1) as seen obliquely from above, showing the intracellular network. Fig. 4. — The intracellular network looked at vertically from above. Fig. 5. — Isolated nucleus showing the intranuclear network. Fig. 6. — A gland-cell, showing the dense network of fine fibrils of the cell-substance; the nucleus has escaped, but there are still left a few fibrils, probably connecting the two networks, viz., the intranuclear and the intracellular. Fig. 7. — An isolated nucleus of a gland-cell ; the wall of the nucleus is broken at one place and the intranuclear fibrils are seen passing outwards. Fig. 8. — A connective tissue corpuscle — endothelial plate — seen in profile ; both the intracellular fibrils and those of the intra- nuclear network are well shown. Fig. 9 — A similar cell seen from its broad surface. Fig. 10 — Portion of a cell ; the intranuclear network shrunk. Fig. 11. — An epithelial cell; the intracellular fibrils are well shown. The top of the cell is seen in an oblique direction, and 202 EXPLANATION OF PLATE. the network of fibrils is therefore brought into view. Prepara- tion treated with Muller’s fluid, and then with mixture of chromic acid and spirit ; see text. Fig. 12. — Isolated endothelial plate of surface of mesentery. The intracellular and intranuclear networks of fibrils are well shown. Fig. 13. — A capillary bloodvessel ; the two upper nuclei are seen from their broad side, the two lower in profile. They all show the network of fibrils. In the lower portion of the wall of the vessel an imperfect network of fibrils may be perceived. Fig. 14, a and h. — Two unstriped muscle-fibres. The intra- nuclear network of fibrils is well seen ; these are in connection with fibrils of the substance of the muscle-fibre ; there are seen numerous transverse markings along almost the whole length of the muscle-fibre. That these transverse markings correspond to rings which constitute the cortical part, i. e., the sheath, is well shown in a. Fig. 15, — A non-medullated nerve-fibre of mesentery of newt ; the nerve-fibre has a delicate sheath, the nuclei of which contain a distinct network of fibrils. Fig. 16. — A connective tissue corpuscle seen sideways. The nucleus contains a network of fibrils, in connection with that of the cell-substance. Figs. 17 and 18. — Two migratory cells ; 17, a common pale one, 18, a coarsely granular one. Their nuclei show the network of fibrils very well. Fig. 19. — A crecal dilatation of a lymphatic vessel of the same membrane, showing the nuclei of the endothelial cells forming the wall of the lymphatic, and also nuclei of lymph-corpuscles. Fig. 20, a and c. — Two connective tissue corpuscles; the dis- tinction between “ ground-plate ” and “ fibrillar substance ” is well shown; the “ fibrillar substance ” is in connection with the in- tranuclear fibrils. 6, a nucleated plate ensheathing a minute non-medullated nerve- fibre. The intranuclear network is seen in connection with the processes and fibrils of the connective tissue corpuscle c. ( r;" i V 1 i m ' t 1 . O kL r- • ■ .r . . J. e