li ®I|c ^. ^. pll pfamrg U /^ ^orll] Cctroltna ^tate College OH307 BaiaB—iiii>ii*iH'Ma£ Date Due 4F'26 20 F '2<^ ^ ^ 60ecS2 V 244pf'5J ■" * ^ \jt J M"/w 1 ;'" ' ' ^ '... mS" "^■^^ 1 1 , i ! _ s L. B. Cat. No. 1 137 John James Audubon - 1785-1851 From a portrait in oil by George P. A. Healy, London, 1838. Courtesy of Mr. Ruthven Dcane. BIOLOGY IN AMERICA R . T. YOUNG WITH MORE THAN TWO HUNDRED ILLUSTRATIONS BOSTON RICHARD G. BADGER THE GORHAM PRESS Copyright, 1922, by Richauu G. Badger All Rights Reserved Made in the United States of America Press of J. J. Little and Ives Company, New York, U. S. A. • LIBRARY fl, C. state College To THE MEMORY OF MY MOTHER 11 J 11 PREFACE To the "man in the street" the biologist, with his "bugs" or his ' ' germs, ' ' frequently appears as a harmless but equally useless individual. Thus in an issue of the "New Republic," shortly after America's entrance into the world war, a serio- comic writer in criticizing the action of President Wilson in appointing a committee on national preparedness from the National Academy of Sciences says, "I doubt if any other nation ever responded to the prospect of war with a scheme of national defense which included a Committee on Zoology and Animal Morphology." What excuse then has the biologist for his existence ? What can he say for the ' ' truth that is in him ' ' ? When half a century ago the Austrian monk, Gregor Mendel, was "puttering" over his sweet peas in the garden of the monastery at Briinn in the Tyrol, the world took small notice of his work, little realizing that he was laying the foundation stones of a science which was to place animal and plant breeding on a scientific basis, and teach us how to build a better race of man himself. When the English army sur- geon Ross in India in 1898 was studying a microscopic organ- ism in the blood of the owl, he could not foresee that his work would in a few years' time virtually abolish malaria in Ismailia on the Suez Canal, where in 1902 there were 1548 cases in a population of about 6,000; that it would render possible the building of the Panama Canal, and convert Havana into a health resort. Of what particular practical importance was Harrison's discovery that a bit of nerve cord transferred from a tadpole to a drop of frog's lymph would develop nerve fibres there? Yet Harrison's method of making that discovery has opened to science an entirely new field in the study of tissue growth, both benign and malignant, has enabled us to observe the growth of the cancer cell, and determine some of the con- ditions of that growth, and may some day lead us to a solu- tion of the cancer problem. When a fish embryo is developed in a solution of magnesium chloride it gives rise to various malformations, most conspicu- ous of which is the ' ' cyclopean eye. ' ' Of what possible value to a workaday world is such a discovery? Very little in ' 7 8 Preface itself. But if the young fish can be distorted into all sorts of monstrous shapes by chemical treatment, why may not the monstrosities observed in man, some of which are not neces- sarily fatal, but which entail on their victims sorrow and suf- fering, be due to a similar cause? And may not the discovery of the cause lead to its control? But the primary aim of science is not utilitarianism. Were this so, it would still be wearing rompers instead of seven league boots. It is a commonplace to say that the aim of science is truth, regardless of what practical value such truth may have. But the "man in the street" frequeiitly fails to realize the connection between purpose and accomplishment in science. Perha})S never has this relation been made more clear than in the recent war. The German Government, recog- nizing the value of science for its own sake, encouraged it with every means in its power, and the German university became a Mecca for scientific students throughout the world. England, on the contrary, was more interested in develop- ing good cricketers and diplomatists than in training scien- tists, and when war came upon her "like a thief in the night" she found herself under a well-nigh fatal handicap. It was farseeing statesmanship which led President Wilson to call for a council of national defense from the National Academy of Sciences on America's entrance into the war. It would have been still farther sighted had this council been established long years ago. American biology, with the lusty vigor of youth, has ad- vanced by leaps and bounds in recent years; and today a wonderful future opens before it. From the days when the early naturalists went hand in hand wuth the pioneer into the depths of our great forests, crossed the boundless prairie and pierced the trackless labyrinth of mountain peak and canyon, to the present, w'hen the names of American biologists stand throughout the world as synonyms of biological progress, their record is one of which our nation and the world may well be proud. It is in the hope of recording, in some small measure, the story of this progress that this book is written. Most of the facts herein recorded have already appeared in the many books dealing with the biological problems of the last few years, but nowhere, so far as I know, has a brief, compre- hensive and simple story of the work of American biologists been told. It is in the hope of presenting such a story that this work has been undertaken. To give a comprehensive as well as simple account of so complex a field as biology is, however, far from easy, A full account of so wide a field would require many volumes, but I shall attempt to touch only Preface 9 upon th3 more salient points. The avoidance of technical terms is in many cases impossible, but I have endeavored to reduce them to a minimum. It is of course impossible in such a story to avoid referring to the work of biologists in other lands. Nor is it desirable. Science is not bounded by political and racial lines, and the work of American biologists can only be appreciated in the light of what their colleagues in other lands have been doing. The book is, however, a record of American biology, so that reference to the work of other biologists will be only incidental to the main trend of the story. A zoologist should perhaps apologize for the title, since the main emphasis will naturally fall on that branch of biology with which he is most familiar. The great principles of life, however, apply equally to plants and animals, and even though the examples which illustrate these principles have been drawn mainly from the animal world, nevertheless the title will be justified if the discoveries recorded are those which in the main illustrate the laws which govern plants aiid animals alike. The writer is indebted to numerous sources for the illustrations and quotations found in this book. Due acknowledgment for each is made in coimection with it. To his wife, Ellen F. P. Young, and sister, IMary Farrar, grateful acknowledgment is due for assistance with the proof and index. CONTENTS CHAPTER PAGE I. Work of Early Biologists. Explorers and Travel- ers, Collectors, Field Naturalists and Museum Men. Early Surveys, State and National ... 19 II. Biological Institutions in America. Universities and Colleges, Museums, Botanical and Zoological Gar- dens, Biological Stations and Endowed Labora- tories 47 III. Descriptive Biology. Development of Plants and Animals; of Sex and Sexual Reproduction, and Al- teration OF Generations. The Path of Vertebrate Evolution 88 IV. The Story of the Rocks. Contribution of Paleon- tology TO Evolution. Rise and Fall of the Faunas of the Past 116 V. Geographical Distribution of Plants and Animals. Relation Between Organism and Environment. Methods of, and Barriers to the Spread of Plants and Animals. Plant and Animal Societies. Life Zones op North America 151 VI. Experimental Biology. Preformation in a New Dress, Organization of the Egg, Regeneration and Grafting, Plastic Surgery, Tissue Culture, the Problem of Death, and Immortality of the Cell . 188 VII. Experimental Biology Continued. The Role of the Chromosomes in Inheritance. Inheritance of Sex and Sex-Linked Characters 202 VIII. Experimental Biology Continued. Influence of En- vironment IN Determining the Development of Or- ganisms. Effects of Temperature, Light, Moisture, Chemicals, and Food upon the Form of Animals and Plants. The Control of Sex 219 IX. Experimental Biology Continued. The Factors of Evolution: Natural Selection, Mutation, Ortho- genesis, Isolation, Inheritance of Acquired Char- acters. Experimental Modification of the Germ Cells 234 X. Experimental Biology Continued. Mendelism and the Multiple Factor Hypothesis. Human Inherit- ance and Eugenics 257 XI. Experimental Biology Continued. Mechanism Versus Vitalism. Physico - chemistry op Vital Processes, Metabolism of Animals and Plants 278 11 12 Contents CHAPTER PAGE XII. Experimental Biology, Mechanism Versus Vitalism Continued. Tropisms, Instincts and Intelligence. Hormones. Artificial Fertilization 301 XIII. Color in Nature. Colors of Flowers and the Inter- relation OF Flowers and Insects. Colors of Animals and Their Physico-chemical Causes. The Theories of Pjiotective Coloration, Warning and Alluring Colors, Mimicry and Recognition Marks 330 XIV. Aquatic Biology. Oceanography, Life of the Sea and Its I']nvikonment. Biology of Inland Waters. Methods of Studying Aquatic Life 349 XV. Economic Biology. Dependence of Man upon Nature. Ignorance of Nature the Cause of Economic Loss. Conservation and Increase of Natural Resources . 385 XVI. Biology and Medicine. Microscopic Life and Its Re- lation to Human Health. The Role of Animals in Spreading Disease. Animal Experimentation and Its Contributions to Human Welfare. The New Medi- cine, Safeguarding the Health of the Nation . . 440 XVII. The Outlook. Some Unsolved Problems of Biology. Possibilities of Larger Service 478 ILLUSTRATIONS 1 John James Audubon, Frontispieo e PAGE 2 Alexander Wilson 21 3 Rafinesque 29 4 Lewis and Clark, Thomas Jefferson, Thomas Nuttall ... 35 5 Louis Agassiz 38 6 James Dwight Dana, Joseph Leidy, Edward Drinker Cope, Othniel Charles Marsh 41 7 Asa Gray 43 8 Spencer Fullerton Baird 44 9 The Academy of Natural Sciences of Philadelphia .... 53 10 The American Museum of Natural History in New York . 54 11 Blue shark and school of young 55 12 Duck hawk at nest 56 13 Florida swamp 56 14 Woolly rhinoceros, saiga antelope and mammoth .... 57 15 Monarch butterfly 58 16 New sources of aquatic food 60 17 The U. S. National Museum 61 18 The Now York Botanical Gardens 64 19 The laurel bank in the Arnold Arboretum 65 20 The "forest primeval" in the Arnold Arboretum 66 21 Marine Biological Laboratory at Woods Hole, Mass. ... 68 22 View of Woods Hole 69 23 Animal community of a New England wharf 70 24 The Station for Experimental Evolution of the Carnegie In- stitution 74 25 Desert Botanical Laboratory of the Carnegie Institution . . 75 26 Old shore line of Salton Sea 78 27 Tortugas Laboratory of the Carnegie Institution 82 28 The yacht "Anton Dohrn" of the Carnegie Institution ... 83 29 Types of Protozoa 90 30 Types of Protozoa 91 31 Lower plant life 93 32 Amoeba proteus 94 33 Life cycle of malarial organism 97 34 Phlox, liverwort and moss 99 35 Invertebrate types 102 36 Vertebrate embryos 104 13 14 Illustrations FACE 37 Head of lamprey, and sucker showing scars made by lamprey 109 38 Lungfish and fossil shark, Cladoselachc 112 39 A trilobite 117 40 A king crab 117 41 Ostracoderms 118 42 Cestracion, Polyterus and Hatteria 121 43 Footprint of a primitive am[)liihi;in 122 44 A stcgoccphalan 123 45 Landscape of the coal-forming period 124 46 Dinosaur tracks 126 47 Brontosaurus 127 48 Stegosaurus 128 49 Triceratops 128 50 Rhamphorhynchus 129 51 Arc'ha'opteryx 131 52 Hesperornis 132 53 Part of feather, showing details 133 54 Tooth of dinosaur and jaw of contemporary mammal . . . 137 55 Opossum 138 56 Spiny ant-eater 139 57 Uintatherium, Coryphodon, and Dromocyon 141 58 Eohippus 143 59 The tarsier 144 60 The saber-toothed tiger 146 61 Excavation of a tar pit at Rancho La Brea, California . . . 148 62 Early days in the tar pools of Southern California .... 149 63 The arctic tern 152 64 A group of lichens 159 65 A glacial pond 160 66 Zoogeographical realms 161 67 Life zones of North America 162 68 Profile of San Francisco Mountain, showing life zones . . . 163 69 An alpine dwarf 164 70 Pika, or Rocky Mountain hare 165 71 Ptarmigan in summer plumage 166 72 Ptarmigan in autumn plumage 166 73 Ptarmigan in winter plumage 167 74 Clarke's crow 167 75 Timber line in the Rocky Mountains 168 76 Polar bears 169 77 Cariboo 169 78 Musk oxen 170 79 Wolverine 170 80 Canadian zone forest in Colorado 171 81 Woodchuck 172 82 Weasel 173 83 Snowshoe rabbit 173 Illustrations 15 PAGE 84 Canadian and transition zone landscape 174 85 Beaver 175 86 Beaver pond 176 87 Cypress swamp 177 88 Cotton rat 178 89 Alligator 179 90 Water moccasin 179 91 Burrowing owl 180 92 Prairie dog 181 93 Prairie dog at burrow 181 94 Horned toad 183 95 Kangaroo rat 183 96 Gila monster 184 97 California big trees 185 98 Mountain beaver 186 99 Beroe 189 100 Organ-forming substances in the egg 190 101 Four-legged tadpoles 195 102 Combination frog 196 103 Reconstruction of wounded soldier's face 198 104 A piece of growing tissue 199 105 Mitosis in a sea urchin's egg, showing chromosomes .... 204 1C6 Diagram of inheritance of size in sweet peas 205 107 Diagram of combinations^ of three pairs of chromosomes . 206 108 Photographs of chromosomes, showing sex chromosomes . . 208 109 Gynandromorph fruit flies 209 110 Diagrams showing distribution of sex chromosomes in ma- turation 211 111 Fruit flies, showing mutations 212 112 Diagrams showing chromosomes in relation to sex linkage . 213 113 Chromosome map showing distribution of linked characters in the fruit fly 216 114 Diagrams of chromosomes in the fruit fly showing result of non-disjunction 217 115 Influence of environment on plants 221 116 Effect of diet on body form in Amblystoma 225 117 Scarlet tanager and bobolink, showing sex differences . . . 226 118 Cyclopean fish 228 119 Human twin monster 229 120 Types of human faces 229 121 A human monster 230 122 Moulted skin and egg case of daphnid 231 123 Diagram showing pure lines in beans 237 124 Hooded rats 238 125 Mutation in (Enothera 239 126 A rumpless fowl 240 127 Diagram showing height variation in man 241 16 Illustrations PAGE 128 Mutations in the potato beetle 247 129 Deer mouse 250 130 Inheritance of color in the four o'clock 258 131 Inheritance in Andalusian fowl 259 132 Inheritance of ear length in rabbits 260 133 Inheritance in guinea pigs 261 134 Diagrams showing Mendelian inheritance of one, two and three pairs of characters respectively 262 135 Hornless cattle 267 136 Diagram showing osmosis 279 137 Effect of diet on man 288 138 Effect of diet on dogs 291 139 Pursuit of food by Amoeba 302 140 Compass plants as seen from different positions 307 141 Mimosa or sensitive plant 308 142 Sundew leaf 309 143 Sagging in a stem 310 144 Relative amount of bending in stems due to unequal growth 311 145 Effect of the kinetic drive on a soldier 322 146 Effect of the kinetic drive on the tissues of the body . . . 323 147 Sebright poultry, normal and castrated 326 148 Relation of bee and flower 331 149 Flatfish photographed on different backgrounds 334 150 Protective form and color in animals 335 151 Leaf insect 336 152 Walking stick insects 336 153 Dead leaf butterfly 337 154 Imitation of an orchid by a mantis 338 155 Skunk 339 156 Porkfish 339 157 Mimicry of monarch by viceroy butterfly 340 158 Biuiiblebee mimicked by fly 340 159 Mimicry in butterflies 341 160 Mimicry of leaf cutting ant by tree hopper 341 161 Antelope 343 162 Male and female wood ducks 344 163 Sexual difference in beetles 345 164 Sexual difference in fish 345 165 The "Albatross" 350 166 A radiolarian 352 167 Deep sea fishes on a light background 354 168 Deep sea fishes on a dark background 355 169 Angler fish and Chiasmodus 356 170 Giant squid and tentacle marks 356 171 Portuguese man of war 357 172 Vellela 358 173 Sunfish and crustacean larva 359 Illustrations 17 rAOF 174 Salmon at hn^c of falls 362 175 Leaping salmon 362 176 Sigsbee sounding machine in use on the "Albatro.--.s" . . 364 177 Bigelow water bottle 368 178 Blake deep sea trawl 369 179 Tow-nets in use on the "Albatross" . . 371 ISO Jaws of whalebone whale 373 181 Hensen's net 374 182 Synura 378 183 Gypsy moths and caterpillars on trees 386 184 Trees stripped by gypsy moth caterpillars 386 185 Alfalfa field ruined by mice 387 186 Red-tailed hawks 388 187 Barn owl . 389 188 Skulls disgorged by barn owls 389 189 Meadow mice 394 190 Apple tree girdled by mice 395 191 Cottontail rabbit 397 192 Brown rat 399 193 Gray wolf and pups 401 194 Ground squirrel 401 195 Pocket gopher 402 196 San Jose scale 403 197 Mass of San Jose scales on tree tnmk 404 198 Apples infested with San Jose scale 405 199 Pitiful ladybird beetle 406 200 Screw worm and cattle ticks 408 201 Bamboo grove 410 202 Udo 411 203 Udo stem, blanched 412 204 Tung oil tree . , 413 205 Fruit of tung oil tree 414 206 Pistache trees 415 207 Indian mango 416 208 Date plantation 417 209 Bunch of dates 418 210 Herd of buffalo 419 211 Elk in Yellowstone Park 420 212 Egret colony 421 213 Group of fur bearing animals 423 214 Otter 424 215 Mink 424 216 Seining salmon 428 217 Salmon eggs 429 218 Interior of salmon hatchery 430 219 Developing fish . . . ' 431 220 Seals on Pribilof Islands 433 18 Illustrations PAGE 221 Glofliidiuia larva 435 222 Dianiorul-back terrapin 437 223 Carroll, Lazcar and Rwd 451 224 War on the mosquito 454 225 Trifhina in mviscle . 462 226 Tapcnvorni of man 463 227 Hookworm 465 228 Hookworm (lisprnsar.v 468 229 Hookworm patient before and after treatment 469 BIOLOGY IN AMERICA BIOLOGY IN AMERICA CHAPTER 1 Work of the early biologists. Explorers and travelers, col- lectors, field naturalists and museuni men. Early surveys, state and nationul. The evolution of human thought parallels that of the indi- vidual mind. Man sees first the effect and then seeks the cause. The falling apple pointed the way to the discovery of the law of gravitation; the amber wand, when rubbed with a bit of fur, to the discovery of electricity, and the "pebrin" disease of the silkworm to the modern science of bacteriology. The story of all science is one of observation of phenomena, speculation as to their cause, and finally the determination '6f cause by means of experiment. The recording of phe- nomena is not however limited to any given sidentific age, but necessarily goes hand in hand with philosophy and experi- ment, forming with them the trinity of scientific progress. It is but imtural, then, that the early history of biology in 'America should be written in the bold characters of stirring adventure. Across the sea in the first years of the last cen- tury came adventurous spirits, keen-eyed and lusty hearted, with the "call of the wild" in their souls. Some of these, llfte the Scotch peddler Wilson, and the eccentric Audubon W&re "ne'er do weels" filled wdth the primitive instinct of the ii'dtead. Others were men of high station in the Old World, tike Lucieii Bonaparte, nephew of the great imperialist, who idame to 'this country, like their humbler comrades, impelled by a spirit of scientific adventure. There were still other naturalists in the early days in America, like the Bartrams, Who Were natives of the soil. 'These early biologists were naturally collectors and field Naturalists, but with the establishment of learneil societies they were soon joined by museum men, who worked up the material collected in the field. The interest of these latter, then as now, was primarily in classification and distribution, but the writings of the field naturalists are replete with interesting accounts of the liomes and habits of the animals 10 20 Biology in America and plants which they collected. Oftentimes collector and classifier were the same, as with Baird, Coues and many othei-s. On tho banks of the Sehnylkill River in Philadelphia stands an okl stone luansion, over whieh the pleasant ivy clambers, and in the garden round about, now a city park, are still growing many of the plants set out there nearly two centuries ago by John Bartram, who was the first American botanist of note, and whose garden, laid out in 1728, was the first botanical garden in America. His old rock wine press is there still, from which the host provided refreshment for Washington, Franklin, Hancock, Rittenhouse, Morris and many others whose names are written large on the pages of our nation's story; and to his home also came many notables from abroad, for his reputation for learning and hospitality was well known. Bartram acted at one time as American botanist to George III, and corresponded with Linmeus, who considered him "the greatest natural botanist in the world,'' as well as with other leading European naturalists of his time, with whom he exchanged many plants for the books which could only be obtained in Europe. Provided with independ- ent means, he made extensive journeys through eastern America, from Lake Ontario to Florida, in search of plants, accounts of which were published by him, as well as several minor papers on natural history. Here was born and died the son, William, a botanist and ornithologist of note. Like his father, he was an extensive traveler, and published an account of his travels, as well as a list of American birds, w^hich was the first extensive work on American ornithology. Over the counter of a little store in Louisville, Kentucky, there occurred in INIareh, 1810, a chance meeting between two men who have stamped their names in indelible letters on the pages of American Science. They were Alexander Wilson, the Scotch weaver, and John James Audubon, the French artist. In his "Ornithological Biography," Audubon has given us an interesting account of tiiis meeting and of his impressions of his co-worker in the field of ornithology. "One fair morning," writes Audubon, "I was suri)rised by the sudden entrance into our conntiug-room at Louisville of Mr. Alexander Wilson, tlie celebrated author of the American Ornithology, of whose existence I had never until that moment been appriseiit judge of my astonishment some time after when, on reading the thirty- ninth page of the ninth volume of Americcui Orniihologij, 1 found in it the following paragraph: " ']\Iarcli 28, ]i)10. 1 bade adieu to Louisville, to which place I liad four letters of reconnnendation, and was taught to expect much of everything there ; but neither received one act of civility from those to whom 1 was recommended, one subserilx-r, nor one new bird; though I delivered my letters, ransacked the woods repeatedlj^, and visited all the characters likely to subscribe. Science or literature has not one friend in this place.' " ^ Alexander Wilson, the "father of American ornithology," was born at Paisley, Scotland, on July G, 1766. lie was the son of a weaver, who, together with liis regular trade, com- bined farming, distilling and smuggling. Destined by his parents for the church, his studies in this direction were early terminated by various vicissitudes in the Wilson family, such avs the advent of a step-mother and sundry children, and the young Wilson became a weaver apprentice, from which pur- suit his raml)ling propensities soon diverted him into the paths of the peildler and poacher. Indulging himself in a little fun at the expense of the master weavers during a trade dispute, he paid i)enance therefor with a brief sojourn in jail, after which he emigrated to America in 1794. Here he earned a precarious living as peddler, printer, and school teacher, the latter profession seeming to have stood as high in ])ublic esteem then as now, until he nuide the acquaintance of the younger Bartram and the engraver Lawson, under whose advice and encouragement he gave himself up to his passion for natural history and learned to draw the objects of his search. lie now devoted liimself to the preparation of his "American Ornithology," in the course of which he roamed the wilderness of the then West, crossing the Alleghanies, sailing down the Ohio, sleeping under the stars or in the fron- tiersman's "shack." In the course of these journeys "in search," as he says, "of birds and subscribers," he made tlie acquaintance of Audubon in the iiuinner above described. The first volume of his work appeared in 1808 and six others followed prior to his early death in 1813, as the result of *Aiutubon's Ornithological Biograpliy, quoted in "Life of Audu- bon," pp. 22-24. Early Naturalists 23 hardship and exposure incurred while seeking the birds he loved so well. To the careful observation of the scientist, Wilson joiueil the literary enthusiasm of poet and nature lover. His account of the passenger pigeon is full of fascinating interest. "In descending the Ohio by myself in the month of Feb- ruary, 1 often rested on my oars to contemplate their aerial manoeuvres. A column eight or ten miles in length would appear from Kentucky, high in air, steering across to Indiana. The leaders of this great body would sometimes gradually vary their course, until it formed a large bend of more than a ndle in diameter, those behind tracing the exact route of their predecessors. This would continue sometimes long after both extremities were beyond the reach of sight; so that the whole, with its glittery undulations, marked a space on the face of the heavens resembling the windings of a vast and majestic river. When this bend became very great, the birds, as if sensible of the unnecessary circuitous course they were taking, suddenly changed their direction ; so that what was in column before became an immense front, straightening all its indentures until it swept the heavens in one vast and in- finitely extended line. Other lesser bodies also united with each other as they happened to approach, with such ease and elegance of evolution, forming new figures, and varying these as they united or separated, that I was never tired of contem- plating them. Sometimes a hawk would make a sweep on a particular part of the column, from a great height, when almost as quick as lightning that part shot downwards out of the common track ; but soon rising again, continued advanc- ing at the same height as before. This intiection was con- tinned by those behind, who on arriving at this point dived down almost perpendicularly to a great depth, and rising, followed the exact path of those that went before. As these vast bodies passed over the river near me, the surface of the water, which was before smooth as glass, appeared marked with innumerable dimples, occasioned by the dropping of their dung, resembling the commencement of a shower of large droi)s of rain or hail. "Happening to go ashore one charming afternoon to pur- chase some milk at a house that stood near the river, and while talking with the people within doors, I was suddenly struck with astonishment at a loud rushing roar, succeeded by in- stant darkness; which on the first moment I took for a tor- nado, about to overwhelm the house and everything around in destruction. The people, observing ray surprise, coolly said, 'It is only the pigeons;' and on running out, I beheld a flock thirty or forty yards in width sweeping along very low, S«r s fi 1 r t* ^ ^5" — , o -J s: *v* « 24 Biology in America between the house and the mountain or height that formed the second bank of the river. These continued passing for more than a quarter of an hour, and at length varied their bearing so as to pass over the mountain, behind which they disappeared before tlie rear came up." And these lines from his verses to the bluebird are full of the sweet freshness of the out-of-doors, and bring back to our minds the days of our care-free, bare-foot, boyhood: "Then loud-piping fi'ogs make the marshes to ring; Then warm glows the sunshine, and fine is the weather; The blue woodland tiowers just beginning to spring, And spicewood and sassafras budding together:" "The slow lingering schoolboys forget they'll be chid, While gazing intent as he warbles before them In mantle of sky-blue, and bosom so red, That each little loiterer seems to adore liim."^ A charming picture of Wilson has been given us by James Lane Allen in his "Kentucky AVarbler, " where we see him, traveling twelve hundred miles on foot through the wilder- ness to visit Niagara Falls and reaching "home 'mid the deep snows of winter with no soles to his boots." And again as he sets forth on his solitary voyage down the Ohio : "... It is the twenty-fourth of February : the river, swol- len with the spring flood, is full of white masses of moving ice. . . . They warned him of his danger, urged him to take a rower, urged him not to go at all. Those who risked the passage of the river floated down on barges called Kentucky arks, or in canoes hollowed each out of a single tree, usually the tulip tree, which you know is very common in our Ken- tucky woods. But to mention danger was to make him go to meet it. He would have no rower, had no money to hire one, had he wished one. He tells us what he had on board : in one end of the boat some biscuit and cheese, a bottle of cordial given him by a gentleman in Pittsburgh, his gun and trunk and overcoat; at the other end himself and his oars and a tin with which to bail out the skifit", if necessary, to keep it from sinking and also to use as his drinking-cup to dip from the river. "That February day— the swollen, rushing river, the masses of white ice — the solitary young boatnum borne away » Quotations from the "Passenger Pigeon" and the "Bluebird" in the "American Ornithology." Eaiiy Naturalists 25 to a new world on his great work : his heart expanding with excitement and joy as he lieaded toward the unexplored wil- derness of the Mississippi Valley. "Wondrous experiences were his: from the densely wooded shores there would reach him as he drifted down the whistle of the red bird — those first spring notes so familiar and so welcome to us on mild days toward the last off February. Away off in dim forest valleys, between bold headlands, lie saw the rising smoke of sugar camps. At other openings on the landscape grotesque leg cabins looked like drg-houses un- der impending mighty mountains. His rapidly steered skiff passed flotillas of Kentucky arks heavily making their way southward, transporting men and women and children — the moving pioneers of the young nation : the first river merchant- marine of the new world ; carrying horses and plows to clear- ings yet to be made for homesteads in the wilderness ; trans- porting mill-stones for mills not yet built on any wilderness stream. . . . "He records what to us now sounds incredible, that on March fifth he saw a flock of parrokeets. Tliink of parro- keets on the Ohio River in March ! . . . Once he encountered a storm of wind and hail and snow and rain, during which the river foamed and rolled like the sea and he had to make good use of his tin to keep the skift' baled out till he could put in to shore. The call of wild turkeys enticed him now toward the shore of Indiana, now toward the shore of Kentucky, but before he reached either they had disappeared. His first night on the Kentucky shore he spent in the cabin of a squat- ter and heard him tell tales of bear-treeing and wildcat-hunt- ing and wolf-baiting. All night wolves howled in the forests near by and kept the dogs in an uproar ; the region swarmed with wolves and wildcats 'black and brown.' "On and on, until at last the skiff* reached the rapids of the Ohio at Louisville and he stepped ashore and sold his frail savior craft, which, at starting, he had named the Orni- thologist. The Kentuckian who bought it as the Ornithologist accepted the droll name as that of some Indian chief. He soon left Louisville, having sent his baggage on by wagon, and plunged into the Kentucky forest on his way to Lexing- ton.^ After Wilson's death, the remaining volumes of his work were completed by his friend, Charles Lucien Bonaparte, the Prince of Cannino and nephew of Napoleon, who in early * From the ' ' Kentucky Warbler, ' ' pp. 82-88, by i>eriiiission of the author and Doubleday, Page and Co. 26 Biology in America life came to America, where he gained reputation as an or- nithologist. Tlie other of these two remarkable men, while an American by birth, was Frencii by parentage and education. Born in Louisiana in 1780, his family shortly lifter removed to the estate of Aux Cayes in St. Domingo, where his mother was killed in the insurrection of the blacks in 1791, his father, with tlie chihlreii, escaping to France, where he remarried, entrust- ing tlie tutelage of his children to their step-mother. She was an easy mistress and the young Audubon was reared in an atmosphere of indulgent plenty. AVith more foresight than his wife, the boy's father insisted on his education, originally intending him for a maritime or engineering career. Tlie tine arts were not, however, neglected in his education, music and drawing being included in his studies, the latter under the famous French artist, David. His studies, however, did not prevent many rambles into the country, from which he "re- turned loaded with objects of natural history, birds' nests, birds' eggs, specimens of moss, curious stones, and other ob- jects attractive to his eye." Audubon also began in his early boyhood to draw birds, completing sketches of two hundred specimens. Finding his son's interest fixed upon other than maritime or military pursuits, the father sent him to America to super- intend his estate of iMill Grove on the I'erkiomen Creek near Philadelphia, where in Audubon's own words, he found a "blessed spot" and where "hunting, fishing and drawing oc- cupied my evpi-y moment, cares I knew not and cared nothing for them." Here, too, he met his future wife, Lucy Bake- well, the daughter of an P^nglish gentleman, residing on an adjoining estate. Before his marriage, Audubon returned for a year t(i France, where he served for a brief time as a midshipman in the French navy, and where he met a young man named Rosier, who later became his partner in his business ventures in America. Subsequent to Audubon's return to America the future partners essayed a business apprenticeship in New York, which Audubon signalized by the loss of several hundred l)ounds in speculation; Rosier similarly losing considerable money. His connncrcial enterprises, however, did not pre- vent Audubon from devoting himself to his favorite pursuits, which caused such a disagreeable odor in liis rooms that \\h neighbors demanded, through a constable, an abatement of the nuisance ! Leaving New York, Audubon journeyed to Louisville, where he invested the proceeds of the sale of the Mill Grove prop- Early Naturalists 27 erty in Ijushioss with Rosier and where lie shortly after brought his wife. Space does not permit us to follow all the wanderings of this brilliant, but eccentric man. His various business ad- ventures were foreordained to failure, and from comfort, it' not opulence, he and his ever brave and loyal wife were soon reduced to penury, Audubon earning a meagre penny by giving lessons in drawing, music, fencing and dancing, while his wife acted as governess in a private family. His roving life in a new and sparsely settled country was full of wild and interesting experiences which are vividly depicted in his journal. His account of an Indian swan hunt in Tennessee gives us a lively picture of the abundance of wild life in America in the early daj^, and some idea of the cause of its rapid disappearance. "The second morning after our arrival at Cash Creek, while I was straining my eyes to discover whether it was fairly day dawn or no, I heard a movement in the Indian camp, and discovered that a canoe, with half a dozeii squaws and as many hunters, was about leaving for Tennessee. I had heard that there was a large lake opposite to us, where immense flocks of swans resorted every morning, and asking permission to join them, I seated myself on my haunches in the canoe, well provided with ammunition and a bottle of whisky, and in a few minutes the paddles were at work, swiftly propelling ns to the opposite shore. I was not much surprised to see the hunters stretch themselves out and go to sleep. On landing, the squaws took charge of the canoe, secured it, and went in search of nuts, while we gentlemen hunters made the best of our way through thick and thin to the lake. Its muddy shores were overgrown with a close growth of cotton trees, too large to be pushed aside, and too thick to pass through except by squeezing yourself at every few steps; and to add to the ditficulty, every few rods we came to small nasty lagoons, which one must jump, leap, or swim, and this not without peril of broken limbs or drowning. ''But when the lake burst on our view there were the swans by hundreds, and white as rich cream, either dipping their black bills in the water, or stretching out one leg on its sur- face, or gently floating alone. According to the Indian mode of hunting, we had divided and approached the lagoon from different sides. The moment our vidette was seen, it seemed as if thousands of large, fat, and heavy swans were startled, and as they made away from him they drew towards the ambush of death ; for the trees had hunters behind them, whose touch of the trigger would carry destruction among them. As the first party fired, the game rose and flew within easy 28 Biology in America distance of the party on the opposite side, when they again fired, and I saw the water covered with birds floating with tlieir backs dowjiwards, and tlieir heads sunk in the water, and tlieir legs kicking in the air. "When the s])ort was over we counted more than tifty of these beautiful biixls, whose skins were intended for the ladies in Europe. There were plenty of geese and ducks, but no one condescended to give them a shoot. A conch wa.s sounded, and after a while the squaws came dragging the canoe, and collecting the dead game, which was taken to the river's edge, fastened to the canoe, and before dusk we were again landed at our camping ground. 1 had heard of sportsmen in England who walked a whole day, and after firing a pound of powder returned in great glee bringing one partridge ; and I could not help won- dering Avhat they would think of the spoil we were bearing from Swan Lake." His picture of the Mississippi in flood is wonderfully im- pressive. "I have floated on the Mississippi and Ohio when thus swollen, and have in different places visited the submerged lands of the interior, propelling a light canoe by the aid of a paddle. In this manner I have traversed immense portions of the country overflowed by the waters of these rivers, and particularly whilst floating over the iMississippi bottom lairds I have been struck with awe at the sight. Little or no current is met with, unless when the canoe passes over the bed of a bayou. All is silent and melancholy, unless when the mourn- ful bleating of the hemmed-in deer reaches your ear, or the dismal scream of an eagle or a heron is heard, or the foul bird rises, disturbed by your approach, from the carcass on which it was allaying its craving appetite. Bears, cougars, lynxes, and all other quadrupeds that can ascend the trees, are ob- served crouched among their top branches; hungry in the midst of abundance, although they see floating around them the animals on which they usually prey. They dare not ven- ture to swim to them. Fatigued by the exertions which they have made in reaching dry land, they will there stand the hunter's fire, as if to die by a ball were better than to perish amid the waste of waters. On occasions like this, all these animals are shot by hundreds." In his journeys Audubon fell in with many interesting characters. One of these was the naturalist Rafinesque. Dur- ing Audubon's residence in Kentucky, Rafinesque visited him, presenting a letter of introduction in which he was described as an "odd fish" as yet undescribed in published works. Audubon's innocent inquiry as to where the *'odd fish" was, led to much amusement and a cordial entente Early Naturalists 29 between the two. "His attire," writes Audubon, "struek me as exceedingly remarkable. A long loose coat of yellow nan- keen, much the worse for the many rubs it had got in its time, and stained all over with the juice of plants, hung loosely about him like a sack. A waistcoat of the same, with enormous pockets, and buttoned up to the chin, reached below over a pair of tight pantaloons, the h)wer parts of which were buttoned down to tlie ankles. His beard was as long as I have known my own to be during some of my peregrinations, and his lank black hair hung loosely over his shoul- ders. His forehead was so broad and prominent that any tyro in phrenology would instantly have pronounced it the residence of a mind of strong powers. His words impressed an assurance of rigid truth, and as he directed the con- versation to the study of the natu- ral sciences, I listened to him with great delight. He requested to see my draAvings, anxious to see the plants I had introduced besides the birds I had drawn. Finding a strange plant among my drawings, he denied its authenticity ; but on my assuring him that it grew in the neighborhood, he insisted on going off instantly to see it. "When I pointed it out the naturalist lost all command over his feelings, and behaved like a maniac in expressing his delight. He plucked the plants one after another, danced, hugged me in his arms, and exultingly told me he had got, not merely a new species, but a new genus. "He immediately took notes of all the needful particulars of the plant in a note-book, which he carried wrapt in a water- proof covering. After a day's pursuit of natural history studies, the stranger was accommodated with a bed in an attic room. We had all retired to rest ; every person I imagined was in deep slumber save myself, when of a sudden I heard a great uproar in the naturalist's room. I got up, reached the place in a few moments, and opened the door; when, to my astonishment, I saw my guest running naked, holding the handle of my favorite violin, the body of which he had bat- tered to pieces against the walls in attempting to kill the bats which had entered by the open window, probably attracted by the insects flying around his candle. I stood amazed, but he Eafinesque From Popular Science Monthly. Copy furnished hy Conrad Lantern Chicago. Slide Company, 30 Biology in A))irrira contiiuu'd ,jmni)ing and riiniiiiix|)edi1ioii they collected voluminous scientific data dealing in ])art with the natural history of the region trav- ersed. It is worth while at this point to glance for a moment at the scientific work of that remarkably versatile man, Thomas Jelferson, a man Avho in many respects was the i)rototype of that other statesman-naturalist who has so recently de- l)arted from iis. Jefferson's interests were very broad. Astronomer, ])hysicist, engineer, anatomist, geologist, zoolo- gist, botanist, palaioutologist, litterateur, educator, lawyer, Early Naturalists 33 farmer, economist and statesman, he indeed was a man of far vision and high achievement, dreamer of dreams and doer of deeds. Writing in the "Magazine of American History" for April, 1885, Mr. Frederic N. Luther says of him : ... In Febrnaiy, 1801, when Congress was vainly trying to untangle the difficulties arising from the tie vote between Jefferson and Burr, when every politician at the capital was busy with schemes and counter-schemes, this man, whose political fate was balanced on a razor's edge, was corresponding with Dr. Wistar in regard to some bones of the mastodon which he had just procured from Shawangunk, Ulster County. Again in 1808, when the excitement over the embargo was highest, when every day brought fresh denuncia- tions of him and his policy, he was carrying on his pahTonto- logical studies in the rooms of the White House itself. . . . Never for a moment, however apparently absorbed in other work, did he lose his warm sympathy with nature." It is amusing to read on the other hand the tribute which his studies called forth from Bryant, then thirteen years old. "Go, wretch, resign the Presidential chair, Disclose thy secret measures, foul or fair. Go, search with curious eyes for horned frogs, 'Mid the wild wastes of Louisianian bogs ; Or, where the Ohio rolls his turbid stream. Dig for huge bones, thy glory and thy theme." One of Jefferson's scientific contemporaries was Buffon, the French evolutionist. Buffon had an idea that the animals of the new world are smaller than their near relatives in the old, and that domesticated types are degenerating in the former as compared with the same types in the latter. These conten- tions were refuted by Jefferson, who exported to Paris speci- mens of several of our large animals as evidence of his contentions. As a result Buffon wrote to Jefferson, "I should have consulted you, Sir, before publishing my 'Natural His- tory,' and then I should have been sure of my facts." Jefferson was one of our pioneer plant importers. While minister to Paris he sent to America large numbers of seeds and plants of various sorts. Most of these were failures, among them the olive, the cork oak and the caper. With rice however he was more successful. Noting the gi-eat demand for this cereal during Lent in France, and noting further the small importations of American as compared with Italian rice, he set about discovering the reason, and soon a.scertained that it was due to the superior quality of the latter grain. In those days importation of plants from one country to 34 Biology in America another was (liffifult, owinj; to the selfish Jack Horner policy of keopiiifi: all the ])liiins at home. Jefferson however visited Italy and carrie\>. Sd-S, l)y jicr- mission of the Maemillan Company. 38 Biology in America While these surveys were primarily topographical and geological in purpose, they were usually accompanied by naturalists, whose duty it was to investigate and report upon the wild life, both plant and animal, of the region visited, and to them much of our knowledge of the natural history of the United States is due. Of prime importance in the work of these naturalists were the discoveries of the paliEontologists. The western plains and mountains constitute a veritable storehouse of buried treasure, and the pick and shovel of the paUeontologist un- covered here a large part of the material for writing the history of ancient life. These were days too when it was lint impossible for one man to cover an extensive field of science. Tlius we find the elder Agassiz equally famed as a geologist and zoologist, and Dana, the noted geologist, i)ro- tVssor at Yale from 1850 to 1890, writing a monumental work on the Z()oi)hytes and Crustacea of the Wilkes Exploring Expedition ; Cope, master not onl}' of vertebrate palaeontology but of modern fishes, am])hibia and reptiles as well, and Lcidy, botanist, mineralogist, geolo- gist, paleontologist, parasitologist, protozoologist and comparative anatomist. A notable event in American science was the advent of Louis Agassiz in 1846. Born in 1807 at the little town of Motiers in Switzerland, the son of a clergyman, he early displayed that love of natural history, which made him famous. Champion fencer and jolly comrade, as well as gifted student, his uni- versity days at Zurich, Heidelberg and Munich found him a leader among his fellows and his room in Munich dubbed by them "The Little Academy." His scientific work early attracted the attention of Humboldt and Cuvier, who gave him all possible assistance in his career. While professor of natural history in the University of Neuchatel, Agassiz gained world wide fame by his studies in zoology, palaeon- tology, and especially on the glaciers of the Alps. In 1846 he came to America, where he remained until his death in 1873. During most of this time he was professor of natural history at Harvard, where he gathered about him a group of men and Louis Agassiz From Popular Science Moiitlily Copy furnished ty Con/rod Lantern Slide Company, Cliicago. Early Naturalists 39 sent them forth to become leaders of biology in America. Indeed, it was as teacher, rather than as investigator, that Agassiz's influence was most widely felt. Possessed of a compelling personality, remarkable diction and inspiring enthusiasm, he left an impress upon biology in this country that can never be effaced. He was the founder of the Museum of Comparative Zoology of Harvard University, while his summer school at Penikese in 1873 was the forerunner of biological stations in America. A disciple of Cuvier, he was ever an ardent champion of his views and an opponent, albeit a warm personal friend of Darwin. Pupil of Agassiz at Neuchatel, and later his co-worker in America, was Girard, who prepared the report on the reptiles of the Wilkes expedition. Girard was better known, however, for his work on flslies, in the course of which he studied much of the material collected by the U. S. Surveys. While exploring naturalists were busy gathering the un- known fruits of our virgin fields and forests, their colleagues in the dim and dusty rooms of museum and college were no less busy in making known the results of their harvests. Dr. Joseph Leidy, a Philadelphia physician, professor of anatomy at the University of Pennsylvania and later professor of natural history at Swarthmore College, was one of the most noted of these early college and museum men. He is a striking example of the "all around" naturalist of the early days, his writings embracing a wealth of subjects of both extinct and living animals, and ranging from the unicellular animals to man. Of his notable works one of the earliest was his account of the fossils from the "bad lands" of Nebraska, collected by one of the surveys of the then (1850) Northwest Territory, conducted by the geologist, David Day Owen, under the direction of the U. S. Treasury Department. Colleagues of Leidy in the study of the fossils brought back from the West by the government surveys, and by exploring parties sent out by museums and colleges, were two men whose names stand in the front rank of our palaeontologists — Othniel Charles Marsh and Edward Drinker Cope. As professor of palaeontology at Yale, Marsh inaugurated in 1870 a series of scientific expeditions into the Western States, the results of which were the splendid collections of vertebrate fossils of Yale and the U. S. National Museum, and the stores of information about the pre-historic life of our con- tinent which Marsh gave to the world and which soon made him famous. His earlier expeditions were undertaken and largely supported by himself, but after the organization of the U. S. Geological Survey in 1879, he became connected with it 40 Biology in America as pala?ontologist and thereafter worked under its auspices. His expeditions took him into the western plains country and the Rocky ^louiitains, where lie discovered the reinarkalile birds witli teeth, lles})erornis and Iclitliyornis, and a host of dinosaurs, the lizard-like reptiles, many of them giants of the animal world, whose bones have been unearthed in such numliers on our western plains, and are now reposing in so many museums both here and abroad, and whose biographies fill so many ponderous volumes on the shelves of our libraries. Here too he collected a series of skeletons of fossil horses which has fnrnislied one of tlie strongest evidences for evolu- tion knuwji, and which served to recast the views regarding the descent of the horse which were current at that time. In 1876 when Huxley visited America, he spent a week with Mai'sh inspecting his collections of fossils at Yale. Huxley was at this time preparing to deliver a lectui'e in New York on the evolution of the horse, and as a result of his study of the Yale collections this lecture was largely rewritten. When ]\Iarsh had brought out box after box of specimens to illustrate various points in their discussion, Huxley finally turned to him and said, "I believe you are a magician; whatever I want, you conjure it up." As a further result of this conference Huxley predicted the discovery of the then unknown five-toed ancestor of the horse, and sure enough, less than two months later Professor Marsh ' ' dug up ' ' the renowned Eohippus in the Eocene strata of the West. Cope, one of the most indefatigable, brilliant and versatile of American biologists, was born and died in Philadelphia. When a young man he served as professor of natural science in Haverford College, later becoming connected with the government surveys of the territories under AVheeler and Hayden. For several years he was curator of the Academy of Natural Sciences of Philadelphia, and finally professor of geology in the University of Pennsylvania. In the literature of modern fishes, and especially of reptiles and amphibians, Cope's work will ever be classic, but it was chiefly in the field of vertebrate palaeontology that he became famous. As a member of government surveys and the Philadelphia Academy his work on the fossil vertebi-ates of the AVest was both able and voluminous, and contributed largely not aloiie to his own fame, but to that of the institutions which he represented. As illustrative of American idealism, a trait for which our people have not hitherto received due credit, it is both pleasant and stimulating to think of Cope on his deathbed putting the finishing touches on his report upon Above, James D wight Dana Above, Joseph Leidy Below, Edward Drinker Cope Below, Othniel Charles Marsh Cuurtt'sy oj Dr. Qeo. P. Merrill. 41 42 Biology in America the fossils of the Port Kennedy cave, then recently discovered on the Schuylkill River near Philadelphia. But if the labors of Leidy and his colleagues were actuated by high-spirited and idealistic love of science, they were none the more free from the comedy of petty selfishness. Ever eager to forestall the others in the announcement of their "finds" they occasional!}^ made ludicrous mistakes through their haste in publication. On one occasion Cope got hold of some bones of an ancient reptile from Kansas. The ani- mal's head was missing and certain other bones which are usually included in the skeleton of any orthodox beast, but Cope in his enthusiasm, and apparently in a state of headless- ness resembling his subject, described them under the dignified title of Elasmosaurus platyurus. But Leidy, ever keen to detect a slip on the part of an opponent, made a more care- ful examination of the defunct and announced an error in the epitaph which Cope had written, as the remains belonged to a different creature altogether, namely Enaliosaurus, Cope's mistake being due to having reversed the animal end for end, and imagined a head where the tail rightfully be- longed. In his early recollections of Leidy, Marsh and Cope, Osborn says that "whereas in Leidy we had a man of the temper of an exact observer, Cope was a man who loved speculation; if Leidy was the natural successor of Cuvier, Cope was the follower of Lamarck, a man of remarkable inventive genius. . . . Marsh . . . was a comparative anatomist of a high order, and had a genius for appreciating what might be called the most important thing in science. He always knew where to explore, where to seek the transition stages, and he never lost the opportunity to point out at the earliest possible mo- ment the most significant fact to be discovered and dissemi- nated. . . . "I had the pleasure of knowing Leidy slightly and of a long personal ac(|uaintanee with Marsh ; I knew Cope very intimately. . . . On one memorable occasion when I visited his house he pulled out a drawer of his black walnut work- table, where he always sat and wrote his papers, and brought out a packet carefully done up in paper and twine, saying, 'Osborn, here are some records that you have never seen before.' I said, 'Well, what are they?' He replied, 'These are my ]\Iarshiana, here is everything relating to the mistakes which that man Marsh has made; and when the time comes, Osborn, I am going to launch this on the world.' Well, he did ; the bombshell was exploded in due time, and this great mass of information regarding the supposed incapacity of Marsh was spread on the pages of the "New York Herald" in Early Naturalists 43 one of its Sunday issues. The very next Sunday, however, Marsh, who, it appears, had likewise been accumulating a private stock of Copeiana, proved with equal success that Cope's life was one long string of errors from first to last. "Heredity makes strange bedfellows. It is only by the most extraordinary combination of personal characteristics that we find among scientific men of the greatest capacity, such strange mixtures of personal qualities side by side with genius." ^ Possibly it was some of these early rivalries which prompted Bret Harte 's classic little gem of comedy, ' ' The Society upon the Stanislow." A pathetic figure among the makers of American science is Lesquereux, the Swiss botanist, and associate of Louis Agassiz, He was born in the province of Nenchatel, Switzerland, in 1806, emigrating to America in 1848. His interest was at first in living plants, but he later devoted himself almost entirely to a study of fossil forms. After coming to America he was connected with several state surveys, and later with the terri- torial surveys under Hayden. His work on the coal forming plants of Pennsylvania, Ohio, Illinois, and Arkansas served chiefly to make his reputation. He worked nnder peculiar disadvantages, being but a poor master of English, and becom- ^^^ Gray ing deaf at an early age. He once From Popular Science Monthly. said of himself, "My deafness cut copy furnished by Oonrad me off from everything that lay cMca'^o ^^^^ company. outside of science. I have lived with nature, the rocks, the trees, the flowers. They know me. I know them. All outside are dead to me. ' ' ® It is in connection with these early surveys that we first meet with the names of many men famous in the annals of American science, who are still living, or have but recently passed away — Jordan, the ichthyologist, and more recently the philosopher and apostle of pacifism, Coulter, the botanist, Gilbert, the ichthyologist, Scudder, the entomologist, Coues, the ornithologist, and Asa Gray, premier botanist of America, and author of the well-known manual of American plants. '"' Proceedings of the Academy of Natural Sciences," 1912, p. xxxiv. •Locus citatua. 44 Biology in Ayncrica Here too Ave meet with Sir Josepli Hooker, director of the Kew Gardens, Eiifjlaiid. l^arwiu's elder brother in science, and the man wlio, with I^yell, Ihe freolo" Journal of the Pilgrims of Pljonouth," 1620, pp. 44-46. Biological Institutions 49 ward Room, on a great Fire, the Juices forced out at the End of short Billets of Wood, by the Heat of the Flame, on which they were laid, yett froze into Ice, at their coming out. This Extremity of the Cold caused mee to desist from the purpose, which I was upon; because I saw it impossible to serve the Lord, without such Distraction as was inconvenient. < ( I (January 11, 1719-20) Tis dreadful cold. My Ink-glass in my Standish is froze & splitt, in my very stove. My Ink in my very pen suffers a congelation : but my witt much more. "... "Sabbath, Jan. 24, 1686, Friday night and Satterday were extream cold, so that the Harbour frozen up, and to the Castle. This day so cold that the' Sacramental Bread is frozen pretty hard, and rattled sadly as broken into the plates. — Samuel Sewall. "Lord's Day, Jan. 15, 1715-6. An Extraordinary Cold Storm of Wind and Snow. Blows much worse as coming home at Noon, and so holds on. Bread was frozen at the Lord 's Table. . . . Though twas so Cold, yet John Tuckerman was baptised. At six a-clock my ink freezes so that I can hardly write by a good fire in my Wive 's Chamber. Yet was very comfortable at Meeting. Laus Deo. — Samuel Sewall. ' ' ^ Such was the cradle of higher education in America. In 1636 the Colony Court "agreed to give £400 towards a schoole or collidge," which in 1637 was located at Cambridge and later received its name from its first patron, the Rev. John Harvard, who died in Charlestown in 1638, leaving one half of his estate (about £800) and his library to the infant college. The first of the buildings erected was known as "The Indian Collidge" with rooms for twenty youthful savages, several of whom attended, but only one of whom graduated from it. History repeats itself in the case of many of the "youthful savages" within its walls today. Here the first college text-books were printed, including the Apostle Eliot's translation of the Bible into the Indian language, primers, grammars, tracts, etc. It is possible that the missionary spirit of the founders of the college was not a wholly disinterested one, since many of its funds were obtained abroad for the express purpose of converting the heathen; or in more materialistic terms, making a bad Christian out of a good savage. Harvard College was followed by William and Maiy's College (1692), Yale (1700), Princeton (1746), the University 'Hanscom, "The Heart of the Puritan," pp. 29-30, 210. By permis- sion of the Macmillan Company, 50 Biology in America of Pennsylvania (1749), and King's College (now Columbia University) in 1754. These early colleges and their succes- sors, prior to the early part of the last century, were sup- ported mainly by private funds, given largely in the form of endowments; but since 1837, when the University of Michigan Avas founded, most of the states maintain universities at public expense. The private institutions have been, almost exclu- sively supported by religious societies, even some of the great universities, which today are non-sectarian, such as Harvard, Yale and Princeton, having been originally established on a religious basis. The early instruction in our colleges and universities was strictl}'^ classical. The appointment of Benjamin Silliman as professor of chemistry and natural science at Yale in 1802, therefore marks an epoch in the history of American educa- tion. It is interesting to note that the young professor, at the time of his appointment but twenty-three years of age, was a lawyer by profession, with no knowledge whatever of the sciences he was to teach. He says of his appointment that it ''was of course the cause of wonder to all, and of cavil to political enemies of the college. Although I persevered in my legal studies ... I soon after the confidential communi- cation of President Dwight (informing him of his probable appointment) obtained a few books on chemistry and kept them secluded in my secretary, occasionally reading in them privately. This reading did not profit me much. Some gen- eral principles were intelligible, but it became at once obvious to me that to see and perform experiments and to become familiar with many substances was indispensable to any progress in chemistry, and of course I must resort to Phila- delphia, which presented more advantage to science than any other place in our country." ^ As Yale was the pioneer in breaking away from "the tra- ditions of the elders," and establishing a professorship in science, so too was it the pioneer in establishing soon after- ward (1824) a distinct organization or school, the Sheffield Scientific School, for scientific instruction. In 1847 a similar organization (the Lawrence Scientific School) was established at Harvard, and soon the teaching of science in American colleges and universities was placed on an equal footing with that of art and letters. At the present time indeed science, tried alike in the fires of war and the sunshine of peace, stands preeminent, both in education and in industry. Biology in American schools owes its birth primarily to Agassiz and Gray, colleagues on the Harvard faculty at the ' Merrill, * ' Contributions to the History of American Geology, ' ' after G. P. Fisher, "Life of B. Silliman," p. 215. Biological Institutions 51 middle of the last century. After the impelling influence of these two great teachers, it has made a lusty growth. In early days the college professor was supposed to be as many sided as the country "school marm" of the present day and genera- tion. No man was sufficiently well educated to occupy a professor's chair unless he was an authority in at least two major sciences, while the idea of a professor confining liis attention to a single branch of one of these sciences was unheard of. Today all our great universities have two en- tirely separate departments of l^iology (botany and zoology) each with a staff of from five to ten or more members, each one of whom has in charge his own particular branch of the subject. To appreciate the multiplicity of modern science one need but turn to any recent program of a scientific society where the papers are arranged by subjects. Thus at the 1921 meeting of the American Society of Zoologists there were papers presented in the following branches of zoology : embry- ology, cytology, parasitology^ evolution, genetics, ecology, dis- tribution, general physiology, and comparative anatomy. The average college catalog contains such a "feast of fat things" as to impair the digestion of even the most voracious of stu- dent "sharks." But with the passing of the "good old days" when every college "prof" was supposed to be a "walking encyclopedia" has come a far more exacting age for teacher and investigator alike, for modern standards of success demand of both a far more encyclopedic knowledge of science, than was expected of their forbears. The inter-relations of the many branches of science, and their intimate dependence one upon the other,, demands a much more extensive, and withal exact knowledge of their subject on the part of biologists today, than was needed in the past. Especially is this true in the field of experimental biology, which has made such remarkable strides in the last two decades, and which employs as its handmaidens its sister sciences of chemistry and physics. Today indeed chemistiy and biology are united in the new science of bio- chemistry, one which, for possibility of discovery of the most elusive secrets of nature, gives more promise than any other field of scientific quest and conquest. With this ever increasing specialization and complexity of biology (and the same is no less true of other sciences) have come ever increasing demands for equipment on the means of our higher institutions of learning. Time was when the biological laboratory was considered equipped if it possessed a few old microscopes, hand lenses and dissecting instruments, a little glassware, a few chemicals and some pickled caricatures of things which were once alive. Today the work shop and 52 Biology in America class room of the well equipped biologist contains not only the most modern microscopes (the instrument par excellence of biological research) but microtomes for cutting sections of microscopic material down to a twenty-five thousandth of an inch in thickness; electrically controlled incubators, where cultures of microscopic organisms and growing tissues can be held within one degree F. of any desired temperature; electrically driven centrifuges running at speeds of from three to four tliousand revolutions per minute; projection appa- ratus for projecting pictures, microscopic preparations, and even living animals themselves upon the demonstration screen, or drawing board ; apparatus for taking photographs of these preparations at magnifications of from one to two thousand diameters; delicate balances for weighing down to a twenty- five thousandth of an ounce or less, and hot houses and aquaria where living material for study may be always avail- able. Such is some of the more common apparatus of the biolog- ical laboratory. In laboratories devoted exclusively or pri- marily to research, such as those at Woods Hole, Cold Spring Harbor and elsewhere, reference to which will be made below, apparatus of a special, and often costly type is usually found in addition to the more common equipment outlined above. The biological laboratory of college or university is not however a separate institution especially devoted to biology, but merely a part of a larger institution dedicated to the dis- semination and advance of all knowledge. Yet it is through this channel that the greatest contributions to biology have thus far come. In considering biological institutions however we are primarily interested in those devoted exclusively to this science, including our museums, government and endowed laboratories, and others of similar character. The early history of biology in America was as we have seen closely associated with the museums. From their mem- bers in many instances went forth the collectors who accom- panied the early explorers into virgin forests, across trackless prairies and through the wild defiles of mountain fastnesses. And it was to the museums that these collectors returned to study and describe the treasures whicli they had found. Numerous as are the splendid natural history museums in America, space limits us to a brief consideration of but three, as typical of the achievements of American science in this field. Of our larger museums, especially those devoted primarily to natural history, the earliest established was the Academy of Natural Sciences in Philadelphia. The dawn of the year 1812 was darkened by the cloud of war which hung low over America, The one amusement house in Philadelphia, Biological Institutions 53 the old Walnut Street Theatre, was seldom open, and the city's youth were wont to gather in tavern and oyster house to discuss the momentous events of the times. Under circum- stances such as these a few young men who were interested in natural history met at the home of one of their number on January 25, 1812, for the organization of a society whose pur- pose, according to the minutes of the meeting, should be "the rational disposition of otherwise leisure moments." Their collections at this time comprised "a few insects, corals and The Acadkmy of Natural Sciences of Philadelphia, 1912 From the Academy "Proceedings." shells, a dried toad fish, and a stuffed monkey." From this primitive beginning has come the great institution which has contributed, perhaps more than any other factor, to making Philadelphia one of the homes, as it was the birthplace of American biology. In the early years of the last century Philadelphia was the Mecca of American biologists. From here Alexander Wilson started on his ornithological travels. Hither came Audubon, seeking support for the "Birds of America," and through the generosity of Edward Harris, a Philadelphian, he was enabled to nud^e his journey up the Missouri River. Lucien Bonaparte, who continued the work of AVilson, after the latter 's death, was for' a time resident at 54 Biology in America Philadelphia. The early naturalist explorers, Say, Nuttall and Townsend, were associated with the Academy at Phila- delphia, two of whose members accompanied the famous Wilkes Expedition to the Antarctic. The Academy was as- sociated also with the early Arctic expeditions under Kane and Hayes, while Peary's Greenland expedition of 1891 was conducted under its auspices. Many are the names famous in the annals of American biology which have been associated with the Academy of Natural Sciences, Leidy, Cope, Cassin, Bachman, Le Sueur, Gill, Osborn and a host of others. The collections of the Academy, descendants of the stuffed monkey and the dried toad of its founders, have grown to occupy the first rank among biological exhibits in America. While they are surpassed in size and display by those of the American Museum of Natural History and the tj. S. National 4'm^imM^ The American Museum of Natural History in New York Courtesy of the Museum. Museum, for reference purposes along certain lines they are second to none in the world. Its library too is one of the best in America in biology, ' especially in the works of the early writers. Pioneer among American museums the Academy of Natural Sciences of Philadelphia has blazed many a trail for biologists into the unknown. It would indeed be difficult to assign a premier place to any one museum of natural history in America, but were one to undertake such a thankless task, his choice would be likely to fall on the American Museum of Natural History in New York City, which in breadth of purpose, in the extent and value of its collections, and in its scientific achievements is second to none in this country. Founded in 1869 it now occupies a $4,000,000 structure in Central Park, which was built and is maintained by the city, while the expense, of the collections and investigations is provided for by an endow- ment, by dues of members and by private contributions. Biological Institutions 55 Truly may it be said of the American Museum that its "lines have gone forth throughout all the earth, and its (men) to the ends of the world." From frigid pole and torrid equator, from rain-soaked forest and from sun-baked desert, from Andean height and Amazonian jungle have come the treasures, which constitute today one of the finest exhibits of natural history in the world. To attempt any adequate ac- count of the Museum and its work in this place would be out of the question, but brief mention may be made of a few of its more important features. The progress of American palaeontology, outlined in another chapter is largely due to the Museum, and its splendid col- The Blue Shark with School op Young Photograph of a group in the American Museum of Natural History in New York. Courtesy of the Museum. lection of fossil vertebrates bears witness to the story of the past, which its investigations have revealed. Until comparatively recent years we have been accustomed in our museums to display case after case and row upon row of more or less indifferently stuffed specimens, with jar after jar of ''pickled" snakes and turtles and case upon case of pinned butterflies and' moths. But no hint was there of the activities and home of the living thing. Today our best museums, largely under the inspiration of the American Museum, are exhibiting groups of birds and mammals, rep- tiles, fish and other forms, illustrating their homes and lives in Nature's setting. Here one finds for example the duck hawks, with their nest and young perched among the rocks The Home of the Ducit Hawk in the Hudson Palisades l^hotoyrapli of :i gioup in the Aineiican Museum of Natural History in New Voik. Conrtcxii of ihc Munvum. A Florida Swamp Photogra})!! of a reptile group in the American Museum of Natural History in New York. Courtesy of the Museum. 56 Biological Institutions 57 of the Palisades, with their great walls painted in the back- ground and the lovely Hudson flowing at their base. There is the reedy border of a lake from central Oregon filled with the wild fowl and their nests. Another exhibit shows a bit of a Florida cypress swamp, with alligators of various ages and the mother guarding the nest in which the young are hatching from the eggs. Here too are shown many species of snakes, and amphibians, all modeled in wax and colored from living specimens. Yet another group illustrates the blue shark with a school of young among the sargassum weed of the Gulf Stream, while still another displays an oak tree in leaf with its branches covered by hosts of the beautiful monarch butterfly as it appears when migrating. A unique feature in the Museum's exhibit is Darwin Hall The Game of the ' * Men of the Old Stone Age ' ' The woolly rhinoceros, with the saiga antelope and mammoth in the distance. Copyrighted ty the American Museum of Natural History. wherein are displayed groups of invertebrate animals illus- trating the evolution of this portion of the animal kingdom from the Protozoa to the ascidians. Among the former are models of disease producing types such as the organisms causing malaria and the deadly African sleeping sickness. Here too are wax and glass models of the Malaria mosquito, reproducing with wonderful delicacy even such minute parts as the bristles on its body. The work of man in molding the form of animals to his will is illustrated by cases of pigeons and other domestic animals, while the results of modern research in heredity are shown among other ways in the offspring of a pair of rats, and in a demonstration of the inheritance of color in the four o'clock. In the Hall of the Age of Man is depicted by painting and model the story of the "Men of the Old Stone Age" as they lived in their cavern homes and hunted with implements of Monarch Butterflies Photofjraiili of a group in the American Museum of Natural History in New York. Courtesy ^0} the Museum. 58 Biological Institutions 59 flint the woolly rhinoceros, the mammoth, mastodon and royal bison, which roamed the world when the glaciers held much of the northern hemisphere within their grasp. But the mere exhibition of nature 's wonders is by no means the only, or even the primary function of the American Museum. The discovery of her workings and her secrets is fundamental to their demonstration in its halls. And so with the gathering of material for its exhibits has gone hand in hand the gathering and publication of information relative thereto, much of which is rehearsed in other chapters of this book. The spread of knowledge through research, publica- tion and exhibition is the comprehensive function of every museum. As further illustration of this function is the work of the public health department of the Museum, whose pur- pose can best be stated in the words of its curator. Its plan is to "present a fairly comprehensive picture of the life of man as an animal, his place in the general scheme of natural history, his relations to his geographical and meteorological surroundings, the parasites which cause his diseases, and the animals and plants which serve him for food and clothing. The plan . . . giving a survey of the cycle of human life, its dangers and its safeguards, complete enough to satisfy the curiosity of the ordinary man and to teach him what he needs to know in order to keep sound and well, is an extensive one. ..." In partial fulfilment of this plan the department has installed exhibits of the disposal of sewage and garbage, the water supply of cities, its relation to rainfall and the ways of safeguarding it from pollution; the composition of water and the microscopic organisms which it contains. Some of the exhibits in this department are a series of models of different sorts of bacteria, models of insect carriers of disease, the flea, louse, yellow fever mosquito and the house- fly. The mosquito exhibit shows among other things the condition of the French hospitals in Panama, as compared with those installed by the Americans, the life history of mosquitoes and methods of combating them by oiling, drain- age, fumigation, etc. The department also maintains a grow- ing collection of living bacteria including hundreds of different varieties, from which were sent out in 1918 over 3,000 cultures free of charge to laboratories throughout the country. During the Great War the Museum aided in the food con- servation movement by the preparation of a food exhibit illustrating the character of food, its use in human metabolism, the adjustment of the daily ration to meet the increasing cost of living, and showing some new and as yet little used sources of food, such as seaweeds, snails, mussels, cuttle fish, etc. 60 Biology in Ama'ica Sueli in brief arc a few of the activities of this splendid institution. One of tlie best additions to the architecture of the new "Washington is tlie buildin. Frecpiently these cells bear cilia and are motile, while the ordinary form is non-motile. In some cases a slight difference in size between the conjugating gametes is suggestive of the differentiation between egg and sperm cell of higher forms. * These figures are given by Morgan in "Heredity and Sex." He disclaims responsibility however for tho mathematical computation in- volved. ' There may be one or two of these latter. Descriptive Biology 97 A still further stage in sex development is shown by a distinct difference in size and activity of the copulating cells. The malaria organism multiplies asexually in the blood cells of its host. After a time, under conditions not well under- stood, some of the malarial cells enlarge. If now the patient is bitten by one of the Anopheles mosquitoes, which transmit the disease, some of these enlarged cells remain quiescent, forming the female cells in the mosquito's stomach, while others cast off a number of small active filaments or male cells. These latter then unite with or fertilize the former, ;© «5' ©I Life Cycle of the Malarial Organism a, parasite in red blood corpuscle; b and c, spore formation; d, female, and e, male cells, which are uniting at f ; g, sporozoites in cyst; h, sporo- zoite free; i, ameboid parasite developed from h, prepared to enter red blood corpuscle, j. Original. and from their union a large number of minute motile cells or "sporozoites" are formed, by which the asexual cycle is repeated when the infected mosquito bites a new victim. Yet a further and final step in sex differentiation among the unicellular forms is found in Volvox, an organism which is on the fence, so to speak, between Protozoa and Protophyta ; and which forms a bone of contention between the botanists and zoologists, each claiming ownership to it. Volvox is a hollow spherical group of cells, numbering in some cases over 20,000, and reaching a diameter of 1/25 of an inch. The cells carry a pair of cilia each, by means of which the organism is 98 Biology in America au active swimmer. Tliey also contain elilorophyl, enabling it to manufacture its own food, so that physiologically it is a plant, but in respect to the possession of cilia, and a red eye spot which is sensitive to light, it resembles more nearly an animal. Its reproduction is partly asexual and partly sexual. In the former method, some cells multiply to form sec- ondary colonies, which lie in the cavity of the mother colony and tinally break tlirough its wall to form new colonies. In the latter, certain large cells lacking cilia are ditferentiated as eggs, while other cells divide to form a varying number of motile sperms. Fertilization results in the formation of a resting cell or "zygote," which after a period of inactivity develops into a new colony. In definiteness of form, close association of cells and espe- cially in the differentiation of sexual cells, Volvox stands as a stepping stone between the unicellular types with their typically asexual reproduction and the many-celled forms which typically reproduce by fertilization. In yet another respect does Volvox approach the higher types. Some species are hermaphroditic, producing both eggs and sperms in the same colony, while in others the two sexes are lodged in separate individuals. There are many other forms, both single-celled and colonial, which resemble animals in having flagella and eye-spots, and plants in possessing chlorophyl. Sometimes it is only the reproductive cells which have all of these features, the ordinary cells being typical alga^ with chlorophyl but neither flagella nor eye-spots. It is passible that the "monads," to which reference has already been made, have developed chlorophyl, giving rise to the plant kingdom, on the one hand ; and have assumed an ameboid form, pro- ducing the animal kingdom on the other. This is suggested by the occasional occurrence of flagellates which are either ameboid at all times, or may assume an ameboid form at certain times in their life cycle. Through the entire series of plants from the lowest to the highest runs a curious phenomenon known as alternation of generations, or the alternate succession of sexual and asexual methods of reproduction. How many of us stop to think when we pluck a violet or smell a rose that the flower was not made to delight our eye or nose, but has developed as a means for the perpetuation and increase of its kind? And how does the flower perform its function? Hidden away at its center, where but few of us ever see them, are the female organs or ovaries, bearing at their summits little processes known as styles, which end in small expansions, the stigmas. Surrounding the ovaries are a ring of delicate filaments, the stamens, each bearing at its tip a sack, the anther. In the Descriptive Biology 99 anther the pollen grains are formed, and these when ripe are scattered by the wind or carried by insects to another flower, where, lighting upon its stigmas, they germinate and send fine tubes down through the styles to reach the ovaries at their base. Through these tubes pass the male nuclei formed within the pollen grain, which unite with the female nuclei within the ovaries, the pollen tube representing the last remnant of the body of the sexual plant in lower forms. Similarly there are contained within the ovary, beside the r Eeproduction of Plants Left: A phlox blossom showing flower parts. Ca, calyx; eo, corolla; sta, stamens; sti, stigma; sty, style. Original. Right: Alternation of generations in 1, fern, showing the sexual form or prothallus bearing the asexual fern, fe; and 2, moss, showing the spore capsule, c. female nucleus, several nuclei, which represent the body of the female sexual plant in mosses or in ferns. The moss plant is the sexual form, which bears the egg and sperm producing organs. From the egg, after fertilization in the ovary springs a slender stalk bearing a capsule at its summit. When this is ripe it bursts, casting forth the tiny spores, which generating give rise in turn to the sexual moss plant. Similar conditions obtain in the liverworts. In these forms therefore the gametjophyte or sexual plant is the chief generation, the sporophyte or asexual form the smaller, secondary one. In ferns the reverse is the ease. If one examine the under- 100 Biology in America side of an ordinary fern leaf he will find its edges? pimpled with rows of little brown capsules somewhat smaller than a pin head, which on bursting scatter to the wind a fine brown dust. This consists of the spores, which after germination produce a leaf-like body, the prothalhis, about a quarter of an inch in diameter. This is the gametophyte, which bears the sexual organs. It grows only in moist places, moisture being necessary for the transfer of the sperm to the (^^^. From the fertilized egg develops the sporophyte or ordinary fern plant, tlius completing the cycle in the life of the fern. Alternation of generations also occurs in some algffi. Here it is the gametophyte which is the conspicuous plant, the sporophyte being usually a smaller structure. Passing upward from the lower to the higher plants we see then the sporophyte progressively increasing and the gametophyte decreasing in importance. While alternation of generations is characteristic of plants it occure occasionally among the many-celled, as well as in unicellular animals. Many of the delicate and beautiful jelly- fish, with which any observant visitor to the seashore is familiar, are the sexual phase of the life cycle of an animal whose asexual form consists of an attached series of disks, which in the course of development separate from one another to form the sexual form or medusa. In certain marine worms (Polycha^ta) also alternation of generations occurs. The anterior part of the body does not develop sex organs, while posteriorly the worm divides into several part ;, whi.-h becom- ing sexually mature separate from the parent stock to form the sexual generation. In some of the curious "sea squirts" or tunicates also this process is found. The tunicates derive their name from the mantle or tunic surrounding the body. Some are fixed, and others free swim- ming as adults; while in the former the animal is frequently free-swimming as a larva. The name of "sea squirt" is derived from the habit of the fixed forms of squirting out a stream of sea water when touched. The larva of the fixed forms is totally different from the adult and the true relationships of the latter could not be understood were it not for the existence of the former. This is a tadpole-like animal with a long tail through which runs a supporting rod, the notochord. At the anterior end of the animal is an adhesive disk by means of which it attaches itself at the time of metamorphosis. The wall of the pharynx is perforated by a number of openings or gill slits which lead into a waste chamber or atrium opening to the exterior by a pore. Dorsal to the pharynx is a nervous mass or primitive brain, and between the two a small duct opening into the Descriptive Biology 101 former which is known as the ''sub-neural gland," and has been compared to the vertebrate hypophysis, which is part of the pituitary body or gland attached to the base of the brain, one of those problematic organs of "internal secretion" which is playing so large a i^art in medicine today. The larva swims actively by means of its long tail, but at metamor- phosis the latter is lost together M'ith its supporting rod or notoehord, and the animal abandons the wandering ways of youth and settles down to its future monotonous existence. In those tunicates in which an alternation of generations occurs, the asexual form gives rise by budding to a colony of "zooids" which more or less directly produce the sexual animals. The meaning of this strange and interesting life history remains for the future to disclose. Until we understand the underlying significance of sex, it is hopeless to attempt to solve the ri»fl^. ^ 1 1 Ti iTriimTOwrrnrn^ri T*: «?•.«"-. .■--in-a' w Stegosaurus From a restoration by Chas. E. Kniglit. Courtesy uj the American Museum of Natural History. Triceratops A former inhabitant of our western planes. From Lucas, "Animals of the Past. ' ' Courtesy o/ the U. S. National Museum. 128 The Story of the Bocks 129 arid plateaus which lie between the Mississippi River and the Rocky Mountains, were swarms of giant lizard-like reptiles known as mososaurs, whose remains have l)een unearthed by thousands in the chalk bluffs of western Kansas. While the mososaur was playing the role of Neptune in the Cretaceous sea, some of liis relatives took to flying and as pterodactyls or flying lizards competed Avith the first of the birds for the mastery of the air. The old classification of beasts that fly and beasts that swim and beasts that walk w^as about as logical as that of the small boy who divided people into men, women and college professors, for many different animals have aspired to fly and most of them Khamphorhynchus, a Winged Reptile From Ncumeyer after Zlttel. have met with eminent success. The success of the reptile at aviation was but short-lived however speaking in terms of biological time, for the pterodactyls soon joined their cousins the dinosaurs, the mososaurs and most of the other antique saurians, and sank to a watery, which later became a rocky, grave, to be resurrected after untold ages by the prying eye and patient pick of the paleontologist. The ptero- dactyls had wings of a thin skin or membrane stretched between fore and hind limbs somewhat like the wings of a bat. In the pterodactyls however only one of the fingers was lengthened as a support for the membrane. While the pterodactyls could not compete with the dino- saurs or mososaurs in respect to size, nevertheless one at least 130 Biology in America attained fairly respectable dimensions, Pteranodon having a winf? spread of twenty to twenty-tive feet. This creature with its long arms outstretched, a slender body and narrow neck, at the top of which was poised a long narrow head, about half of which was beak, might well have served as a model for some P^gyptian or Assyrian god or goddess. Rhampho- rhynchus, on the other hand, with his long tail, semi-human form and claw-like fingers, would have made a very good model for a winged Satan. AVhile the pterodactyls are not directly related to birds, they nevertheless show certain distinctly avian features, one of the most notable of which is the hollow bones. In birds air sacs extend from the lungs throughout the body even into the bones, while the lungs themselves are small, but richly supplied with blood vessels. These air sacs serve as reservoirs for air, somewhat after the manner of a rubber bulb on a pipette, serving to force strong currents in and out of the body through the lungs, and thereby gain efficient aeration for the blood ; which in birds is kept at a high temperature b}- the active oxidation which takes place in the body in correspond- ence with their great activity. Not only do these spaces in the bones serve as air reservoirs, but they also serve to lighten the bones, increasing their size, relative strength, and surface for attachment for muscles, without unduly increasing their weight ; just as the greatest strength in a pillar for a given amount of material is obtained by making the pillar hollow. AVhile we know very little about the lungs in the ptero- dactyls it is interesting to find precisely the same adaptation for lightness and strength of bone as we find in the birds. This suggests Lamarck's idea that use (flight) produces change (lightness of bone) in flying reptile as in flying bird. But let us not be too hasty in swallowing alluring hypotheses. We find to a certain extent the same air spaces in the bones of the crocodile, which has never had any aspirations for flying, Avhile the lizard, which is also in the main satisfied with a mundane existence, has small air spaces or reservoirs attached to its lungs. Thus we are driven to the conclusion that the pterodactyl and the bird have made use of their opportunities and have learned to fly because they "were built that way,'' while the opportunities for flight of the lizard and the crocodile are too small for them to use. But there are yet other j)oints of resemblance between bird and pterodactyl. In ])irds of flight the sternum or breast bone has a prominent ridge or keel like a boat, which has given them the title of Carinata? or keeled. This keel fur- nishes an additional surface for the attachment of the power- ful wing muscles. So too the pterodactyl had a keeled ster- The Story of the Rocks 131 num. The pterodactyl's skull is prolonged into a prominent beak like that of a bird, while in some instances its teeth are as scarce as those of the proverbial hen. Yet others pos- sessed numerous strong, sharp teeth lodged in sockets in the jaw. The cavity of the skull bears a great similarity to that of birds, while the sutures or lines of union of the skull bones, as in the bird, have largely disappeared. The zo- ologist believes this to be a case of "parallel evolution." The pterodactyl had dreams of becoming a bird, but never quite achieved his ambition. But if the attempt at aviation by the true rep- tile was short-lived, he yet produced the great- est aviators among ani- mals— the birds. In the famous Solen- hofen quarries in Ger- many there was discov- ered on August 15, 1861, the print of a single feather, and a few weeks later the impresdon of the bird itself was dis- covered. Archaeopteryx, the primitive or ancient bird, as his name signi- fies, was indeed primi- was distinctly for he wore a distinction Restoration of Arcii^opteryx From Lucas, ' ' Animals of the Past. ' ' Conriid Lantern Slide <'i)l>jl fuDiislieil hi/ CoiniHtity, Cltii-ayn. tive, but a bird, feathers, possessed by none of his reptilian ancestors that we now know. And yet the improbability of a bird hatching full-fledged out of a reptile's egg, as St. Ililaire suggested, is so unlikely, that we must assume many intermediate stages in avian development; stages, which Mother Earth has as yet declined to reveal. While Archas opteryx is a full-fledged bird so far as its feathers are concerned, it shows its reptilian parentage in several ways. The modern l)ird possesses only a few small vertebra in lieu of a fully formed tail, from which the tail feathers radiate fan-like; Archaopteryx however liad a long reptilian tail, with numerous vertebrae, and the feathers arranged in a row on either side. It still had a full set of teeth like the other early birds, Hesperornis and Ichthyornis, which were discovered by Professor Marsh in 1870 in the chalk beds of 132 Biology in America western Kansas, which were once at the bottom of the old Cre- taceous Sea. Traces of teeth still occur in the embryos of some birds of the j)resent, a heritage from some ancestor of the distant past. While Icthyornis still had teeth, it had pro- gressed much further along the path of avian development than Archffiopteryx in the structure of the hand. Nature in her experiments is prodigal in the production of variations, most of which she will never use in the development of new species ; but once she is on the track of a useful variation she becomes a strict conservationist and wastes no energy in the Hesperornis extinct diving bird with teeth, an inhabitant of the great Creta- sea wliif h once covered our Great Plains. From Lucas, ' ' Animals Au ceous of the Past. ' ' Courtesy of the U. -b'. yatiuiuil Museum. maintenance of useless parts. So in the hand of the modern bird and in Icthyornis as well, we find one of the fingers being greatly strengthened for the support of the wing feathers, and the others correspondingly reduced. The typical reptile has five fingers, which in the modern bird are reduced to one plus two rudiments, while Archa?opteryx had dropped only two of his digits and still remained in possession of the claws on his wings wliich the modern bird has dispensed with as entirely out of date. There is however one conservative member of the class who still retains a reminder of his rep- tilian past in the form of a claw at the angle of the wing, The Story of the Rocks ii^ Apteryx, or the kiwi of New Zealand, a country which in its fauna is a sort of old curiosity shop, retaining such relics of the past as the Port Jackson sliark, the tuatara, the kiwi and until recently the moas. Yet a further legacy from his reptilian ancestry did Archaiopteryx possess. This is a set of abdominal ribs, or rib-like bones in the ventral wall of the abdomen, which he shared in common with the New Zealand lizard and the crocodile. As to how birds took to flying we of course have no certain knowledge. But we have some very ingenious and interesting theories. In the first place what was the probable origin of the feathers? A feather consists of a central shaft or quill from which extend two rows of branches or barbs, and these Part of a Feather Showing shaft, barbs, barlniles and liooks. Original. in turn give rise to a series of little barbs or barbules which interlock with one another by means of rows of small hooks; the whole forming a firm resistant membrane serving as a propeller in the case of the wing feather, a rudder in that of the tail feathers, and a protective and insulating covering for the general body surface. At the base of the quill is a small papilla or projection of the dermis, or lower layer of the skin, which carries nerves and blood vessels and serves to nourish the growing feather. The feather itself arises as a tube of modified horny cells derived from the epidermis, or outer skin layer, whicli splits into several parts in develop- ment, which spread out to form the barbs and barbules. This 134 Biology in America applies to the ordinary or "contour" feather. The ''down" and "liair" feathers differ in development, although all have essentially the same structure. Hairs are also developed fundamentally in the same way as the feathers, with a dermal papilla, or core, at the base and a horny shaft, which however is solid and not hollow as in the feather. Both of these structures, being derived from the horny layer of the skin, are believed to be modifications of the horny reptilian scale, which in its turn probably owes its origin to the epidcniial layer or enamel of the placoid scale of the shark, from which also has evolved the enamel of the mammalian tooth. But to return to the original question of the origin of the birds. The theory of the Plungarian palaeontologist, Nopsca, supposes the bird to have arisen from a long-legged, long- tailed, short-armed running reptile, which as it ran flopped its arms to aid its motion, on somewhat the same principle that a man uses his arms in a race. If some of the scales along the posterior angle of the arm and along either side of the tail were to enlarge, they might readily aid the forerunner of the bird in its motion and by further enlargement and modification give rise to feathers, and the arm become a wing, and the reptile a bird. Another theory, advocated by Osborn, and more recently by Beebe, assumes an arboreal reptile as the ancestral bird. This creature is supposed to have been gifted with four wings instead of two and a long tail, which it used much as a flying squirrel uses its tail in sailing from tree to tree. AVitli loss of the hind pair of wings and strengthening and improvement of the front pair, the sailing reptile became a flying bird. In support of this theory Beebe adduces a veiy interesting fact. lie points out that in the newly hatched bird there is a row of quills running along the outer side of the leg, in such a position that, if developed, they would produce a miniature wing. And further, just as in the case of the "secondaries" (the smaller of the flight feathers in a bird's wing) there develops above these quills and alternating with them a second row of quills, which if developed would produce "covert" feathers. Similar tufts of feathers occurred in Archffiopteryx, which is strong evidence for Beebe 's theory, for as we have already seen, higher animals tend to repeat in an abbreviated way the structure of their ancestors. Yot others adopt a compromise theory and assume that while ArcluL'opteryx lived in trees, using his wings as well as his feet for grasping the branches, yet his flight was not merely a sailing one, but that the wings were actively used for this purpose. The Story of the Bocks 135 But whatever may have been the development of feathers and origin of tiight in birds we find in Archieopteryx one of the best "links" between two great groups anywhere to be found in the animal kingdom. While Archa3opteryx was smaller than a crow many of his extinct relatives maintained the reputation of their reptilian connections for size. Among these are the moas of New Zealand, which must have become extinct within the memory of man, for less than a century ago the Maoris firmly believed in their existence. Their largest representative was the giant moa, Dinornis maximus, which was at least ten feet high. Another giant of the bird world was ^pyornis of Madagascar, legends of which may have served as the basis for the roc in the tales of Sinbad the Sailor ; but this was equalled by Phoreracbis, the giant of the Patagonian pampas, who flour- ished in Miocene days, long before the advent of man, and who was seven or eight feet in height and had a skull larger than that of a horse. Another although smaller bird was the vulture, whose remains have recently been unearthed or rather untarred from the tar pits of Rancho La Brea near Los Angeles, Cal., whose spread of wing was probably greater than that of the great condor, which today circles about the Andean peaks of South America. And so for the present we may leave the extinct reptiles and their feathered kin, who in days of yore ruled earth and sea and sky. "For the wind passeth over it and it is gone and the place thereof shall know it no more." So passed these creatures of antiquity, to give place to races better fitted to cope with the new environments of the passing ages and the changing earth. Many if not all of them will in their turn go down in life's struggle before the advancing armies of future generations, these in turn giving place to others, until life itself shall be no more. The reptiles and the birds form one of the topmost branches of the vertebrate tree, while the mammals form the other. The latter, while less spectacular in their evolution than the former, are of even greater interest since man himself is one of them, and since they are the latest, and in many ways dominant group among the vertebrates of today. As in the case of all great groups of animals and plants the actual ancestor of the mammals is unknown. Nor is it certain whether they are the offspring of amphibian, reptile or some intermediate stock. Their first appearance was near the beginning of the Mesozoic era, when the reptilian dynasty was arising to rule the earth. The first of the mammals were small creatures and were probably the prey of the carnivorous reptiles, although they in turn may have been one cause of 136 Biology in America the extinction of many of the latter, by destroying their eggs with sharp gnawing teeth which well served them for this j)urpose. Although the origin of mainiuals is uncertain we find a possible source in a group of reptiles known as cynodonts from the dog-like character of their teeth, which occur in triassic rocks in South Africa. The skull in many respects resembles that of a mammal, while in othei^ it shows reptilian characters. But the cynodonts are found in the Trias, at the very be- ginning of the Mesozoic era, at a time when the great rep- tilian tree was but a slender sapling, while the "age of mam- mals" does not commence until the close of the Mesozoic era many millions of years later. What happened then to retard mammalian development during the a;ons of time in which ' ' great oceans waxed and waned and tiny hills to moun- tains grew"? It is possible that during all this time our an- cestors were living, like the Israelites of old, in bondage to the Pharaohs, who in this instance were represented by the car- nivorous reptiles; but when the "first born" of the reptiles were cut down and the reptilian stock smitten by the inex- orable hand of time, then the mammals arose, to take their "place in the sun" and become the "lords of creation." Or perchance the available food supply was not abundant at the time of their birth and thus their development was checked until a more favorable season. "Perhaps the most remarkable thing which the history of the Mesozoic brings forth is the immense period of evo- lutionary stagnation on the part of the mammals. They are first actually recorded in the Upper Triassic rocks of three rather remote localities. North Carolina, Germany, and South Africa, and are already differentiated in dietary habits. During the Mesozoic, they develop in numbers and to a cer- tain extent in tooth specialization. They do not, however, increase markedly in size, but are humble folk, so far as our records have revealed them, until the extinction of the dino- saurs has been accomplished. One cannot but associate the idea of mammalian suppression with that of dinosaurian dominance in the relation of cause and effect, unless it shall some day be revealed that the mammals were undergoing a marked evolution beyond the temperature-limited habitat of the reptiles. That the former showed no marked evolu- tionary advance in the place where the dinosaurs actually occurred is an attested fact, and the significance of the dino- saurian check is no more graphically shown than by two specimens in tlie Yale Museum. . . . The figure here repro- duced is from a simultaneous photograph of these two sped- The Story of the Roclcs 137 mens, which are therefore on exactly the same scale. The single dinosanrian tooth p-ceatly exceeds not only the tooth of the nianniial, but the (•< ntaininj; jaw or even the entire creature as the imaj>ination conjure.-; it up. "2 As to the cause of mammalian development we can again only conjecture. Lull has suggested that increasing dryness of climate and corresponding desert conditions, necessitar- ing speed on the part of animals in search of food and water, or in flight from their enemies, coupled with the extensive glaciation in the Southern hemisphere in late Palaeozoic times, Tooth of a Dinosaur Compared with the Jaw of a Coxtempuraky Mammal From Lull 's ' ' Organic Evolution. ' ' Courtesji of Professor Lull mid tlit' Miicmilhiii ComiJiniii. which glaciation would mean increasing cold and the nred of a furry covering, were the inciting causes. But apart from the fact that this explanation implies, if it does not state, an acceptance of Lamarck's doctrine, which at the present time is in the discard with most zoologists, is the further fact that the succeeding or Mesozoic era was one which witnessed the remarkable development of reptiles, which are distinctly types not adapted to aridity and cold- ness of climate. Perhaps the best we can do after all, when, as so frequently happens in pliilosophy and science, we find ^Lull, "Evolution of the Earth," pp. 133-134. By permission of the Yale University Press. 138 Biology in America ourselves "up a stump," is to accept the philosophy of Topsy and admit that they "jest grew." Tlie ]\Iesozoic and early Eocene mammals were all primi- tive types and most of them disappeared from the face of the earth without leaving any descendants. "It is the mammals which were the strangest element of Paleoccne life, and (an) imaginary observer would find no creature tliat he had ever seen before. The difference from modern mammalian life was not merely one of species, genera or even families, but of orders, for only one, or at most two, The Opossum The only marsupial at j)reseiit found in the United States. Photo hij Elu-iih /'. Sa)iJ)orn. By permission of the Neic York Zoological Society. of the orders now living were then to be found in North America, and both of these (marsupials and insectivores) were primitive and archaic groups, which seem like belated sur- vivals in the modern world." ^ It is possible however that the marsupial types of these early mammals have come down to us as the marsupials of the present. The marsupials derive their name from the marsupium or pouch in which they carry the young for some time after birth. These latter are born in a very undevel- oped condition and at birth are transferred by the mother 'Scott, "History of Land Mammals in the Western Hemisphere," p. 284. By permission of the Macmillan Company. The Story of the Rocks 139 to her pouch where their mouths become temporarily attached to the mother's teats and where they grow in safety until ready for their second debut in the world. AVell-known ex-- amples are our own opossum, and the Australian kangaroo. The distribution of modern marsupials is very peculiar and with otlier facts has given rise to interesting speculations re- garding the earlier form of Mother Earth. Their repre- sentatives are found today exclusively in Australia and ad- jacent regions, South America and tropical North America, with the exception of the opossum of the United States. In The 8riNY Ant-Eater A luoiiotreme, one of the most prii)iitive of. mammals. Photo by Elivin R. Sanhorn By permisawti of the Xeiv York Zoological Society. Mesozoic and Eocene time however the marsupial stock was distributed over North America and Europe and possibly Asia as well. The distribution of the ostrich in Africa and its relatives, the rhea in South America, and cassowary and emu in Aus- tralia and the East Indies and the recently extinct moa of New Zealand, is similar to that of the marsupials. These facts and other similar ones have led many biologists and palaeontologists to the belief in a migration of life from the northern hemisphere into the southern at some very early period in the earth's history. They have also suggested the existence of former land connections between South Amer- 140 Biology in America iea, Africa, Tndi.i jiikI Australia known as Antarctica and Gondwana Land wliii-li is sniijxisod to account for the simi- larity of many of the forms of life in the two reg:ions, not oidy of birds and mammals but of reptiles, amphibia, fishes, invertebrates and plants as well. Wliih' the early luaniinals disappeared for the most part without issue there were amony them some which were elected to serve as pro«jenitors of the mighty tribe which has since peopled the ciirlh. Whence came the present monotremes and marsupials is matter of much doubt, tlieir relationship to the pi-imitive members of these groups being uncertain, but the origin of modern carnivores is pretty certainly to be found in tlie ancient creodonts. After the close of the Cretaceous period with the rise of the western part of the North American continent and con- sequent draining of the great inland sea, which formerly stretched from the Arctic Ocean to the Gulf of Mexico, there appeared extensive swamps or fresh water lakes in what is now North Dakota, Montana and the Rocky Mountain and Great Basin regions and British Columbia. These various lakes did not all appear at once, but succeeded one another with succeeding changes in elevation and form of the land. It was now that the lignite beds of North Dakota and Mon- tana were laid down, covering an area approximately 60,000 square miles in extent. "The clijnate, as shown by the plants, was much milder and more uniform than that of the Recent epoch, though some indication of climatic zones may already be noted. The vegetation was essentially modern in character; nearly all our modern types of forest-trees, such as willows, poplars, sycamores, oaks, elms, maples, walnuts and many others, were abundantly represented in the vast forests which would seem to have covered nearly the entire continent from ocean to ocean and extended north into Alaska and Greenland, where no such vegetation is possible under present conditions. Nu- merous conifers were mingled with the deciduous trees, but we do not find exclusively coniferous forests. Palms, though not extending into Greenland, flourished magnificently far to the north of their present range. On the other hand, the Paleocene fiora of England points to a merely temperate cli- mate, while that of the succeeding Eocene was subtropical."* Upon the land and in the lakes were laid down deposits of wind-driven dust or loess and volcanic ash or tufa, while the streams deposited in their deltas sand and gravel carried down from the higher lands in which they took their rise. The majestic Rocky Mountains of today were then in their * Scott, locus citatus, pp. 102-103. 'jt • 4 [|gjp*-SN.\ SR^^Rr^B^^^H^F^jEpA^ "■SWftW'' ^^B nB ^^pc ' ^^w ^W'^llm i "jh^Wi-r Top — Restoration of Uixtatherium Center — Restoration of Coryphodon Boifom- — Restoration of the Creodont Dromocyon From (Irnwings by Horsfall in Scott's " Mjiiunials of the Western Hemisphere. ' ' Bi/ permission of the MacmilUin Company. Copy furniished by Conrad Lantern Slide Company, Chicago. 141 142 Biology in America infancy, and great was the travail of the earth in bringing them forth, for several active volcanoes marked their course. From these, great clouds of ashes were hurled forth to set- tle upon earth and water. Such was the home of the creo- donts, the forerunners of modern Carnivora. Of these the j\Iiacid;i? are believed to represent the progressive branch des- tined to flourish and bring forth fruit, while the other branches have withered and died. They were creatures much like the modern carnivores in general appearance, but with small brain-case and a very high ridge on the upper side of the skull for attachment of the powerful jaw muscles, and the teeth were not so well formed for eating flesh as in mod- ern carnivores. Remains of the LliacidiE have been found from "Wyoming to New Mexico. As in many another case of evolution in animals, the old adage "great oaks from little acorns grow" applied to the iNIiacidae, for the forerunners of the "king of beasts" and the man-eating tiger were little fellows content to prey on smaller fry of field and forest. Many of their relatives however were larger fellows, equalling in size a small bear. Associated with the creodonts were other creatures, many of them of huge size and ungainly form. Here shambled the coryphodonts, ugly brutes, equal- ling a small rhinoceros in size and somewhat resembling a hippopotamus in form, with heavy tusks, elephantine feet and short, heavy legs, and Uintatherium, a creature so bizarre in form that it seems as if Nature had designed it to grace a pala^ontological dime museum. The skull of this beast, not being able to find room for growth along ordinary lines, ran riot in the matter of horns. He had horns on his snout and horns on his forehead and horns at the back of his head and as if these were not enough to gratify his propensity for horny embellishment, his upper canine teeth were prolonged into gi'cat tusks, or horns turned upside down. The female however Avas much more conservative in the matter of horns, while she lacked the tusks entirely. The general form of the beast was quite similar to that of its relatives, the cory- phodonts. Beside these ungainly beasts there were othei'S resembling the present sloths of South America and repre- sentatives of the modern shrews and moles. As in the case of man the aborigine has given place to the invader from distant lands, so too the primitive mammals of North America, which were natives of the country, have been displaced by more recent types which have immigrated from other regions. "Whence they came cannot certainly be determined, but probably Asia was their birthplace, whence like the human race they have wandered throughout the world. It has repeatedly happened in geologic history that The Story of the Rocks 143 North America has been connected with Asia by a mass of land or "bridg:e" across Behrinonora/t Lo^ar ionoran Profile of San Francisco and 0 'Leary Peaks in Arizona To illustrate their life zones. The left side of the diagram is S. W., the right is N. E. The horizontal lines indicate contour intervals of IjUUU feet. Modified after Merriam 's "Biological Survey of the Sail Francisco Mountain Region . . . Arizona," North American Fauna, No. 3. clearly in the case of an isolated group of mountains such as those of which San Francisco Mountain forms the principal peak, than it does in an extended range such as the Rockies or the Sierra Nevada, where the zones are more or less broken up by the irregular contour of the mountains, with their jum- bled masses of peaks and valleys. These mountains further include more zones from base to summit than do those of like altitude further north, where the temperature range from base to summit is less. San Francisco Mountain is located in north central Ari- zona on the elevated plateau tlirough which the Colorado River has cut its titanic chasm. The town of Flagstaff, site of the Lowell Observatory, from which the late Professor Lowell 164 Biology in America brought us so many wonderful messages from Mars, is located near its southern base. The mountain, 12,794 feet in height, marks the grave of an extinct volcano, and several lesser vol- canic peaks rise from the plateau near the main peak. If we reverse the usual order of things and fancy ourselves deposited by aeroplane on the summit of the peak we shall find ourselves in a treeless, wind swept area of "bare vol- An Alpine Dwarf At 13,000 feet on Pike's Peak, Colorado. From "Plant Indicators." Courtesy of Doctor F. E. Clements and the Carnegie Institution. canie rock," which even in this southern latitude (35°N.) is snow-clad for three-fourths of the year. Here many of the herbs tend to form spreading rosettes, their leaves keeping close to the earth, and sending up a short flower stalk from the center. In the intense sunlight of the clear mountain air, growth is rapid and flowers and fruits mature early. To paraphrase an old saw the plants make fruit while the sun shines. Most of th=em are species occurring on high moun- Geographical Distribution 165 tain summits and arctic lands in North America, while some extend around the world. On the mountain summits they form isolated groups, cut off from their congeners of the north by the wide intervening plains and valleys. How have they come there? In glacial days, when the ice sea swept southward to New Jersey, Illinois and Nebraska, and gla- ciers covered the higher slopes of our western mountains, plants and animals were forced to move before it ; for the Ice King is an inexorable landloi-d, and when he undertook to dispossess the tenants of the lands there was no gainsay- PiKA, OR EocKY Mountain Hare An inhabitant of rock slides both above and below timber line. Photo by E. R. Warren. From Metcalf, "Organic Evolution," By permission of the Maimillan ComiJany. ing his wishes in the matter. But with the retreat of the ice the former tenants returned to their old abodes. Some of them however instead of moving north once more after the retreating ice, found a more convenient path up the mountain sides and thus came to settle in a new home, on the bleak mountain tops where they found the climate to their liking. So too the animal life of alpine summits contains many species, common alike to inonntain top and ban-en ground of tlie far North, tiiongh the number repoi'ted for the San Fran- cisco Mountain is too few to allow any generalizations con- ITARMIGAN IN (SUMMER PLUMAGE Photo hy E. R. Warren. Ptaemigan in Autumn Plumage Photo ly E. R. Warren. 166 Ptarmigan in Winter Plumage Photo hy E. R. Warren. Clarke's Crow A characteristic bird of the high mountains. Photo by E. R. Warren. 167 168 Biology in America cerning them. On alpine summits of the Rocky Mountains and Sierra Nevada however one meets with several more or less characteristie species. Here the marmot's whistle and the sharp call of the pika or mountain hare, mingled with the harsh note of the leucosticte, and the pipit's plaintive call are carried across the barren slopes by the rush of the wind. Here too is the home of the ptarmigan, whose changing fash- ion with the changing season — white in winter, mottled black, - w^ l^tf'''^^ 'f^SHKS .^ ■-^■lijf-ssr .v.^4 ^ &rfi^'^ .'■^^ ■-',•■■'■ H^Bj^^^BPi- — .^"^ oMm ..-^^'^ -1^ ^ ^-^ .t-'". *i ^^•ffeS- '•>*-i*»3>'f" ^ 't^t.^immmi-^ ■-■••' '."^V^yr-o-.V ^-•^;;.i^^;(^:.^ ..>iys?.>- ■ .-1-.- . ;>/» ^ \% -i ^ ©Ifgpi g^^ :*^^ ^p' ' H^^ 0-- '^^b^9^^^?^i^^^^^^^Bjflnl^|R .>--^ """'^'^■t;^:'' ^^p^*^^^ % ^2^^::'^ ^^^^ Timber Line in the Rocky Mountains Alpine firs at 11,000 feet altitude on Long's Peak, Colorado. From "Plant Indicators." Courtemj of Doctor F. E. Clements and tite Carnegie Institution. buff or white in summer — matches them so closely with their background, that one stumbles upon them before he is aware of it. The birds seem to realize their protection, for they are very tame and may sometimes be killed with a stick or stone. This lameness is however more likely due to infre- quent molestation. The ptarmigan is also a characteristic member of the arctic community nesting on the tundras of the far north, together with the little lapland longspur and the snow bunting, wliofie change of coat in spring and au- tumn resembles that of the ptarmigan. Even the gauzy- Polar Bears Courtesy of the National Zoological Park. The Cariboo Photo hy Elwin R. Sanborn. Courtesy of the Neio York Zooloyiral KocUty. 1G9 -Mmr^^-^ >ft5*>-.- .- Musk Oxen Inhabitants of the barren lands. Photo by Elwin E. Sanborn. Courtesy of the New York Zoological Society. The Wolverine A prowling marauder of the north woods. Courtesy of the New York Zoological Society. 170 Canadian Zone Forest in Colorado The spruce tree in the middle foreground is a striking example of symmetry. Original. 171 172 Biology in America winjred butterfly may be found flitting over the barren lands of the Arctic and the highest mountain peaks. Many other types of insects may also be found here. Over the ice and snow fields of the Arctic the polar bear holds sway, the mortal enemy of the seal, while the arctic fox plays the part of a hanger-on at court, feasting upon the remains of seal which Canadian and Transition Zone Landscape Fir forest of Canadian zone at left, open pine timber of transition zone at right, showing effect of slope exposure. Courtesy of the V. S. Bureau of Biological Survey. United States. Some of the better known which inhabit it throughout the United States and Canada are the elk, moose and woodland caribou; the weasel, fisher, martin, mink, red fox, wolverine, gray wolf; the marmot or woodchuck, por- cupine, pika and snowshoe rabbit; most of the mountain sheep and the Rocky Mountain goat, which is not a goat at all, but a relative of the European chamois or antelope. "The mammals of this sub-region (boreal) are largely of old world origin, many of them coming in with the great immigra- tions of the Pliocene and Pleistocene epochs, but there are also native American elements and even one genus of South Geographical Distribution 175 American origin, the short-tailed or Canada porcupine."^ Of birds there are a large number of characteristic species, a mere enumeration of which would hardly carry conviction to the general reader. Leaving behind us the forests of Douglas sprace and bal- sam fir, we enter an open "forest of statelj^ pines . . . which average at least ... 100 feet in height. There is no under- growth to obstruct the view, and after the rainy season the grass is knee-deep in places. ..." This forest covers the mountain side between 7,000 and 8,200 feet, some of its trees extending even to 8,800 feet among the spruce and fir. It ■^ K' '■ . mm^n m^ The Beaveb From a group in the American Museum of Natural History. Courtesy of the Museum. marks a debatable area, where boreal forms come down co- mingling with southern types, and hence has been aptly termed the transition zone. It has but few distinctive spe- cies either on San Francisco jMountain or elsewhere, being characterized rather by a mixture of types. In general it occupies the northern half of the United States, bending far southward along the mountain ranges, and running north along the river valleys, which serve as paths of northern in- vasion for southern forms. Southern animals which cross 'Scott, "History of Land Mammals of the Western Hemisphere," p. 151. By permission of the Macmillan Company. 176 Biology in America the transition zone inclndo tlio mountain "lion" or puma, whit'h extends liis j)ro\vIinS'. Bureau of Biological Survey. and chestnut, while in the swamps of the South are the cy- press, magnolia and palmetto. In its large features the animal life of this region does not differ from that of the Canadian, transition and upper Sonoran zones of a western mountain, which has already been described; although differing therefrom in many minor details. But along the southeastern coast occur a few spe- cies which distinguish this region from other parts of the country. In the rice fields of the South occurs the rice rat, while the cotton rat is another animal characteristic of the South Atlantic and Gulf States. The Florida Everglades are Alligators Enjoying a Quiet Siesta Photo by Ehvin R. l^anhorn. Courtesy of the New York ZoUloylcal Society. The Water Moccasin An inhabitant of the lowhuuls of tlie South Atlantic and Gulf States. Courtesy of the A'civ York Zoological Society. 179 180 Biology in America included in tlie tropical zone, which except here and at the mouth of the Rio Grande does not enter the United States. In the streams of southern Florida lives the alligator, while the dark forests are the home of the parrakeet, an intruder from the numerous family of parrots in South and Central America. A hundred years ago this bird ranged as far north as the Great Lakes, but it is at present restricted to a few areas in our Southern States, if indeed it is not wholly extinct at present. Crossing the Appalachians our traveler descends into the The Burrowing O'vvl Photo by Eiwin R. Sunburii: Courtesy uf the A'e/r York ZoiiJoniiul Hoviity. great valley of the IMississippi River, with its branches stretch- ing far to east and west and draining nearly half the total area of the United States. Here he at first encounters a climate not greatly different from that of the eastern seaboard, al- though subject to somewhat greater extremes of temperature. The fauna and the flora too are similar to those of the At- lantic Coast. As he passes westward however out of the basin of the Mississippi, rising over the slope of the Great Plains to the foothills of the Rockies, the climate changes, the rain- fall materially decreasing and the temperature extremes in- creasing. Accompanying these changes of climate occur marked changes in the life of the land. The eastern forests disap- Prairie Dog Prairie Dog at Burrow The **dog towns" of the West are familiar objects. Courtesy of the U. S. Bureau of Biological Survey. 181 182 Biology in America pear save for a fringe of timber along the stream bottoms, giving place to the vast prairies of the west. New types of animals also appear upon the scene. Squatting on his haunches outside the entrance to his subterranean home the prairie dog squeaks defiance at the passing traveler, and the burrowing owl utters its shrill cry in protest at the pres- ence of the intruder. Several species of ground squirrels or gophers are characteristic members of the animal commun- ity, some of which extend eastward across the Mississippi. The black and white of the lark bunting is a conspicuous fea- ture of the landscape, while the magpie in his coat of green and white lends color as well as noise to the cottonwood groves along the rivers. The Great Plains form an inter- esting "tension line," as the biologist calls it, "where east is west and west is east and ever the twain shall meet. ' ' ^ The eastern and western movement of the western and eastern flora and fauna respectively is one of the most interesting features of this area. The dicksissel, one of the sparrow family, a characteristic bird of the Mississippi Valley, has only in recent years ventured from his ancestral home across the vast prairies to the west. Conversely the magpie appears to be moving slowly eastward. The red-eyed vireo, whose home is in the eastern United States, appears within recent years to have followed the Missouri Valley westward, crossed the Rocky Mountains and established itself in the northwest- ern United States and British Columbia. An interesting suggestion as to how the migration routes of various birds may have become established, many of which are very devious and hard to explain, is to be found in the route of this bird. Wintering in South America, it moves northward in spring following the course of the Mississippi River to near its headwaters, whence it turns northwestward across mountains to its breeding grounds in the North. A much shorter route lies west of the Rockies ; but inherited in- stinct (or is it parental example?) carries the bird in the path of its forefathers far from the course which is most easy and direct. Another interesting case of recent extension of a bird's breeding range is furnished by the bobolink, which is an in- habitant of marsh and meadow land. With the settling of the arid territory of the West, accompanied by its irrigation, the bobolink is accompanying the western march of empire, and settling itself in Nevada, Oregon and other western states. Between the Rockies and the Sierras lies the Great Basin, scorched with the torrid heat of summer and frozen with the icy blasts of winter, a land parched with endless drouth. "With apologies to Mr. Kipling. The Horned Toad Which is not a "toad" at all, but a lizard, resembling in its scaly attire a miniature monster of the past. Photo hy Eltoin R. Sanborn. Courtesy of the Netv York Zoological Society. The Kangaroo Rat Characteristic of the arid Southwest. Courtesy of the U. S. Bureau of Biological Survey. 183 184 Biology in America The life of this region is widely different from that of the East, but the mere enumeration of the names of its inhabi- tants would be of little interest. Many of its species are in- habitants of the ground and buslies and are more or less bleached in color corresponding to the backgi'ound upon which they live. IIow this adaptation has been effected no one can surely say. But more of this in a later chapter. One of the most characteristic of its inhabitants is the "horned toad," which is not a toad at all, but a lizard. This little creature with its horned head is a miniature Triceratops, the giant dinosaur which once shambled across our plains. The towering Sierras rising like a mighty wall shut off the Great Basin from the interior valleys of California, and these in turn are separated from the Pacific Coast by the Coast Kange of mountains, which while pygmies compared The Gila Monster Characleristic of the arid Southwest. Froui Ditmars, "Reptiles of All Lands," in "National Geographic Magazine," Vol. 22. with their mighty neighbors to the east, nevertheless form a very efficient climatic barrier to the moisture laden winds sweeping landward from the sea. The climatic diff'erences thus caused are reflected in the life of the interior valleys and the coastal slope. In no similar area in North America are there such gi-eat extremes of climate or more marked dif- ferences in the corresponding life. Especially is this true of Death Valley in the interior of southern California, whose lowest point is 276 feet below the surface of the sea. Here the temperature in summer frequently reaches 125°F. in the shade, and the relentless sun scarce ever hides its shameless face behind a cloud. Here lives a little community of desert dwellers, for the most part characteristic of their arid home. The fauna and flora of California are peculiar to them- selves, following however the general principles of distri- bution of life elsewhere. Here occur the Goliaths among plants — the California big trees. At one time in the past Geographical Distribution 185 these trees were widely distributed over North America, but today they are restricted to our western coast/° and it may be are doomed to extinction, Amono- the most characteristic, and witlial attractive mem- bers of California society are the hummiii<^ birds, a group occurring only in America. The several species found along A California Big Tree Grove Courtcny of the U. t>. Bureau of Bioloykul Surrey. the Pacific Coast and the few occurring elsewlierc are in- vaders from the tropics where most of the more than four hundred species find a home. Another interesting inhabitant of southern California and Arizona is the great condor, which spreads its wings from eight and a half to eleven feet. Dwelling in the damp forests of Oregon and Cialifornia "Sequoia gigantea is limited to a few small areas in California, while S. sempervirens or the "redwood" extends north along the coast into Oregon. ISfi Biology in America is the last representative of a once thriving family, which at one time had a much wider distribution than at present. The sewellel is an animal somewhat resembling a large rat, which digs his home among the roots of the forest trees and stores therein the harvest which he gathers from its herbs. Several million years ago, more or less, there lived in North America a numerous race of animals related to the opossum and kangaroo, the marsupials, to which reference has been made in the preceding chapter. Then they disappeared from what is now the United States, for what reason we do not Mountain Beaver, or Sewellel Courtesy of the U. 8. Bureau of Biological Survey. know— a mysterious disappearance of the past, which the palffiontological sleuth may never solve. The most likely ex- planation is that they were driven south by the wolves and tigers and others of their ilk, the robber barons of the ani- mal world. More recently one of their number, the opossum, has once more ventured northward as far as the northern United States (Michigan and New York). Have all these facts laboriously gathered by many men in many years any practical value? Even had they none they would still be well worth while because of the light which they, in conjunction with the "hard facts" of palaBoutology, Geographical Distribution 187 throw upon llie great questions of evolution, adaptation and the vicissitudes and changes of plants and animals in the past. But apart from this purely ''theoretical" interest they have an important hearing upon human life today, for they give us a clue to the suitability of any region for crops of a given type. Thus if a settler in a given region wishes to know what kind of crops will grow best in his region, it is essential for him to know, not only the character of the soil in his area and the amount of rainfall, temperature range, etc., but the type of plants which will grow well in that par- ticular climate, or in other words the life zone in which his area lies. To make this information available to our farmers the Biological Survey has prepared a life zone map of the United States and Canada, together with a list of the various cereals, fruits and vegetables best adapted to each zone. Thus does the biologist seek to make his knowledge "prac- tical" in the rendering of service to the world. CHAPTER VI Experim^ital hiologt/. Prcfannation in a new dress, organ- izaiimi of the egg, regeneration and gmfting, plastic mrgery, tissue culture, the prahleni of death, and im- mortality of the cell. The last thirty years have seen remarkable developments in the field of experimental biology. True it is that the method of experiment was a very early one, especially among human and plant physiologists. Nevertheless experimental' biolog\^ has lagged behind experimental physics and chem- istry and has but recently found its proper place among the other branches of biological science. In the development of this field Germany and America have played the leading part, while with the recent upheaval in Europe, and conse- quent check to scientific progress there, the coming era of reconstruction finds this country better fitted than any other to lead in the development of the new science. "While the earlier biologists were in the main satisfied with the observation of phenomena, and speculation as to their causes, the experimental biologist demands that these pl^e- nomena shall be analyzed under certain imposed conditions, in order that their causes may be scientifically ascertained. Thus the method of transmission of yellow fever could only be conjectured until the Yellow Fever Commission in 1900, by exposing subjects to all possible conditions of infection, proved that the bite of the mosquito (Stegomyia) was the only natural means of transfer. Experimental biology has followed a few main lines of thought, with many side lines which are branched and in- terwoven with one another in an intricate maze. A gen- eral review may best be given by tracing the main lines, the branches being folloAved only so far as they are essential to an understanding of the former. The principal questions then with which we shall deal are the following: Are the factors which determine the development of an organism internal or external ? AYhy does an organism grow old and die? What are the factors of organic evolution? Is the organism a machine, governed by the laws of physics and chemistry, or is there a "vital principle," an "en- telechy" or a "soul," transcending in its activity the bounds of the purely material universe? A century and a half ago Caspar Friedrich Wolff overthrew 1 The Organization of the Egg 189 the generally accepted doctrine of piefoniialion, according to which the adult animal was present in miniature within the egg or the sperm cell, both of which had their advocates, so that embryologists were divided into the rival schools of "ovists" and "spermatists. " One enthusiastic and imagina- tive observer even pictured a miniature human body within the spermatozoon. sp BERoii Showing tlie four rows of swiinuiing ]>lntes, sj Chun. Vrom Lankosfcr, after While such fancies have long since been laid to rest, pre- formation, in a new dress, is playing a very important role on the biological stage today. The importance of this theory is due largely to the work of two American biologists — Morgan at Columbia and Conklin at Princeton. In modern form preformation assumes the presence in the sex cells of certain formative stutfs or entities (more exact terminology is impossible in the present state of our knowl- edge) which determine the development of parts or features of the adult organism. These things, whatever they are, may reside either in the nucleus or the cytoplasm. In the former 190 Biology in America case tliey are present in both sperm and egg cell ; in the latter case only in the egg, the amount of cytoplasm in the typical sperm being too small to contain the ''organ-forming sub- stances." If such formative stuffs are unequally distributed to dif- ferent daughter cells in the division of the egg, then we should expect each of these cells to give rise to a definite part of the embryo and to that part only. If, on the other hand, these ••y-:»lv.---.-. . ■ ;,'-A:'5; I P' (Left) The Egg of thk Tunicate Cynthia Showing the ' ' organ forming substances ' ' and their distribution in different stages, a, anterior; p, posterior pole of egg; c, clear proto- plasm; cr, yellow crescent; e, cortex containing yellow pigment; g.v., germinal vesicle; k, chorion; p. b., polar bodies; t, test cells; y, yolk; y. h., yellow hemisphere; 6, sperm nucleus. Prom Kellicott, after Wilson. (Eight) Development of the Mollusc Dentalium A, distribution of materials in undivided egg; B, commencement of division showing the "polar lobe" p, which in C and D (division stages) is found at D and X respectively. In E the cell X is absent, the polar lobe having been removed at an earlier stage. F and H, normal larvae of twenty-four and seventy-two hours, respectively, G and I, larvae of the same ages lacking the "polar lobe" material. From Kellicott after Wilson. stuffs are equally distributed to the daughter cells, then these cells should be mutually interchangeable, and any one of them, if isolated from its fellows, should give rise to com- plete, though dwarfed embryos. Is the egg a mosaic, or is it uniform in its structure? The ctenophore Beroe has normally eight rows of ciliary bands. After one division of the egg, if the two resulting The Organization of the Egg 191 cells are separated, each one will develop into a half larva, with only four rows of bands. Similarly each cell of the four and even the eight cell stage may be made to develop into a partial larva with two or even only one row of bands. And further if a part be removed from the egg before divi- sion, a defective larva is the result. The egg of the aseidian Cynthia has been shown by Conklin to contain at least five different "organ-forming substances," distinguishable by color and texture, which are symmetrically placed with reference to the median plane of the embryo, but differentially located antero-posteriorly. If one of the first two cleavage cells (for example the right) is killed, the other develops into the opposite (left) half of the body, which contains all the normal part>;, but of one-half the norn'ial size. But if in the four cell stage, when the second cleavage has differentiated the anterior from the posterior ends of the body, one or both of the anterior or posterior cells is killed, the resulting larva lacks those parts which are present only in the cells which have been destroyed. A similar result has been obtained by Wilson in the egg of the mollusc Dentalium, in which three different substance.^ can be identified. Thus the yolk is here at first located at one pole of the egg, and later in a single one of the cleavage cells. If this "yolk lobe" be removed from the egg, when it starts to divide, the resulting larva lacks certain parts (foot, mantle, shell, etc.) normally formed from the yolk cell. Centrifuging the egg of Cynthia with consequent dis- arrangement of the organ-forming substances may so disturb the development that the resulting larva may be turned inside out, with entoderm on the outside and ectoderm within. At the posterior end of one of the chrysomelid beetles (Calligrapha) occurs a disk of granules, which seemingly function as germ cell determinants, for if the end of the egg containing this disk be pricked, and its component gran- ules allowed to escape, or if the disk be destroyed with a hot needle, and the egg is then allowed to develop, the resulting embryo lacks germ cells. There are many experiments however which point to dif- ferent conclusions. Thus in eggs of fresh water snails and certain annelids, substances of different color and specific gravity occur, but these may be displaced from their normal positions by centrifuging, without in any way affecting the development. This has led Lillie and others to the conclusion that the so-called organ-forming substances are not in reality such, but merely an accompaniment of a more pro- found organization resident in the protoplasmic framework 192 Biology in America of the egrfr, which cannot be mechanically rearranged by centrifuginj? or otherwise. The foregroing experiments seem to show conclusively that the developing animal is in some sense at least prefonned in the egg. No less conclusive however is the evidence of a directly opposite character. In Amphioxus and many Ilydromedusa' isolated cleavage cells give rise to complete though dwarf larvfp, while on the contrary it has been pos- sible in some eases (Ascaris, Sphterechinus) to produce nor- mal, though giant larvae, by the fusion of two eggs or embryos. Many intermediate forms exist between those eggs in which one of the cleavage cells produces a partial, and those in which it forms an entire larva. In some cases, as for instance in certain echinoderms, an isolated cleavage cell may undergo at first a partial development, but later a process of regula- tion may ensue, resulting in the formation of a complete larva. Different results may be obtained in the same animal, depending on the method of experimentation. Thus if one of the first two cleavage cells of a frog's egg be destroyed with a hot needle and the egg left in its normal position a half embryo results, but if the position be inverted a whole embryo develops in the majority of cases. In this maze of conflicting evidence a final word can scarcely be spoken. Undoubtedly different eggs differ in the extent of their organization. If a part of the egg of the nemertine Cerebratulus be removed prior to fertilization, no disturbance of development ensues. If the two cells of the first cleavage are separated, they undergo for a time a partial cleavage, but very soon the normal development is resumed. But if one of the four cells, resulting from the second cleavage, be iso- lated, partial development proceeds for a longer time than in the preceding case, the normal process not being resumed until much later. We find here a possible explanation of the divergent behavior of different eggs. In some the embryo may be preformed in the egg, in others only in later stages of cleavage. The phenomena of regeneration speak strongly for the uniformity of both egg and adult. If the parts of the or- ganism are predetermined in the former, then when one of these parts is lost its replacement should be impossible; but if the egg be isotropic (one part the same as another), and if this uniformity persist in the adult, then a lost part should be replaceable. The ability of regeneration in many animals has long been known, being mentioned by Aristotle and Pliny. In the mid- dle of the eighteenth century, the famous work of Trembley on Hydra attracted widespread attention and several workers entered this field. Tho Organization of Ihc Egg 193 Rpgeneratioii occurs to a greater or less extent in all the great groups of animals and plants. If Hydra be cut into several pieces each will develop into a new animal. Earth- worms and flatworms can regenerate either head or tail if these be removed. The starfish can have a new arm made to order; the lobster a claw; the snail may acquire a new head, and the sea cucumber a new stomach. In higher plants a piece of leaf or root may give rise to an entire new plant. Among animals the regenerative power decreases with in- creasing specialization. The relative size of a piece of Hydra necessary to produce a new animal is much less than that of a crab or a frog. In vertebrates the amphibians have been most used for regeneration experiments. There are many salamanders which can regenerate legs or tail, but there appear to be differences in the regenerative ability of different forms. Age has an influence, as well as degrees of specialization, for while the tadpole will readily regenerate a lost limb the frog is unable to do so. In man the power of regeneration is relatively slight, although skin, muscles^ bone and other tissues show this power to some extent in the healing of wounds, while the lens of the eye may occasionally regenerate. There are some remark- able cases on record of regeneration of internal organs in mammals, although these are sometimes merely cases of hyper- trophy of part of an organ, in compensation for the loss of another part of that same organ, rather than instances of true regeneration. Thus the removal of one-half or even three- fourths of the liver of a dog or rabbit may result in the enlargement of the remainder, without any replacement of the lost part. It is well known that in man injury to a lung or kidney may be compensated by increased growth and activity of its opposite. There are recorded instances how- ever of true regeneration of internal organs in mammals. In the rabbit removal of as much as five-sixths of a salivary gland may be followed by complete regeneration, and the kidney of a rat or a rabbit may develop new tissue to a certain extent, after part has been removed. The regeneration of the lens in vertebrates ha« been a bone of contention among zoologists for many years. In the development of the normal eye there first arises an evagina- tion of the primary forebrain forming a primary optic cup or vesicle, wliich is shoi-tly followed by an invagination of the adjacent ectoderm to foi'm a secondary cuj) or vesicle, from which is formed the lens. The question at issue is: Is the lens dependent upon the presence of the primary vesicle for its development, or may it arise independently of the latter? Many ingenious expei'iments have been performed, prin- cipally on amphibian larvaj, in the attempt to solve this 194 Biology in America problem, with unfortunately widely divergent results. The ectoderm has been eut around the developing primary vesicle, and the tlap folded back so as to expose the latter; vidiich has then been excised, the tiap replaced and the wound allowed to heal. In other experiments the primary vesicle has been supposedly destroyed by pricking it with a hot needle; and in still others the vesicle has been transplanted to a strange area of the same, or a different species, such as the abdominal wall. In the latter experiments lenses have been formed from parts of the ectoderm which never give rise to them in nature, and similar results have been obtained by destroying a lens already formed, thereby causing its regeneration from the iris. In the former experiments the results have been incon- sistent, a lens sometimes regenerating and sometimes failing to do so, after the removal of the primary vesicle. Werber has suggested that this apparent inconsistency is due to the incomplete destruction of the vesicle in some cases in which it had supposedly been entirely removed, and the consequent formation of a " lens stimulus ' ' by small pieces of the vesicle which remained. Of interest in this connection are the experi- ments of Stoekard, Werber and others in the production of Cyclopean and other monsters, which will be considered later. In some of these experiments a single median eye has been produced in place of two lateral ones, with the resultant formation of a single lens associated Avith the single eye, and the absence of any lateral lenses. In other cases lenses have developed at almost any place on the monster, apparently unassociated with any optic material. Werber has suggested' however that these so-called "independent lenses" owe their origin to the stimulus of microscopic bits of optic vesicles scattered over the body of the monster, through a process of blastolysis or tissue destruction induced by chemical or osmotic action, and in some cases he is able to demonstrate what he considers bits of such material in close proximity to these lenses. Whatever the truth of the matter may be, the evidence is I think conclusive that lenses, and presumably other organs also, are not iji any sense preformed, but result from the interaction between the parts of the organism itself and their environment. Nearly related to experiments on regeneration are those on grafting. The custom of grafting in plants has been prac- tised by horticulturists for a long time. Trembley with his celebrated woik on Hydra was a pioneer in this field among animals. JMoi'e recently this work has been continued by King, Rand, Peebles and others in this country. The an- terior end of one Hydra may be grafted onto the posterior The Organization of the Egg 195 end of another ; two Hydras may be united by either anterior or posterior ends, or one Hydra may be o-rafted onto the side of another. The results differ depending upon the condi- tions of the experiment, and the speeies of Hydra employed; but the general result is that a process of regulation ensues whereby a new animal is formed, similar in size and pro- portion to the normal individual. One of the most interest- ing results l)earing on the question of predetermination of parts is that obtained by grafting two Hydras by their anterior ends and then cutting off' the posterior end of one near the graft line. In this case a new head forms on the Four-Legged Tadpoles Produced by transplanting the limbs from one tadpole to anotlicr. After Harrison, "Journal of Experimental Zoology,'' Vol. 4. (originally) posterior end of the graft, where a head, in the ordinary course of events would never develop. Some of the most interesting grafting work of recent years has been done by Harrison, in connection with studies on the developing nerve fiber. Two positions have been held on this question — one, that the axone of the nerve cell, the conducting part of the nerve fiber, arose in situ from surrounding cells ; the other, that the axone was an outgrowth from the nerve cell itself. The latter view appears to have been definitely established by Harrison. Our interest here however centers primarily upon certain secondary results of Harrison's work rather than upon the question of nerve fiber development. In these experiments Harrison has shown that limb buds can be transplanted from one tadpole to another, the tail of one 196 Biology in America species of tadpole can be grafted on that of another species, two entire animals may be united, and even the head of one species (Rana virescens) can be united to the body of another (R. palustris), and a young frog reared from the combina- tion. Similar results have been obtained by Crampton in the union of tlie puinn of moths, (■()ml)inations of ceeropia moths with promethea and polyphenuis mollis having been successfully made. Most remarfeable of grafting results witli higher animals A Combination Frog With the head of one species grafted onto the body of another. The tadpole to the left, the adult to the right. From Harrison, in the "Anatomical Record,'' Vol. 2. have been those of Carrel on mammals. lie has removed sections of arteries of one animal and replaced them with pieces of vessels taken from another. He has even made this graft successfully with vessels which had been kept in an ice chest for several weeks after death. Thus a piece of a human artery taken from an amputated leg and pre- served for twenty-five days in cold storage was used to replace a piece of the aorta of a small dog. The graft took and the dog recovered and lived for over four years, during which time she bore several litters of pupi)ies, finally dying during The Organization of the Egg 197 labor. A post-mortem examination sliowed the p^rafted vessel to be slightly dilated and lacking muscular tissue, but other- wise normal. Carrel's success in grafting vessels enabled him to transplant entire organs. He performed this operation on cats' kidneys, with a certain amount of temporary success, the transplanted organ functioning for a number of weeks. Ultimately however the animals died. But even the tem- porary success of so daring an operation gives ground for hope that complete success may ultimately be possible. Grafting on the human body or plastic surgery is supposed to have been practised by the Egyptians as early as 1,500 B. C. In recent years great advances have been made in this branch of surgery, and not only have skin, bones, muscles, fascia and tendons been transplanted, but parts of internal organs have been used to repair defects in other parts. Thus the urethra has been replaced by the appendix and a vagina has been made from a piece of intestine. A piece of cornea from a human eye kept in cold storage for eight days has been successfully used to partially restore the sight of a man blinded by alkali. The story of the recent achievements of surgery in repair- ing the features of soldiers, who had been so badly wounded as to be merely caricatures of their former selves, reads almost like a tale from the "Arabian Nights." Jaws, noses, ears, cheeks, almost entire faces have been remade, so that the vic- tims have in the end presented a fairly good facsimile of their former selves. While details cannot be given here, a brief outline of the method may be of interest. A former picture of the patient if available is taken as the model of what the surgeon aims to make. Then a piece of bone of the proper size and shape to refit the lost part (a jaw or nose) will be cut out of a rib or shin bone and inserted beneath the skin of an adjoining part (the neck or forehead). After the skin has attached itself to the inserted bone, the latter is cut out on three sides, leaving a stalk on one side to maintain the circulation, the skin is now cut open around the scar and the new member inserted in the open cavity. The adjoining skin is attached to the insert, and after the graft has "taken," its stalk is cut away, and when finally healed the skin is massaged, and the scar removed in this way as far as possible. Thus a fairly natural part may be made to replace a jawless mouth or a repulsive hole where a nose once grew. Carrel and others have shown that not only blood vessels and cornea, but also skin, fascia, tendon, bone and cartilage may be preserved in a condition of latent life for weeks or months in cold storage, and still be used successfully for transplantation. Thus pieces of skin taken from the body 198 Biology m America of an iufaiit, which died during labor, and preserved in vaseline at a temperature of -|-3°C. were successfully used for grafts after forty-two days; and pieces of fat, bone and cartilage taken from amputations have been similarly pre- served in cold storage for varying lengths of time, and later used in grafting operations. Seemingly the day is not far distant when cold storage will supply us with our tissues as well as our foods. The liberties which may be taken with living tissues and their ability to grow in strange surroundings is I believe strong evidence for the plasticity of the cell, showing as they do the profound influence of environment on its development. Such a view of course must not be pushed too far. It would Three Stages in the Eeconstruction of a Wounded Soldier's Face From Esser in ' ' Annals of Surgery, ' ' Yol. 65. By pennisskm of J. li. Liiiitincott Company. be absurd to expect that every cell could be modified by its surroundings so as to form every other kind. With high specialization the cell loses j^ari passu its adaptability. But in the lower organisms there is abundant evidence of the ability of cells to be molded into new structures, even after they have reached the usual limits of their development. Further evidence in favor of this view is afforded by the apparently unlimited power of reproduction possessed by certain cells. If the development of the organism were pre- determined in the egg, then the growth of its parts should" be limited, and there should come a time in its development, as ordinarily there does come in the life of the individual, when growth should cease and the power of repair should not exceed the need created by waste. But in some cases, notably The Organization of the Egg 199 in cancer, certain cells possess the power of seemingly un- limited growth, increasing- at the expense of other tissues, running wild within the body, and finally destroying it as a result of their riotous living. This power of seemingly un- limited growth of the cell may in many cases be initiated artificially. Unquestionably the most important of Harrison's results A Piece of Growing Tissue The (lark center is the original tissue, the brandling boilies radiating out from it are the growing cells. It has been possible to cultivate in glass cells many different kinds of tissue, including those from man himself. This method has been used for studying the growth and reaction of cancer cells, and may throw light on the cause of this dreail malady. After Lambert and Hanes, "Journal of Experimental Medi- cine." Vol. 13. on nerve growth was his development of the method of grow- ing tissues outside of the animal body. He transplanted bits of the central nervous system of the tadpole to drops of coagulable lymph from the frog, and by placing these in a glass cell under the microscope, he was able to follow the growth of the nerve fibers. More recently a large number of workers, mostly Americans, have developed Harrison's method and applied it to both embryonic and adult tissues of birds and mammals. The method has been applied to the 200 Biology in America study of tlio growth not only of normal but of pathological tissues, such as tumors and cancers. When a bii of tissue is removed from a living, or recently killed animal, and placed in a suitable medium (blood plasma is the one mostly emjjloyed) at a pr()i)er temperatun^ it sooner or later, depending on the age of the animal from which it is taken, begins to grow, sending out sheets of cells in all directions into the surrounding medium. After a time however growth ceases, but may recommence if the tissue be removed, washed and transferred to a fresh medium. In this way tissues have been kept alive for more than nine years and carried through nearly two thousand transfers. Carrel has grown chick tissues in this way, which had been kept in cold storage for six days, and even human tissues taken from a cadaver several hours after death may grow. But what is death if our tissues, as well as our actions, will live after we are gone? Does the grim specter lie in wait for us in the coils of our intestines, as jMetsehnikolf would have us believe ? Or is it the hardening of our arteries which ushers us into the great unknown? Is death inherent in life, or were the first living things immortal, and death an adapta- tion secondarily acquired for the benefit of the race, although working to the detriment of the individual, as AVeismann has suggested ? For an answer to these questions let us turn to the uni- cellular organisms and see what they have to teach us. If a single Paranuecium be put in a fresh infusion of hay in water it soon divides to form two daughter cells, which divide again in their tuin, and so on ; until the infusion is teeming with millions, all offspring of one cell, which is still living in its descendants. For this reason Weismann maintained that the Protozoa were immortal. But after a time repro- duction ceases and the Paramo'cia begin to die off. The cul- ture has passed its climax and begun to retrograde. Finally the Pai'am(ecia disappear entirely, unless fresh material be meantime added to the culture. But if this be done the cells ac(iuire a new lease of life and connnence to multiply again as merrily as ever. By using a varied culture of hay, leaves, moss, etc. in rotation and transferring his animals daily to fresh culture. Woodruff has carried a race of ParauKccia through some seven thousand generations extending over a period of twelve years, without any evidence of degeneration. While an exact analy- sis of the different stimuli controlling the Paramo^cia in a hay infusion has not been made, it has been shown ])retty conclusively that waste products materially check their growth, while purity of the culture in this respect stimulates The Organization of the Egg 201 growth and keeps tlie animals healthy. The food supply- must also exercise a controlling influence, the growth of bacteria, which serve as food, being also cheeked by waste products (toxins) in the culture. It can be shown however that even in the presence of abundant food supply, stale culture will inhibit tlie growth of ParanKecia. We can compai-e the metazoan with a culture of Paramrecia, all descendants of one cell. The former, as well as the latter, starts as a single cell (the fertilized egg). After a period of active division or growth the climax is reached, when the processes of repair can only keep pace with those of waste, and from then on the organism passes through the decline of old age followed by death. But if a few cells be removed from the parent body and transferred to a fresh medium (blood plasma) they forthwith start to grow abundantly, and this growth can apparently be maintained indefinitely, if the transfers be repeated from time to time. The influence of the age of the animal from which the plasma is taken is very marked. In that from young animals growth is much more active than in that taken from adults, but if an extract of the tissues of a young animal be added to the latter the growth is materially increased. May not then old age and death be caused by waste prod- ucts excreted by the cells of the metazoan body? May it not be a process of auto-intoxication, not localized as Metseh- nikoff suggests, in the intestines, but generalized throughout the entire body? Whatever answer to this question the future may make, the faculty of unlimited growth possessed by most, if not all the tissues of higher animals, suggests not only the indeterminate nature of development, but also the inherent immortality of the cell. CHAPTER VII Experimental hiology continued. The role of the chromosomes in inheritance. Inhcritanee of sex and sex-linked char- acters. In the preceding chapter we have considered the question of the influence of the cytoplasm upon development, par- ticularly in respect to the "orfi,an-formin«i' sub.tances" winch it contains ; and the ability of one part of an organism to regenerate, not only itself, but some other part normally foreign to it. We shall now consider the role of the nucleus in development, especially that of the chromosomes. Whether or not development be locally predetermined in the egg, there is of course no question that the latter is pre- determined in its general development. J\Ien do not gather "grapes of thorns or figs of thistles," nor can the specific, e. g., characteristic of the species, development be altered by any change in the environment. AVhat is it then which deter- mines the specific characters of the organism? While the theory of cellular units responsible for the hereditary transmission of specifie and individual characters, originated with Darwin as the well known "pangenesis" theory, in an attempt to explain the origin of new characters by environmental influence, and was amplified and more definitely formulated by Weismann, it has never received stronger support than througli tlie ejioch-making work of Mor- gan and his students at Columbia University within the last decade.^ In order to appreciate the significance of this work, it is necessary to turn back the pages of time for a half century and pause a moment to look into the garden of the monastery at Briinn in the Tyrol, where the monk Gregor Mendel was busy with his peas. Mendel was monk and later abbot at Briinn, and for a time ^I do not wish in this statement to accuse modern biologists of accepting Darwin's theory of "pangenesis" in its entirety. Darwin- ian and modern viewpoints have in common however the assumption oi some sort of cell units, be they physical or be they chemical, which are responsible for reappearance in the offspring of characters pres- ent in the parent. 202 The Role of the Chromosomes 203 taught tlie physical and natural sciences in the monastery school. While monk and teacher he was essentially a great investigator, and in spite of his other duties, he found time to perform a large number of breeding experiments with sweet peas, the results of which he published in 1865 in the ' * Proceedings of the Natural History Society of Briinn. ' ' This paper, which he sent to his friend Niigeli the botanist, made no impression on the latter and attracted no attention, until thirty-five years later, when Mendel's principle was inde- pendently discovered by three botanists — DeVries, Correns and Tschermak. Since then, Mendel's discovery has been recognized as one of the greatest in biology, and his paper has become a great scientific classic. The results of his work have been so extensively quoted, and are known so widely and so well that their rehearsal is needless here. There are certain features of his results how- ever which, while well known to biologists, are perhaps not fully appreciated by the general reader, and which it may therefore be worth while to emphasize. Thus it is commonly known, for example, that a cross between a tall pea and a dwarf produces only tall offspring, which, when bred to- gether, produce, on the average, three tall and one dwarf descendants. But the meaning of this well-known Mendelian ratio is possibly not widely understood. A ready explanation is found however in the behavior of the chromosomes of the germ cells, prior to, and during fertilization. The nucleus of an undividing or resting cell contains a sub- stance known as chromatin, which, when the cell is sectioned and stained for microscopic study, appears as a mass of deeply stained blotches and specks scattered indiscriminately over a very delicate network of threads or "linin" fibrils. When the cell becomes active and starts to divide this chromatin material is gathered together into an irregular twisted thread known as the "skein" or "spireme," which is at first long and thin, but soon shortens and thickens and then breaks up into a number of segments in the form of rods, loops or balls, the number of which is characteristic for any given species of plant or animal. ])ut which varies in different species from two to upwards of two hundred. In division these chromosomes are equally divided so that each new cell receives the same number as the parent cell contains. But when the animal or plant is ready to reproduce there is a striking difference in the behavior of the chromosomes— a difference to which is probably related all the varied and wonderful phenomena displayed by Mendelian inheritance. Nearly forty years ago Van Beneden ascertained that the germ cells of Ascaris, an intestinal parasite of the horse, each contained, at the time of fertilization, one-half the number 204 Biology in Amrrica of chromosomes characteristic of the species; which number was thci-cfore restored at the time of fertilization by the union of tlie egg and sperm inielei. Now, if this reduction in number can be shown to involve the separation of definite mwmmh Photographs of Chromosomes Showing various stages in the division of a sea urchin 's egg. The minute dark masses at the center of the egg are the chromosomes. The light areas, surrounded by dark radiations to either side of the chromo- somes are the "asters," so-called from their star-like appearance. Biologists are still in the dark as to the cause of this wonderful process of cell division. In certain respects it closely resem))les an electro- magnetic phenomenon, the poles of the magnet being located at the centers of the asters. These chromosomes are more delicate than the finest filament of a sjjider 's web. Fig. B is magnified 3,000 times, the others 1,500. After Wilson, "Atlas of Fertilization and Karyokinesis of the Ovum. ' ' Bi/ pcrminKion of the Macmlllan Company. chromosomes from one another so that different sex cells receive different chroinosonie combinations, then an ideal arrangement exists in the cell, for realization of the Men- del ian results. Referring to the case of the tall and dwarf peas, let us suppose that both partners in the cross are "pure," The Role of the Chromosomes 205 T t T It Tt t It tt e. g., that all the germ cells of the tall pea carry the deter- miner for talliiess (T) and all those of the dwarf pea the determiner for dwarf ness (t). If now we cross the tall (T) with the dwarf (t) we shall have in the cells of the hybrid both T and t, and the resnlt will be a tall pea (since tallness* dominates dwarfness) carrying latent the determiner for dwarfness. Before the germ cells of the hybrid are ready for fertiliza- tion they must undergo a process of ripening or maturation in the course of which the chromosomes of each are reduced to one-half the number in the l)ody cells of the species. This reduction is effected by the union of the chromosomes in pairs and their subse(iuent division as apparently single, though in reality double elements. One of these divisions, kiiown as the "reducing division" is as- sum,ed to separate the paired elements from each other. If now we assume that the determiner for tallness be carried by one chromosome and that for dwarfness by another, and that these two chromo- somes pair with one another in the matu- ration of the germ cells of the hybrid, separating from each other in the reduc- ing division, then the germ cells of the latter will be of two kinds, e. g., those containing the T chromosome and those containing t. Now when the hybrids are crossed with one another there will be three possible combinations resulting from the union of their germ cells, in the fol- lowing ratio (ITT, 2Tt, Itt), which re- sults from the chance combination of T and T with t and t. These chance results may be demonstrated by a simple ex- periment. If four billiard balls, two black and two white, be shaken together in a box and drawn out in pairs, one- fourth of the drawings will be two blacks, one-fourth tAVO whites and one-half a black and a white. If then the behavior of the chromosomes at the time of maturation and fertilization is as assumed, and if secondly the chromosomes carry "deter- miners" (whatever they may be) for the characters of the organism ; then the Mendelian results must follow as a mathematical necessity of the chance separation and recom- bination of till' chromosomes in the maturation and fertiliza- tion of the germ cells. We have used a iuntil)er of "ifs" in the above discussion. Are our conclusions based purely on assumptions? Let us see. In the ease cited we have assumed in the first place Diagram to illus- trate inheritance of size in' the sweet pea. A cross of a tall with a dwarf pea produces 3 tall and 1 dwarf pea in the second generation. 200 Biology in America that chromosomes carrying: the alternative determiners for tallness and dwarfness pair with each other and later separate in the maturation divisions, goin 0 ^. It It 13 /# 7S- Photographs of Chrojiosomes From an insect magnified 1,500 times. The pair of sex chromosomes is shown at x in Fig. 3. In Figs. 14 and 15, which show the chromo- somes divided into two groups, each of which passes into a new cell, the larger one of the pair, which ' ' determines ' ' the female sex, is seen passing to the loAver group. After Wilson, ' ' Journal of Experimental Zoology, ' ' Vol. 6. Still stronger evidence of the behavior of the chromosomes as outlined above is afforded by that of the sex chromosomes, which have been found in a large and ever increasing number of animals. Like the devils in the herd of swine on the shores of Galilee, the number of hypotheses regarding the cause of sex, which have in times past infested the human mind, is legion. As early as the eighteentli century- Drelin- court enumerated 262 untenable theories of sex determination, and as Blumenbach aptly said, "Drelincourt's theory formed the 263rd." Since then, possibly as many more sex theories have blossomed and Avithered without bearing fruit. Recent investigation indicates that sex determination is in Nature's The Role of the Chromosomes 209 hands, and that tlio most wliich niaii can experimentally accomplisli is to intlnence tlie survival ratio between males and females. In many animals, including insects, myriapods, arachnids, nematodes, echinoderms, fowls, amj)liil)ians, rats, guinea pigs and man, difiPerences occur in the number or size of the chro- mosomes of the male and the female. In some cases one sex, usually the female, has from one to several more chromosomes than the male ; in others there is a size difference between two chromosomes of a corresponding pair, which consists in the female of two large chromosomes, in the male, on the Gynandromorph Fruit Flies Courtesy of Professor T. H. Morgan. contrary, of a large and a small element. The ** accessory" or sex chromosome may occur either free or attached to another chromosome, while the relative differences in size between the unequal members of a pair of sex chromosomes varies all the way from equality in the two members to absence of the smaller one. The process of sex determination in these forms is briefly as follows : In the reduction division in the maturation of the sex cells in the male, the members of the unequal pair of sex chromosomes separate from each other, the larger passing into one cell and the smaller into another cell; or one or more elements may pass into one cell, while its sister cell receives none or a smaller number. The details vary, but the general 210 Biology in Amryica result is tlio samo, namely, an uneven distribution of chromo- somes to (litiferent sex eells, judical in<>' clearly a separation of entire clirumosomes from one another in maturation, and the production of different kinds of sex cells as a result thereof. Now when a sperm carrying a larger nmnber of chromosomes, or a lai'ger member of an nnequal pair, unites with an egg, the resulting oftspring is a female; while those sperms which carry fewer or smaller chromosomes, upon fertilizing an egg, give rise to males. In most cases studied thus far the differential divisions occur in the male, the spei'm being of two classes, male and female producing; but in a few animals, notably birds, m( tl.s and butterflies, the eggs are of two classes and sex determina- tion occurs in the female. While the greatest mass of evidence available thus far indicates that sex is predetermined in the fertilized egg, there is some recent work which does not apparently agree with this theory. A consideration of this evidence however may best be deferred to a later chapter. There are also two sexual conditions of more or less common occurrence in plants and animals, which are dif^cult to explain on the basis of sex chromosomes. One of these, hermaphro- ditism, is of very general occurrence in plants and certain groups of animals; and the other, gynandromorphism, occurs occasionally in animals. In the former case both sex glands are normally present in the same animal ; in the latter vary- ing conditions of the glands occur, sometimes male, sometimes female, sometimes both are present, while externally the body may be of different sexes on opposite sides, or opposite ends, or one-fourth may differ from the remaining three-fourths;^ in fact, almost any mosaic of external sex characters may occur. Hermaphroditism is characteristic of most worms, and some molluscs, and occurs occasionally elsewhere. In vertebrates it is rare, l)eing characteristic only of the hagtish (Myxine). In mammals true hermaphroditism is not known, so-called hermaphrodites having only the external sex organs hermaph- roditic. Various hypotheses have been advanced to bring these conditions into line with the chromosome hypothesis, but thus far without any marked degree of success. By far the most valuable contribution of recent years to the chromosome theory of inheritance is the work of ^Morgan and his students at Columbia on the fruit fly, Drosophila. By a combination of breeding and cytological studies they have carried this theory almost to the point of fact. Droso- phila is a little fly, about half the size of the ordinary house fly, which breeds abundantly in decaying fruit and vegetables, The Role of the Chromosomes 211 and may be reared ad libitum on ripe bananas to whicb a little yeast has been added. The fly has many variable char- acters which are well marked and readily Mendelized. Tiie chromosomes also are well defined, so that it furnishes an exceptionally good subject for studies of this character. The fruit fiy has typically four pairs of chromosomes, and thus far more than 400 distinct characters have been found. Now if these characters has each its determiner in one of the chromosomes, it is obvious that each chromosome must A ►>* •;• #^^ '•^1 — lilMiTill m ■''I'll 'illllll ••••• B Diagrams Illustrating the Distribution cf the Sex Chkojisomes AT Maturation A, in the female; B, in the male; C, the resulting possible combina- tions in fertilization. A and B from Morgan, "Heredity and Sex," by permision of the Columbia University Press; C from Loeb, after Wilson. carry a large number of characters. That being so, all those characters which are lodged in one chromosome should be inherited as a unit. And that is precisely what happens in many cases, giving rise to the phenomenon known as "link- age." One of the best known examples of this is shown by certain sex-linked (sometimes incorrectly called "sex-limited" characters.) Fruit Flies The two uj)per figures show the male (right) and female (left) of the fryit fly. The six lower figures show some of its 200 ami uiore muta- tions, some of the most striking of which are shown by the wings. Note the wingless individual in the lower riglitliand corner, and the one with asymmetrical wings just above. By their extensive studies of this humble insect, Professor Morgan and his students have added vastly to our knowledge of tlie laws of inheritance, which luild true not only for lower animals, but for num himself. After Morgan, "Heredity and Sex, ' ' By permlf:xion of the Cohimhia Univcrk-iii/ Press. 212 The Hole of the Chromosomes 2l3 Usually the fruit fly has red eyes, but occasional individuals occur with white eyes. If a red-eyed male be mated with a white-eyed female the offspring will be of two classes of approximately equal numbers, namely, red-eyed females and white-eyetl males. If now the first generation be inbred, four classes will appear in the second generation, of approximately equal numbers each, namely, white-eyed and red-eyed nuiles and females. If the reciprocal cross be made, i. e., white- eyed males by red-eyed females, the results will differ depend- ing upon the purity or impurity of the mother in respect to eye color (i. e., whether or not she carries the white-eye color latent). In the former case (the mother pure red) the first generation will all have red eyes, while the second generation, xY XX xY^Xx XY Xx Xx XX XY xY XX Xx XY xY Diagrams Eepresenting the EOle of the Chromosomes in Deter- mining Sex and Eye Color in the Fruit Fly The female of this fly carries a pair of chromosomes, represented by XX or XX in the diagrams, and the male a pair differing in respect to one member, thus represented as XY or xY. The factor for red eye color is represented as carried by X. Thus a red-eyed female has the formula XX or Xx and a white-eyed female xx, while red-eyed and white-eyed males are respectively XY and xY. In the right-hand diagram is shown a mating between a white-eyed male and a red-eyed female, all of the offspring of which are red-eyed. If these are mated with each otlier, four kinds of offspring result, which are sliown in the third row, all the females having red eyes, while half the males have white eyes. The reciprocal cross and its results are shown in the left-hand diagram. resulting from inbreeding the former, will have red and white eyes in the ratio of three to one. In the latter ease (the mother red-eyed with white latent) the results will be the same as those obtained by inbreeding the first generation of the red-eyed male by the white-eyed female cross. Sex in the fruit fly appears to be determined by a pair of chromosomes, which differ slightly in form and size from the others. This pair is called the XX pair in the female and the XY pair in the male. 214 Biology in America The results of the crosses above described can be most readily explained by assnining that one of the X chromosomes cariics the determiner for r(\l eye color and another X the determiner for white. They are shown graphically in the accompanying diagrams, in which the chromosomes carrying the determiner for red eyes ai-e shown as capitals, and those carrying the white eye determiner as small letters. Many other cases of sex-linked inheritance occur in animals, notably in moths, fish, birds and mammals, including man. In the latter, color blindness and hfemopliilia (imperfect clot- ting of the blood causing continuous How from wounds) are examples, although the manner of inheritance here is slightly different than that of eye color in the fruit fly. While the phenomena of linkage are clearly shown in the fruit fly, not only in the eye color but also in color of wings and body, size of wings, etc., the linkage in many cases is imperfect, some of the combinations of characters in the off- spring being different from those shown by the parents. Some fruit flies have vestigial wings and black bodies, while the ordinary type has long gray wings and a light yellow body, banded with black on the abdomen. Black body and vestigial wings tend to stay together in inheritance, indicating that their determiners are both lodged in the same chromo- some. But there are some exceptions to this rule. If a black fly with vestigial wings be crossed with one having long gray wings, the offspring will all have long gray wings, this type dominating the former. If now we "back cross" these offspring with the black vestigial parent, we obtain a curious result. If on the one hand we back cross a hybrid male with a black vestigial female, we obtain only black vestigial and gray long flies. The characters have "stuck together," com- ing out of the cross in the same combination in which they entered it. The linkage is perfect and the evidence is strong that the determiners for the characters tested are lodged in the same chromosome (black vestigial in one, gray long in another), which retains its identity throughout the matura- tion and fertilization processes. But if, on the other hand, we back cross a female hybrid and a black vestigial male we obtain a very different result; namely, 41.5% of black ves- tigial and gray long offspring respectively, and 8.5% of black long and gray vestigial. In other words, some of the charac- ters have become mixed in the shuffle and the cards are not dealt "according to Hoyle." Is such a result a fatal blow to the chromosome hypothesis ? On the contrary it furnishes indirectly one of the strongest evidences in its favor. We have seen above that the chromosomes pair with one I The Rule of the Chromosomes 215 another in maturation and then separate in the reduction division, so that dififerent germ cells receive different contri- butions. We have not however considered how the chromo- somes pair, whether end to end, or side by side. INIuch dis- pute has arisen over this question, which is probably due to the occurrence of different methods in different species. In some cases at least there is definite evidence of a side by side conjugation or " parasynapsis, " and in some of these it has been shown that the chromosomes do not lie parallel but wind about one another, forming a more or less twisted braid. When this occurs it is probable, although not definitely proven, that in separating the chromosomes do not unwind but rather pull apart irrespective of the twist, so that a part of one chromosome may now be switched over into another chromo- some and vice versa. This phenomenon of "crossing over" as it is called, would readily explain the 8.5% of gray vestigial and black long files obtained in the last experiment ; for if the chromosomes carrying the black vestigial and gray long determiners were occasionally to wind about each other and then separate without untwisting the determiners would be apt to get mixed up and find themselves in the wrong pews, so to speak. Why this should occur only in the female and not in the male is a problem. Possibly more extensive experi- ments would show it to occur in the male also. However, the lack of cross-overs in the male of another species of Droso- phila (viriles) suggest that it is a constant feature of this genus. Now if this explanation of crossing over be correct, we should expect those characters to cross over most frequently, the loci of whose determiners in the chromosomes are most widely separated, for in the twisting, points at either end of a pair of chromosomes would be more apt to interchange places from one chromosome to the other, than closely adjoin- ing points. And as a matter of fact, great differences do exist in the amount of crossing over between diff'erent charac- ters. On the basis of these differences Morgan and his students have made a plan of the chromosomes, locating with a high degree of probability in tiny threads of protoplasm, possibly the diameter of the finest filameit of a spider's web, the determiners of more than two hundred characters already studied in the fruit fly. The fact that all these characters fall into four groups in respect to their linkages, thus corresponding to the four pairs of chromosomes in the fruit fly; and further, that the cal- culated separation between the extremes in each series, based upon the frequency of the cross-overs, corresponds to the relative lengths of the chromosomes, is very strong addi- ^o' 216 Biology in America tional evidence for the cliromosome hypothesis as outlined a])()ve. In the course of their experiments tlie students of the fruit fly were suddenly confronted with an unexpected, and at first sight unexplaiiuihle case, which seemingly set the chromo- some hypothesis on its head. As already explained, if a pure 0 0 VI I LOW. SPOT II 7 I.MHAL I I ..WHITF.iOMN. CMERKy I.U AnSOKllAL '.0 BKIU 14 7 CLUB ■ 100 SHlfTED •«.•• I mm V. ■»v» iniiM IV, f 0!>EPIA -loo DACHS :S.U PINK PEACH •■MBOSr.VJOTT. '1 ''.WOftULA. Chromosome ATap Hhowing Distkiiuition of Linked Characters in The Fruit Fly After Morgan, "Heretlity and Sex." By permission of the Columbia University Press. white-eyed female be mated to a red-eyed male, red-eyed daughters and white-eyed sons in approximately equal num- bers are the result. But in one set of experiments this cross produced, in addition to the expected classes of . offspring, about 2.5% of white-eyed females and an equal number of red-eyed males. Such a result is readily explainable how- ever "on the assumption that the two X chromosomes of the The Role of the Chromosomes 217 female stick together in the reduction division, so that one class of eggs receives two X and the other none. A detailed analysis of all the possible combinations resulting from snch a case is rather too complicated for consideration here. Suffice it to say that the unexpected class of white- eyed females could be obtained by tlie fertilization of an XX egg by a Y sperm, and that of red-eyed males by the union of an egg lacking an X with an X sperm (the X being the important chromosome in sex determination, the Y ai)i)arently l\. I\ ^.^ /»^ Diagrammatic Kepresentation of the Chromosomes of the Fruit Fly The female (left) and male (right). The chroinosomos are shown in pairs, the sex jjairs being indicated by XX (female) and XY" (male) respectively. In the lower figuie is shown tlie peculiar case of a female carrying 2 X and 1 Y, owing to the failure of the 2 X to separate from each otlier in the ripening divisions of the egg. This condition explains certain unusual results found by Morgan and his students in bree: things, or only the more superficial are determined by the latter, cannot at pres- ent be said. In this tinj'' workshop of the cell wonderful things are taking place. Here is recorded the liistory of the past, and here is meted out the fate of generations yet unborn. CHAPTER VIII Experimental biology continued. Influence of environment in determining the development of organisms. Effects of temperature, light, moisture, chemicals and food upon the form of ammals and plants. The control of sex. And what of the development of this marvelous cell ? What hand glides the growth of the future organism in all its wonderful detail from this apparently simple, but unspeakably complex drop of protoplasm? Is it predestined, or is it plastic, to be molded by the experimenter at his will 1 These two possibilities are in no wise incompatible with each other. While the pattern of the cloth may be fixed, the form of the garment to be shaped therefrom is as variable as the caprice of fashion. Nor can the former be permanently fixed, unless evolution is a myth. As we have already seen in IMendelian inheritance the char- acter determiners are apparently distributed according to the laws of chance. But there is evidence showing that this dis- tribution can, to some extent at least, be controlled. If the female fruit i\y be exposed to temperatures ranging from 50° to 86° C. at a certain period during the maturation of her germ cells, it is found that the amount of crossing over between two factors may be increased by more than 100%, That external factors may profoun(ily influence Mendelian results has been clearly shown by Tower. The genus Leptinotarsa, of which the common potato beetle is a member, shows several color variations, which have been designated as species. When the female L. signaticollis is crossed with the male L. diversa at an average temperature of 75°-79° F. and a relative humidity of 75%, the hybrid offspring fall into two distinct groups of practically equal numbers, one of them indistinguishable from the mother and the other intermediate between the two parents. The former group breeds true for several generations ; but the latter when inbred give the typical Mendelian ratio of 1 signaticollis, 2 intermediate and 1 diversa, the first and last of which breed true, but the second continues to split up in further breeding, into the two parent and the intermediate types. If however the crossing be done at an average temperature of 50° to 75° 219 220 liioloyii ill America F. aiul ivl;itivc linmidity of 50-80% only tlic intonnediate form is obtainod. Not only ai'o llioso rosidts jriven by dif- ferent pairs of elosely related individuals, brothers and sistei-s, l)ut 1h(" same pair wlien mated under different conditions give ditfereut I'esults. While ^lendelian eliaraeters are evidently represented by definite determiners in the germ cells, there is abundant evi- dence that the development of these characters can be con- trolled by enviroument. There is a sex-linked dominant chaiacter iti Drosophila known as abnormal abdomen, in which the usual black bands upon tiie abdomen are irregular and broken and may even be absent. That this character depends on the type of food (whether wet or dry) for its development may be shown by tiie following experiment. If an abnormal male be crossed with a normal female and the larvae fed on wet food, the daughters will be abnormal and the sons normal ; but if the food be drv^, both daughters and sons will "be noi-mal. From these latter daughters however abnormal off- spring may be obtained if the conditions are favorable, show- ing that the determiner for abnormality is present, regardless of external conditions, but the development of the character itself is dependent upon tliis latter factor. The influence of environment in determining the form of the individual animal or plant is so well known as to be connnonplace. Food, temperature, pressure, moisture, chem- icals, radiation may, one or more, so profoundly change the development of an organism that two differently cultured individuals may not be recognizable as members of the same species. The effect of environment on individual development is perhaps nowhere more strikingly shown than in many species of mountain plants, which range froni the low moist valleysi to the high arid slopes above timber line. Seeds of the same species will produce in the former situation tall stemmed plants, with large thin leaves, small roots and pale flowers, which require from two to three months to mature seed ; while in the latfer environment they develop plants with short stems, small, thick leaves, and bright colored flowers, which set seed within a few weeks after the blossoms open ; all of which, possibly excepting the flower color, are adaptations to their different environments. A test of the influence of the environment upon plants has been made by the Department of Hotanical Eesearch of the Carnegie Institution, by the introduction of various species of ])lants into areas having very different climates, in the hot dry . Appleton and Company. While Plutarch's information was i)robably faulty, viewed in the light of modern research, his statement nevertheless sliows the belief of his day in the controlling influence of heredity in human life. 257 258 Biology in America luodilird by oilier trails) in the make-up of the organism. The basis of this persistence we liave already seen to bo the chromosome. In those cases in which one character domi- nates anotlier (tallness vs. dwarfness in peas, color vs. al- binism in animals, etc.), we have the phenomenon known as latency, in which the determiner of a character may be passed along for several generations, without the character itself coming to expression. In such cases the character is definite and the individual is distinct in respect to its pos- session. There is no uncertainty for example, as to whether InHEKITANCE of COLOIi IN THE FoUR O'CLOCK F], Fo, first and second generations. From Morgan, Stiirtcvtint, Mul- ler and Bridges, "Mechanism of Mendclian Inheritance." By permission of J. B. Lippincott Company. a guinea pig is spotted or uniform in color, or a man's liair is curly or straight. There are cases however in which the organism is neither "fish, flesh, nor good red herring," or speaking scientifically dominance is imperfect or incomplete. The four o'clock (INlirabilis jalapa) has a white- and a red- flowered race, which when crossed produce plants with pink flowers. When these pink-fiowered plants however are bred inter se they produce 1 red to 2 pink to 1 white offspring, the firet and last classes of which breed true, while the mid- dle class when inbred continues to "throw" red, white and pink plants in the above ratio. A crude chemical analogy to these phenomena may be made in the following way : At Mendelism 259 ordinary temperatures chromic sulphate forms a violet-col- ored solution in water, but at lower temperatures the salt crystallizes out leaving the water colorless as before. A con- centrated solution, deep violet in color, may be taken to rep- resent the color of the red-flowered four o'clock, while water may represent the color of the white-flowered variety. By mixing the concentrated solution and water in equal quanti- ties, a solution of light violet color is obtained, which may represent the pink-flowered hybi-ids of tlie first generation. If this dilute soliilion be now divided into four equal parts, Inheritance in Andalusian Fowl P„ parents; F^ and Fj, the first and second generation offspring of the cross. From Morgan, "The Physical Basis of Heredity." By permission of J. B. Lippincott Company. to one of which a sufficient volume of salt be added to restore the original color, while two are left unchanged and the fourth is cooled, thereby separating the salt from the water and leav- ing the latter colorless, a superficial analogy to the phenom- ena of color inheritance in the four o 'clock is obtained. I say ''superficial" or "crude" analogy, because the physical proc- ess outlined above is far too simple to represent the compli- cated bio-chemical processes involved in that of inheritance. One of the liest known cases of imperfect dominance is that shown by Andalusian fowls, although as we shall see this case is not strictly comparal)le to the preceding. The "blue" Andalusian is a chicken in which black is mixed with white 260 Biology in America in very small flecks. If two blue Andalusians are crossed they produce one black, two blue, and one white splashed with black ; while when the first and last of these offspring are interbred, only "blue" fowls result — a Mendelian pro- ceeding, which is strictly "according to Hoyle." Here we have two factors, black and white, which instead of blending in the cross enter into it unmodified, but distributed in such a way as to produce a result different from that of either parent. Furthermore, the ' ' recessives ' ' Tiere carry a little of the "dominant" factor in the splashes of black on a white background. Inheritance of Ear Length in Eabbits Figs. A and B, parents; C and D, offspring of the first and second generations, respectively, with ear lengths intermediate between those of the parents. From Castle, "Genetics and Eugenics." By permission of Harvard University Press. A closely similar case is that of red and white cattle, which, when interbred, produce "roan" offspring, these latter in their turn "throwing" red, roan and white in the proportion of 1:2:1. In some cases of supposedly complete dominance careful measurements show that the dominant factor is slightly modi- fied by the recessive. Thus when wild fruit flies are crossed with those having small wings, the long wings of the for- mer dominate the short wings of the latter ; but not com- pletely, for the wings of the hybrid average slightly less than those of the wild parent. And this gives rise to the ques- tion whether dominance is ever perfect, even in those cases in Mendetism 261 which it appears to be so. The fundamental fact in Men- delian inheritance then is segregation, not dominance. In the cases just cited segregation is perfectly evident in the second generation, but there are cases in which it is not. There is a breed of domestic rabbit known as the "lop- eared" rabbit in which the ears are very long and pendant. When such a rabbit is paired with the ordinary kind, the ears of the hybrid are intermediate in length, and this condi- tion persists in succeeding generations. Is this not a true 3 J3 Inheritance in Guinea Pigs Figs. A and B, the parents; C, the first generation, the second gener- tion containing animals of all four types, A, B, C and D. From Castle, ' ' Genetics and Eugenics. ' ' By permission of Harvard University Press. "blend" between different degrees of ear length? The mu- latto is another example of an apparent blending of charac- ters in inheritance. Is a different interpretation possible? There are certain varieties of corn with yellow kernels, which when crossed with white corn give yellow offspring. These latter, when mated with each other, give, instead of the usual Mendelian ratio of 3 :1, fifteen yellows to one white. This is exactly what we should expect if there were two char- acters involved in producing the color of the yellow variety, for when two pairs of factors are involved in a cross — i.e., tall, red peas x dwarf whites; long-winged, gray fruit files x black, dwarf -winged ; black, rough ("rosette") haired guinea B b B BB Bb b Bb bb BP Br bR br Bf? BR BR Bp BR bR BR br BR Br Bfr Br Br Br bR Br br Br bR BR bR Br bR bR bR br bR br BR br Br br bR br br br BRS BR3 BrS Brs bRS bRs brS brs BRS BRS BRs BRS BrS BRS Brs BRS bRS BRS bRs BRS brS BRS brs BRS BR5 BRS BRs BRs BR5 BrS BRs Brs BRs bRS BRs bRs BRs brS BRs brs BR« BrS BRS BrS BRs BrS BrS BrS Brs 3r5 bR5 BrS bRs BrS brS BrS brs BrS Brs BRS Brs BRs Brs BrS 3rs Brs Brs bRS Brs bRs brS Brs brs Brs bRS BRS bRS BRs bRS BrS bRS Brs bRS bRS bRS bRs bRS brS bRS brs bRS bf?s BRS bRs BRs bRs BrS bRs Brs bRs bRS bRs bRs bRs brS bRs brs bRs brS BRS brS BRs brS &r5 brS Brs brS bRS brS bRs brS brS brS brs brS br5 BRS brs BRs brs BrS brs Brs brs bRS brs bRs brs brS brs brs brs Diagrams Illusteating Inheritance in Guinea Pigs Of one, two and three pairs of characters respectively. B=black, b = white, R = rough coat, r = smooth coat, S = short hair, and s = long hair. The second generation results are, respectively, 3 black, 1 white; 9 black-rough, 3 black-smooth, 3 white-rough, 1 white-smooth; and 27 black-rough-sliort, 9 black-rough-long, 9 black-smooth-short, 9 white-rough-short, 3 black-smooth-long, 3 white-smooth-short, 3 white- rough-long, and 1 whitesmooth-long, which result from the summation of the combinations in the above diagrams. 262 Mendelism 263 pigs X albino, smooth-haired; dark, curly x light, straight hair in man, etc., there is only one out of sixteen offspring in the second generation in which both of the recessive factore come to expression. Thus in the case of black rough x white smooth hair in guinea pigs, only one in sixteen second gen- eration offspring will be white with smooth hair. This re- sult follows as a mathematical necessity of the chance com- bination of two pairs of characters, just as the 3 :1 ratio re- sults from the combination of one pair. Similarly if three pairs of characters are involved in a cross, i.e., black, rough, short and white, smooth, long hair in guinea pigs, there will be only one out of sixty-four offspring in the second genera- tion, which will show all three recessive characters. And if four pairs are involved, only 1 in 25G, etc. A graphical rep- resentation of these results is given in the accompanying dia- grams, which make sufficiently clear the chance combination of characters in Mendelian inheritance. That two factors may be involved in the production of an apparently simple character is conclusively shown in the case of the sweet peas described by the English naturalist, Bate- son. Bateson found that when two white peas were crossed they produced colored offspring, which he interpreted as due to the presence of two factors, one in each of the white par- ents, which, uniting in the cross, produced a colored pea. The results obtained by inbreeding these colored offspring, details of which need not figure here, showed clearly that two pairs of Mendelian factors were concerned. In the case of the corn cited above a single factor for yellow produces the same apparent result in the first generation, as do two fac- tors, but in a variety of oats described by the Swedish breeder Nilsson-Ehle, a different result is obtained. In this case a variety of oats characterized by dark brown glumes or husks, when crossed with a white-glumed variety produced in the second generation nine plants with dark brown, six with light brown, and one with white glumes. This result may be ex- plained as due to the presence of two factors for brown in the dark-glumed plants, one only in those wath light brown glumes and none in those with white glumes. It is obtained in the same way as in the second diagram, two factors for brown being substituted for black, rough. The theory that two or more factors may in some cases com- bine to produce an apparently simple result is known as the "multiple factor" hypothesis. In the case of lop-ear in rab- bits and color in man, the results are readily explicable by means of this hypothesis on the assumption (1) that several factors are involved in the production of the character in question, (2) that in order to produce the maximum result 2G4 Biology in America the full number must be present, and (3) as a corollary to (2) if less than the full number are present the result will be more or less intermediate or "blending" between the maximum of the character and its total absence. Thus, let us assume with Davenport that the African negro contains four factors for blackness, while the white man has none. Two factors produce a "mulatto," one a "quadroon," and three a "sambo," while the "octoroon" and the "near- white" resemble the pure white, so far at least as skin color is concerned. The offspring of a cross between a full black and a white will be a mulatto containing two factors for black. If the latter marry a white the offspring will be of three classes, 1 mulatto, 2 quadroons and 1 " near- white. " A cross between two mulattoes will result in 1 black, 4 sambos, 6 mulattoes, 4 quadroons and 1 "near-white," a result readily derived from the second diagram on page 262 if for the domi- nant factors we substitute the factors for negro color BB. Thus the chance of either original color (black or white) ap- pearing in the second generation is only 1 :16, Avhile there are 14 chances of an intermediate or "blending" color appearing. If more than four factors are involved, the chance of either of the original characters reappearing in the second generation of a cross will be correspondingly lessened. Thus if six factors (3 pairs) are involved the chance will be 1 :64, with 8 fac- tors (4 pairs) 1:256, with 10 factors (5 pairs) 1:1024 and with 12 factors (6 pairs) only 1:4096. Such an hypothesis readily explains on a Mendelian basis the case of the lop- eared rabbit if we assume the necessity of several factors in the production of a superficially simple, but fundamentally complex result. An interesting corollary of Davenport's main thesis, founded on a study of more than a hundred negro-white fam- ilies in Jamaica, Bermuda and Louisiana, is the overthrow, or at least serious weakening of the popular belief that a mar- riage of two "near-whites" may result in children of negro color. His results indicate that the offspring of a cross be- tween persons of negro ancestry, can in no event have more than the sum of the factors for black of the two parents; so that the children of two "near- white" parents can never produce other than w^iite children, while a near- white and a quadroon can at most have only quadroon children. The basis of Mendelian inheritance is, as we have seen, the chance combination in calculable proportions of definite char- acters, which are segregable from one another, and do not form permanent "blends." How well do the calculated or Mendelism 265 "expected" results agree with those actually obtained in breeding experiments? Obviously the larger the number of individuals the greater the probability of agreement between expectation and realization, and when the former is small, say 1 :64 or 256, a very large number of tests may be neces- sary before it can be realized. While the correspondence be- tween expectation and realization is seldom exact, the agree- ment is nevertheless generally close enough to furnish a sub- stantial basis for the theory. A few random examples may be cited. In the common weed, the shepherd's purse (Bursa bursa-pastoris) there is a variety with round and another with triangular fruits. The latter dominates the former and is determined by two factors. Therefore the expectation for round vs. triangular fruits is 1 in 16. In a total of 2907 sec- ond generation hybrids Shull found 2782 with triangular and 125 with round fruits, a ratio of 23.3 to 1, as compared with an expectation of 2725 of the former and 182 of the latter, a ratio of 16 to 1. In crosses between quadroons and whites Davenport found out of 99 children there were 42 "near- whites," 56 quadroons and 1 mulatto, whereas the expectation was an equal number of "near-whites" and quadroons and no mulattoes. In another series of matings between quadroons he found out of a total of 134 children, 24 "near-whites," 87 quadroons and 23 mulattoes, the expectation being 3.5, 67 and 33.5 respectively. Any rabbit breeder knows what a mixture of colors and markings he may expect in his product. Professor Castle, who has recently analyzed the color varieties of rabbits, clas- sifies them as follows: gray, black, yellow (with white belly and tail), sooty (a variety of yellow with the belly and tail colored like the rest of the body), and white. The first four of these may in turn be modified by intensity of pigment (dark or light), by its uniformity, or lack of uniformity (spotting), and the white may be either wholly so or cream colored with black nose, ears, feet and tail (the so-called "Himalayan" of the fanciers). This makes a total of eighteen varieties in all, which when interbred can theoretically produce 243 different varieties, different, that is, from the viewpoint of their hereditary structure, not in their external appearance, for things "are (very often) not what they seem" in genetics. Many of these varieties have been obtained, others still re- main to be "created." There are thirty-two possibilities in gray rabbits, many of which are already known. As a com- parison of the results realized with those expected when one variety of these grays is crossed with itself, the following table from Professor Castle 's paper is of interest : 266 Biology in America Color Observed Expected Gray 24 27 Black 8 9 Yellow 16 9 Sooty 2 9 Blue-gray 8 3 ]31ue 2 3 Cream 3 3 Pale sooty 2 1 Another cross between two grays of a different sort gave the following results as compared with those to be expected: Color Observed Expected Gray 20 27 Black 8 9 Yellow 12 9 Sooty 1 3 Blue-gray 7 9 Blue 4 3 Cream (?) 3 Pale sooty 1 1 White 8 21 "The categoiy yellow is probably too large because of a failure on our part to discriminate between yellow and cream, a difference which at first we failed to record. It is possible also that albino young were not enumerated in all the rec- ords which we have combined, and so albinos are apparently deficient in number. "2 What is the new science of genetics doing for the world in a practical way? It is scarcely necessary to suggest that a knowledge of inheritance is fundamental to the practice of breeding animals and plants. But the new genetics is scarce two decades old, while during the preceding centuries man has produced the wonderful diversity in domesticated varie- ties which we know today. Has all this earlier improvement been due to chance alone? Is the scientific breeder a prod- uct of the last twenty years? Hardly, for we are using today the same principle of selection which has been the magic wand of the breeder in the past. But to this prin- ciple has been added more accurate knowledge of kinds of variation and the laws of their inheritance, so that today the breeder can work more surely and swiftly than his predeces- sor in the past. ='(;:istlo " Inhoritaiicc in TJabliils," Ciriiegie TiistitutioTi, Publica- tion No. 114, p. 5'J. Mendelism 267 A few examples of what breeders have accomplished may be of interest. Professor Castle has shown that there is in guinea pigs a factor which restricts black and brown pigment to the eyes, while yellow pigment is unaffected by it. When a brown pig is crossed with a black-eyed yellow one con- taining this factor, some of the offspring receive it in com- bination with the factor for brown and are consequently brown-eyed yellow — a new "creation" unknown before Cas- tle's experiments were made. "While brown-eyed yellow A Herd of Hornless Cattle Hornlessness may be bred in cattle by proper attention to Mendelian laws. Courtesy of the U. 8. Bureau of Animal Industry. guinea pigs may not mean any more to the fancier in dol- lars and cents than do black-eyed yellow ones, nevertheless the experiment demonstrates the possibility of scientific breeding in the production of varieties which do have eco- nomic value. The presence of horns on a vicious bull, or a refractory cow, has always constituted a serious menace to tlie owner's peace of mind, and often such animals have to be dehorned. But the breeder has a better means for dehorning his stock, for lack of horns in cattle is dominant to the horned condi- tion, and by crossing horned cattle with hornless ones of other 268 Biology in America breeds it is possible to produce hornless cattle in breeds which are usually horned. The "upland" cotton of the South has a short fiber which is worth much less than the long fiber of the "sea island" variety. The former however is a much better bearer than the latter, and has a pod which opens widely, rendering the cotton more easy to pick, while the latter is more easily ginned, tlie fibres not adhering so tightly to the seeds. By crossing "upland" and "sea island" plants, the U. S. Department of Agriculture has produced a prolific race of "sea island" cotton, with wide-opening bolls, thereby adding hundreds of thousands, if not millions of dollars annually to the value of the cotton crop in the United States. We are all familiar with the frequent alarms that come from Florida to the effect that the orange crop is a failure due to some recent freeze. And we can never be quite sure whether the freeze is genuine, or faked for the purpose of making us pay a premium for Florida's delicious fruit. Oft- times however the danger to the orange grower is very real, and many a sleepless night he spends tending the bonfires in his groves to save his crop from ruin. And so the plant breeder has come to his rescue and by crossing the hardy, frost-resistant orange of Japan with the Florida orange, has produced a fruit known as the citrange with many of the good qualities of the orange and yet capable of resisting a temperature as low as 8°F. These instances might be multiplied many-fold, but they must suffice as a suggestion merely of the possibilities open to the scientific breeder of the future. But in no direction has Mendelism better served than in the development of the new science of eugenics, concerning which we hear so much today, both of fact and fancy. The germ of the eugenic idea is contained in the witticism of Oliver Wendell Holmes, who, when asked for advice on how to reach a good old age, replied that the best way was to select long- lived grandparents. It is indeed true that, as Kimball says in his fascinating essays on the "Romance of Evolution": "The scientific way of selecting a wife and falling in love, going first to a phrenol- ogist and getting a chart of her skull with all its bumps, com- bativeness, destructiveness and the like marked upon it, then to the physiologist to find out whether her temperament is bilious or phlegmatic, then to the family physician to make sure she is free from scrofula and consumption and then to the woman herself to exchange, not vows but charts and cer- tificates, is not certainly on the face of it quite so romantic as where Arthur and Amelia fall in love with each other at Mendelism 269 first sight, and after the requisite number of haunted castles, diabolic rivals and cruel partings rush exactly at the end of the second volume ecstatic into each other's arms. But this destructive and prosaic side of science is only its beginning, only the clearing away of the old rubbish to lay the founda- tion of a nobler and fairer structure. Its first object is in- deed truth, truth whatever the ugliness and humility of its outlines may be. But truth and beauty in their final result are always sure to blend together and always nourish and require in those who follow them to the end something at least of their own grand and heroic qualities. Truth here, the same as elsewhere, is found to be stranger than fiction, the world effect, however prosaic its surface may be, to have roots which go down to infinite depths of mystery. And sci- entific discovery dealing with these truths and facts has come already to a revelation, lit up the world too with a light, that for romance and wonder surpasses all that was ever seen or dreamed of in the grandest days of old. ' ' ^ We speak of eugenics as new and yet as a matter of fact the eugenic idea dates back to the time of Plato, who advo- cated in his republic the building of a better state by the elimination of the unfit, and who urged the appointment of a state official for this purpose. Since Plato's day many vi- sionary schemes have been suggested for the improvement of the human race, but the modern movement is due to the great English geneticist. Sir Francis Galton, who, in his "Hereditary Genius" published in 1869, pointed out the desirability of improving the human race. His suggestions fell upon stony ground, but with the confidence bred of con- viction he returned undaunted to the struggle, and the out- come of his efi^orts was the establishment of the Eugenics Laboratory of the University of London in 1905, which under the direction of Karl Pearson is collecting data on human inheritance, and publishing them in its "Treasury of Hu- man Inheritance. ' ' In America the movement for race betterment has been largely in the hands of the Eugenics Section of the Amer- ican Breeders' Association and the Eugenics Laboratory, a brief account of the work of which latter institution has been given in the chapter on American Biological Insti- tutions. In the following pages we shall consider briefly a few examples of human inheritance, both mental and physical, and the burden of the unfit which society has to bear, to- gether with an outline of what the practical eugenist pro- ^ Kimball, "The Eomance of Evolution," pp. 3-4. American Uni- tarian Association. 270 Biology in America poses for the amelioration of social ills and the building of a better Iminan race. The cases of the Jukes and the Kal- likaks on the one hand, and the family of Jonathan Edwards on the other, are classics and have been cited so widely as to require no repetition here. An equally instructive case is that cited by Goddard from his studies of the inmates of the New Jersey Training School for the Feeble-minded. The his- tory of this case is described by Goddard in the following words: "Here we have a feeble-minded woman who has had three husbands (including one 'who was not her husband'), and the result has been nothing but feeble-minded children. The stoiy may be told as follows: "This w'oman was a handsome girl, apparently having in- herited some refinement from her mother, although her father was a feeble-minded, alcoholic brute. Somewhere about the age of seventeen or eighteen she went out to do housework in a family in one of the towns of this State (New Jersey). She soon became the mother of an illegitimate child. It was born in an almshouse to which she fled after she had been discharged from the home where she had been at work. After this, charitably disposed people tried to do what they could for her, giving her a home for herself and her child in return for the work which she could do. However she soon appeared in the same condition. An effort was then made to discover the father of this second child, and when he was found to be a drunken, feeble-minded epileptic living in the neighborhood, in order to save the legitimacy of the child, her friends (sic) saw to it that a marriage ceremony took place. Later another feeble-minded child was born to them. Then the whole family secured a home with an unmarried farmer in the neighborhood. They lived there together until another child was forthcoming which the husband refused to own. When finally the farmer acknowledged this child to be his, the same good friends (sic) interfered, went into the courts and procured a divorce from the husband, and had the woman married to the father of the expected fourth child. This proved to be feeble-minded, and they have had four other feeble-minded children, making eight in all, born of this woman. There have also been one child stillborn and one miscarriage. "... This woman had four feeble-minded brothers and sisters. These are all married and have children. The older of the two sisters had a child by her own father, when she was thirteen years old. The child died at about six years of age. This woman has since married. The two brothers have each at least one child of whose mental condition noth- ing is known. The other sister married a feeble-minded man Mendel ism 27 1 and had three children. Two of these are feeble-minded and the other died in infancy. . . ,"* Not alone in her descendants, but also in her ancestry and collateral relatives does this woman illustrate the influence of defective germ plasm in a family. Of twenty-seven chil- dren, one or both of whose parents were feeble-minded, twen- ty-four showed the defect, the character of the other three being unknown. The following eases cited by Davenport are further exam- ples of the blight which defective inheritance so often casts upon a human life. This case "is an eleven year old boy who began to steal at 3 years; at 4 set fire to a pantry resulting in an explosion that caused his mother 's death ; and at 8 set fire to a mattress. He is physically sound, able and well informed, polite, gen- tlemanly and very smooth, but he is an inveterate thief and has a court record. His older brother, 14, has been full of deviltry, has stolen and set fires but is now settled down and is earning a living. Their father is an unusually fine, thoughtful intelligent man, a grocer, for a time sang on the vaudeville stage ; his mother, who died at 32, is said to have been a normal woman of excellent character. There is how- ever a taint on both sides. The father's father was wild and drank when young and had a brother w^ha was an in- veterate thief. The mother's father was alcoholic and when drunk mean and vicious. Some of the mother's brothers stole or were sexually immoral, "A healthy man employed on a railroad as a fireman and using neither alcohol nor tobacco married a woman who was born in the mountains of West Virginia near the Kentucky line and who shows many symptoms of defectiveness. She has epileptic convulsions as often as two or three times a week, has an ungovernable temper, smokes, chews and drinks, is illiterate and sexually immoral. There are 10 children, of whom something is known about seven. One died early of chorea, one of the others seems normal ; one has killed two men including a policeman; another had her husband killed and lives with the slayer; one was an epileptic and cigarette fiend, convicted of assault ; another has hysterical convulsions and is afraid in sleep ; while still another has migraine. The combination in the fraternity of migraine, chorea, hysteria, epilepsy and sexual immorality and tendency to assault is striking and appalling. "A 10 year old boy who was precocious as a raconteur at 22 months, does well at school except for inattention ; is fond of reading and athletics, cheerful, and polite. But he prefers * '"'American Breeders Magazine," Vol. I, pp. 176-8. 272 Binlor/jf in Amrrica the companionship of okler, wild boys and cannot be weaned from thom. lie lies, iniiis up accounts in his parents' name, is acquiring bad sexual habits, and runs away from home. lie has two, fine, studious brothers. His father is a strong character and a successful lawyer, his mother an excellent woman, intelligent and firm. She has a brother who left home at 14 to seek a life of adventure. He finally settled down to a steady life. Their father's father was erratic. He loved Indian outdoor life, always used an Indian blanket and at over 70 years swam the IMississippi River. He traced back his ancestry to Pocahontas. He has another grandson, who is an unruly character with a roving disposition ; he joined the navy and his whereabouts are unknown ; his father was a lawyer and a fine character. "An intelligent physician with training abroad as well as in this country and of a good family (his brother is a college professor and his father a Methodist preacher) married a lady of good family, with much musical talent, but subject to migraine and formerly to chorea. They have two sons born in the best of environments. The younger is still in the kindergarten, seems wholly normal, truth-telling and lovable ; the other, now 13, developed normally, has had no convulsions, and lias never been seriously sick and ordinarily sleeps well. He has regular, refined features and a normal alert attitude and is very industrious. He attends Sunday school regu- larly, has excellent talent for music. At 3 years of age he walked to a nearby railroad, boarded a train and was carried 12 miles before the conductor discovered him; since then he has run away very many times. From an institution for difficult boys, where he was placed, he ran away 13 times. He escapes from his home after dark and sleeps in neighbor- ing doorways. His mother used to make Saturday a treat day. She would take a violin lesson with him and spend the afternoon in the Public Library which he much enjoyed but he would slip away from her on the way home and be gone until midnight. He is an unconscionable liar. He con- tracts debts, steals when he has no use for the articles stolen and has been convicted for burglary. Much money and effort have been spent on him in vain. His mother's father (of whom he has never heard) was a western desperado, drank hard and was involved in a murder, but finally married a very good woman, and has 2 normal daughters in addition to this boy's mother." ^ As examples of the inheritance of physical defects may be cited that of deaf -mutism, hare lip and cleft palate, imperfect "Davenport, "Heredity in Kelation to Eugenics," pp. 85-90. Bj per- mission of Henry Holt and Company. Mendelism 273 clotting of the blood resulting in the persistent bleeding of wounds, cretinism or infantile imbecility and dwarfism, and many others. But the picture has also a brighter side, for physical and mental ability are inherited just as surely as are their oppo- sites. The families of the Edwards, the Lees, the Corbins and the Fitzhughs have put the stamp of beauty and of strength upon the face of America. The family of the great musician Bach included twenty eminent musicians, and twice as many of lesser eminence. Macaulay's father and grandfather, two uncles, a cousin and a nephew were all noted writers. The records of the Pomeroy family date back to 1630. "The first of the family in America was Eltweed Pomeroy at Dorchester . . . and later at Windsor, Connecticut. He was by trade a black- smith, which in those days comprehended practically all mechanical trades. His sons and grandsons, with few excep- tions, followed this trade. 'In the settlement of new towns in Massachusetts and Connecticut the Pomeroys were welcome artisans. Large grants of land were awarded to them to induce them to settle and carry on their business. ' ' The pecu- liar faculty of the Pomeroys is not the result of training and hardly of perceptible voluntary effort in the individual. Their powers are due to an inherited capacity from ancestry more or less remote, developed for generations under some unconscious cerebration.' There was Setli Pomeroy (1706- 1777) an ingenious and skillful mechanic who followed the trade of gunsmith. At the capture of Louisburg in 1745 he was a major and had charge of more than twenty smiths who were engaged in drilling captured cannon. Other members of the family manufactured guns which in the French and Indian wars were in great demand and in the Revolution, also, the Pomeroy guns were indispensable. 'Long before the United States had a national armory, the private armories of the Pomeroys were famous. There was Lemuel Pomeroy, the pioneer manufacturer of Pittsburg, stubborn but clear- headed, of whom a friend said : ' There would at times be no living with him if he were not always right. ' There was also Elisha M. Pomeroy of Wallingford, a tinner by trade. He invented the razor strop and profited much by its success. In the sixth generation we find Benjamin Pomeroy a suc- cessful lawyer entrusted with important public offices. 'But he was conscious of powers for which his law practice gave him no scope. He had a taste for mechanical execution and as a pastime between his professional duties undertook the construction of difficult public works — the more difficult the better he liked them. The chief of the United States 274 Biology in America Topogiaphit'al Engineers was a friend of Mr. Pomeroy and repeatedly eonsnlted liim in emei'gencies wlierein his extraor- dinary capacity was made useful to the government. By him were constructed on the Atlantic coast beacons and various structures in circumstances tliat had baffled previous attempts.' The value to this country of the mechanical trait in this one germ plasm can hardly be estimated. Especially is it to be noted that, despite constant out-marriages, it goes its course unreduced and unmodified through the genera- tions. ""^ Well, what is the eugenist "going to do about it?" In the first place gather data upon which to base a constructive program. While our knowledge of inheritance in plants and animals has grown by leaps and bounds in the past twenty years, and data concerning human inheritance are accumulat- ing rapidly, the science of genetics, and especially eugenics is yet in its infancy. Our knowledge of human inheritance is still very fragmentary; comparatively few characters have yet been studied, and these by no means exhaustively. Recog- nizing information as the primary need of the social student of today, the Eugenics Laboratory in London and the Eugenics Record Office at Cold Spring Harbor are devoting their energies chiefly to a study of the laws of human inheritance, with the ultimate view of formulating from those laws a con- structive program of eugenics, supported by a public opinion, alive on the one hand to the menace, and on the other to the splendid possibilities of human inheritance. But while gathering more information are we to sit idle and not use the information which we have? What can we "do about it" now? First of all, we need more sanity and less self-confidence, more cool calculation and less hot enthu- siasm. The advocates of the "rabbit theory" of society, who cry out from the house-tops against the suicide of the race, should realize that propagation is as dangerous as propaganda if the subjects thereof are unworthy or unfit. On the other hand, the advocates of "birth control" should not forget that "a little knowledge is a dangerous thing" and that knowledge of this practise by the selfish, the ignorant or the unwise might prove to be a match in the hands of a child. The fundamental principle of eugenics is the promotion of a better race by the marriage of the fit, and the elimination of the undesirable members of society by the prevention of their increase. But in a matter of so highly personal a nature as marriage, where personal tastes and emotions play so large a part, how is anything like scientific control possible? The only answer is that it is not possible, nor desirable. If men ' Davenport, locus citatus, pp. 55-57. Mendelism 275 and women chose their partners as they choose a pet dog or a suit of clothes, the divorce courts would have to work overtime. But on the other hand no one has the right to insure his own temporary happiness at the risk of the misery of those who are to follow him. And here is where eugenics has its major role to play — namely, in the education of the youth as to the inflexibility of inheritance, the methods of its operation, and their duty to generations yet unborn. The rights of the individual form one of the corner stones of a democracy, while those of society, or the group of indi- viduals, form the other. In so far as the former does not conflict with the latter it must be fully insured or democracy becomes an empty name, but no man has a right to personal freedom when that freedom encroaches upon the welfare of society, and one of the functions of eugenics is to preserve that welfare by preventing the increase of the feeble-minded, the alcoholic, the sexually immoral and the diseased — or in general, the unfit. The simplest and safest way in fact, is sterilization. This can be accomplished by a very simple and harmless operation in man, requiring only a few minutes of time and the use of a local anesthetic. In woman it is a more serious operation, but in neither case, if carefully performed, is it dangerous or productive of evil after-effects. Needless to say, the practise of sterilization should be surrounded by every precaution to protect the rights of the individual, and should not be practised except by expert and responsible sur- geons. Thus far eleven states have sterilization laws, though but few operations under these laws have as yet been per- formed. In some instances individuals have voluntarily sub- mitted themselves to the operation. The first of these to be adopted was the Indiana law, which is here quoted: "An Act, entitled, An act to prevent pro- creation of criminals, idiots, imbeciles, and rapists — providing that superintendents, or boards of managers, of institutions where such persons are confined shall have the authority, and are empowered to appoint a committee of experts, con- sisting of two physicians, to examine into the mental condi- tion of such inmates. "Whereas, Heredity plays a most important part in the transmission of crime, idiocy, and imbecility; "Therefore, Be it enacted by the General Assembly of the State of Indiana, That on and after the passage of this act it shall be compulsory for each and every institution in the State, entrusted with the care of confirmed criminals, idiots, rapists and imbeciles, to appoint upon its staff, in addition to the regular institutional physician, two (2) skilled surgeons of recognized ability, whose duty it shall be, in conjunction 276 Biology in America with the chief physician of the institution, to examine the mental and physical condition of such inmates as are recom- mended by the institutional physician and board of managers. If, in the judgment of this committee of experts and the board of managers, procreation is inadvisable, and there is no probability of improvement of the mental and physical condition of the inmate, it shall be lawful for the surgeons to perform such operation for the prevention of procreation as shall be decided safest, and most etfective. But this opera- tion shall not be performed except in cases that have been pronounced unimprovable: Provided, That in no case shall the consultation fee be more than three (3) dollars to each expert, to be paid out of the funds appropriated for the maintenance of such institution. ' ' The question of elimination of defectives, by preventing their procreation, leads to the delicate one of elimination of human misery by taking the life of children, so hopelessly deformed or diseased, that they can never by any possible chance be anything but sources of suffering to themselves, and of unhappiness to their friends. The practise of destroy- ing those infants considered unlikely to develop into vigorous men, and good soldiers is well known as the policy of Sparta in ancient Greece, and among savages infanticide has some- times been practised for a similar reason. In India the kill- ing of girl babies to save them the dishonor of remaining unmarried or of marrying below their caste, as well as to avoid the excessive expense incident to marriage ceremonies, was prevalent among many tribes previous to the middle of the last century, when it was terminated by the British Gov- ernment. Among civilized peoples infanticide is generally regarded as a crime equal to, or but slightly less than murder. Abortion, unless practised to save the life or health of the mother, is criminal, though of a much lower degree than infanticide. The logic of a distinction between a foetus a few days before birth and a baby a few days after, is some- what difficult however to appreciate. The reverence for human life has even extended to the dead body, so that in the early days of anatomy, cadavers for dis- section could only be obtained by devious means. The sacredness in which we hold life has led us to take every means for its preservation, even to abolition in many states and foreign countries of capital punishment, the forcible restraint of attempted suicides, and the most careful nurture of helpless cripples and hopeless idiots. Because of our reverence for human life we sometimes practise the most refined cruelty to those we love the best, a cruelty we would' not tolerate for a moment if practised upon the dumb brute. Mendelism 277 It was therefore with a feeling akin to horror that many- read in the public press in 1915 of the action of Dr. Haiselden of Chicago; who, with the consent of the child's parents, refused to perform an operation which would have saved to a life of suffering, an infant, which by his refusal was allowed to die. This question however is not one of eugenics proper, although closely related thereto. But it is one which the thoughtful student of human life will do well to ponder carefully. And yet a final duty of the eugenist is to combat those anti-social measures which put a premium on celibacy, and a discount on parenthood, such as the payment of non-living wages to workmen, the industrialization of women, the penalization of teachers for marriage or motherhood. A for- ward step in the right direction has been the payment by many states of mothers' pensions, while further action should be taken to relieve the mother during the early months of maternity from the necessity of bread winning. We have come already a long way in the paths of social righteousness, but the way is never-ending and the forces of selfishness, reaction and ignorance beset us on every hand, so that it behooves us to gird up our loins in order that we, like Paul, may ' ' run with patience the race that is set before us." CHAPTER XI Experimental biology continued. Mechcmisni versus vitalism. Physico-chcmistnj of vital processes, metalolism of ani- mals and plants. Is tliere one law for the living and another for the dead, or is tlie universe a unit in its working and all matter gov- erned by universal law? The former is the contention of the "vitalist," the latter of the "mechanist." What is life? Is it some inscrutable process, controlled by a "vital prin- ciple" operating outside the realm of physics and of chem- istry ? Or is it merely a special expression of the forces which control inorganic matter? Our only answer to these ques- tions is that we do not know. Neither the substance nor the energ}' of life has ever been analyzed, and the only way in which we can identify life is by its manifestations. What are these manifestations, and what light if any do they throw upon the ultimate nature of life itself? Firstly, what is the stuff of which living things are made? An analysis of living substances or protoplasm is exceedingly difficult if not impossible. In order to analyze it, it must be killed, and the readiness with which protoplasm breaks down into innumerable simpler substances leads us to suspect that after protoplasm is killed it is protoplasm no longer, so that we are analyzing not protoplasm at all, but something else. Our analyses are sufficient to show us however that proto- plasm contains the same elements of which inorganic matter is composed, united into a marvellously complex whole. All life is "of the dust, and turn(s) to dust again." The mani- fold varieties of life which we know lead us to believe in as groat a variety of protoplasm which determines this variability in living things. In spite of its variability however all proto- plasm alike contains protein consisting of carbon, hydrogen, nitrogen, oxygen and sulphur, without which it cannot exist. Protein however is founcl outside of protoplasm in egg albu- men for example and in the various albumens and globulins of the blood. These substances while protoplasmic products are not protoplasm itself ; hence we see that in its composition at least living matter does not differ fundamentally from non- living, since both contain the same materials. 278 The Living Machine 279 One of the most characteristic features of life is its power of waste and repair and growth. It is folly to attempt, as some have done, to compare these processes in their entirety with any process in the non-living world. There is nothing with which they can be compared. And yet if we analyze them into their component processes, we find that they are composed of a series of chemical and physical reactions, many of which at least can be exactly reproduced in the laboratory. In the warm spring days when the remnants of last j'car's crop of potatoes in the cellar start to sprout, and those wliieh are served upon your table have an unpleasant sweetish taste, you are the victim of a ferment known as diastase, of wide- Diagram illustrating osmosis through an egg membrane. Original. spread if not universal distribution among plants, which changes starch, the stored-up food stuff of the plant, into one of the sugars. When the maple sugar sap is flowing in the spring we know that a similar action has been taking place within the tree, and all the beauty of the young spring's growth depends upon it. A similar action takes place in our own stomach, under the influence of an animal ferment known as ptyalin, and present in the saliva of many mammals. But a similar result can also be obtained in the test tube of the chemist by boiling starch in dilute acid. In order that the water of the soil with its dissolved salts may enter the root, or the digested food stuffs in the intestine pass into the streams of blood and lymph, the process of os- 280 Biology in America mosis, or the passage of solutions through membranes must occur. But if the shell be chipped off from both ends of a hen's egg, the shell membranes being left intact at one end, and the yolk and white removed from the other, into which a glass tube is sealed Avith a few drops of sealing wax; and if now the egg be filled with a solution of sugar, and then im- mersed in water, until the water is at the same level with the solution in the tube, the latter will soon be seen to rise due to the passage of water through the egg membrane into tlie sugar solution; while more slowly the sugar will ditt'use in the re- verse direction. Here we see in non-living matter the same phenomenon of osmosis, which is so fundamental a factor in all living processes. In the exchange of materials between the cell and its environment, its membrane determines what substances shall enter and leave the cell. Thus an uninjured beet may be placed in water without losing any of its color. But cut the beet and its color readily diffuses outward. So in the absorption by roots of substances from the soil and by the walls of the intestine from the digested food stuffs, the cell membrane exercises what is known as "selective absorption," taking some and rejecting others. In the passage of sub- stances between mother and child, through the walls of the placenta, the cells of the latter exercise a selective function, allowing food materials and oxygen to pass from mother to child, and waste materials to pass in the reverse direction. This selective activity of living membranes is strikingly shown by experiments on barley seeds, which are not killed by sulphuric acid because it cannot penetrate them, but are destroyed by bichloride of mercury, which readily enters. In the burning coal of the furnace and in the forest's decaying logs, one of the final products of combustion or decay is carbon dioxide. So too when we exhale the carbon dioxide from our lungs we are casting off one of the end products in the combustion or oxidation of our foods and our tissues. Throughout the entire process of metabolism, of growth, repair, decay, the body of animal or plant is a physico- chemical laboratory in which are taking place the processes of the non-living world. Another characteristic feature of living things is their power of movement. This is not evident at firet sight in all organisms, notably plants. In fact, one of the criteria formerly presented as distinguishing plants from animals was the fixity of the former as compared with the motility of the latter. This distinction we now know to be false however, for even in the apparently non-motile plants there is circu- The Living Machine 281 lation of cell sap, and movements of leaves and roots in response to stimuli ; while among animals, the attached forms such as sponges, sea anemones, barnacles, etc., either lack locomotive power or possess it in very slight degree. All living things then are motile to greater or less degree. But is this quality lacking in the non-living world ? Place a diluted drop of ink under the microscope and it becomes a microcosm of violent activity. Wind and water are ever active. The earth is flying through space at the rate of 18i/^ miles a second, and the universe is a realm of eternal motion. Light and sound are expressions of movement, and the elec- tronic theory of matter postulates that matter itself is a cosmos of ceaseless energy. But the vitalist tells us that living matter possesses '"spontaneity," which is lacking in the non-living world. The living thing moves of its own ''volition," the non-living only under the influence of forces external to itself. But what evidence have we of "volition" on the part of an Amoiba or bacterium, while the energy of the living machine is as truly the result of oxidation of fuel as is that of the steam turbine or the automobile. Any distinction then on the basis of motion alone between the world of the living and the non-living is a fallacy. Adaptation is one of the most characteristic features of life. The bird and bat are adapted for flight, the flsh for swimming, the monkey for climbing: one need not enumerate, for one cannot name a single living thing which is not adapted to the conditions of its existence; otherwise it would not exist. Adaptation is the very keynote of life, and the tablets of the past are crowded with the records of creatures, which, serving well their day and generation, failed to adapt themselves to changing conditions, and so were trampled under foot by the onrush of the fit in the bitter struggle for existence. But are living things alone adapted to their environment? Does not the river adapt itself to its channel, the lake to its basin, and the gas to the fonn and size of its container? Ice exists in winter because it is adapted to the cold and dis- appears in summer because it is not adapted to the heat. Adaptation indeed is merely an expression of action and re- action, of cause and effect. But, argues the vitalist, these are merely examples of the direct physical influence of one thing upon another, while life adapts itself only in indirect and as yet unknown ways. The fact of adaptation in the inorganic world remains however, and when the riddles of life have been solved it is not unlikely that the process of adaptation of living things can be resolved into simple physico-mechanical terms, just as surely as can the adjust- 282 Biology in America ment of the river to its channel, or the snow drift to the wind. Yet another manifestation of life is its irritability or power of response to stimuli. Examples of this are so common that it is merely trite to repeat them. There is no form of life so primitive or so sluggish as to escape this universal law. But is tliis phenomenon limited to life alone? Does not life- less matter also respond to stimuli, or changes in its environ- ment? Examples of such changes must occur to the mind of everyone — changes in volume or in state, whether solid, liquid or gaseous, in response to changes in temperature or pressure, are among the most familiar instances of these responses. If a metal be heated its electrical conductivity is decreased, sound travels faster the higher the temperature, while atmospheric conditions will materially affect the messages flashed from the wires of the radio. While the responses of living things and changes in their environment are infinitely more complex and indirect than are those of the non-living, yet the same principle holds true for both, and when we know more of the mechanism of life it may be possible to resolve its complex reactions into their simpler terms. Yet one great characteristic of life remains, namely, repro- duction. The development of a human being with his myriad cells, more varied in form than the manifold parts of the most complicated machine, ranging in size from the tiny corpuscles of the blood, less than one four-thousandth of an inch in size, to the motor nerve cells of the spinal cord, which may reach a length of over three feet; and including the intricate structures of the brain by which are performed all the wonderfully complex functions of the human body, in- cluding the as yet inscrutable processes of thought ; all these coming from an apparently simple cell a little more than one one-hundredth of an inch in size, is a wonder beside which the magic of an Aladdin or the miracles of holy writ fade into ghostly paleness. The enthusiast in the ranks of the mech- anists has attempted however to remove even this most distinctive feature of living things, by showing that non- living matter may in a certain sense reproduce itself, as new crystals form in an evaporating salt solution. However feeble such a comparison may be, it is nevertheless true that all phases of reproduction — the growth of the germ cells, their union, the entrance of the spermatozoon, the division of the fertilized egg, the growth and differentiation of the tissues are all intimately associated with physico-chemical changes taking place in these cells, and can, as we shall see later, to a certain extent at least be induced by artificial means. The Living MacJiinc 283 "Whatever the answer to the riddle of life may ultimately be it is at least certain that our present most hopeful line of attack lies in the, at least partially known, fields of physics and chemistry, rather than in the unknown metaphysical one of ''vital principles," "entelechies" and other hypothetical factors. What information then does the bio-chemist have to give us which may help us in the solution of our problem ? The writer once accompanied a class of school-boys through a Colorado mine. On the mine track stood a string of empty cars, and one of the boys asked the conductor of the party what kind of fuel they used for their engines in the mine. "Hay," replied tlie conductor, which somewhat puzzled the boys, until they learned that mules furnished the motive power for the cars. One of the earliest speculations of physi- ologists was regarding the nature of animal heat. Some animals (birds and mammals) have a constant body tempera- ture which is usually higher than that of their surroundings. "What is this heat, and whence does it come?" the early investigators asked themselves. It was at first supposed that heat was a substance which entered and left the body in some unknown way. Toward the beginning of the eight- eenth century speculation began to call experiment to its aid, and Mayow, Boyle and Priestley tried keeping small animals in closed chambers, with the result that they soon died. They also tried introducing lighted candles into similar chambers and found that just as the "flame of life" was soon extinguished, so too the candles went out, if denied air. They further found that an animal could not live so long in a jar in which the air had been exhausted by a burning candle as in one in which the air was fresh; and vice versa the candle would not burn where an animal had exhausted the air before it, nor would one animal live as well in a chamber formerly occupied by another, or one candle burn as well where another had been previously burned, as in one containing air which had not been used up previously. These experiments led them to suspect that the breathing of the animal and the burning of the candle were similar processes. Soon after followed Priestley's discovery of oxygen which he called by the sophisticated title of dephlogisticated air, from the Greek word phlogiston or inflammable. Now fol- lowed Lavoisier's discovery that when a candle was burned, or an animal breathed, the oxygen or dephlogisticated air of Priestley, which formed one-fifth of the volume of ordinary air, was converted into what was formerly known as "fixed air," a compound of carbon and oxygen. Lavoisier now assumed that the heat of the animal body was produced in a manner analogous to that of the burning candle, namely 284 Biology in America by the combustion of the carbon in the body, or its union with oxvf^en to j)ro(luee carbon dioxide. In support of this assumption he pointed out that in birds, whose temperature is higher than that of mammals, there is a greater production of carbon dioxide in respiration. To test tliis hypothesis Lavoisier constructed a primitive calorimeter for measuring the heat production of the animal body. This consisted essentially of two chambers, an inner, for holding the animal whose heat production was to be measured, and ^n outer of double walls, the space between which, as well as that of the outer chamber itself, was packed with ice. Knowing the amount of heat required to melt a given quantity of ice, and measuring the carbon dioxide and water produced by the animal, it should be possible to deter- mine whether the respiration of the animal was of the proper amount to account for the heat produced. Without going into details regarding these experiments of Lavoisier, and his suc- cessors Dulong and Depretz, it is sufficient to say that the results of these early experimenters showed a very close correspondence between the heat calculated from the respira- tory products formed, and the actual production of heat in the calorimeter and led to the conclusion established by later observers that the production of energy in the animal body is dependent on the oxidation of the food consumed, and further that conservation of energy is just as true of the latter as of any non-living machine. The work of these early experimenters has been continued in recent years by Benedict and Atwater at the Nutrition Laboratory of the Carnegie Institution in a series of brilliant investigations with the aid of a very ingenious and intricate respiration calorimeter. This in brief consists of a chamber large enough for a man to live in for several days at a time, and containing apparatus (i. e., a bicycle) on which exercise may be taken. The chamber is constructed of a double metal wall with a contained air space and is surrounded with a double wall of wood containing a second air space, while between metal and wooden walls is an intermediate air space, the whole very effectively preventing any exchange of heat between the interior and exterior of the chamber. As a fur- ther precaution to prevent such exchange of heat special electrical devices are installed for keeping the two walls of the metal chamber at the same temperature, and any difference in temperature between them is recorded on a galvanometer on the observer's desk in the laboratory. Connected with the chamber are various devices for measuring the intake of oxygen, the outgo of carbon dioxide and water, the heat lost by the subject during the experiment and the amount of The Living Machine 285 energy expended in muscular activity. To illustrate the extreme care taken to avoid error in the use of this apparatus may be cited the precautions used in measuring the amount of heat generated by the subject in the calorimeter. This is determined by reading the temperatures of a stream of water which circulates through coils of pipe in the chamber. To the ordinary person it would seem as though it were suffi- ciently accurate to read these temperatures as given by accurate thermometers. But in order to eliminate all possible error corrections are made for the effect of pressure of water on the bulb of the thermometer. "Within the chamber is a folding cot, chair, table and other conveniences. During an experiment the entrance to the chamber is tightly sealed by glass which serves as a window, while a small opening serves for exchange of food, water, excreta, etc. A telephone en- ables the occupant to talk to persons on the outside. The apparatus is so delicate that the slight rise in temperature caused by the subject rising from his chair is recorded by it. The respiration calorimeter is used for investigating the many intricate problems of human nutrition and especially for determining the relation between different kinds of food and the energy furnished by them. To test its accuracy its designers performed a series of check experiments in which alcohol instead of human tissue was burned, and the amounts of carbon dioxide, water and heat produced, and oxygen con- sumed, were measured and compared with the amount re- quired by calculation from the amount of alcohol used. Four such experiments showed an average difference between the calculated and experimental results of less than one-half of one per cent. Experiments with the calorimeter can be made to show what proportion of the energy available in the food consumed is used in the work done by the subject. It is a fact well known to all mechanical engineers that no machine can utilize all the energy of its fuel. This is largely due to loss of heat by radiation from the surface of the machine and in friction. Our best engines can use perhaps not more than one-tenth of the energy available in their fuel. In this respect the human machine is a more perfect mechanism, for it can use about 15-20% of the energy available in its fuel (food) for mechanical (muscular, nervous, etc.) work. The subject of human nutrition is one to fill volumes in itself. We can only note here in passing a few of the most interesting and important results obtained from experiments in this field. Two of the perquisites which the Englishman of past generations has regarded as his inalienable right have been 286 Biology in America liis meat aiul liis ale, and his descendants on this side of the water have maintained fairly well the reputation of their ancestors. But "those who dance must pay the fiddler" and higli living has hrought in its train not only higli grocer's, l)ut high doctor's bills and mortality rates as well. The advent of meat cards and meatless days during the war brought about a cut in the size of our steaks if not of our butcher's bills. If this seeming privation teaches us that an excessive meat diet is not essential to our health and happiness the game will indeed prove ' ' worth the candle. ' ' But there were even in early days voices raised in warning against prevalent excesses in diet. One of these was the plea for moderation in eating by the English physician Thomas Cogan, published in 159G under the title "The Haven of Health," in which he says: "The second thing that is to be considered of meates is the quantitie, which ought of all men greatly to be re- garded, for therein lyeth no small occasion of health or sickness, of life or death. For as want of meate consumeth the very substance of our flesh, so doth excesse and surfet extinguish and suffocate naturall heat wherein life con- sisteth." Again, "Use a measure in eating, that thou maist live long : and if thou wilst be in health, then hold thine hands. But the greatest occasion why men passe the measure in eating, is varietie of meats at one meale. "Which fault is most common among us in England farre above all other nations. For such is our custome by reason of plentie (as I think) that they which be of abilitie, are served with sundry sortes of meate at one meale. Yea the more we would wel- come our friends the more dishes we prepare. And when we are well satisfied with one dish or two, then come other more delicate and procureth us by that means, to eate more than nature doth require. Thus varietie bringeth us to excesse, and sometimes to surfet also. But Phisicke teacheth us to faede moderately upon one kinde of meate only at one meale, or at leastwise not upon many of contrarie natures. . . . This disease, (I mean surfet) is verie common: for common is that saying and most true: That more die by surfet than by the sword. And as Georgius Pictorius saith, all surfet is ill, but of bread worst of all. And if nature be so strong in many, and they be not sicke upon a full gorge, yet they are drowsie and hcavie, and more desirous to lo.yter than to labor, accord- ing to that old master, when the belly is full, the bones would be at rest. Yea the minde and wit is so oppressed and over- whelmed with excesse that it lyeth as it were drowned for a time, and unable to use his force, " ^ 1 Quoted from Chittenden, " The Nutrition of Man, "pp. 166-7. The Living Machine 287 In recent times physiologists, both pseudo and scientific, including a great variety of cranks of all sorts and sizes, have been turning their attention more and more to matters of diet, and the layman is beginning to learn that it is possible for him to select his food, not only with respect to price and palatability, but also for its value as a fuel for the human machine. The principal elements in human diet are proteins (meat, eggs and, to a less extent, milk, grain and vegetables), carbohydrates (sugar and starch) and fats. One of the greatest services rendered by modern students of human nutrition has been to show that a high protein diet is not only unnecessary, but actually in many cases detrimental to health. Studies of this sort have been largely conducted in this coun- try by Professors Chittenden and Fisher at Yale, the results of two of the most striking of whose experiments are here summarized. The first of these was conducted upon a group of thirteen United States soldiers, for a period of six months, and the second on eight college athletes for five months. The ordinary diet of the soldiers prior to the experiment may be illustrated by the following average day's menu: Breakfast — Beefsteak 8 oz., gravy 2.4 oz., fried potatoes 8.2 oz., onions 1.2 oz., bread 5 oz., coffee 24 oz., sugar 0.6 oz. Dinner — Beef 6 oz., boiled potatoes 12.3 oz., onions 2 oz., bread 8.2 oz., coffee 32.3 oz., sugar 1 oz. Supper — Corned beef 6.9 oz., potatoes 6 oz., onions 0.7 oz., bread 5.5 oz., fruit jelly 3.7 oz., coffee 15.0 oz., sugar 9.7 oz. During the experiment the amount of meat was gradually reduced until the men were living on a diet of which the following day's menu is a sample: Breakfast — Wheat griddle cakes 7 oz., syrup 1.7 oz., one cup coffee, with milk and sugar, 12.3 oz. Dinner — Codfish balls (4 parts potato, 1 part fish, fried in pork fat) 5.3 oz., stewed tomato 7 oz., bread 2.6 oz., one cup coffee 13.3 oz., apple pie 3.3 oz. Supper — Apple fritters 7 oz., stewed prunes 4.4 oz., bread 1.7 oz., butter 0.4 oz., one cup tea 12.3 oz. As a result of this change of diet some of the men showed a slight loss of weight which occurred at the start, and in others an actual gain for the entire period. In only one case, that of a stout man, was there any noticeable decrease, which in his case was to his advantage, rather than the reverse. Not only was there no harmful loss of weight, but the general health was maintained and in some cases improved. "Most conspicuous, however, though something that was entirely unlocked for, was the effect observed on the muscular strength of the various subjects," which showed not a loss, but on the contrary a decided gain, "and furthermore," says 288 Biology in America Professor Cliittenden, "tlioro was a noticoablc gain in self- reliance and conrage in their athletic work, both of Avhich are likewise indicative of an improved condition of the body. How far these improvements are attribntable to training and to the more regular life the men were leading, and how far to the change in diet, cannot be definitely determined. AVe may venture the opinion, however, . . . that the change in A Soldier after a Six-Months' Diet Low in Meat After Chittenden, "The Nutrition of Man." By permission of F. A. Stokes Company. diet was in a measure at least responsible for the increased efficiency. As the writer has already expressed it, there must be enough food to make good the daily waste of tissue, enough food to furnish the energy of muscular contraction, but any surplus over and above what is necessary to supply the^se needs is not only a waste, but may prove an incubus, retard- ing the smooth working of the machinery and detracting from the power of the organism to do its best work." The Living Machine 289 Concerning the second experiment above mentioned Profes- sor Chittenden says: "Here, again, we see that a relatively small intake of proteid food will not only bring about and maintain nitrogen eqnilibrium for many months, and probably indefinitely, but that such a form of diet is equally as effective with vigorous athletes, accustomed to strenuous muscular ef- fort, as with professional men of more sedentaiy habits. Fur- ther, these many months of observation with different individ- uals all lead to the opinion that there are no harmful results of any kind produced by a reduction in the amount of proteid food to a level commensurate with the actual needs of the body. Body-weight, health, physical strength, and muscular tone can all be maintained, in partial illustration of which may be offered two photogi*aphs of one of the eight athletes taken toward the end of the experiment; pictures which are certainly the antithesis of enfeebled muscular structure, or diminished physical vigor." Similar results have been obtained with professional men. Altogether they show very conclusively the possibility of not only maintaining, but also of improving human health with a diet relatively low in proteid matter. What now will be the result if an animal, which in its natural state was exclusively carnivorous, and even in domes- tication is still largely so, be fed on a proteid-poor diet? Some of the earlier experimenters in Europe found that a reduction in the meat of a dog's diet resulted in gastro- intestinal disturbance followed by death. These experiments however were conducted with dogs kept in close confinement and as Chittenden says "It is doubtful if there is full appre- ciation of the possible effect of monotony, in the ordinary dietary experiments on dogs. Man quickly feels the effect; the sportsman camping in the woods by brook or lake enjoys his first meal of speckled trout and has no thought of ever becoming tired of such a delicacy; but as trout cooked in various ways continue to be placed before him three times a day, and with perhaps very little else, he soon passes into a frame of mind where salt pork would be a luxury, and where he would prefer to go hungry rather than eat the delicacy, if indeed he has appetite to eat anything. Is it strange that dogs confined in cages barely large enough to permit of their turning around, and fed day after day and month after month with exactly the same amount of desiccated meat, fat, and rice, should show signs and symptoms, if nothing worse, of disturbed nutrition? It is necessary in experiments of this kind that the animals be confined for given periods, at least. ... It is possible, however, to limit the time of close confinement to, say, ten consecutive days, this to be followed 290 Biology in America by a like period of comparative freedom, thus insuring oppor- tunities for an abundance of fresh air and exercise." In order to test the effects of a proteid-poor diet on dogs living under conditions as nearly ideal as possible a series of experiments were carried out on some twenty animals, some of these lasting an entire year, ''AH of the . . . dogs . . . were fed on a mixed diet, with some fresh meat each day ; bread, cracker dust, milk, lard, and rice being the other foods drawn upon to complete the dietary. The animals were fed twice a day, each meal being accurately weighed and of defi- 'nite chemical composition. A large, light, and airj^ room, kept scrupulously clean, and in the winter time properly heated by steam, served as their main abiding place. In this room were a suitable number of smaller compartments, the walls of which were composed of open lattice work (of iron), so as not to interfere with light or air, and yet adequate to keep the dogs apart. These compartments were not cages in the or- dinary sense, but were truly large and roomy. ... In pleas- ant weather, immediately after their first meal, the dogs were taken out of doors to a large enclosure near by, where they were allowed perfect freedom until about four o'clock, when they were taken in for their second meal (between four and five o'clock in the afternoon). The outdoor enclosure was inaccessible to every one except the holder of the key, and the dogs while there were wholly free from annoyance. Once every month, during a period of ten consecutive days, each dog was confined in the metabolism cage so as to admit of the collection of all excreta, in order to make a determination of the nitrogen balance. Practically, therefore, each dog was in close confinement only one-third of the month, the remaining two-thirds being spent in much more congenial surroundings." While details regarding all of these experiments cannot be given here one case may be selected as an example. "The animal employed in this experiment . . . was apparently full grown, but was thin and had the appearance of being under- fed. At first, it was given daily 172 grams of meat, 124 grams of cracker dust, and 72 grams of lard. . . . (Later) a radical change was made in the diet, by reducing the amount of meat to 70 gi-ams daily ; . . . the cracker dust and lard being kept at essentially the same levels as before . . . the dog in the meantime gaining in body-weight. ... In this manner, the experiment was continued with frequent changes in the char- acter of the diet, but always maintaining essentially the same (food) values . . . (for) just eleven months, with the ani- mal at the close of the experiment still gaining in body- weight, . . . and with every indication of good health and The Living Machine 291 stren^h." The results of his entire series of experiments led Chittenden to the conclusion that: ''These experiments on the influence of a low proteid diet on dogs, as a type of high proteid consumers, taken in their entirety, afford con- vincing proof that such animals can live and thrive on amounts of proteid and non-nitrogenous food far below the (usual) standards. . . . The deleterious results reported by these in- vestigators were not due to the effects of low proteid or to diminished consumption of non-nitrogenous foods, but are to be ascribed mainly to non-hygienic conditions, or to a lack of care and physiological good sense in the prescription of a narrow dietary not suited to the habits and needs of this Effect of Diet on Dogs Left — A dog fed on a diet containing one-half pound of meat daily. Eight — The same animal after several months on a diet with less than half as much meat. From Chittenden, "The Nutrition of Man." By permission of F. A. Stokes Company. class of animals. Further, it is obvious that the more or less broad deductions so frequently drawn from . . . experiments (on dogs) . . . especially in their application to mankind, are entirely unwarranted and without foundation in fact. Our experiments offer satisfying proof that not only can dogs live on quantities of proteid food per day smaller than (are usually) . . . deemed necessary, and with a fuel value far below the (usual) standard . . . ; but, in addition, tliat these animals are quite able on such a diet to gain in body-weight . . . , thereby indicating that even small quantities of food might suffice to meet their true physiological requirements. "The results of these experiments with dogs, which we 292 Biology in America have recorded in such detail, are in perfect haiTDiony with the conclusions arrived at by our experiments and observations with man, and serve to strengthen the opinion, so many times expressed, tliat the dietary habits of mankind and the dietary standards based thereon are not always in accord with the true physiological requirements of the body. ' ' There is one experiment in the foregoing series regarding which a further word may be said. In this experiment a dog which had been fed on a diet of meat, milk, bread and lard was changed to a diet of bread and lard only, the food and fuel value however of the diet remaining unchanged. "In four days' time however a change began to creep over the animal ; the appetite diminished, and there was apparent a condition of lassitude and general weakness which deterred the animal from moving about as usual. "During the next week the animal grew steadily worse, and would eat only when coaxed with a little milk or with bread softened with milk, the diet of bread and lard being invariably refused. There was marked disturbance of the gastro-intestinal tract; bloody discharges were frequent; the mucous membrane of the mouth was greatly inflamed and very sore ; body-weight fell off, and the animal was in a very enfeebled condition. This continued until December 4, with every indication that the animal would not long survive, but by feeding carefully with a little milk and occasionally some meat, improvement finally manifested itself, and by December 18 there was good appetite, provided bread was not con- spicuous in the food. Body-weight . . . was . . . slowly re- gained (until finally) ... in general condition there was nothing to be desired." ^ Similar results have been obtained by Hopkins and Nevill who kept twenty-four young rats on a diet of protein, starch, lactose (milk-sugar) and salts. They ate well and took sufficient food to supply them with needed energy, but soon ceased to grow and in a few days actually began to lose weight, fourteen of them dying in forty days. With six of the rats there was added to the diet, after the decline in weight had commenced, a small portion of milk daily, which was followed by an immediate improvement in health, and re- newed growth. There are certain problematical diseases in man, which' may be due to a lack of something in the food. Beri beri, a disease common among Filipinos, Japanese and East Indians, and characterized by paralysis, swelling and degeneration of the muscles, has been attributed to an extensive diet of *The foregoing quotations arc from Chittenden, "The Nutrition of Man," pp. 187 et sot]., Ity permission of Fred'd A. Stokes Co. The Living Machine 293 polished rice which lacks the reddish husk of the kernel. If fowls are fed on an exclusive diet of this they die after some weeks. If fed on unpolished rice, they do not contract the disease, and if an extract of the husk or bran be injected into fowls ill from eating the polished grain they will recover. Similarly men who eat the unpolished rice are not subject to beri-beri. It seems then that the rice husk contains some substance which is essential to life. Pellagra, a disease common among the poorer classes in tropical and sub-tropical countries practically throughout the world, is characterized by weakness, pains, digestive disturb- ances, skin eruptions and mental disorders, terminating in insanity and finally death. In its earlier stages the disease is recurrent, appearing each spring for several years with increasing severity until it becomes a permanent condition. It has been ascribed to a too extensive diet of corn or to eating spoiled corn. It has also been laid at the door of the villains of so many sanitary (or insanitary) tragedies — the insects. One investigator has recently attempted to find an hereditary basis for the disease. Whatever the ultimate cause it is clearly a disease of disturbed metabolism, and evidence is accumulating to show that imperfect diet is responsible. Scurvy has long been known as a disease of mal-nutrition, common especially among sailors, who were forced to live on a diet largely of salt meat, so that in the maritime laws of many nations captains were required to furnish their seamen with a ration of vinegar, lime juice or other acid as a pre- ventive. While the subject of human nutrition is yet in its infancy, especially as regards our knowledge of these problematical substances, which are essential to health, and to some of which, especially those present in milk, the term vitamine has been applied ; the evidence is clear that to furnish the living machine with the fuel needed for its proper working, it is not sufficient merely to supply the necessary material for energy, repair and growth, but that other things are needed to enable it to properly utilize this fuel. While therefore excesses in eating are but little if any less injurious than those in drinking or other indulgence, there is no place in the regime of the sane and normal individual for the dietary fads and foolishness which some enthusiasts have advocated with great eclat. While most of us undoubtedly eat too much meat, there is small excuse for adopting a strictly vegetarian diet. Our teeth are made for service, and not for the exclusive benefit of the dentist, but while thorough mastication is un- doubtedly essential to a ripe old age with good digestion, most of us will hardly find it necessary to chew by the stop- 294 Biology in America watch, or to reflate our bites as we do our setting-up exer- cises. In the feeding of hens for egg productivity Pearl has shown that hens witli a mixed diet, from which they were permitted to choose at will, maintained better health than those limited strictly to certain articles. ''Eeason in all things, excess in none," is a fundamental rule for sanity in diet as in other of our life activities. What of the mechanism whereby this wonderful machine of life utilizes its fuel? Herein lies one of the fundamental differences between the living and the non-living machine. "Whereas the latter uses its fuel solely in the conversion of potential energy into heat and work, the former, in addition to these two functions, also converts some of its fuel into its own substance to take the place of worn-out parts, and to build new parts and enlarge those already formed in develop- ment and growth. We have already seen that the living engine is much more efficient in the conversion of the potential energy of its fuel into work than is the non-living machine. How convenient it would be if the latter like the former were automatically repaired as it wore out ! Given a good machine to start with, proper fuel and draft, and preventing anyone from throwing in dirt (disease) and the living machine will run without repair for the time of its natural life. How is this done? In the non-living machine the process of converting fuel energy into work energy is comparatively simple. The carbon of the fuel is in such shape that it can'' be more or less directly oxidized to carbon dioxide, and heat energy thereby released. But in the utilization of the food or fuel of the living machine a large number of intermediate steps are necessary, which steps often consist of a cycle of changes which are partly degenerative (breaking down com- plex substance and thereby releasing energy) and partly constructive (building up simpler into more complex sub- stance and storing energy thereby). The food as taken into the body of most animals is in such shape that it cannot be directly burned to furnish energy^ or built up into body substance. While our knowledge of the many complicated changes undergone by food stuffs in the animal body is as yet very meagre, we have nevertheless enough information to enable us to follow in a general way these changes. Probably the food most readily convertible into energy is fat. Some fat is an exception to the statement made above that food is not directly convertible into energy. The Esquimaux use seal blubber both as food and fuel for heating their igloos, * I refer here to ordinary conditions of combustion. Any food sub- stance may be burned in a special apparatus known as a bomb calorime- ter and its energy content thereby determined. The Living Machine 295 and various vegetable oils can be burned in a lamp. "When taken into the digestive tract however the fat is not usable as fuel any more than any other food substance, but must first undergo digestion. The function of digestion of all food is to put it into such shape that it can be absorbed by the blood and lymph through the walls of the digestive tract. This transfer or absorption of the food through the latter takes place, as we have seen, by a process of osmosis. The food as eaten is not ordinarily in solution and cannot be passed through a membrane or dialyzed, the function of digestion being to render it soluble and dialyzable. This is accomplished by a process known as hydrolysis which consists in the splitting up of the food into simpler, compounds by the addition of water. This process is effected by means of certain remarkable substances formed by all animals and plants and known as enzymes or ferments. When a little yeast is added to a solution of sugar and certain salts and kept at a proper temperature, bubbles of gas (carbon dioxide) soon begin to rise to the surface of the solution. The sugar is being broken down into two simpler substances, carbon dioxide and alcohol, by the ferment secreted by the yeast cells. So far as we know the ferment itself does not change, but acting as by magic affects a change in certain substances with which it comes in contact. Yet even this remarkable activity of the living cell has its counterpart in inorganic nature. If hydrogen and oxygen be brought to- gether at ordinary temperatures there is "nothin' doin' " — to use the English language up to date. But introduce a little finely divided platinum into the situation, and under its seemingly magic influence combination occure and drops of water form where before there was but gas. The heat generated by this reaction soon raises the platinum to a red heat and this principle was employed in the construction of a self-lighting lamp, in which a jet of hydrogen played upon a bit of spongy platinum, which soon heated — igniting the gas. The platinum here is known as a catalyzer. Its action is similar to that of the ferment since it in some way brings about a change in other substances, without itself entering into that change. The activity of the ferment-forming cell is responsible to itself for its continuation, for when the products of ferment action become too great this action ceases, and will not recommence until these products are removed, or at least lessened in amount. Among vertebrate animals the digestive ferments are formed chiefly by the stomach, pancreas and intestine, al- though the liver, and in some instances the mouth glands play a minor part; while the simplified and soluble (digested) 296 Biology in America food stuffs are absorbed mainly at least by the walls of the intestine, whence they are carried by the body fluids (blood and lymph) to the tissues of tlie body, where probably under the influence of other ferments they are again built up into complex substances, which compose the protoplasm of the body cells.* Thus the kernel of the wheat, or the muscle of the beef, is iu some mysterious way transformed into the muscle and the nerves, the blood and bone of the animal which consumes them. The various steps in the digestive and absorptive processes are extremely complicated and their character is not fully understood. The large number of prod- ucts formed in tlie digestion of the proteid molecule form one evidence of the complex nature of protoplasm. Leaving out of consideration the simpler processes of digestion of starch, sugar and fat, and dealing with proteid digestion alone; passing over also the many and complicated stages in the journey of the proteid molecule through the digestive tract, we come to the end products of digestion, the amino- acids or "l)uilding stones of proteid," as they have l)een called. Tliese amino-aeids include a large number of sub- stances, all built around the common nucleus of NHo. Witli these as a basis the constructive ferments of the l)ody build up its marvelously complex materials. A comparison of the animal body with a machine, the food of the former corresponding to the fuel of the latter is only partially exact, for in the machine, as we have seen, the fuel is directly consumed to furnish energy, while in the animal the change of food energy into work energy is effected in part only through the medium of the body substance itself. After the conversion of the digested food stuffs into the protoplasm of the l)ody this must in turn be broken down through the action of the oxydizing, or destructive ferments, into a whole series of decomposition products, of gradually decreasing complexity, the principal end results being carbon dioxide and urea. Some of the food stuffs, notably those with the highest energy content, the fats and carbohydrates, and to a less extent the proteids also, may after digestion be directly oxidized to furnish energy; or may in the case of fat and glycogen be stored by the body as a reserve supply for future need. Thus a hibernating animal, such as a bear, during the summer lays up for himself a bountiful supply of fat upon whieli to draw during the long winter's fast. This storage of energy in the form of reserve food stuffs by the living *Sueh a brief statement as the above naturally overlooks the many intermediate steps in this very complicated process. The Living Machine 297 machine finds a parallel in the storage of electrical energy in a storage battery. Turning from the world of animals to that of plants, we find in the latter a parallel to all of the metabolic processes of the former. The average person is accustomed to think of a plant in terms of the green thing which he finds in garden, field or forest. But when we go a-hunting mushrooms, or poke aside the rotting remains of a fallen tree, we discover other plants which live a different sort of life from that of tree or shrub or herb. And should we delve yet further into Nature's recesses, and penetrate that hidden world to which the microscope gives entrance, we should discover creatures concerning whom no one can say whether they are plant or animal. Some of these uncertain forms are claimed by both botanist and zoologist as belonging in their own especial field of study, for in some respects they are distinctly animal, in others plant in nature, as we have already seen in an earlier chapter. But while one stands at the portals of life in a realm which is neither plant nor animal ; advancing into either kingdom he must follow ever more widely diverging paths; until when he reaches the farthest bounds of this wonderful world he finds its two kingdoms, while governed by the same fundamental laws, nevertheless differing profoundly in their expression. Perhaps the most fundamental difference between the higher plants and animals is in their metabolism. "While the latter are spenders, the former are hoarders of energy, taking raw materials, carbon dioxide from the air and water from both air and soil, and from these constructing by the energy of the sun, acting through the green chlorophyl of leaf and stem, their own food-stuffs; thereby converting the radiant energy of sunlight into the chemical energy of sugar and of starch. From the soil and air the plant obtains its nitrogen, and from the soil the other inorganic substances which it needs to build its protoplasm, and combining these in some as yet but little understood way, with the sugar, by the action of constructive ferments, it builds up its protoplasm. This is what is hap- pening in the blade of grass, the spreading leaf and the stag- nant pool, covered with a thick green scum, a little chemical laboratory, where Nature is busily at work making sugar and releasing oxygen. Some day perchance the chemist, imitat- ing Nature, will learn to make our starch and sugar for us, and bid defiance to the "man with a hoe." This indeed is the possibility, perhaps not immediate, but none the less ulti- mate, of the studies on photosynthesis now under way at the Desert Botanical Laboratory of the Carnegie Institution at 298 Biology in America Tucson, Arizona, whose work we have considered in a previous chapter. Synthetic chemistry may well doff its hat and bow low before the greatest creative chemist in the world — the green plant. Tlie world today hungers and thirsts after nitrogen. We must have nitrogen to fertilize our fields, in order that we may not starve, and we must have nitrogen to rend asunder the bowels of the earth and lay bare the treasures hidden therein, and we must have nitrogen that we may slaughter our fellow men. So we have cleaned the guano beds of Chile, where the sea fowl have been laying down treasure and stench for years untold. We have dug deep into the nitrate beds of Cliile and Peru, and today we are harnessing the water- fall and bidding it harvest for us the nitrogen of the air. Meanwhile the silent plant has been putting man 's ingenuity to shame, and in its laboratory working wonders, whereat science well may marvel. Truly should man "consider the lilies of the field. ' ' But the green plant is not unassisted in the wonders which it works. On the roots of plants of the pea family occur little swellings or "nodules" which are fonned by bacteria which have the power of extracting the nitrogen from the air in the soil and using it to build their own bodies. Hence they are known as the "nitrogen-fixing" bacteria. As these bacteria die they give to the soil compounds of the nitrogen which they have taken from the air. Thus it is that peas and their relatives such as beans and alfalfa are such valuable plants for crop rotation, for if a soil from which the nitrogen has been largely exhausted by continuous cropping with grain be planted for a year or two to beans or alfalfa, the nitrogen- fixing bacteria on the roots of the latter will replace the nitrogen and give to the worn-out soil a new lease of life. But what share does the bean or the alfalfa and the bacteria have in this co-operative association ? The latter during their life probably absorb sugars and other substances formed in the leaves of the former and passed down into the roots, while on their death some of the nitrogenous material formed by the bacteria is absorbed Ijy tlie green plant. The heirs to the riches laid up by these two industrious partners are the plants which follow the peas, beans or alfalfa in rotation. There are other soil bacteria which aid the farmer by changing the ammonia in the soil into nitrites and nitrates, in which form it becomes available as food for the green plants, while vice versa other soil bacteria perform exactly the reverse operation and change nitrites and nitrates into ammonia. All life is a cycle. No sooner does one agency build up than The Living Machine 299 another tears down, and so it goes, in the lives of the unseen bacteria of the soil, as well as in the affairs of man. But while most animals and plants differ so widely in their metabolism, fundamentally their ways of life are alike. Both must have food, from the combustion of which their energy is derived, and from which their wastage is replaced and growth material obtained. And this food must be rendered soluble and dialyzable in order that it may pass through membranes which surround each cell, i. e., must be digested. While in the higher animal there is a special place where digestion and absorption occur (the digestive tract) and the digestive ferments are formed by special glands (liver, pan- creas, etc.), in the plant there is no such specialized tract or glands for the functions of digestion and absorption, these taking place generally in the leaves. There are however cer- tain specialized tubes of cells in the root and stem which taken together form "conducting paths," for the water, with its dissolved salts ascending from the soil, and the sugar descending from the leaves to root and stem, there to be stored as starch for future use. And after digestion the food must circulate through the plant to all its parts, and be built up into its tissues by constructive ferments analogous to those of animals. In this circulation of water with its dissolved substances through root and stem we see one of those marvelous, and as yet inexplicable phenomena of life, which have caused so many biologists to throw up their hands in despair and ascribe to life some occult power undiscoverable by the sci- entific methods of the physicist and chemist. From the leafy surface of humblest herb and mightiest tree, transpiration takes place, or the loss of water absorbed by the roots from the soil. During the day this water is usually quickly evaporated, but in the cooler air of night evaporation is reduced and some of the transpired water remains as dew upon the leaf. The pressure lifting the water from the soil to the leaf may be as great in some cases as that which would be exerted on the earth's surface by an atmosphere six to eight times the thickness of the present one, a pressure suffi- cient to support a column of water between two and three hundred feet high. Various attempts have been made to explain the rise of sap in plants but as yet with no great success. The evapora- tion from the leaves and the absorption of water by the cells are the principal factors claimed as causing this wonderful phenomenon. Neither factor however is adequate, and the best we can do here, as in so many other cases, is to confess our ignorance, and press onward in the search for knowledge. 300 Biology in America In this marvellous laboratory of the living body with its countless millions of little test tubes or cells, and its manifold reagents, many of which we do not know, wonderful reactions are continually taking place, whose complexity is at once the joy and the despair of the chemist, and whose study is one of the newest, most fascinating and withal most difficult fields into which chemistry has been privileged to enter. And yet marvelous as are the transformations within the body of the living being they are all without exception undoubtedly effected by physical and chemical means. CHAPTER XII Experimental biology, mechanism versus vitalism continued. Tropisms, iyistincts and intelligence. H&rmanes. Arti- ficial fertilization. But can physics or chemistry explain the as yet unknown processes of nervous action; the bewildering pei-plexity of the instinct of bee or bird or beast, or the yet more amazing intricacies of human thought? To answer this question, as indeed to solve any of the problems of living matter aright, it is essential that we turn to the lowest rather than to the highest organisms, to those which present to us in their simplest terms, all the fundamental processes of the living thing. If the extended process or pseudopodium of an Amoeba, one of the simplest types of living things, be touched with a finely drawn out thread of glass, the process is retracted and the direction of movement of the animal is altered thereby. If on the other hand Amceba comes in contact with some object, which serves as food, it reacts positively toward it, thrusting out its processes and engulfing the object. Further- more Amceba can pursue its food, so that to the observer it seems as if this tiny bit of protoplasm, so small that the largest specimens appear to the naked eye as mere specks of white, were endowed with a sort of primitive intelligence. This pursuit of food has been described by Jennings as follows : "I had attempted to cut an Amoeba in two with the tip of a glass rod. The posterior third of the Amoeba, in the form of a wrinkled ball, remained attached to the body only by a slender cord, the remains of the ectosarc. The Amceba began to creep away, dragging with it this ball. I will call this Amoeba a, while the ball will be designated b, A larger Amoeba (c) approached, moving at right angles to the path of the first Amoeba; its course accidentally brought it into contact with the ball b, which was dragging past its front. Amoeba c thereupon turned, followed Amoeba a, and began to engulf the ball b. A large cavity was formed in the an- terior end of Amoeba c, reaching back nearly or quite to its middle, and much more than sufficient to contain the ball b. Amoeba a now turned into a new path; Amceba c followed (4). After the pursuit had lasted for some time the 301 302 Biology hi America ball b had become completely enveloped by Amoeba c; the cord connecting it with Amoeba a broke, and the latter went on its way (at 5) and disappears from our account. Now the anterior opening of the cavity in Amoeba c became partly closed, leaving a slender canal (5). The ball b was thus Pursuit of Food by Amceba From Jennings, "Contributions to the study of the behavior of lower organisms." Carnegie Institution, Publication No. 16. For description see text. completely inclosed, together with a quantity of water. There was no union or adhesion of the protoplasm of b and c; on the contrary (as the sequel will show clearly) both remained quite separate, c merely inclosing b. *'Now the large Amoeba c stopped, then began to move in another direction (5-6), carrying with it its meal. But The Livhuj Machine 303 the meal, the ball b, now began to show signs of life, sent out pseudopodia, and indeed, became very active. \Ve shall henceforth, therefore, speak of it as Amu?ba b. It began to creep out through the still open canal, sending forth its psetidopodia to the outside (7). Thereupon Am(eba c sent forth its pseudopodia in the same direction, and after creeping in that direction several times its own length, again c()ni|)l('tely inclosed b (7-8). The latter again partly escaped (D), and was again engulfed completely (30). Amoeba c now started again in the opposite direction (11), whereupon Amieba b, by a few rapid movements, escaped entirely from tlie posterior end of c, and was free, being completely separated from e (11-12). Thereupon c reversed its course (12), crept up to b, engulfed it completely again (13), and started away. Amoeba b now contracted into a ball, its protoplasm clearly set off from the protoplasm of its captor, and remained quiet for a time. Apparently the drama w^as over. Amoeba c went on its way for about five minutes, without any sign of life in b. In the movements of the Amoeba c the ball b gradually became transferred to the posterior end of c, until finally there was only a thin layer between b and the outer water. Now b began to move again, sent out pseudopodia to the outside through the thin wall, and then passed botlily out into the water (14) . This time Amoeba c did not return and recapture b. The two Amoebae moved in different directions and re- mained completely separated. The whole performance occu- pied, I should judge, about 12 to 15 minutes (the time was not taken till several minutes after the beginning) . "After working with simple stimuli and getting always direct simple responses, so that one begins to feel that he understands the behavior of the animal, it is somewhat bewildering to become a spectator of so striking and com- plicated a drama. . . . The action is remarkably like that of a higher animal. Doubtless we must assume chemical and mechanical stimuli as directives for each of the movements of c, but the analysis so obtained seems not very complete or satisfactory. " ^ Injurious chemicals cause Amoeba to withdraw from them. Similarly, if the water on one side of an Aiiueba be warmed, the animal will contract on that side, and thrusting forth its pseudopodia on the other side, move in the opposite direction. If a weak electric current be passed through the water con- taining Amoeba, its behavior is similar to that under a heat stimulus. The side toward the anode or positive pole con- tracts, while from the opposite side pseudopodia are extended, ^Jennings, "Contributions to the Study of the Behavior of Lower Organisms," Carnegie Institution, Publication No. 16. 304 Biolofjy in Am eric, and the animal moves toward the cathode or negative pole. Tlio hrhavioi- of Amoeba moreover is not stereotyped, l)ut can be adapted to suit varying conditions. If a bright light be thrown upon it, it contracts into a small inactive mass, but after a time the psendopodia are again thrust out and activity resumed. When starved, Amceba l)e('omes more active than usual, while after a heavy meal it becomes sluggish. "All these responses are purposive in that they are adapted to the preservation of the organism. Simple as AuKcba ap- parently is it manages to cope very effectively with the condi- tions of its existence. One might conceivably construct a machine which would run itself, gather tlie food needed to supply the energy used in its workings, avoid automatically contact with obstacles which would impair its running, move away from regions too hot or too cold for its efficient opera- tion, protect itself by producing coverings in unfavorable situations, and guide itself into the most favorable regions for its maintenance ; but Avhat a wonderfully complicated mechanism it would have to be! Yet a simple, apparently almost structureless mass of jelly does all this and more. And if our mechanism had the property of repairing its own injuries and producing other pieces of mechanism like itself, its structural arrangements would be almost if not quite beyond our power to conceive. One cannot, therefore, but look with a feeling of admiration and wonder at so com- paratively simple a creature as Amoeba, which is capable of performing so much. . . . "The behavior of Amoeba is essentially like that of higher animals : it avoids things which are injurious ; it seeks things Avhich are beneficial and it adapts its behavior to new condi- tions. Life is very much the same sort of thing whether in an Amceba or a man." ^ One must not however be too sure as to the simplicity of an Am(pba. While to the eye of the microseopist it ajijieai-s as an "almost structureless mass of jelly," nevertheless the complexity of the molecules composing this jelly is such as to defy analysis by the most skillful chemist. And even were it possible to obtain an exact analysis of the Amoeba molecules, the number of atoms composing the latter is so great as to render possible several million combinations of these atoms, each in a different way and each possibly resi)0]i- sible for every ncAV response which it makes to its sur- roundings. While the behavior of Amoeba is generally such as to benefit, rather than harm it, this is not invariably true of all organ- Mlolinos, "The Evolulion of Aiiinial Intelligence," pp. 70-71. By permission of Henry Holt and Company. The Living Machine 305 isms. Thus a one por cent solution of morphine attracts certain bacteria even though it is fatal to them. This is an unusual condition however as morphine is a substance not encountered in nature by bacteria. A similar behavior is to be found, as we shall see later, in higher animals. Nature sometimes plays the role of the enchantress C'ii'ce witii the humblest, as well as the proudest of her creatures. A step hig:her on the stage of life we come to Paramoecium, whose acquaintance we have already been privileged to make. Here we have an animal with definite organs of locomotion (cilia) arranged in definite (spiral) lines upon the body; "an oral groove or food trough, leading to a gullet or primitive digestive tract, a definite anal spot for the discharge of undigested materials, specialized organs (contractile vacuoles) for excretion, and specialized nuclei which play a complicated role in the processes of metabolism and reproduction. Para- mceeium swims in a spiral path, directed by the spirally ar- ranged cilia, and oblique oral groove. Its active movement and peculiar form have caused many an unhappy hour to the tyro in biology. If one place a drop of weak acid in the dish of water in which Paramcpcia are restlessly zig-zagging to and fro, they will be found after a time to have gathered in the drop ; while vice versa a grain of salt will soon be sur- rounded by a zone of water free from Paramoecia save for the dead bodies of a few, which have ventured too near the fatal spot and failed to extricate themselves therefrom, ere death o'ertook them. How are these results accomplished? Are Paramcecia at- tracted by, and do they swim into the drop of acid because they ''like" it? And, similarly, do they avoid the salt be- cause they "know it is bad for them"? Let us follow their maneuvers a little more closely. If a Paramoecium in swim- ming at random through the water, happens to approach a drop of acid it is not repelled by it, and hence goes into the drop if its direction of movement happens to take it there; once inside the drop however should it ''attempt" to escape it cannot do so, for when it approaches the water outside the drop it is seemingly repelled by the latter, for it backs up, turns on its tail and swims away. Thus it can enter the drop but cannot leave it, and in a short time a large number of Paramoecia may be trapped in this manner. This behavior of Paramoecium has been likened by Jennings who described it, to a sort of "trial and error" behavior, similar to that of the dog who learns to open a gate by putting his paw on the latch, as a result of numberless fruitless pawings, in an at- tempt to escape from the yard in which he is penned up. Loeb however sees in this behavior something yet more simple 306 Biology in America than doos Jciiiiiiifrs;, ascribing tlio backing and tnrning movement of tlie animal on its approach to au unfavorable environment, to a reversal of the ciliary movement on the side stimulated, and to the asymmetrical shape of the body. The controversial pliase of the snl)ject is one which does not interest tlie general reader; the important point is that a primitive animal like Paramoecinm, lacking any specialized sense organs or nervous system, is nevertheless as sensitive to stimuli as the higlier organism, with its indescribably complex organs of sense, and intricate maze of nervous paths. Many of the unicellular organisms, both plant and animal, are exceedingly sensitive to light. This is especially well shown by the ciliate Stentor. This is a gourd-shaped cell, completely covered with cilia, except at the basal end or "foot" by means of which the animal occasionally attaches itself. At one end is a flattened or hollow disk surrounded by a band of strong cilia which guide the food to a depression in the tlisk, the mouth. Close to the outer surface of the animal are a number of delicate contractile fibrils which func- tion as muscles, in which respect Stentor shows a marked advance in structure over Paramnecium. If the water in which this ciliate is swimming be suddenly illuminated, the animal reverses its movements, turns always in the same direction (in respect to the sides of the body) and then goes ahead once more. This reaction may be repeated a number of times, with the final result that the animal, through a series of ' ' trials and errors" is finally brought into a region of less light. Many of the unicellular plants and animals are provided with little spots of red pigment which are sensitive to light. In these forms, which belong to the group of flagellates, or forms bearing one or more long, whip-like cilia, and many of which are on the problematical fence between plants and animals, light reactions are well marked. The reactions may be either positive or negative, vigorous or weak, and may vary with the physiological state or condition of the organism at different times; but all serve to bring it into that strength of light which the organism "likes" best, i. e., to which it is best adapted. We are accustomed to think of unicellular organisms as expressing life in its simplest terras, but we have seen never- theless that many of them are indeed very complex creatures, possessing organs of locomotion, digestion, excretion, contrac- tion and even in some cases of special sense ("eye spots"). Kecently Kofoid and his students working at the University of California have discovered structures in certain Protozoa which they believe represent a primitive nervous system. These are delicate fibrils which can be clearly brought out The Living Machine 307 by appropriate staining, and are connected on the one hand with the tiagella or cilia and on the other with certain deeply staining granules in the body of the animal. To operate on creatures less than 1/150 inch in length is a surgical "stunt" of no small difficulty. Yet this has been done and these delicate fibrils cut, with the resultant cessation of move- ment of the connected fiagella. It is clear then that these fibrils represent a primitive nerve-muscle structure such as occurs in more diff'erentiated form in some of the simpler of the many-celled animals. The ability of higher plants to respond to stimuli is a Compass Plants as Seen from Different Positions From Kerner (translation by Oliver), "Natural History of Plants," Henry Holt and Company. Print furnished hii Vnunnl I. (intern Slide Couipmnj , Chicago. matter of common knowledge. We place a i)lant in our win- dow and soon leaves and stems are bending toward the light. The compass plant is a devoted worshipper of the sun. In the dawn it turns its opening flowers eastward to greet the rising sun, while at eventide they face the west attendant on its setting. The mold Piloljolus grows upon horse manure. When its spores ripen they are thrown by the plant with considerable force, surrounded by the spore cases, in the direction of the light. Jf a little fresh horse manure be placed in a box with a small window, the filaments of the mold turn toward the window, and as the spores ripen they are thrown in their cases against the window to which they adhere. A tree is felled by a land-slide or a tornado 308 Biology in America and some of its roots are left embedded in the ground. Soon the young flexible branches turn and grow upward opposite to the direction of gravity. Roots, on the contrary, when placed in a horizontal position, or inverted so as to point upward, will soon respond to the pull of gravity and grow downward. A seedling is suspended with its rootlets im- mersed in a stream of water, and soon they bend and grow against the current of the stream. Touch the leaves of the Mimosa or sensitive plant and almost immediately the paired MiNOSA OK Sensitive Plant From Kerncr (translation l)y Oliver), "Natural History of Plants,' Henry Holt and Company. lobes of the leaflets fold together and the leaf itself droops slightly, soon however resuming their original position if un- disturbed. The flowers of some plants serve as insect traps. In the sun dew (Drosera) the leaves are covered with numerous little hairs or tentacles, which secrete a sticky fluid, v;hich glistens in the sun like drops of dew, whence the plant derives its common name of "sun dew." Certain glands in the leaf secrete a digestive enzyme similar to the pepsin of an animal's stomach. If a drop of rain, or a grain of dust blown by The Living Machine 309 the wind, fall on the leaf, there is no movement of the ten- tacles or secretion of digestive fluid, but should an unlucky- insect alight on a sun dew leaf attracted by the honey-like drops upon the tentacles, they bend over and figuratively speaking seize upon the intruder, while the edges of the leaf fold together, thus wrapping the leaf about its body. The digestive glands complete the tragedy and what was once an insect now becomes incorporated in a leaf. Here we find a relatively complex series of reactions co-ordinated, or working in harmony, in an organism lacking any special nervous or co-ordinating system altogether. :.-->diL: - -3 ^^^^^^^^^ • F 1 if i!5!^^^^^^" Sun Dew Leaf Showing sticky hairs and entrapped insect. From Needham and Lloyd, "The Life of inland Waters," Comstock Publishing Company. Can these responses of the unicellular animals and plants be explained on a physico-chemical basis? This the leader of the mechanist school in America, Jacques Loeb, endeavors to do with his "forced movement" or "tropism theory'." According to this theory every organism is in a state of physiological equilibrium or balance with respect to a median plane of symmetry, until it is subjected on one side or the other to a stimulus, such as heat, light, electricity, etc. ; which stimulus induces certain physico-chemical changes, differing in degree on either side of the body, this difference forcing the organism to respond unequally on the two sides, and then perform a "forced movement" or a "tropism" (turning). While a great many of the one-celled organisms 310 Biology in America are not strictly symmetrical they may be assumed to be so for the purposes of the theory. Thus if a Paramoecium be acted upon by an electric current whose direction is oblique to the long axis of its body, the cilia on the side toward the negative pole beat more vigorously than do those on the positive side, and in the opposite direction, causing the animal to turn until it is in line with the current when it swims ahead, toward the negative pole. The stem of a plant turns toward the light, or bends upward, because of a difference in amount of chemical substances on the two sides, and ''this causes a difference in the velocity of chemical reactions be- tween (the two sides)." The organism has no control over its behavior but is so to speak blown about "by every wind that blows" as helplessly as a derelict ship upon the sea. Sagging in a Stem Due to unequal growth on the two sides. From Loeb, "Forced Move- ments, Tropisnis and Animal Conduct." By permission oj J. B. Lippincott Company. But what proof have we that such chemical changes as Loeb asvsumes do occur in the organism? If we suspend a stem of a plant in a horizontal position, it soon bends downward, taking the form of a U. This bending is not due to sagging of the stem as a rope sags, but rather to unequal growth of the two sides, which can be proven by marking equal dis- tances on upper and lower sides by lines of India ink and later measuring the amount of growth occurring between the marks. If the amount of bending in such a stem with leaves attached be compared with that in a stem lacking leaves, it will be found to be much greater in the former due to the greater amount of growth material available, and similarly there is greater bending in a stem furnished with a The Living Machine 311 complete leaf than in one with a leaf which has been partly cut awa3^ "What has been demonstrated in this case explains probably also why the apex of many plants when put into a horizontal position grows upward, and why certain roots under similar conditions grow downward. It disposes also in all probability of the suggestion that the apex of a posi- tively geotropic root has 'brain functions.' It is chemical mass action and not 'brain functions' which are needed to produce the changes in growth underlying geotropic curva- ture. "^ Such an explanation however is difficult to apply to many Eelative Amount of Bending Due to unequal growth in stems with and those without leaves. Loeb, "Forced Movements, Tropisms and Animal Conduct." By permission of J. B. Mppincott Company. From of the reactions of a Stentor or a Paramoecium. AVhile the latter animal reacts to an electric current by a cjifference in the beat of the cilia on the two sides, and the animal is thus turned so as to swim with the current, by a process seem- ingly as mechanical as that of turning a boat; in other cases, as when running into a salt solution, the behavior of Paramoecium is not so simply explained, for in this circum- stance it always turns in the same direction, regardless of the angle at which it meets the salt current, and even though * Loeb, "Forced Movements, Tropisms and Animal Conduct," i)p. 121-2. By permission of J. B. Lippincott Company. 312 Biology in America this turning may bring it towards, rather than away from tlie unfavorable medium. Its behavior in this case is fixed in character, and not so clearly mechanical as in the former case. A remarkable imitation of a living creature responsive to light stimuli has been invented by the American engineer John Hays Hammond, Jr. It "consists of a rectangular box about 3 feet long, li/o feet wide and 1 foot high mounted on three wheels, two of which are geared to a driving motor, while the third and rear wheel can be turned by electro- magnets and thus serve for guiding the machine. Two 5-inch condensing lenses on the forward end appear very much like large eyes. ' ' The operation of the machine is affected through the action of light on two selenium cells controlling electro- magnetic switches. "When one cell or both are illuminated the current is switched on to the driving motor ; when one cell alone is illuminated an electro-magnet is energized and aifects the turning of the rear steering wheel . . . thus bringing the shaded cell into the light. As soon and as long as both cells are equally illuminated in sufficient intensity, the machine moves in a straiglit line toward the light source. By throw- ing a switch which reverses the driving motors, the machine can be made to back away from the light in a most surpris- ing manner. "Upon shading or switching off the light the 'dog' can be stopped immediately, but it will resume its course behind the moving light so long as the light reaches the condensing lenses in sufficient intensity. Indeed, it is more faithful in this respect than the proverbial ass behind the bucket of oats. To the uninitiated the performance of the pseudo dog is very uncainiy indeed."* But what is the case with those animals with a nervous sys- tem by means of which their complex functions are made to work in orderly fashion? It would take us too far afi<'ld to attempt to trace, as Professor Parker has recently done in his admirable little book on the "Elementary Nervous System," the relation between the specialization of the latter, and the (delicacy) of their nervous responses. Suffice it to say that even in animals with a highly developed nervous system such as insects the responses in many cases at least appear to be purely mechanical. The attraction of the candle flame for the moth is proverbial, and even so highly organized an animal as a bird fre(|uently appears to be as much a creature of cir- cumstance as the moth, for birds often beat themselves to death in great numbers against light-houses. The purely mechanical response of an animal to stimuli is beautifully ^Mit'ssner, "Electrical Experimenter," Sept., 1915, p. 202. The Living Machine 313 illustrated by the behavior of the caterpillar of the butterfly (Porthesia chrysorrhcea). "This butterfly lays its eggs upon a shrub, on which the larvae hatch in the fall and on which they hibernate, as a rule, not far from the ground. As soon as the temperature reaches a certain height, they leave the nest; under natural conditions this happens in the spring when the first leaves have begun to form on the shrub. (The larvaB can however be induced to leave the nest at any time in the winter provided the temperature is raised sufficiently.) After leaving the nest, they crawl directly upward on the shrub where they And the leaves on which they feed. If the caterpillars should move down the shrub they would starve, but this they never do, always crawling upward to where they find their food. What gives the caterpillar this never-failing certainty which saves its life and for which the human being might envy the little larva? Is it a dim recol- lection of experience of former generations, as Samuel Butler would have us believe? It can be shown that this instinct is merely positive heliotropism and that the light reflected from the sky guides the animals upward. The caterpillars upon waking from their winter sleep are violently positively heliotropic, and it is this heliotropism which makes the ani- mals move upward. At the top of the branch they come in contact with a growing bud and chemical and tactile influ- ences set the mandibles of the young caterpillar into activ- ity. If we put these caterpillars into closed test tubes which lie with their longitudinal axes at right angles to the window they will all migrate to the window end where they will stay and starve, even if we put their favorite leaves into the test tube close behind them. These larva? are in this condition slaves of the light. * ' The few young leaves on top of a twig are quickly eaten by the caterpillar. The light which saved its life by making it creep upward where it finds its food would cause it to starve could the animal not free itself from the bondage of positive heliotropism. After having eaten it is no longer a slave of light but can and does creep downward. It can be shown that a caterpillar after having been fed loses its positive heliotropism almost completely and permanently. If we sub- mit unfed and fed caterpillars of the same nest to the same artificial or natural source of light in two different test tubes the unfed will creep to the light and stay there until tliey die, while those that have eaten will pay little or no attention to the light. Their positive heliotropism has disappeared and the animal after having eaten can creep in any direction. The restlessness which accompanies the condition of starva- tion makes the animal leave the top of the branches and creep 314 Biology in America downward — which is the only direction open to it — where it finds new young leaves on which it can feed. The wonderful hereditary instinct upon wliicli tlie life of the animal depends is its positive heliotropism in the unfed condition and the loss of this heliotropism after having eaten. The chemical changes following the taking up of the food abolish the heliotropism just as CO, arouses positive heliotropism in certain Daphnia," ° Such an instinct as that of this caterpillar is however a relatively simple one. Can those wonderfully complex in- stincts of so many animals which are connected with the pro- duction and care of the young be likewise relegated to the realm of the purely mechanical? To bring the reactions of so complex an organism as a vertebrate animal with its highly developed brain, nerves and sense organs into line with those of a unicellular form or a non-nervous plant in the present state of our knowledge is a matter of great difficulty. It can be shown with a reasonable degree of probability however that even here what we call "instinct" may be purely a response to physical or chemical stimuli, modified by certain substances secreted by the body and known as "hormones" from the Greek verb hormao to excite. The role of tliese substances and the bearing which they have on the "mechanistic conception of life" we shall dis- cuss later, merely bearing in mind their existence at this point, in order to appreciate what follows. ^ In many fish, as for example the minnow Fundulus, the act of mating consists in the sexes pressing their bodies close together in such a way that as the eggs are laid by the fe- male the sperms are pressed out by the male and are thus mixed with, and fertilize the eggs in the water. That this behavior on the part of the female at least is similar to a response to a solid object is shown by keeping the sexes sepa- rate at the spawning season, in which case the female will mate with the glass wall of the aquarium, when she happens to come in contact with it. This reaction is usually devel- oped only in the spawning season through the influence of the hormones secreted at that time, but if the female is kept permanently isolated from the male she may perform this act at any time of year. Loeb quotes the late Professor Whitman to the effect that male pigeons isolated from the females will attempt to mate with any solid object in their field of vision, e.g., glass bot- tles, and even with objects which give only the optical im- pression of a solid, namely their own shadow on the ground. And Craig has shown that male pigeons under these eircum- " Loeb, locus citatus, pp. 161-2. The Living Machine 315 stances will respond to a human hand. ." 'The dove was kept in a room where several men were at work, and he directed his display behavior toward these men just as if they be- longed to his own species. Each time I put food in his cage he became greatly excited, charging up and down the cage, bowing and cooing to me, and pecking my hand whenever it came within his cage. From that day until the day of his death, Jack continued to react in this social manner to hu- man beings. He would bow-and-coo to me at a distance, or to my face when near the cage ; but he paid greatest atten- tion to the hand — naturally so, because it was the only part with which he daily came into direct contact. He treated the hand much as if it were a living bird. Not only were his own activities directed toward the hand as if it were a bird, but he received treatment by the hand in the same spirit. The hand could stroke him, preen his neck, even pull the feathers sharply. Jack had absolutely no fear, but ran to the hand to be stroked or teased, showing the joy that all doves show in the attentions of their companions.' When this pigeon was almost a year old it was put into a cage with a female pigeon, but although the female aroused the sexual instinct of the formerly isolated male the latter did not mate with her, but mated with the hand of his attendant when the hand was put into the cage, and this continued throughout the season. Thus the memory images acquired by the bird at an impressionable age and period perverted its sexual tropisms. ' ' '^ Light response is a common phenomenon among the fresh water crustaceans. During broad daylight the upper levels of a lake may be almost uninhabited by these little animals, while at greater depths they occur in large numbers. As night comes on they return to the upper regions which they have deserted by day. Loeb has shown that the behavior of some of these animals with respect to light can be totally changed by chemical treatment. Thus the fresh water Daph- nia, Gammarus and other Crustacea when in a condition in which they do not respond to light can be made intensely positively heliotropic by adding some acid to the fresh water, especially weak CO,. If carbonated water or beer be added to water containing some of these animals they "will collect in a dense cluster on the window side of the dish." Other chemicals including alcohol give the same results. The light- minded reader may be inclined to draw an analogy between this behavior and the tendency of some individuals to enter into close communion with a lamp post in the "wee sma' hours." The alkaloids caffein and strychnin on the other ' Quoted from Loeb, locus citatus, pp. 168-9. 316 Biology in America hand will Tiiak(> the "fresh water Crustacean Diaptomus in- tensely nefjatively heliotropie." Changes of temperature and osmotic pressure may bring about similar results. The social life of the wasps, bees and ants has long been a subject for wonder and admiration. In the busy ant hive is a nest full of conundrums for the student of animal be- havior, the half of which have as yet scarcely been stated. The life of these social insects is seemingly so complex that we are accustomed to think of it in terms of human life and so we have ''castes" of "drones" ' and "queens" and "work- ers." Some of these latter are "soldiers," among whom we find "scouts" and "officers," others are "nurees," still oth- ers are "harvesters" whose duty it is to fill the "granaries," while yet others are "slave-makers," whose duty it is to go out and capture "slaves." Some ants play the part of "thieves" in other ants' nests. Yet others act as "hosts" entertaining other species of ants as "guests," while some keep aphids which they milk as "cows." Some give to other ants a "shampoo," in return for which the "delighted" ant yields a drop of honey, which the shampooer licks up greed- ily. Ants are "brave" and fight with "ferocity," while all are "industrious" and endowed with "wisdom," Mark Twain to the contrary notwithstanding. Can such ' ' human ' ' behavior be removed from the realm of poetrj^ and relegated to the prosaic one of purely mechanical reflex ? One of the most remarkable periods in the life of the ant is the swarming time, w'hen the winged males and "queens" perform their "nuptial" flight, rushing forth in "ecstasy" from their nest to found new colonies. After this flight the males die, the females pull off their wings and crawling into the ground either alone or accompanied by a group of work- ers, settle down to the humdrum duty of egg laying. Is such behavior a response to a purely physical or chemical stimu- lus? According to Loeb this "wedding flight" is a "helio- tropie phenomenon presumably due to substances produced in the body during this period, . . . (for) at a certain time — in the writer's observation toward sunset, when the sky is illuminated at the horizon only — the whole swarm of males and females leave the nest and fly in the direction of the glow"* After removing her wings the female loses her heliotropism and becomes strongly stereotropic, responding to touch stimuli, for if placed in a dark box containing folds of cloth, she is found snugly tucked aw^ay among the folds. ' This term belongs of course properly to insects, and is applied sec- ondarilj' to man. ' Loeb, locus citatus, p. 158. The Living Machine 317 It is this stereotropism which causes her to seok a hidinj? place ill the earth wherein to lay her eggs. This explanation would be very simple and satisfying did we know what it is which makes the ant at one moment responsive to light and at another to touch. "Presumably" Locb's explanation is cor- rect, but so long as it is founded on presumption only, it can hardly be said to be strictly scientific. Professor Vernon Kellogg has however made some observa- tions on the swarming of bees which prove pretty conclu- sively that this behavior is due to positive heliotropism in this insect. Professor Kellogg 's bees were kept in a cloth jacketed hive, with a small opening at the bottom. He says, "Last spring at the normal swarming time, while standing near the jacketed hive, I heard the excited hum of a begin- ning swarm and noted the first issuers rushing pellinell from the entrance. Interested to see the behavior of the com- munity in the hive during such an ecstatic condition as that of swarming, I lifted the cloth jacket, when the excited mass of bees which was pushing frantically down to the small exit in the lower corner of the hive turned with one accord about face and rushed directly upward away from the opening toward and to the top of the hive. Here the bees jammed, struggling violently. I slipped the jacket partly on ; the ones covered turned down ; the ones below stood undecided ; I dropped the jacket completely ; the mass began issuing from the exit again ; I pulled off the jacket, and again the whole community of excited bees flowed — that is the word for it, so perfectly aligned and so evenly moving were all the indi- viduals of the bee current — up to the closed top of the hive. Leaving the jacket off permanently, I prevented the issuing of the swarm until the ecstasy was passed and the usual quietly busy life of the hive was resumed. About three hours later there was a similar performance and failure to issue from the quickly unjacketed hive. On the next daj^ another attempt to swarm was made, and after nearly an hour of struggling and moving up and down, depending on my manipulation of the black jacket, most of the bees got out of the hive's opening and the swarming came off on a weed bunch near the laboratory. That the issuance from the hive at swarming time depends upon a sudden extra-development of positive heliotropism seems obvious. The ecstasy comes and the bees crowd for the one spot of light in the normal hive, namely, the entrance opening. But Avhen the covering jacket is lifted and the light comes strongly in from above — my hive was under a skylight — they rush toward tlie top, that is, toward the light. Jacket on and light shut off from above, down they rush; jacket off and light stronger from 318 Biology in America above tliaii })clo\v and tlicy respond like iron filings in front of an eleetromagnet which has its current suddenly turned on."« Our knowledge of what occurs when an impulse is sent over a nerve is very vague, but we have certain knowledge that physical and chemical changes take place in nerve cells and fibers coincident with such impulses, so that we are justified in believing that these impulses are physico-chemical phenom- ena. At the University of Chicago a young Japanese, Tashiro, a few years ago designed a very delicate little in- strument which he calls the biometer, or measurer of life. By means of this instrument he is able to detect traces of carbon dioxide as small as one thirty-millionth of an ounce. If a living nerve fiber be placed in the biometer and stimu- lated by an electrical current it is found to give off carbon dioxide as the other tissues of the body when they are made to work. There is combustion of living matter then when an impulse travels along a nerve. In the body of a nerve cell are certain peculiarly staining masses known as the Nissl bodies. When a nerve cell is stimulated successively several times these bodies disappear. Some chemical sub- stance has been consumed in the activity of the cell. Nervous activity develops electrical currents which can be meas- ured on a galvanometer, and with very delicate instruments electrical currents can even be detected in the resting nerve. The impulse is not instantaneous but requires measurable time for its transmission. The intensity of the impulses can be measured, as one measures the intensity of sound, light, electrical energ>^ or other physical energy. Nerve ac- tion can be checked by means of suitable chemicals (anes- thetics), while on the other hand certain substances, such as sodium, increase it. Anesthetics may produce similar ef- fects in non-nervous tissues and even in non-living matter. Thus Osterhout has shown that small quantities of anesthet- ics in the sea water decrease the electrical conductivity of seaweed, and several obseryers have shown that they check the passage of substances through cell membranes. If char- coal made from blood be mixed with a solution of oxalic acid containing free oxygen, the acid is changed to carbon diox- ide and water, the charcoal acting as a catalyzer. This catalytic power of the charcoal can be retarded by certain substances (i.e., carbon bisulphide) which act as anesthetics and which can also check the action of finely divided plat- inum in the separation (catalysis) of hydrogen peroxide to w^ater and oxygen. If therefore anesthetics produce effects in non-nervous and even in non-living substances similar to » Kellogg, V, "Some Insect Keflexes," "Science," XVIII, pp. 693-4. The Living Machine 319 those which they produce in nerves, we have good reason to believe that their action on the latter is similar to that on the former or that the prevention of nervous action, and therefore that action itself is fundamentally a physico-chem- ical one. But can physics and chemistry explain all the complicated instincts of the insect, bird and mammal, or the as yet un- solved riddle of human thought? Frankly we must admit that at present we do not know. According to Loeb these are merely ''tropistic reactions" modified by "memory images," which have an "orienting effect" upon the organ- ism, and which he attempts to explain by an illustration from the behavior of the solitary wasp Ammophila, which digs a hole in the ground in which to lay its eggs. Ammophila, a solitary wasp, makes a small hole in the ground and then goes out to hunt for a caterpillar, which, when found, it paralyzes by one or several stings. The wasp carries the caterpillar back to the nest, puts it into the hole, and covers the latter with sand. Before this is done, it de- posits its eggs on the caterpillar which serves the young larva as food. "An Ammophila had made a hole in a flower bed and left" the flower bed flying. A little later I saw an Ammophila running on the sidewalk of the street in front of the garden, dragging a caterpillar which it held in its mouth. The weight of the caterpillar prevented the wasp from flying. The garden was higher than the sidewalk and separated from it by a stone wall. The wasp repeatedly made an attempt to climb upon the stone wall, but kept falling down. Sus- pecting that it might have a hole prepared in the garden, I was curious to see whether and how it would find the hole. It followed the wall until it reached the neighboring yard, which had no wall. It now left the street and crawled into this yard, dragging the caterpillar along. Then crawling through the fence which separated the two yards, it dropped the caterpillar near the foot of a tree, and flew away. After a short zigzag flight it alighted on a flower bed in which I noticed two small holes. It soon left the bed and flew back to the tree, not in a straight line but in three stages, stopping twice on its way. At the third stop it landed at the place where the caterpillar lay. The catei-pillar was then dragged to the hole, pulled into it, and the hole was covered with tiny stones in the usual Avay. ' ' ^° Aside from the fact that we have no explanation of the physico-chemical processes underlying these "memory images," it is difficult to apply the theory to many of the "Loeb, locus citatus, p. 170. 320 Biology in America common reactions of higher animals. Can "memory images" teach a bird liow to build its nest for the first time, or guide the bees in the eonstruetiou of theii* wonderful condjs? Can tlieir "oi-ientiug effect" explain the return to its nest of the terns 'whieh AVatson carried from the Florida Keys to Cape Ilatteras, a distance of 150 miles from their houu\ into a re- gion never before visited by the birds? Possibly, although it requires a mighty effort of the imagination to unite cause and effect in this instance. But it is easy to find flaws in any theory Avhieh boldly ventures into the comparatively uncharted sea of animal reactions, and endeavors tliere to lay down a course which we may in safety follow ; so let us comfort ourselves with believing that "free will" has no place in science, but is merely an expression of the "verbal- ists," and tliat we simply "go where our legs carry us," a theory which has at least the advantage of enabling us to smile complacently, while ancient preachers hurl their an- athemas at the damned. We have spoken above of certain substances secreted by the animal body and known as hormones, which exercise a determining influence in animal behavior. What are these substances, how are they formed and what role do they play in animal physiology? The recognition of the value of various organs in curing disease goes back to the days of Hippocrates, the "father of medicine," and since his time many such remedies have been proposed. Thus the liver of the pigeon or the wolf were used in cases of disease of the liver, the rabbit's brain was given for tremors, and the lung of the fox for difficulty in breathing. The testicles of the donkey or the stag were rec- ommended by Pliny foi- the renovation of the debauchee, and even today (castoreum) a preparation obtained from the prei)utial glands of the beaver is sometimes employed for colic, hysteria and other disorders. In more recent days the French physiologist Claude Bernai'd advanced the view that all tissues give some secretion to the blood, which is of use in the nutrition of the body, and while our knowledge of these substances is as yet very fragmentary, their great im- portance in the life of the animal and their usefulness in the treatment of various disorck'rs, are widely recognized. It is known for example that diabetes, which is marked by the presence of sugar in the urine, is not a kidney disorder, but is due to improper actio]i of the pancreas, as a result of which a specific secretion, passed by the latter into the blood stream and functioning in sugar metabolism, is absent or re- duced in amount. Imperfect development of the thyroid gland leads to the The Living Machine 321 condition of under development both mental and physical, which is known as cretinism from tlie French word cretin. Feeding the extract of the thyroid gland of a sheep, or the gland itself, either raw or cooked, results in great increase in growth and development of both mind and body in such cases. The use of adrenalin (extract of the adrenal ghmd of some animal) is a common practise in certain diseases and in- juries as, for example, asthma, in which injections of the drug relax the bronchial muscles, and greatly relieve the suf- ferer. Attached to the lower, central part of the brain is a small gland, the pituitary body, which some enthusiastic the- orists have fancied to be the seat of the soul. If this gland be partly removed from a young puppy it ceases to grow ex- cept for the accumulation of fat. It keeps its puppy hair and milk teeth, while the development of the genital organs, and of the intelligence is much retarded. After partial digestion in the stomach, the food is further digested in the upper end of the small intestine. The di- gestive juices come in part from the liver and wall of the intestine itself, and in part from the pancreas. When the* partly digested and acid food passes from the stomach into the intestine, it causes the pancreatic juice to flow as auto- matically as the movement of the piston in a gasoline engine causes the intake of gasoline from the supply tank. The pancreas is activated by the acid food in the intestine. It was formerly supposed that this activation was effected by reflex nerve action, but we now know of an entirely differ- ent mechanism for this function. If an acid extract of the lining of the intestine be injected into the blood it causes the pancreas to secrete its juice as surely as does the presence of acid food in the intestine ; while similar extracts of other organs have no such effect. Here there is clear evidence of an internal secretion formed by the intestine, which reach- ing the pancreas via the blood causes the latter to act. A beautiful example of the chemical control of bodily func- tions. On the run of any through train between the terminals of a great trunk line there is a change of engines about once every 200 or 250 miles. Neither engine nor crew can give as effective service if operating for greater distances. The non-living, as well as the living machine needs rest after a certain period of work. Recently the well-known surgeon, Crile of Cleveland, has advanced an interesting theory which he calls the "kinetic drive" to explain the running down of the human mechan- ism. In the "kinetic drive" of modern life, when the hu- man machine is being driven at top speed, stored or poten- 322 Biology in Ame7'ica tial eiierfry is convert chI into active or kinetic energy, and the tissues of the body sutler corresponding loss. According to Crile certain pai-ts of the brain furnish the nervous en- ergy, which is probably identical with electrical energy, and wliich controls muscular, and otlier activity. The adrenal ghiiids furnish adrenalin, which in some way determines the oxidation processes in the brain to which the nervous energy is due. The thyroid gland, which Crile calls the ''pace- maker" of the body, furnishes iodin to the tissues and ren- Effect of the Kinetic Drive Photograph of a sohlier under extreme mental and physical stress. From Crile, " Tlie Kinetic Drive." "Journal of the American Medical Association," Vol. LXV. ders them more permeable to the nervous impulses. In the conversion of energy in 'the body certain acid waste products are formed which are eliminated by the liver, kidneys and lungs. The blood is thus kept alkaline, in Avhich condition only is the carriage of oxygen to the tissues possible. If the production of adrenalin, the secretion of the ad- renal glands, be prevented, either by removal of these glands, by cutting the nerves which supply them or by narcotizing the latter Avith morphin, activity is reduced. On the other hand administration of adrenalin produces results similar to The Living Machine 323 those of exertion, emotion, injury, etc., all of which lead to increase of energy change, while its continual adminis- tration leads to symptoms of exhaustion siuih as disorders of heart or kidney. Excessive doses of iodine also "cause Effect of the Kinetic Drive on The Tissues op the Body. Above, left to right, section of normal cerobelhun, adrenal and liver; below, sections of the same organs of a soldier who ' ' had snffered from hunger, thirst and loss of sleep, had made the extraordinary forced march of 180 miles from Mons to the Marne; in the midst of the great battle was wounded by the explosion of a shell; lay for hours awaiting help and died from exhaustion soon after reaeliing the ambulance. ' ' From Crile, "The Kinetic Drive," "Journal of the American Medical Association," Vol. LXV. all the phenomena of emotion and exertion, and inversely . . . emotion, infection, exertion, etc., cause changes in the iodine content of the thyroid." The results of the kinetii; diive are evident in changes of the tissues. The brain of a man who has died from exhaus- 324 Biology in America tion gives a very different picture from that of a man killed accidentally, certain of the cells having almost disappeared in the forme?'. The injection of poison (i.e. diphtheria toxin) into a dog- will produce similar changes in the l)rain, hut these changes can he in large measure prevented by the injection of mori)hin at the same time as the toxin, the former check- ing the nervous action induced by the latter. "Never before has there been such an opportunity for studying the behavior of the human mechanism uiidci- the strongest physical and psychic stress as in wari-ing Europe today. Tlioi-e ol)servations of the injured, of soldiers in the field, of ])i'isoners and of refugees gave me an unparalleled opportunity for studying the human kinetic drive on a vast scale. The illustration shows the gross effect of the combina- tion of extreme emotion and exertion as they are manifested in the faces and bearing of Belgium refugees and of wounded soldiers. "Turning now from the individual acutely driven by in- jury, by infection, by emotion, let us consider the individual chronically driven by the stinuili of want, ambition, anger, jealousy or grief, by infection, by pain and by autointoxica- tion. In the acute kinetic drive the individual is endan- gered by death from exhaustion or from acid intoxication, whereas in the chronic drive, the danger is that one or an- other of the overdriven organs or tissues may be perma- nently injured. "The common chronic drives are mental and physical over- work, chronic infections, excessive diet and pregnancy, the emotions of fear, hate, jealousy, shame and despair, and for- eign proteins, as in intestinal stasis. These conditions pre- sent every-day problems and demand but little discussion. Since the lesions of these various driving causes are the same, however; since infection, emotion. and overwork produce iden- tical end-effects; since usually two or more of these operate simultaneously, and since the emotional states are most amen- able to control, it becomes obvious why these conditions have often been controlled by means which have apparently no direct therapeutic value, such as faith in the physician, travel, diversion, prayer, healing springs, philosophy and Christian Science. Again and again, in the domain of regular medi- cine as in the domain of irregular medicine, the exclusion of worry has relieved the drive sufficiently to allow the body processes to overcome the primary disease. But the reverse is true also — innumerable men, under tlie strain of a chronic drive, are pushed beyond the narrow limits of safety by the added drive of grief, worry or shame. Is it not possible that when it is understood that the various kinetic stimuli have The Living Machine 325 interchangeable physical values, the game of health will be more skilfully played f"^^ Not only may poisons, emotion and fatigue induce the kinetic drive, but surgical shock, while the patient is an- esthetized, coupled with the terror of the knife before the operation, are also powerfidly inducing causes. While the jjatient may be entirely unconscious during the operation, there is nevertheless a great drain upon tlie nervous system induced by the action of the knife. To overcome these as much as possible Doctor Crile takes every ])ains to render the patient mentally at ease before the operation and block the kinetic drive by the use of morphin and by local anesthesia. Doctor Crile's theory and this operative method are gen- erally known as that of "anoci-association," or the pre- vention of the exhaustion of nervous energy through opera- tive shock. Experiments upon which it is based have led him to many other discoveries in the field of operative sur- gery, which have rendered his name famous, but this brief sketch must suffice as an illustration of the automatic and mechanical operation of the human machine. One of the most striking examples of the role of hormones or internal secretions is the action of the sex glands in con- trolling both body form and mental activity. The physical and mental changes occurring in both boj^s and girls at the time of puberty are too well known to require even passing mention here, while the dependence on the proper function- ing of the sex glands of the secondary sexual characters, such as the horns of the deer, the comb and feathering of the cock, the size of the stallion, and innumerable others, is equally familiar to everyone. Horses and cattle are castrated to ren- der them docile and serviceable as draft animals, and the cock is castrated in order that he may take on more flesh and become a welcome member of our dinner parties. A curious case is that of the race of poultry known as sebrights where the male goes masquerading in female attire, while the fe- male wears the habit of the male. Castration of either sex of these chickens results curiously enough in their adoption of their proper garb, either male or female. We are accustomed to think of the control of mind over matter and to regard the processes of thought as transcend- ing the bounds of the purely material universe, and yet where could we have a more beautiful example of the chemical (and therefore purely material) control of living processes, men- tal as well as physical, tlian in the case of the hormones or internal secretions of the animal body? "Crile, "Journal of the Aiuerican Medical Association," LXV, p. 213 2. Sebright Poultry Photoj^raplis of a normal scbrijjlit cock (ahovo), Avhich has the plumage of the hen, and castrated cock (below), which has male feathers. After Morgan, "Physical Basis of Heredity." Courtesy of Professor Morgan and the J. B. Lipphuott Company. 326 The Living Machine 327 Of all the features characteristic of living matter, none is more so than reproduction. Attempts have, it is true, been made to compare the growth of many crystals of salt in a concentrating solution with this miracle of life, but such at- tempts sound like a mere play upon words. There is noth- ing in the inorganic world in any way comparable to this wonderful phenomenon. Here then, if anywhere in the world of life, we should tind evidence of some force higher than the physical forces, did any such exist. But what do we find? We have seen in a previous chapter that the method of reproduction (bi-sexual or parthenogenetic) can be altered by external means; furthermore in Hydra it can similarly be changed from asexual (budding) to sexual. In some plants likewise the kind of reproduction may be determined by external factors. But beyond the mere shifting of the mode of reproduction by physical or chemical stimuli, it has been found that the process of sexual reproduction itself is a physico-chemical one and can be accomplished by arti- ficial means. In the first place the attraction between the sex cells is in some cases, though apparently not in all, a chem- ical one. If a capillary glass tube containing a weak solu- tion of malic acid (the acid found in apples and other fruits) be placed in water containing the sperms of ferns and mosses, the latter are attracted by the acid, and will enter the tube in great numbers. The action here however may be similar to that described above of "trapping" Paramoecium in a drop of acid. With the spermatozoa of the sea urchin however such chemical attraction appears not to exist. The union of egg and sperm in cases where chemical attraction cannot be proven appears to be due to chance. It is a well-known fact that it is very difficult to cross different species of ani- mals, this difference indeed being made the basis for a physi- ological definition of species, those animals which breed to- gether and produce fertile offspring being grouped as one species ; and those which do not interbreed, or do not at least produce fertile offspring being classed as distinct. In lower animals union of egg and sperm of different species may be prevented by physical differences such as size, or -ihemical differences may prevent the development of an egg into which by chance a foreign sperm has entered. In some cases it is possible to fertilize the egg of species A with the sperm of B, but the reciprocal cross is impossible. Among higher types there appears to exist a mutual repugnance to union, which effectually bars intermingling. Yet even here occasional in- stances of crossing and the production of fertile offs]iring are known, in crosses of hares and rabbits, various species of fish, etc. Crosses between members of widely distinct groups 328 Biology in America of animals are practically unknown in nature, and yet Loeb has succeeded in cross fertilizing tlie sea urchin's egg with the spenu of several s])ecies of starfish and one of tlie brittle stars, by simply adding a little sodium hydroxide or car- bonate to the sea water containing the eggs. The entrance of the sperm into the egg induces changes in tlie latter which can likewise be induced by chemical means. When the sperm of a sea urchin strikes the egg the two adhere to each other, due prol)al)ly to a sticky secretion of the latter. A few moments later the very delicate mem- brane surrounding the egg is pushed off from the surface and considerably thickened, due probably to absorption of water. The cause of this membrane formation (or better, membrane extrusion) is the li(iuefying of the surface of the egg just beneath the membrane and its consequent absorp- tion of water. Subsequent to this membrane formation the sperm head or nucleus penetrates still farther into the egg leaving the tail adherent to the egg membrane, while the egg nucleus advances to meet it, the two fuse and fertilization^ is accomplished, to be followed shortly by the division of the egg into first two, then four, eight, sixteen cells, and so on. INlany Avorkers have succeeded in imitating the processes of fertilization and causing the eggs of a large number of spe- cies of animals to develop parthenogenetically by various methods of treatment. In the case of the sea urchin Loeb fii'st treats the egg with some chemical (i.e., butyric or other monobasic fatty acid) which induces membrane formation, and then follows this treatment by placing the egg in sea water containing a little more salt than usual, or into nor- mal sea water lacking oxygen. The two procedures are es- sential to development, for if the first alone be employed the egg disintegrates after extruding its membrane, without fur- ther development. A similar result sometimes occurs when a sea urchin egg is fertilized by starfish sperm. Here the entrance of the sperm is very slow, some ten to fifty min- utes compared with about a minute in the case of sperm of the same species. In the former case, owing no doubt to the slow penetration of the spcimi, the latter does not always en- ter the egg, but remains attached to the extruded membrane. It seems therefore that the sperm secretes two distinct sub- stances, one of which causes liquefaction of the surface layer of the egg, with consequent al)sorption of water and extru- sion of the membrane, while the other causes the initial de- velopment (division of the egg) to ensue. The action of this second substance is not yet clearly understood but apart from the experiments in artificial parthenogenesis and the occasional cessation of devcloijuient after membrane forma- The Living Machine 329 tion in the cross fertilization experiments just mentioned, there are numerous other evidences of the action of two substances in fertilization. If, for example, the sea urchin egg be treated with the sperm of sharks or roosters, or with the blood or extracts of the organs of some invertebrates, or the blood sera of cattle, sheep, pigs or rabbits, membrane extrusion is induced but development soon ceases, unless the egg be transferred to a strengthened solution of sea water, in which development progresses for a time at least. The initial effect here (membrane extrusion) is the same as that obtained by the use of a fatty acid in artificial partheno- genesis, the second effect (division of the egg) being obtained in the same manner in both cases. There are many other ways in which eggs can be made to develop without fertiliza- tion: brushing the surface of the egg with a tine brush, plung- ing it for a few moments into concentrated sulphuric acid and pricking the egg membrane have all been successfully employed. The egg of even so highly organized an animal as the frog has been made to develop simply by pricking the egg membrane, and the resulting embryo reared to the adult state. What more striking evidence could be asked of the physico- chemical nature of life, than the development of a new be- ing by these means ? Far distant though we be from a solution of the "riddle of life" our only present hope of ultimate success is to pro- ceed from the known to the unknown, working on the hy- pothesis that nature is a unity and not a duality, and that the same fundamental laws control organic and inorganic worlds alike. CHAPTER XIII Color in Nature. Colors of floivcrs and the inter-relation of flowers and insects. Colors of animals and their physico- chemical causes. The theories of protective coloration, warri- ing and alluring colors, mimicry and recognition marks. But few American naturalists have entered the broad and fascinating field of Nature's colors. The subject was one of intense interest to Darwin and his co-workers, Wallace, Bates and Fritz Miiller, and has been largely developed by the recent Darwinians in Germany and England. A few Americans however have made valuable contributions to the subject w4iich w'e shall consider in this chapter. What is the cause and what the function of the bewilder- ing array of colors which we find on every hand? Are they useful to their possessors, and hence preserved through se- lection, or are they simply an expression of a reckless gener- osity of Nature, who lavishes her gifts with wild prodigality upon her creatures, regardless of whether they are bene- fited thereby or no? In the case of chlorophyl, the green coloring matter of leaves, and haemoglobin to which the red color of the blood is due, we know of course the physiolog- ical value, but most colors (those of flowers and insects for example) are of uncertain value, although many very pretty theories have been invented to account for them. The colors of flowers are formed as by-products of their metabolism. Their function is possibly to attract insects and thus aid in their fertilization. We have all of us been fa- miliar since childhood with the "busy little bee," and how_ it' "employs each shining hour" has ever been set before us for our edification and emulation; but the beautiful manner in which Nature has fashioned her children, both bee and flower, for the accomplishment of her "purpose" is not so familiar to us all. To attempt to recount here even in small measure the life of the bee would carry us too far aside from our main theme, and would moreover be a thankless task for one following in the footsteps of a Maeterlinck or a Fabre. We may however pause for a moment to consider the relation between a single sort of bee and a single kind of flower, in order to gain some notion of the wonderful co-adaptation 330 Color in Nature 331 existing between them. The body of a worker honey bee, which gathers the honey and the pollen for the hive, and performs all the other "chores" of the bee community, such as those of nurse maid, house cleaner, biitler, architect, po- liceman, and even executioner and undertaker, is clothed with numerous branched hairs, to which the pollen adheres as &e bee goes crawling about in the cups of the flowers which it visits. On one of the joints of the middle leg of the bee is a groove, overhung by rows of stiff bristles, form- ing the "pollen basket," while another joint of the same leg carries several rows of bristles or "pollen combs," by means of which the pollen is combed out of the hairs and trans- ferred to the pollen basket where it sticks in the form of a large ball. The "basket" enables the bee to carry more Eelation of Bee and Flower, a Salvia. 1, flower parts in usual position; 2, anthers ereet; 3, anthers tipped down; 4, bee entering flower; 5, flower with extruded style. From Kellogg, after Lubbock. pollen to its hive than it could if it depended solely on the hairs for this purpose. A part of the bee's esophagus is enlarged to form a "honey sac" in which is stored the nec- tar which it sucks from the flowei-s, and which in the hive is evaporated to form the honey. As the bee goes buzzing about from flower to flower, in search of nectar, some of the pollen from one flower is trans- ferred to another, and fertilization is thus effected. The manifold modifications of various types of flowers to ensure transference of pollen by insects, and to admit only those species which will pay for their supply of honey by trans- ferring pollen, the insect Bolsheviki and I.W.W.'s, which would appropriate the honey but carry no pollen in return, 332 Biology in America being debarred from entrance, are so numerous and won- derful as to need for their description a volume in itself. We must content ourselves with a single instance. In one of tlie Salvias (S. officinalis) the stamens ripen before the pistil, so tliat the flower cannot fertilize itself with its own pollen/ Tlie corolla of the flower consists of two lobes or lips, an upper and a lower, the former enclos- ing the style and stamens and the lower serving as a landing stage for insect visitors. Before the ovary ripens the style is withdrawn within the upper lobe of the corolla, as shown at 1 in the preceding figure; after ripening it hangs down over the lower lip, 5. In the former position it is not ordi- narily toiiclied l)y an insect entering the flower, while in the latter it obviously must be. The functional stamens are two in number, placed close together at the base of the hood. Each stamen bears two anthers, separated by a long connec- tive, which stands upright beneath the hood. The lower pair of anthers contain little or no pollen, while the upper pair are full of it. If a bee alights on the lower lip and attempts to make his way into the flower tube, where the nec- tar is hidden, his head must first of all encounter the lower pair of partly developed anthers. As these are pushed before him in his effort to enter, the upper pair are swung down upon their hinge, striking the bee's back and depositing thereon their load of pollen. Thus the bee, visiting this Salvia, is either besprinkled with pollen to be carried to an- other flower, or deposits some of its pollen upon the hanging styles ready to receive it, according to the stage of develop- ment of ovaries and stamens. The question of the part played by flower color in these transactions is very perplexing, and calls for much more in- vestigation. Some authors maintain, while others deny, the power of insects to distinguish color, and more especially to discriminate between color i)atterns in flowers. An in- sect's power of sight is probably very limited, so that its distinction of the form, and possibly also of the color of flowers at any considerable distance is doubtful. There are however some very clear experiments showing ability on the part of insects to distinguish color, but the whole question is still very doubtful. Animal colors fall into two classes — the chemical and the physical, or a combination of the two. The chemical colors are due to pigments diffused inainly through either the sur- ' In sonic species of plants tlic flowers are on the contrary so con- structed as to insure self-fertilization. The whole question of the in- fluence of inbreedinjj upon virility in both plants and animals is very uncertain at the present time. See page 85. Color in Nature 333 face cells, the cnticula or elsewhere, or else lodged in spe- cial cells knowu as chroniat()j)hores, the absorption of cer- tain rays of light by these pigments, and the reflection of their complementary rays causing the various colors. Pig- ments develop through the action of an oxidizing ferment upon a color-forming substance or chromogen, and numy different pigments may be merely different stages in the mcxli- fication of a single chromogen. Thus the brown and black pigments of animals pass through yellow, orange and red stages, before attaining their final color. The influence of external factors in producing more or less permanent color changes in animals has been discussed in a previous chapter, dealing with the influence of the en- vironment upon the development of the individual. Tem- porary changes in the hue or color of animals may resultin response to external stimuli. The chameleon is the class- ical example of this. Temperature and light appear to be the controlling stimuli although their effects differ in differ- ent species. Fear may affect the color of an animal. Thus it is possible to cause a frog to "turn pale with fear" by continually disturbing it with a stick or otherwise. The color changes in these cases are due to changes in the distribution of the granules of pigment in the chromatophores ; when the pigment is distributed throughout the cell the color is darker, when concentrated around the nucleus the reverse is true. One of the most remarkable cases of color adaptation known is that of the flatfish. Symmetrical both in form and color in its early stages this fish soon turns on its side and thereafter lies on the bottom of the sea. Accompanying this change in life the eyes, fins and mouth shift to the upper side of the body, and the lower side loses its color. But, as the English naturalist Cunningham has shown, the color will return to the lower side in fish kept in an a"x;^^ r- ' ': -^ Ws ^■i''^' ' '-^"'^- ^'"^ "^ '*- ■»'•*'' '^M w ■.<•': ,-.---■• V - -.V IMIt. ■ The Antelope Which carries a recognition mark ui)ou its rump. A vanishing species which once thronged our western plains.- Courtesy of the National Zoiilof/ical Park. among the most striking and beautiful objects in nature ; while the females must be content with quiet colors, remU'ring them wholly different in appearance from their mates. Once again the Darwinian comes to rescue us from our dih-mma witli his theory of sexual selection, which was proposed auii ably defended by Darwin himself in his "Origin of Species." "This form of selection depends, not on a struggle for existence in relation to other organic beiiig-s or to external conditions, but on a struggle between the indivitluals of one sex, generally the males, for the possession of the other sex. 344 Biology in America The result is not death to the unsuccessful competitor, but few or no offspring. . , . Generally, the most vigorous males, those whicli are best fitted for their places in nature, will leave most progeny. But in many cases, victory depends not so much on general vigor, as on having special weapons, con- fined to the male sex. A hornless stag or spurless cock would have a poor chance of leaving numerous offspring. Sexual selection, by always allowing the victor to breed, might surely give indomitable courage, length to the spur, and strength Male and Female Wood Ducks Showing sexual differences in color, from an illustration by Louis Agassiz Fuertes. Courtesy of the U. 8. Bureau of Biological Survey. to the wing to strike in the spurred leg, in nearly the same manner as does the brutal cockfighter by the careful selection of his best cocks. How low in the scale of nature the law of battle descends, I know not; male alligators have been described as fighting, bellowing, and whirling around, like Indians in a war-dance, for the possession of the females; male salmons have been observed fighting all day long; male stag-beetles sometimes bear wounds from the huge mandibles of other males; the males of certain hymenopterous insects have been frequently seen by that inimitable observer M, Fabre, fighting for a particular female who sits by, an ap- Sexual Difference in Beetles The males to the left, and females to the right. From Darwin's "Descent of Man," D. Applet on and Company. Sexual Difference in Fish The male above, the female below. From Darwin's "Descent of Man," D. Appleton and Company. 345 346 Biology in America parently unconcerned beholder of the struggle, and then re- tires with the conqueror. The war is, perhaps, severest be- tween tlie males of polygamous animals, and these seem oftenest provided with special weapons. The males of car- nivorous animals are already well armed ; though to them and to others, special means of defense may be given through means of sexual selection, as the mane of the lion, and the hooked jaw to the male salmon; for the shield may be as im- portant for victory as the sword or spear. Amongst birds, the contest is often of a more peaceful cliaracter. All those who have attended to the subject, be- lieve that there is the severest rivalry between the males of many species to attract, by singing, the females. The rock- thrush of Guiana, birds of paradise, and some others, congre- gate ; and successive males display with the most elaborate care, and show off in the best manner, their gorgeous plumage ; they likewise perform strange antics before the females, which standing by as spectators at last choose the most attractive partner. Those who have closely attended to birds in con- tinement well know that they often take individual prefer- ences and dislikes : thus Sir R. Heron has described how a pied peacock was eminently attractive to all his hen birds. I cannot here enter on the necessary details; but if man can in a short time give beauty and an elegant carriage to his bantams, according to his standard of beauty, I can see no good reason to doubt tliat female birds, by selecting, during thousands of generations, the most melodious or beautiful males, according to their standards of beauty, might produce a marked effect. ' ' - These various theories of animal color are unfortunately mainly founded on an "anthropomorphic" basis. If it is difficult for us to discover the frog in the grass or a lizard on a stump, assuredly it must be so likewise to the natural enemies of these creatures. If a butterfly or a toad has a foul taste, or an unpleasant odor to man, it must imj)ress its enemies with the same unpleasant feature. If the white tail of the rabbit renders him easier for us to follow as he dashes away, it must also aid the young in their flight to keep near the mother. It does not follow however that be- cause an object is difficult for man to see, it is likewise difficult for the eye of bird or beast to follow it, or because another object is unpleasant to man's senses, that it is also unpleasant to those of the creatures of the wild. Recent experiments tend in particular to refute the theory of warning color. This is based very largely, though not =■ Darwin, "Origin of Species," 6th eel., pp. 108-109. By permission of D. Appleton and Company. Color in Nature 347 exclusively on the colors of certain butterflies, whose natural enemies are assumed to be birds, to which they arc supposedly obnoxious through unpleasant taste or odor. Two distinct assumptions are involved in the theory — first that butterflies are the natural prey of birds, and second that certain species are avoided by the latter by reason of some unpleasant characteristic. The first of these hypotheses is founded on very slender evidence. There are, it is true, a few scattered records of birds feeding; on butterflies in nature, but, consider- ing the extent to which birds and butterflies have been studied in the field, these records are few and far between. But, confronted by the paucity of evidence in one direction, the ever facile mind of the Darwinian turns immediately in an- other. Butterflies carry with them, he maintains, evidence of the peril in which they live, in the form of nicks in the hind wings; which, since they frequently have the form of a bird's beak, must be the result of unsuccessful attacks by birds, from which the butterflies have made hairbreadth escapes. But if one studies a series of butterflies taken in late summer or early autumn, he will probably find the wings of nearly all of them torn and broken in such a way that only a little Darwinian imagination is required to conjure up out of all these tattered wings a tale of the tragedies which might have been. The more natural interpretation is however that the butterflies' wings merely show the result of the wear and tear of a summer's flight through field and thicket. If butterflies are the natural prey of birds an examination of their stomachs should prove it. Such examinations have been made for many years by the U. S. Biological Survey, in the study of the relation of birds to agriculture, but out of some 80,000 examinations made butterfly remains have been found in but very few. The second point involved in the theory has rather more evidence in its support. There are a number of observations on record of birds refusing the strikingly colored and evi- dently distasteful species of butterflies. These observations cover not merely butterflies but other insects also. But there is also much evidence to the contrary. Thus Judd, in a number of feeding experiments, has shown that obnoxious forms such as various species of bugs (TIemiptera) whether warningly colored or not are occasionally eaten, as well as stinging insects such as bees. Judd's results must however be accepted with caution, having been obtained with caged birds. It is not certain that captive animals show normal tastes. In some of my own experiments I have found that young birds will eat almost anything which is offered 348 Biolofjy in America them, and in some cases will pick up bits of leaves, etc., which never in any likelihood form part of their normal food under mitural conditions. Stomach examinations however show that supposedly disagreeable insects form a considerable part of birds' food. Thus hairy caterpillars, stinging bees and wasps, ants and species of foul-tasting or smelling bugs and beetles are eaten by a great variety of birds. Greater doubt is cast upon the theory of warning color by the work of Reighard at the Dry Tortugas. These are isolated groups of coral islands lying off the Florida coast, and sur- rounded by coral reefs. Inhabiting these latter are many species of brilliantly colored fishes, which supposedly come within the category of warningly colored forms. Living in the same reefs is a predaceous fish, the gray snapper. Reig- hard has shown that the brilliantly colored fishes of the reefs are readily eaten by the snapper, once they are outside the protection of the reefs. That the snappers can distinguish different colors how^ever and can learn to associate them with unpleasant tastes was proved by attaching the stinging ten- tacles of a jellyfish (Cassiopea) to a small fish upon which the snappers commonly feed, and coloring the prey red. After several unpleasant experiences the snappers learned to leave the red fish severely alone, whether with or without the tentacles attached, while they took fish which were colored white even though the stinging tentacles were attached to them. Longley also has made extensive studies of these fishes, as a result of which he finds that the apparently conspicuous and contrasting colors of so many coral reef fishes are really protective, harmonizing their possessors with their surround- ings and have no relation to warning color whatever. Long- ley strongly inclines to the hypothesis of Thayer that the greater the contrasts in an animal's color, the more readily will it harmonize with its background, a principle most strikingly illustrated in the bizarre effects of our camouflaged ships in the recent war. CHAPTER XIV Aquatic hiologij. Oceanography, life of the sea and its environment. Biology of inland waters. Methods of studying aquatic life. The development of aquatic biology, especially of its marine phase, both here and abroad, has gone very nearly hand in hand with the development of interest in the fisheries". Per- haps nowhere else in biology has there been a better recog- nition of the dependence of commercial interest upon scientific knowledge — of the national stomach ii])on the national brains. The recognition of this fact in Europe led to the establishment of the marine stations at Kiel, Lowestoft, Boulogne and else- where, and to the development of the International Council for the Investigation of the Sea, conducted jointly by Great Britain, Norway, Sweden, Denmark, Holland, Germany, Belgium and Russia, an enterprise which before the great war was achieving results of vast scientific and practical value, and which it is to be hoped will soon be re-established, following the advent of peace. The earliest attempts at exploration of the sea were obser- vations on currents, tides, waves and temperature. Tliere were however occasional efforts to determine the depth of tjie ocean by the earlier navigators, some of them undertaken with very ingenious, but not very successful apparatus. The first map of the Gulf Stream was published by Ben- jamin Franklin in 1770, and a few years later temperature observations along the north Atlantic coast, were made by the Englishman, Blagden. The U. S. Exploring Expedition in 1839-42, under the direction of Captain AVilkes, accomi)anied by the geologist Dana, made a number of deep-sea dredgings. The U. S. Coast Survey has made important contributions to our knowl- edge of the sea since the early part of the last century and the first successful apparatus for deej) sea sounding was devised by Midshipman Brooke of the U. S. Navy. As the result of dredgings conducted by tlu^ Survey off the coasts of Florida and Cuba between 1867 and 1870, uuder the direction of the elder Agassiz, he reached tlie conclusion that former oceanic and continental areas were similar to those of the 349 350 Biology in America prosojit. Expoditioiis hy several sliii)s of tlie U. S. Navy and Coast ►Survey during tlie latter iialf of the last century- have made valuable additions to our knowledge of the sea, among Avhieh may be mentioned the cruises of the "Blake" in th(> ('ari))beaii Sea and tlie Gulf of Mexico from 1877 to 18SU under the direction of the late Alexander Agassiz, of the ]\Iuseum of Comparative Zoolog;\^ of Harvard. University, and son of the great Swiss-American naturalist. The establishment of the U. S. Fish Connnission in 1871 early led to marine expeditions conducted under its auspices. The ' ' Albatross ' ' of the U. S. Bureau op Fisheries. The pioneer American vessel engaged in oceanography. She was in charge of Alexander Agassiz during his cruises on the Pacific and has added much to our knowledge of the fisheries of the Pacific Coast, espe- cially Alaska. After Smith, in Bulletin of the U. S. Bureau of Fisheries for 1908. although partly financed by private money. The Commission was at first dependent upon vessels loaned to it by the U. S. Revenue Cutter Service, the Navy, and the Coast Survey, but in 1880 it accpiired for its own use the steamer "Fish Hawk," which has since then been used on the Atlantic coast, partly for scientific investigations and partly as a floating fish hatchery; and two years later the "Albatross," which has been mainly employed in scientific and practical investi- gations on the Pacific Ocean, but during the recent war was in naval service on the Atlantic, and is at present temporarily out of commission at Baltimore. Much of the hazard of the fisherman's trade is due to the Life of the Waters 351 dangerous construction of his craft. In order to minimize so far as possible this danger the Commission constructed a model fishing- schooner, the "Grampus," designed to overcome some of the defects in the okler type of boat hitherto in use. The construction of this vessel has largely revolutionized that of the New England fishing boats and some idea of its influence in the saving of wealth and life may be gained by comparing the loss of 82 vessels from Gloucester alone during the decade previous to 1883, at a cost of $400,000 and 895 lives, with that of the period from 1898-1907, in which only one-fourth as many vessels and lives were sacrificed. Besides serving as a model fishing boat, the ''Grampus" has also been used in scientific investigations along the Atlantic coast. In addition to tlie more extended researches of the "Alba- tross" in the Pacific considerable local work has been done by the boats of the marine station of the University of California, now known as the Scripps Institution, and some desultory observations have been made by occasional workers elsewhere. There has been however no systematic or concerted program by American workers in the great field of oceanography similar to that undertaken by the European countries already mentioned prior to the war, a neglect which is scarcely pardonable in view of the richness and extent of our oceanic domain, the ever-growing cry for food, and the financial resources of our nation both public and private.^ The biology of inland waters has also been largely depend- ent upon economic interests, in part those furthered by the Bureau of Fisheries, and in part by various state surveys. The work of the oceanographer' as related to biology is concerned with investigating the physical and chemical con- ditions of life in the sea, and in determining how marine life is related to these conditions. The economic phase of the science deals with those forms useful to man for food_ or otherwise, in their relation to their environment both physical and biological, and endeavors to discover the best meansof obtaining, protecting and increasing them. A consideration of this latter phase may best be left to another chapter. In a review like the present we must needs pass over much that is interesting and important in this great field, touching briefly however on some of its most salient features. If one were to construct a model of the earth with a diameter of six feet, a scratch on the surface of the globe, about one-tenth of an inch deep would represent the greatest irregularity of the earth's surface, from the summit of Mt. Everest, rearing its yet unconquered front nearly six miles into the clouds, to the abysmal depth of 31,614 feet or 2,600 » Plans are at present on foot, looking toward such an end. 352 Biology in Americo. feet greater than the height of Everest, which is the greatest depth yet recorded in any ocean. This deptli was found by tlie U. !S. 8. "Nero," in the north raeiiic near the island of Guam. The floor of the ocean is covered with fine ooze composed largely of the fragments of shells of many kinds of animals and some plants, predominant among which in many places wm ^d//.J^,. « 1 ■. -^SIB o H^k^R ■ • ,-- t ' "4 Hipwil ■: jggggi r-^ t'^'- ■ / ^ / - E^KKm'^^/^^^B^&^b 1* .•*-J- . : ! ■<^ . \ A Eadiolarian Courtesy of the American Museum of Natural History. are the minute and wonderfully sculptured shells of uni- cellular animals, Radiolaria, and Foraminifera, which in life are floating at the surface of the sea. The shells of these minute creatures often make up so large a part of the bottom deposits, that the latter are named from them. One of the commonest of them is Globigerina, which has given its name to extensive bottom deposits in the sea. The shells of certain small species of molluscs, the pteropods or "wing- Life of Ike Waters 353 feet," so named from the wiiig-like expansions of the muscuhir foot whicli protrnde from Uie shell and by means of whieh they swim, make up the great mass of tlie ooze in other places, hence the name pteropod ooze, while the marvellously beau- tiful little diatoms, so named from Ihe two parts of the shell, which fit together like the two halves of a pill box predominate in other places, producing the diatom ooze, which is com- mon in the circumpolar regions, both north and south. Not only do the shells of animals and plants settle to the ocean floor, but contained within these shells are their dead bodies, which serve as food for bottom living animals, whose digestive tracts are found full of mud from which the suitable food material is digested and absorbed, the greater amount being discharged as waste. It is thus that oysters and clams are nourished, and as we enjoy our "bluepoints" and "little necks," on the half shell, we may relish them all the more to know that we too are scavengers of the sea. Far to the eastward from our southern coast extends the "Sargasso Sea," so called from the sargassum weed, which floats in great masses at the surface of the ocean, and is borne out from the warm waters of the Gulf of Mexico by the Gulf Stream to the northeast. Making its own food from the inorganic materials in the sea, by means of the action of sunlight on its chlorophyl, it contributes largely through its death and decay to the food supply for animals upon the ocean floor. Then too organic dust, containing the decayed remains of land plants and animals, is carried by wind and current far from land and gradually settles to the bottom as it goes. How far this detritus may be carried out to sea we do not know. It probably varies greatly in different oceans, dependent on wind and current. Volcanic dust however has been carried around the world. What are the conditions of life for the "dwellers in the deep"? How do they "live and move and have their being" in the abysmal depths of the sea? While by far the greater number of marine organisms are found in comparatively shal- low water, or floating and swimming freely at the surface, there are a few "dwellers in darkness," who, in the struggle for existence, have sought out the "fathomless depths" as an abiding place, there to live their lives unknown, save when the trawl of the explorer brings them forth from their retreat. Even at depths of over 24,000 feet life has been found within the sea. At such a depth any object is under a pres- sure of over 10,000 pounds per square inch. The pressure on the ordinary concrete foundation for a bridge pier or a New York "skyscraper" is only 350 pounds per square inch, so that some of the inhabitants of the sea have to 'J 354 Biology in America sustain roufjlily llircc times the pressure on the foundations of the Woohvorfli Building or the Metropolitan Life. To withstand such a pressure tlie body of an animal would have to be surrounded by an exceedingly strong shell, or else it must be of such a character that the pressure is easily ren- dered the same Avithin and without. The latter method is the one Avhich Nature has adopted, and the bodies of deep sea animals are so soft and permeable that they lose their Deep Sea Fishes as Seen Against a Light Background. Photograph of a group in the American Museum of Natural History in New York. Courtesy of the Museum. are shape very easily when brought to the surface and consequently hard to preserve in their natural form. Below depths of three thousand feet light is virtually absent in the sea. Animals therefore living below this comparatively shallow depth are in perpetual darkness, save for such light as they themselves generate. Many of these deep sea forms carry their own lanterns about w'itli them in the form of phosphorescent organs. The firefly is an object of common experience to many a country dweller, but only the ocean voyager or the inhabitant of its shores, who has seen the Life of the Waters 355 crest of a wave break into myriad opalescent drops, can fully appreciate the beauty and the wonder of this strange, un- canny light. The physiology of light production in animals is not yet well understood. It is known to be due however to some secretion which combines readily with oxygen, this action producing the light. Phosphorescence is by no means limited to deep sea animals, nor do all of the latter possess it. One of the most interesting cases of light production is Deep Sea Fishes as Seen Against a Dark Background Photograph of a group in the American Museum of Natural History in New York. Courtesy of tfie Museum. that of the deep sea angler fish, Gigantactus, where the snout is modified to form a luminous organ, suspended on a stalk above the head of the fish. This organ is supposed to act as a lure to attract smaller fish which readily fall victims to the angler's appetite. The occurrence of eyes in deep sea fishes foniis a very perplexing problem. In some the eyes are large, and in others extremely small or entirely lacking. By analogy with the cave dwellers among land and fresh water animals, we sliould expect the deep sea fishes to be blind. But on the other hand 356 Biology in America Two Dknizens of the Deep Left. An angler fish which carries a lure on its head to entice its prey within reach of its capacious jaws. From the "National Geo- graphic Magazine," Vol. 21. Right. Chiasinodus niger, champion cannibal among fishes. From Murray, "Depths of the Ocean," By permission of the Macmillan Company. of what advantage would it be to a species of fisli to have light forming organs, and no means of seeing them? The whole question of sight organs and light production by deep sea forms is a veritable ' ' Chinese puzzle, ' ' which no one has yet had ingenuity enough to solve. It is not merely a ques- GiANT Squid And skin of Avhale showing marks of giant squid tentacles. From Murray, ' ' Depths of the Ocean. ' ' Bj/ permission of the Macmillan Company. Life of the Waters 357 tion of two animals of the same species seeing and recognizing one another; but of one species finding its prey and another escaping from its enemies ; while in many cases light produc- The Portuguese Man of War, an Animal "U-Boat " The balloon-like float filled with gas secreted by its walls floats at the surface of the sea, so that the colony is carried hither and yon by wind and tide. Each of the thread-like processes pendent from the float is an individual member of the colony having its own special function to perform, some having stinging cells for capture of prey, others serving as feelers and still others as feeders, the mouths and stomachs of the colony. By contraction of the float the gas is expelled and the animal can submej-ge. A southern form, it is often curried by the Gulf Stream into the North Atlantic. Courtesy of the Amcfican Museum of Xatural Hustory. tion may be purely incidental to other processes in the life of the animal. And furtlicr, the same ends are attained in different ways in different species. Nature knows "more 358 Biology in America than one way to kill a cat," and, vice versa, to save its life and preserve its kind. The depths of the sea are the scene of many a drama. If Science but had the key to Davy Jones' Locker, what a wealth of secrets, tragic as well as comic, she might reveal! There is the fate of the flatfish who fell over on his side before he grew up, and remained lop-sided ever after. And there is the champion cannibal of the animal world, Chias- modus niger, who swallowed his elder brother, acquiring thereby a portly figure of which the most accomplished gour- mand might well be proud. Many a terrific battle has been fought upon the sea — titanic struggles of giant squids and mighty whales, battling to the death. Some of these squids have a spread of tentacles of over eighty feet, and the whales, which are probably the invariable victors in these encounters, bear with them well- Velella Ori^jinal from a specimen in the zoological collection of the Univer- sity of North Dakota. earned decorations as evidence of their prowess, in the form of circular scars left upon the skin by the suckers of the squid. Floating at the surface of the sea is a host of beings large and small, "creatures of circumstance" driven hither and yon by "every wind that blows." Delicately tinted jelly- fish, Velellas with their tiny sails, the "Portuguese Man of War" with its balloon-like float and its vicious stinging tentacles trailing below, the rotund sunfish, and a legion of crustaceans, molluscs and many others, live at or near the surface. What enables them to float so easily? Some are lighter than the water, as the jellyfish and the sunfish, with its jacket of fat beneath the skin. Still others have floating sacks or bladders containing gas, like the "Portuguese Man of War," while others still, the great majority, have pro- jections of some sort, which increase their "specific surface," i. e., the ratio between surface and weight, and hinder their sinking. A tin plate will sink slower than a leaden bullet Above. An Ocean Sunfish. Photo by C. H. Townsend. By permission of the New York Zoological Society. Below. A Crustacean Lakva, slio\vin