Popular Science Monthly/Volume 31/October 1887/What American Zoologists Have Done for Evolution: 1887 Speech I
By Professor EDWARD S. MORSE.
ELEVEN years ago I had the honor of reading before this Association an address in which an attempt was made to show what American zoölogists had done for evolution. (See "Popular Science Monthly," Vol. X, pages 1 and 181.) My reasons for selecting this subject were, first, that no general review of this nature had been made; and, second, that many of the oft-repeated examples in support of the derivative theory were from European sources and did not carry the weight of equally important facts, the records of which were concealed in our own scientific journals. Darwin was pleased to write to me that most of the facts I had mentioned were familiar to him; but, to use his own words, he was amazed at their number and importance when brought together in this manner. The encouragement of his recognition has led me to select a continuation of this theme as a subject for the customary presidential address, a task which is at best a thankless if not a profitless one. Had I faintly realized, however, the increasing number and importance of the contributions made by our students on this subject, I should certainly have chosen a different theme.
Incomplete as is this record of ten years' work, I am compelled to present it. In the Buffalo address two marked periods in the work of the zoölogists in this country are recognized: the one period embracing the work of the topographers, the field-surveyors in the science; the other period elating from the advent of Agassiz, with the wonderful impulse he imparted to the study by his enthusiasm and devotion. A third period in American zoölogical science, and by far the most important awakening, dates from the publication of Darwin's "Origin of Species." Its effect on zoölogical literature was striking. The papers were first tinged with the new doctrine, then saturated, and now, without reference to the theory, derivation is taken for granted.
As zoölogists we are indebted to Darwin for the wide-spread public interest in our work. Before Darwin the importance of our special studies was far outweighed by the practical value placed upon science, in the application of which an immediate material gain was assured. Chemistry, physics, geology were important to the public only because a practical application of these sciences was capable of showing an immediate material return.
Agassiz, in his appeal to the State for appropriations for the great museum at Cambridge, insisted that there were higher dividends than those of money to be looked for in endowments for zoölogical museums, and these were intellectual dividends. "While the force of this appeal will always remain true, the transcendent importance of the naturalist's studies from the standpoint of Darwin is widely recognized. Man now becomes an object of rigid scientific scrutiny from the new position which has shed such a flood of light upon the animals below him. His habits, behavior, the physical influences of his environment and their effects upon him, transmission of peculiarities through the laws of heredity—all these factors are directly implicated in the burning questions and problems which agitate him to-day. Questions of labor, temperance, prison reform, distribution of charities, religious agitations, are questions immediately concerning the mammal man, and are now to be seriously studied from the solid standpoint of observation and experiment and not from the emotional and often incongruous attitude of the Church. To a naturalist it may seem well-nigh profitless to discuss the question of evolution since the battle has been won, and if there be any discussion it is as to the relative merits and force of the various factors involved. The public, however, are greatly interested in the matter, as may be seen by a renewal of the fight in the English reviews, and the agitation is still kept up by well-meaning though ignorant advisers, who insist that Science has not yet accepted the doctrine; and great Church organizations meet to condemn and expel their teachers of science from certain schools of learning because their teachings are imbued with the heresy.
Dr. Asa Gray, in his discriminating biographical memoir of Darwin, says, in regard to the "Doctrine of Descent": "It is an advance from which it is evidently impossible to recede. As has been said of the theory of the Conservation of Energy, so of this: 'The proof of this great generalization, like that of all other generalizations, lies mainly in the fact that the evidence in its favor is continually augmenting, while that against it is continually diminishing, as the progress of science reveals to us more and more the working of the universe.'" Let us examine, then, the evidences, trivial as well as important, that have been recorded by American zoölogists within the past ten years in support of the derivative theory.
Without further apology for the very imperfect character of this survey, let me at once begin by calling attention first to the testimony regarding the variation in habits and evidences of reasoning power in animals. The establishment of individual variation in mental powers, change in habits, etc., lies at the foundation of Darwinism as furnishing material for selective action. There is no group of animals which exceeds the birds in varied and suggestive material for the evolutionist. It is a significant fact that the birds, which appeared to Cuvier and his contemporaries a closed type, a group that seemed to fulfill the ideal conception of a class archetype, as compared with other groups which had their open as well as obscure relationships, should be of all groups the one that first yielded its exclusive characteristics. In fact, there is no group in which the barriers have been so completely demolished as in this apparently distinct and isolated class. An attentive and patient study of the birds has established almost every point defined by Darwin in his theory of natural selection. One has only to recall the marked reptilian affinities as shown in their embryological and paleontological history. Besides all these structural relationships, the birds possess as a group remarkable and striking illustrations of variation in color, size, marking, nesting, albinism, molting, migration, song, geographical variation, sexual selection, secondary sexual characters, protective coloring; and in their habits show surprising mechanical cunning and ingenuity, curious and inexplicable freaks, parental affection, hybridity indeed, the student need go no further than the birds to establish every principle of the derivative theory.
The many observations on the nesting habits of birds would form a curious chapter as illustrating the individual peculiarities of these creatures.
Dr. A. S. Packard records the fact, as related to him by Mr. Wyatt, of wild geese nesting in large cottonwood-trees on Snake River, west of the Rocky Mountains; and Dr. Coues, in his "Birds of the Northwest," says wild geese "nest in various parts of the Upper Missouri and Yellowstone regions in trees." Mr. H. W. Turner observes a robin nesting on the ground. The late Dr. T. M. Brewer points out some very curious "variations in the nests of the same species of birds." He not only observes individual variation in nest-structure, but shows that in different regions of the country birds of the same species build different kinds of nests, and in reflecting on these peculiarities he is led to say, "If we can not understand what it can be that stimulates an Empidonax in Staten Island to build a pensile nest, while its fellow in Indiana builds one like a deep cup and surrounded with thorns, and another group in Pennsylvania put theirs on an exposed tree-top, and so flat that the eggs seem liable to roll out, we must see that some cause, hidden to us, is gradually effecting changes that sooner or later may become universal in the species, though which it is to be we may not be able to imagine."
Mr. J. A. Allen, in writing on the inadequate theory of birds' nests, shows grave and important exceptions to Wallace's theory, though he subscribes heartily to his philosophy of birds' nests. He expresses surprise that closely allied species of birds should oftentimes build divers kinds of nests, overlooking the fact that even closely allied varieties of man build entirely unlike houses.
Mr. F. H. Knowlton records a cliff-swallow appropriating, for the construction of its own nest, pellets of mud which were being brought by another swallow. Also the curious fact that a number of swallows were observed busily engaged in sealing up a nest in which one of their comrades lay dead. Among the curious traits of birds, Mr. H. B. Bailey communicates some new ones observed in the red-headed woodpecker by Mr. Agersborg, of Dakota Territory. This gentleman had observed one of these birds wedging grasshoppers in a large crack of an old oak-post. Nearly a hundred were stored away in this manner, the bird afterward feeding at leisure on the supply. This parallels the habit of the California woodpecker storing acorns in holes in the tree and subsequently feeding on the fully developed larvæ within the seed.
Mr. O. P. Hay, in a late number of "The Auk," has an interesting paper on the red-headed woodpecker as a hoarder, showing that the bird makes accumulations of beechnuts, pounding them between the shingles of a roof, wedging them into crevices, and storing them in cavities in trees.
The plausible suggestion made by Darwin as to the agency of aquatic birds in the wide dispersal of fresh-water mollusks, was singularly confirmed several years after by Mr. Arthur F. Gray shooting a duck which had clinging to one of its toes a fresh-water mussel. Dr. J. W. Fewkes has recently recorded the shooting of a duck in Sebec, Maine, which was in like manner transporting a fresh-water mussel. The same bird had been observed several days before with this curious companion clinging to its foot, and had the duck been migrating at the time it might have transported the mussel many hundreds of miles. In this connection it would be an interesting inquiry as to how far the similarity observed in north temperate and circumpolar animals is due to the annual migration of birds north and south.
Mr. William Brewster notes some interesting features in the habits of a young Kittiwake gull of the St. Lawrence. He brought home a young one, its mate having died of thirst, the other one surviving through the accidental discovery that the bird drank only salt-water! Both the birds obstinately refused to drink fresh water. Observations on this bird by Professor A. Hyatt showed how slowly and timidly it acquired the art of swimming and flying. The bird when first forced to fly was thrown into the air, and, to the surprise of Professor Hyatt, flew with great rapidity and precision, circling about the house and through the apple-trees, and, finally, flew near him several times in the greatest agitation till he caught the bird, which was completely exhausted. For a long time the bird went through this manœuvre, showing that while he knew how to fly it could not alight, though it finally acquired this faculty. Professor L. A. Lee records a remarkable attack made on him by a marsh-hawk, and Mr. Abbott M. Frazer tells of a tame crow deliberately standing on an ant-hill and permitting the ants to remove the parasites from its feathers. In this connection a paper by Mr. Joseph F. James should be read, in which he shows by a number of arguments that animals not only present a reasoning faculty, but that this faculty has been the result of slow evolution.
Mr. Xenos Clark, in an exceedingly interesting article on the music of animals, and particularly the music of birds, concludes by saying there is "a theory for the origin of melody, whether human or extrahuman, which, besides the usual basis of physiological acoustics, employs the law of modified, inherited, selected, and adapted structure—i.e., the law of evolution."
Mr. Ruthven Deane records cases of albinism and melanism in a great many families of birds; and Mr. N. C. Brown shows the variable abundance of birds at the same locality in different years. In this connection it will be of interest to read Dr. L. P. Gratacap's paper entitled "Zoic Maxima, or Periods of Numerical Variations in Animals."
The behavior of wild birds when kept in confinement, and the attempts made in domesticating them, have always furnished an interesting field for study. The curious freaks and impulses which they often betray, the changes they show under the new conditions, indicate in some measure the plasticity of their organization.
Hon. John D. Caton in an interesting paper on "Unnatural Attachments among Animals," records a curious fondness shown by a crane for a number of pigs; and in another paper on the "Wild Turkey and its Domestication," this writer has made some valuable records of the successive changes which take place in the bird during this process: changes in color, during which the more conspicuous features of protective coloring are lost; changes in habit, in which is seen the undoing or relaxing of those features which indicate constant vigilance, from carrying itself in a semi-erect attitude, perching on the tallest trees, covering up the eggs carefully with leaves when off the nest, etc., to moving in an horizontal attitude, perching near the ground, covering the eggs but slightly, or carelessly, etc., and losing that wildness which characterizes the bird in its wild state. At the breeding season, however, the females became wild again, but this was a feature too deeply implanted to show modification in the time allotted to Mr. Caton's experiment. The same writer has also observed in the Hawaiian Islands the effects of reversion to a wild state of different kinds of domestic animals which have from time to time been carried there. Among other animals he was fortunate enough to observe the undoing stages in the domestic turkey and the assumption of those features which characterize the wild bird.
A great many facts illustrating the plainest features of natural selection, protective coloring, mimicry, etc., have been recorded in our journals from time to time. A brief allusion may be made to a few of these.
Professor Samuel F. Clarke notices a pronounced case of natural selection, a case which must often occur in nature. He kept in large glass jars masses of eggs of Amblystoma. As soon as these eggs began to hatch he found it difficult to provide the young with suitable food, and yet they seemed to thrive. On examination, many of them were seen to be engaged in nibbling the branchia of others, and as they increased in size they were seen to swallow the weaker individuals bodily and hence grow with increased rapidity. "Here, then," he says, "was a very interesting case of natural selection by survival of the fittest, all the weaker individuals being destroyed and actually aiding the stronger ones by serving them as food until they could pass through their changes and escape to other regions where food was more abundant." Professor B. G. Wilder has recorded a similar condition of things in a species of spider where the young spiders within the case inclosing the eggs were feeding on the weaker ones. Professor Henry L. Osborn observes a curious case of mimicry at Beaufort in the coloring of a species of Ovulum which frequents a species of Leptogorgia. The Ovulum was yellow in color on the yellow variety of this sea-fan, and purple when living on the purple variety. Dr. R. E. C. Stearns has made some interesting notes on protective coloring in Phrynosomæ. Having collected these horned lizards (or toads as they are commonly called) in Central California, he has noticed that if the ground region they frequent is yellowish, the lizards are without exception of that color; if ashen-gray, then that color is simulated, and this without exception. Further than this he is "led to believe that a sufficient number of living specimens will show a similar protective factor in degree of development of the scale imbrications, tubercles, so called, and horns—or, in brief, in the sculpture aspect as related to the surface texture of the ground which forms the local habitat of these forms." Dr. A. S. Packard has observed the partiality of white butterflies for white flowers. He notices the European cabbage-butterfly, which is white, go directly to the white aster and rarely visit the golden-rod; while the yellow sulphur butterfly visits the yellow flowers of the golden-rod oftener than those of the aster. The same author also observed a harmless Egerian moth which deceived the sharp eye of a trained entomologist by its resemblance to a wasp, and asks why a bird may not be equally deceived. Miss Sarah P. Monks observed a case of mimetic coloring in tadpoles, their tails precisely resembling the leaves of an aquatic plant, Ludovidgia.
Miss Mary E. Murtfeldt having noticed that the butterfly, Pyrameis Hunteri, always deposited its eggs on the plant Antennaria, she was surprised to find a number of larvæ of this butterfly on Artemisia. The customary plant being rare in the immediate vicinity, the butterfly had been misled by the surface resemblance of the white, cottony leaves of the Artemisia to those of the accustomed food-plant. In this case the larvæ all died.
An unquestionable fact has been finally established by recent methods of observation on the habits of insects and other animals, and that is that individuals of the same species vary in intelligence; that they are not automata; that they are not impelled by a blind instinct to perform certain acts with unerring accuracy, but, on the contrary, that they vary and often greatly vary in their ability to provide for their young, in their skill to secure sufficient food, in their wit to avoid danger—in other words, they make blunders and mistakes and involve their progeny and even their colony in ruin. This individual variation in intelligence is brought out very clearly by a patient series of observations made by Drs. G. W. and E. G. Peckham on the special senses of wasps. They not only repeated many of the experiments of Sir John Lubbock, but many new and ingenious experiments were devised. Their studies were for the purpose of investigating the mental power, sense of hearing, color, direction, memory, emotion, power of communication, general intelligence, etc. An interesting result of their painstaking work was the determination of individual differences as to the faculty of memory and power of distinguishing color and direction. This kind of study of the habits of insects has brought to light features of the most surprising character. The remarkable studies of Sir John Lubbock, Dr. Moggridge, and others in Europe, have been paralleled in this country not only by the observations above quoted, but notably by the labors of Rev. H. C. McCook in his studies of the American ants and spiders. In various papers published in the "Proceedings of the Philadelphia Academy of Natural Sciences" and in the "American Naturalist," be has shown many extraordinary and curious features in the life-histories of these animals. The great variety and extent of his work must be my excuse for not referring to it in detail.
Professor G. F. Atkinson, in studying a new species of trap-door spider, confirms the observations of others as to the creature deliberately attaching fragments of moss to the lid of its nest in order to conceal its position. Dr. Thomas Meehan describes a hornet that was gifted with great intelligence. He saw this insect struggling with a large locust in unsuccessful attempts to fly away with it. After several fruitless efforts to fly up from the ground with his victim, he finally dragged it fully thirty feet to a tree, to the top of which he laboriously ascended, still clinging to his burden, and having attained this elevated position he flew off in a horizontal direction with the locust. Dr. Meehan truly says, "There was more than instinct in this act, there was reasoning on certain facts and judgment accordingly, and the insect's judgment had proved correct."
A curious case of circumspection in ants is recorded by Dr. Joseph Leidy. In an empty house he observed some ants feeding on crumbs of bread left by the workman. He at once placed pieces of bread in the different rooms in the house only to find them the next day covered with ants, which he destroyed by causing them to fall into a dish of turpentine. After a few days the ants no longer visited the bread, and he supposed they had been exterminated. A few days after, however, he observed a number of ants in the attic feeding on the body of a dead fly. He immediately got a lot of grasshoppers and distributed their bodies in all the rooms, only to find that they were soon covered with ants, which he destroyed as before. This treat continued attractive for a few days only, when the ants abandoned the food. In brief, he tried meat, cake, and various other articles in turn; the ants for a while frequenting these snares, only to learn the danger involved, and finally avoided them.
The gradual dispersion of species in recent times is of great interest, and careful records should be made of the facts as observed and a collection of large numbers of individuals made, in order to compare them with specimens of the same species in future years, to ascertain the variation which may have taken place and the tendency of that variation. A number of observatians have been published within the last ten years, showing new areas of distribution. Littorina litorea, which has been creeping along the coast since 1869, as recorded by Gray, Verrill, and others, has now reached the southern side of Long Island Sound, as observed by Mr. Henry Prime. Lioplax subcarinata, an Ohio River species, has been found in the Hudson River at Catskill Landing. Limax maximus, first found at Newport, Rhode Islan d, by Mr. Powel, has since been found at Cambridge, Massachusetts, by Professor Hyatt. Bythinia tentaculata, first recorded from Oswego, New York, by Rev. W. M. Beauchamp, is reported as having been found at Burlington, Vermont, by G. H. Hudson. In the Mohawk River is a thriving community of this species, the first having been placed there by Dr. James Lewis.
Dr. R. E. C. Stearns, in commenting on the occurrence of Mya arenaria in San Francisco Bay, states that the first record of the species in California was made by Dr. Newcomb in 1874. Within a few years it has increased in great numbers, furnishing a new food-supply for the people. The evidence that it is a recent introduction is seen in the fact that so large and conspicuous a species could not have escaped the eye of the collector. No trace of it has ever been found in the numerous shell-heaps of California, though it is found on the Asiatic coast, from Kamtchatka to the southernmost limits of Japan. Dr. Stearns believes it to have been imported with the oyster transplanted from the Atlantic coast. From large numbers of the shells that I measured, the low index would show that it came from some southern point on the Atlantic coast.
The delicate balance of conditions between organisms, whether it be between individuals of the same species or between widely-separated groups, is an important feature in the question of survival. Professor S. A. Forbes, in a thoughtful study of certain species of entomostraca in Lake Michigan and the surrounding waters, calls attention to the important part played by these minute crustaceans, showing how they furnished almost the entire food for young fishes, larger crustaceans and even insect larvæ. He writes: "Mollusca, one would say, could afford to be indifferent to them, since they neither eat them nor are eaten by them, nor seem to come in contact with them anywhere, through any of their habits or necessities. But for this very reason these two classes afford an excellent illustration of the stringent system of reactions by which an assemblage of even the most diverse and seemingly independent organisms is held together. ... If there were no entomostraca for young fishes to eat, there would be very few fishes indeed to feed upon mollusca, and that class would flourish almost without restraint; while, on the other hand, if there were no mollusca for the support of adult fishes, entomostraca would be relieved from a considerable part of the drain upon their numbers, and would multiply accordingly." He is much struck with the fact that in the larger bodies of water, the species of entomostraca show an inferior development in numbers, size, and robustness, and in reproductive power. Their smaller number and size are doubtless due to the relative scarcity of food. "The difference of reproductive energy, as shown by the much smaller egg-masses borne by the lacustrine species, depends upon the vastly greater destruction to which the paludinal crustacea are subjected. Many of the latter occupy waters liable to be exhausted by drought, with a consequent enormous waste of entomostracan life. The opportunity for reproduction is here greatly limited—in some situations to early spring alone—and the chances for destruction of the summer eggs in the dry and often dusty-soil are so numerous that only the most prolific species can maintain themselves under such conditions.
"Further, the marshes and shallower lakes are the favorite breeding-grounds of fishes, which migrate to them in spawning-time, if possible, and it is from the entomostraca found here that most young fishes get their earliest food-supplies—a danger from which the deep-water species are measurably free. Not only is a high reproductive power therefore rendered unnecessary among the latter by their freedom from many dangers to which the shallow-water species are exposed, but in view of the relatively small amount of food available for them, a high rate of multiplication would be a positive injury, and could result only in wholesale starvation."
The effect of birds on insect-life has engaged the attention of the same author. His inquiry was to ascertain whether birds originated any oscillations in the numerical proportion of insects upon which they feed. Many interesting facts are given which space forbids quoting.
A number of contributions have been made on the influence of environment and on geographical variation, to some of which reference must be made. Prof essor Alpheus Hyatt bears unequivocal testimony to the derivative theory, and recognizes clearly the influence of external surroundings in a memoir on the cephalopods, when in stating the law of organic equivalence he says: "The action of physical changes takes effect upon the irritable organism, which necessarily responds to external stimulants by an internal reaction or effort. This action from within upon the parts of the organism modifies their hereditary forms by the production of new growths or changes which are, therefore, adapted to the conditions of the habitat or the physical agents and forces from which they directly or indirectly originate"; or, slightly changing this interpretation in accordance with the same facts, each individual is more or less susceptible to the action of physical influences and those which respond most quickly to these influences, come more promptly in harmony with their environment, which is natural selection pure and simple.
Mr. Charles Morris, in a series of papers on "Organic Physics" and the "Polar Organization of Animals," presents many new and suggestive thoughts on the physico-chemical action in life and development. He concludes that "there are inherent in the germ energies and tendencies, chemical, molecular, or whatever we choose to call them, adapted to the complete unfoldment of the typical form. But, as appears evident, their operation can be checked by influences from external nature. There is a struggle between these contact influences and the innate organic tendencies."
[To be continued.]