# Popular Science Monthly/Volume 78/February 1911/Alpheus Hyatt, 1838-1902

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* ALPHEUS HYATT, 1838-1902
By Dr. ALFRED GOLDSBOROUGH MAYER
MARINE BIOLOGICAL LABORATORY, TORTUGAS
ALPHEUS HYATT, junior, was born in Washington, D. C, on April 5, 1838.
Late in the seventeenth century, the ancestors of Alpheus Hyatt moved northward from Virginia into the young colony of Maryland, where they soon became large landed proprietors and raisers of tobacco; the colonial manor of Tewkesbury on the Potomac River being owned by Charles Hyatt, Esqr., the great-grandfather of Alpheus Hyatt, senior. Hyattsville was also the seat of certain of Alpheus Hyatt's ancestors.
Alpheus Hyatt's father was a leading merchant of Baltimore, and in common with many men of affairs in southern cities, he made his home in the country; each day driving in to his counting-house in the city. The old Hyatt home was "Wansbeck," a colonial mansion shaded by great oak trees and placed upon the summit of a hill far from the city's dust and turmoil. It still stands to-day, but is now in the heart of the city at the corner of Franklin and Schroeder Streets, where it serves as the Child's Nursery and Hospital of Baltimore.
Here among the woods and fields of "Wansbeck" young Hyatt began his studies in natural history, becoming an ardent collector of insects and aquatic life; a pursuit which brought him into intimate comradeship with young Alfred Marshall Mayer, a boy of nearly his own age. The friendship between the little naturalists lasted through life, although Hyatt, true to his early inclination, remained constantly a student of animal life, while Mayer eventually became a physicist. Hyatt's interest in paleontology was first awakened by the sight of a collection of minerals and fossils possessed by one of his early teachers, Captain Allen, a retired army officer.
Although none of Hyatt's ancestors had been distinguished for remarkable mental characteristics, and none had sought intellectual or even professional careers, his mother was a woman of strong and decided character and an amateur artist of considerable ability, some of her copies of old masters and tapestries being noteworthy. The abundant means possessed by his father afforded him every educational advantage of the day, and his early education was commenced under private tutors, but soon he was sent to the Military Academy of Oxford, Maryland, to be prepared for Yale University, which he entered as a freshman in 1856.
It may be of interest to observe that upon his arrival in New Haven his father presented his name to various tradesmen of the city, directing them to supply his son's demands upon them, and as these included the opportunity to order all that livery stables or wine cellars could provide, it is greatly to young Hyatt's credit that he was a sober, serious minded, hard-working student from the moment of his arrival in New Haven.
He remained only one year at Yale, and then his mother withdrew him from college and took him to Italy, where he came under the influence of certain catholic friends of the family who sought to convert him to the service of the church. In his journal he gives a graphic description of the magnificence of the papal court, but is distressed that "the Swiss guards in their harlequin uniforms stand fencing off the high altar from the approach of common people." He might still have acceded to the counsels of his mother's catholic friends had he not one day seen the pope's dragoons charge wantonly and without warning upon a crowd of merrymakers on the Corso, crushing four of them to death. The horror of this scene, and the filth and misgovernment of Rome under Pius IX., turned him with loathing from all thought of serving such a heartless regime as that of the papacy of those days, and in his journal he exclaims:
​He was but nineteen years of age, yet he had now determined to devote his life to science.
In 1858 he returned to America and entered the Lawrence Scientific School of Harvard University, studying engineering, but the great Louis Agassiz, always seeking promising young pupils to instruct, soon discovered Hyatt and drew him into his own laboratory of natural history, where in an inspiring atmosphere of research and study he was to form close and life-long friendships with his fellow students Clarke, Morse, Packard, Putnam, Scudder, Shaler, and Verrill. With them in 1860 he formed the Agassiz Society which met at frequent intervals to discuss zoological questions. Professor Agassiz himself attending the meetings, and in the summer of 1861 with Shaler and Verrill as companions he went to Anticosti Island in the Gulf or St. Lawrence, collecting fossils and marine animals.
Louis Agassiz's lucid exposition of von Baer's law and his own additions thereto, and his high praise of the philosophy of Oken, produced a profound effect upon young Hyatt's mind, and he is said to have learned Agassiz's "Essay on Classification" by heart. One of the most graphic of Louis Agassiz's lectures was upon the coiling and final uncoiling of the shells of fossil ammonoids in which he compared the twisted forms found in the Cretaceous just before the extinction of the group, to the writhing contortions of a death struggle. Listening to this lecture, Hyatt became so inspired that he determined then and there to devote
​his life to the study of these fossils. It can not be said, however, that he was entirely moulded by Agassiz, for Hyatt was a fearless and independent thinker, and though modest in the expounding of his views, he nevertheless clung tenaciously to his own opinions.
Few men of science have been so free from egotism as was he. He was a kind friend to many a young student of Harvard, for he never seemed to lose his contact with youthful thought, and delighted to receive instruction from old and young and every one great or small around him. In his address before the Agassiz Association in Mechanics Hall in Boston he tells of this, and unwittingly gives us a charming picture of his own generous mind and kindly heart. He was speaking of things the association might do to disseminate an understanding of natural history, and told of his friendship with an old farmer who had formed some geological theories of his own and who knew Professor Hyatt simply as "the man as studies rocks." Hyatt says:
The wonder and delight in his old, wrinkled, weather-beaten face on finding that his ideas were not merely local, but universally true, and what he had thought out was not ridiculed but regarded with respect was a sight I have never forgotten.
He concluded this address by saying:
The minerals, the rocks, the plants, the animals, the earth, the planets and the stars are full of facts unknown as yet to us. These are nature's books, the volumes are everywhere and no one is so poor that he can not have access to them—these are the books of the future, and eventually we shall have them collected in museums and issued as printed volumes now are for the instruction of the people.
In 1863 Hyatt graduated from Harvard with the degree of B.S., his scholarly standing being higher than that of any of Agassiz's pupils who had until then obtained this degree.
His inclinations were all for science, but the civil war had broken out and he felt it his duty to serve in the Union Army. His mother he succeeded in persuading into an acceptance of his views, but it was far otherwise with the remaining members of his family, from whom he became estranged only to be reunited after years of silence. He aided in raising a militia company in Cambridge and enlisted as a private, but was almost immediately commissioned a lieutenant and afterwards promoted to be a captain of the 47th Massachusetts regiment. For a time he was stationed upon Cape Cod and afterwards ordered to New Orleans, where he served as aide-de-camp on General Emory's staff.
I have a letter of this period written by the late Professor N. S. Shaler to their mutual friend, George H. Emerson, in which he says:
So Hyatt has gone into the smoke of the great battle. May God defend him and grant him immunity from the fate of so many of our brave. He will win success and will make at once a good follower and an equally good leader.
The war being over, he was honorably discharged, and returned to Cambridge in 1865 to continue his studies. Louis Agassiz at once ​placed him in charge of the fossil cephalopods and this collection remained under his care until his death in 1902.
In 1865 lie published his first scientific paper, a short one of only five pages in which he states that the Beatricidæ which he collected at Anticosti in 1861 are not fossil plants as others had supposed, but cephalopods. We know, however, that he was himself mistaken, for they are now believed to be hydrocorallines.
In the same year he wrote an appreciative notice of the life of his young college chum, George H. Emerson, a chemist of great promise, whose untimely death from overwork had terminated at its very beginning a useful life in science. While in college together Emerson and Hyatt had begun the critical study of the bible, Hyatt coming to entertain liberal views while Emerson became a ritualist. It was characteristic of Hyatt to disagree upon essential matters with his closest friends and yet never in any sense to lessen the mutual esteem and affection between him and them. His simple honesty, freedom from conceit and above all his cordial and generous nature made this possible. Thus it was that within a year of the time when he began his studies under Agassiz he became an evolutionist and an admirer of Lamarck, whom Agassiz characterized as "an absurd egotist." Independent of the theoretical side of his work Hyatt will be remembered as a great teacher and a leader in systematic zoology, for he was an uncommonly accurate observer and his publications present a vast body of well-founded facts.
The year 1865 saw Louis Agassiz's pupils, whom the war had scattered, again working by their master's side at Harvard. But the old relation of master and pupil could not long endure, for the truth was that the time had come for the young birds to fly from the paternal nest, and in 1867 Morse, Packard, Putnam and Hyatt severed their relations with Agassiz and cast in their lot with the Essex Institute of Salem; this movement being known as the "Salem secession." Salem thus became an active center in the natural sciences and so much public interest was awakened that in 1869 these four young men cooperated with a number of progressive citizens of the town to found the Peabody Academy of Sciences, and with the aid of Scudder and others they succeeded in establishing the first permanent American journal devoted to the natural sciences. The American Naturalist, Hyatt being one of its editors from 1868 to 1871.
On January 7, 1867, he married Miss Audella Beebe, daughter of Smith M. Beebe, Esq., of Kinderhook, N. Y.
During the period of his residence in Salem, Hyatt continued to study and to describe the fossil cephalopods of the Museum of Comparative Zoology at Harvard. Suess and Hyatt were indeed the first zoologists to attempt to distinguish genera and species among the ammonites, and Hyatt was the first to announce the fact that these ​fossils constitute a great group of the animal kingdom probably equivalent to a suborder. In 1867 he named 26 genera and 126 species of ammonites.
He also made a detailed and very careful study of the anatomy of the so-called "moss-animals," or fresh-water Polyzoa, the structural details of the species being tabulated in order to facilitate comparisons. This work was published in the Proceedings of the Essex Institute, in 1866-67, and also in the American Naturalist, and is illustrated by careful and accurate outline figures drawn from life by Hyatt and beautifully engraved on wood by that matchless draughtsman E. S. Morse. In this and all of his subsequent papers Hyatt furnishes a model that systematic zoologists will do well to follow in the accurate and detailed description of species.
While at Salem he also began that study of sponges which was to make him the leading authority among systematic zoologists of America upon these animals. His principal papers upon sponges were not published, however, until 1875-78 in the Proceedings and Memoirs of Boston Society of Natural History. He agrees with MacAllister that sponges constitute a subkingdom or branch of the animal kingdom equivalent to one of the larger divisions. He describes 36 new species, and gives an excellent account of the methods of the commercial sponge fisheries of Florida, and discourses upon the embryology, anatomy, physiology and relationships of sponges, deciding, in common with Barrois, that in sponges there is no gastrula stage.
But Salem was too small to provide careers for so many young, active and well-trained students of natural history. Of the four friends, Morse remained in Salem; Packard went to Brown University; Putnam became an anthropologist and curator of the Peabody Museum in Cambridge and also in other institutions; and on May 4, 1870, Hyatt was elected custodian of the Boston Society of Natural History. In 1881 he became its curator and remained the scientific head of the society until his death in 1902.
After 1873 he made his home in Cambridge, where he could be near the great collection of cephalopods of the Museum of Comparative Zoology, and in 1879, under the auspices of the Woman's Educational Association of Boston, he established a summer laboratory for the study of marine zoology upon his country place at Annisquam, Mass. At this time also he owned a 60-foot schooner yacht, the Arethusa, with which he made scientific cruises along the New England coast, going as far north during the summer of 1885 as the west coast of Newfoundland and lower Labrador, to study the fossils and the general geology of these regions. His companions upon this cruise were five young men, among whom were Professor George Barton and the late Dr. E. A. Gardiner.
The situation of Annisquam was found to be unfavorable for the site ​of a general marine laboratory, nor was Hyatt sufficiently interested in the minutæ of executive detail to make a good director of a permanent station, so after a few years the Annisquam project was abandoned and the laboratory was removed to Woods Hole, Hyatt being the first president of its board of trustees.
Hyatt was a great, generous-minded, altruistic man; who formed warm and enduring friendships with those about him. He was a teacher and a student rather than an executive, and his faith in young men was one of the beautiful sides of his character. Advocates of peculiar theories of their own making are commonly conceited or narrow-minded men, but Hyatt was the reverse of this, for his modesty was real, and his breadth of view, founded as it was in superior knowledge of science, and in interest and respect for those about him, was constantly expanding. Xo man could have been more approachable, and no educator of his generation was more highly esteemed for his kindly personal qualities than was Alpheus Hyatt.
His interests in educational affairs in Boston caused him to be appointed professor of zoology and paleontology in the Massachusetts Institute of Technology, a chair which he held for eighteen years. He was also professor of biology and zoology in the Boston University from 1877 until his death in 1902.
But it is as a teacher of teachers that he will be best remembered by the public of Boston. He loved to teach, but was never a pedant, for as he says:
Teacher and scholars should recognize that science is infinite, and they should work as companions learning from each other's observations. Better a child should learn to handle one animal, to see and know its structure and how it lives and moves, than to go through the whole animal kingdom with the best teacher.
His knowledge of invertebrate zoology was profound and extensive, and he had an apt manner in illustration which made his lectures popular and brought his pupils close to nature; as Agassiz said of him, "he possessed the essential element with which to engage the attention of an audience—knowledge thoroughly his own." In 1870 with support from Mr. John C. Cummings and the cooperation of many educational leaders and philanthropists, he organized the Teacher's School of Science and gave courses of lectures upon biology to the public school teachers of Boston. Between 1870 and 1902 more than 1,200 school teachers attended these lectures, and the school is still being successfully conducted by Professor George Barton. A good account of the origin and history of this school is given by Frances Zirngiebel in Popular Science Monthly, August and September, 1899.
Professor Goodale suggested that guide-books of a peculiar character should be written for the benefit of the teachers who might attend these lecture courses; accordingly, between 1878 and 1896, thirteen short ​guide-books designed to meet the requirements of the school were published, the authors being Mrs. Agassiz, Dr. H. P. Bowditch, Professor George L. Goodale, H. L. Clapp, Ellen H. Richards, W. 0. Crosby, Hyatt, and Hyatt and Arms. Five of these pamphlets are by Hyatt; their titles are "About Pebbles," "Commercial and other Sponges," "Common Hydroids, Corals and Echinoderms," "The Oyster, Clam and other Common Mollusks," and "Worms and Crustacea"; and in 1890 he published in collaboration with Miss Jennie M. Arms (now Mrs. Sheldon) a remarkably clear, concise and well-worded book upon insects. This is the most elaborate guide-book of its series, and no work could give a clearer idea of the distinctive characters of the sixteen orders of insects classified in accordance with Brauer's scheme from the lowly organized Thysanura to the highly specialized Diptera. As a school-teacher's guide it is unsurpassed, and its clear explanations are admirably supplemented by 223 outline figures of common American insects. It is far more than an anatomical treatise, however, for it presents charmingly worded accounts of the development, physiology, habits and ancestry of the various orders of insects. Yet it is not a theoretical treatise, but aims to present to the teachers well-established and incontrovertible facts. Indeed, the authors take pains to advise teachers to avoid presenting mere theories to immature minds.
This association with the teachers in which Hyatt was so deeply interested won high appreciation from the intelligent public of Boston, a concrete manifestation of which appeared after his death in the founding by general subscription of an endowment known as the Hyatt Memorial Fund, the income from which is used annually to transport school children from the city into the country in order that they may be taught to observe nature in the field.
Altogether Hyatt's best work, apart from his researches, was that among the school-teachers of Boston.
Mrs. Jennie Arms Sheldon, than whom none is better prepared to speak, states that "as a museum curator Hyatt never lost interest in the larger plan or 'scheme' which his comprehensive mind had worked out for the arrangement of the material at his command. His 'natural classification' claimed much of his time and thought, and lie sought to find assistants who could carry out the details which, naturally, did not interest a mind like his." His plan was that the museum should be so arranged that the visitor on entering should pass from the simple and more generalized groups to those more specialized. He possessed considerable mechanical skill, and delighted in hours of recreation to work as a carpenter and machinist upon his country place at Annisquam, and his invention, the "Hyatt bracket," has proved useful not only in museums but elsewhere.
At first sight, it must seem strange that so able, inspiring and ​lovable a teacher as Hyatt should have left so few disciples of his school of research, but it must be remembered that he enjoyed no opportunity to teach the young men who were pursuing the higher courses in zoology at Harvard. Through an unfortunate arrangement those who had charge of the various collections in the Museum of Comparative Zoology were not encouraged to give lectures to students, and they worked on throughout the years, their voices silenced, yet with active young minds eager to listen and to learn always near them. Moreover, the spirit of the department of zoology at Harvard during Hyatt's life-time was dominated by Weismannism, and Hyatt's views were thus in disfavor. Upon the rare occasions of his lectures he felt obliged to present not facts—the foundation-stones of his theories—but the theories themselves. Thus the impression grew up that Hyatt was a dreamer and that his theories were based upon erroneous or meager observations. Nothing could have been farther from the truth, for I have myself been surprised, in reading over his publications, to discover that his writings are crowded with accurate observations of indisputable fact, and even if the future should demonstrate that his theoretical deductions are wholly false, he will still be remembered as a great and accurate observer of nature. Concerning the truth or falsity of his so-called acceleration or "old age theory" we are obliged to admit that it has never been disproved even if it be not yet accepted as true. Hyatt's fate may be that of Lamarck and of many another theorizer: Appreciation and respect for his views must come only years after his death.
I will endeavor to give a simple explanation of his theories of evolution, avoiding the complex technical terms which he employed. He believed that the race, like the individual, has only a limited store of vitality and that both must develop, progress, decline and die in obedience to one and the same law. Thus the growth-stages of the individual actually resemble the stages in the evolution of the race to which it belongs; as he puts it, "the cycle of ontogeny is an individual expression and abbreviated recapitulation of the cycle that occurs in the phylogeny of the same stock." "Phylogeny, like ontogeny, is first progressive and thus attains an acme of progress. This acme is followed, however, by a stage of retrogression ending in extinction."
Hyatt derived his ideas of evolution from a study of the fossil nautiloids and ammonoids, those beautiful chambered shells which appear in the Cambrian; and the ammonoid branch of which becomes extinct in the Cretaceous, while to-day the half-dozen species of Nautilus are all that remain of the nautiloids. He was an ardent student of these fossils, and of the 103 titles in the list of his papers, 38 are upon these shells. He proved that the ammonoids are descended from the nautiloids, for he discovered that the protoconch or primitive shell of the nautiloids is soft and composed of flexible conchiolin so that it is ​usually lost after the chambered shell grows out from it, but in the aramonoids the protoconch is hard and calcareous and is always found at the narrow end of the series of chambers composing the shell.
The undisputed facts are that in Silurian times straight conical shells with smooth outer surface were common, and coiled shells were rare. In the Carboniferous the coiled shells gain in number and nodules, ribs or keels begin to develop upon their outer surfaces. In the Jurassic we find only close-coiled, or uncoiling shells, and those that uncoil tend to become straight with smooth surfaces, as were their ancestors long ago in Silurian times. The ammonoids arose as coiled forms from the nautiloids in Cambrian times, but in the Jurassic and Cretaceous they uncoil and thus resemble their straight-shelled nautiloid ancestors, the oldest of their race. Uhlig, Neumayr, Zittel, Hyatt and all other students of the group agree upon these points, and indeed Hyatt's observations of fact have won high respect for both their accuracy and their number. It is only in matters of inference that he is at variance with many zoologists.
Hyatt found that in the very young ammonoids the shell is at first straight and smooth, then as growth proceeds it coils upon itself, and may acquire a keeled, ribbed or nodular surface. Finally, if the species be a Jurassic or Cretaceous form it is apt to uncoil in later life, and the uncoiled part of the shell tends to become smooth and relatively straight like its own young stage. D'Orbigny observed these facts even before Hyatt, and they are well authenticated by numerous students of the group. Hyatt, however, pointed out the interesting fact that there is a parallelism between the growth-stages of the individual, and the genetic succession of species through which the race has developed. For example, the young shell is smooth and straight as were the adult shells of its primitive nautiloid ancestors of Cambrian times. The adult shell is coiled and ornamented as were those of the ammonites of the Devonian when the race was dominant. The old shell is again straight and smooth as were its Cambrian ancestors and the vanishing remnants of the race that died out in upper Cretaceous times. Thus the growth-phases of the individual—embryonic, larval, adolescent, adult and old age—are correlated with the changes which occur in the geological history of the group to which it belongs.
It may be a mere coincidence, but certainly in ammonites there is a surprisingly close correspondence between the growth-stages of the individual and the phylogeny of its race. Hyatt believes that this fact is not due to accident, but that the life of the individual and the life of the race are related and obey one and the same law.
Zoologists can not understand why this must necessarily be so, but there are many laws in nature which man has discovered, and the logical necessity for which we have not yet understood, and its incomprehensibility has naught to do with the truth or falsity of Hyatt's theory.
​One can not, however, establish a general law upon the study of a highly specialized race of animals such as the shell-bearing cephalopods, and we must search through the entire animal kingdom to thoroughly test Hyatt's hypothesis; and zoologists have not yet done this, for the paramount interest in studies of heredity now centers around Mendel's law. Yet Hyatt has raised a burning question—is the course of evolution a predetermined thing, and do the growth-stages of the individual reveal to us the past, present and future of its race? Hyatt says they do, for he states that organisms tend to produce offspring varying in a certain well-defined direction so that we may indicate with tolerable certainty what species a given form can or might produce.
It is sad to think that so few young men have followed him into this great field of study, for a student's life is not wasted even if after years of labor he discovers that his preconceived hypotheses were false and he can not fathom nature's secrets, for it is not for science to advocate, but only to search, hoping to discover.
We will now take up the discussion of Hyatt's law of acceleration or tachygenesis as he finally called it; although it was commonly known as the "old age theory." According to Hyatt, modifications, once they appear, tend to develop in successive generations at earlier and earlier stages of growth, so that modifications which first appear in adult life or even in old age before the animal becomes sterile will afterwards be developed in the young stages of descendants. Finally, indeed, they appear in the embryos or are crowded out and replaced by later characters, Hyatt believed this law of acceleration to be an invariable mode of action of heredity.
He also believed in the inheritance of acquired characters, and held that the organism is plastic and irritable and responds to external stimuli by internal reactions which manifest themselves as hereditary modifications of structure. It is interesting to see that the recent researches of Tower and MacDougal have shown that artificially produced changes in the environment may affect the germ-cells and produce hereditary modification of structure.
Hyatt maintained that the evolution of new forms has been more rapid than is generally supposed, and in this he has been supported by the classic work of DeVries, who shows how suddenly a new form may appear and maintain itself. It also accords with Bateson's demonstrations of the frequency of "discontinuous variations." As Farlow says: "Our so-called species are merely snap-shots at the procession of nature as it passes along before us."
Hyatt also states that the development of ancestral forms is usually simple and direct; that of their more specialized descendants becomes gradually indirect with complicated larval or intermediate stages; and that of the terminal retrogressive stages, before extinction becomes again more or less direct. Thus the last is like the first.
​He states that most existing types arose in early Paleozoic times when evolution was most rapid. Then came a period of slow changes, especially slow in all races which were in the acme or most flourishing period of their phylogeny. Finally, when retrogression sets in the pace of evolution again becomes more rapid, and startling new modifications are often introduced.
Hyatt acknowledged that natural selection was a factor which modified the course of evolution, but he believed that the history of a race was a predetermined thing and that natural selection played but a minor role in comparison with the effects of the environment. In this latter respect he was a neo-Lamarckian; a view which is now more popular than it was at the time of his death.
He believed that when a number of more or less distantly related or even unrelated forms live in the same environment they acquire a resemblance one to the other; the similarity of external conditions producing a "morphological equivalence" or parallelism.
These are the chief features of Hyatt's theories of evolution and heredity. To go deeper into the subject would, I fear, only introduce confusion into the mind of the reader.
The paleontologist possesses at least one advantage over the student of existing animals in that he may observe the changes that develop during thousands of generations, whereas the zoologist sees the present but dares not even vaguely guess upon the future of the race he studies. Accordingly, Hyatt made little impression upon zoologists, but some of the most brilliant paleontologists have applied his principles to the unraveling of the genealogy of fossil and living animals. We need only mention the classic studies of Professor Charles Emerson Beecher upon brachiopods and trilobites, or the many researches of Hyatt's former assistant. Professor Robert Tracy Jackson, at present one of the most progressive leaders of the Hyatt school, among whom are such active investigators as Bather, Buckman, J. M. Clarke, Cumings, Grabau, Ruedemann, Stanton, J. Perrin Smith, Burnet Smith, Schuchert and Van Ingen. In the untimely death of Professor Beecher in 1904, the school suffered a most serious and almost irreparable loss. The general attitude of zoologists toward Hyatt's theory of evolution is probably best expressed by quoting from two of the letters which Charles Darwin wrote to Professor Hyatt in 1872, in which Darwin says:
After long reflection I can not avoid the conviction that no innate tendency to progressive development exists, as is now held by so many able naturalists, perhaps by yourself. . . . The longer I live the more I become convinced how ignorant we are of the extent to which all sorts of structures are serviceable to each species. But that characters supervening during maturity in one species should appear so regularly as you state to be the case in succeeding species seems to me very surprising and inexplicable.
​Hyatt believed in the inheritance of acquired characters. By such he understood modifications which appear in adult or late stages of growth, and are due to the influence of external conditions and not caused by heredity. Probably the most interesting and important paper which Hyatt wrote is his "Phylogeny of an Acquired Characteristic" published in the Proceedings of the American Philosophical Society in 1893. In this he shows that at first the young shell in the nautiloids is nearly straight, but soon the shell bends around and grows over the outer side of its older part. The cross section of the young shell before it overgrows itself is round, but when it presses against its first whorl it is squeezed inward on one side, or impressed. This impressed region is due entirely to the pressure of the shell in overgrowing its older whorl, for in the Silurian and Devonian nautiloids the shell does not become impressed until it actually comes in contact with the older whorl, and is thus squeezed inward on its inner side as it passes around the outer side of its older part. That this is due solely to pressure is shown by the fact that when these Silurian and Devonian forms uncoil the impressed zone disappears at once in the uncoiled part, the cross-section of which is round as in the young shell before it grew over its first-formed whorl.
In the Carboniferous species Coloceras globiatum, however, the impressed zone appears in the young whorl long before it has touched and grown over its first whorl, and in the Jura most of the nautiloids develop an impressed zone before the shell touches its first whorl. As Hyatt states, the character has become hereditary and appears at an earlier stage than in the Devonian ancestors. There is also a quicker development of the coiling tendency in Jurassic shells and still more so in the Cretaceous.
It is hard to escape the conclusion that this is actually an acquired character which becomes hereditary, and finally appears at a stage earlier than that in which it first developed. Indeed, it is one of the classic instances of an acquired character, and one of the best established cases of this sort in the whole field of zoology.
In order to establish these interesting facts Hyatt was obliged carefully to crack apart a large collection of nautiloid shells to make a microscopic study of their earliest whorls.
In 1889, Hyatt published his final paper upon the "Genesis of the Arietidæ," a large family of the ammonoids. He agrees with Neumayr that three of the four great branches of this family are descended from a single species, Psiloceras planorbe, which was itself derived from P. caliphyllum of the northeastern Alps. The race then migrated into Italy, south Germany, and the Cote-d'Or in which last place new progressive forms migrated back again into the northeastern Alps and thence during Bucklandian and later times into parts of Germany, ​Italy and central Europe. Hyatt carefully traces out the complicated genealogy of the related forms and describes their migrations, and his monograph is beautifully illustrated by heliographic plates. In order to carry out these studies, he visited the museums of Stuttgardt, Tübingen, Würzburg, Munich, Zurich, Paris, Semur, the British and Geological Society Museums of London, and other places in Europe.
In 1872-73, Hyatt lived in Würtemberg in order to study ammonites and also variations and evolution of the fossil snail shells Planorbis from the ancient Tertiary lake at Steinheim. As is well known, this lake gradually filled with gravel and limestone mud, and thus the later shells lived at higher and higher levels until the lake became wholly dry. Hyatt agrees with Hilgendorf that all of the species of Planorbis found at Steinheim are descended from four varieties of Planorbis levis which entered the lake in early times. At first hybrids were developed between these four varieties, but as the original stocks diverged more and more one from another, these hybrids died out. Hyatt finds that in all four stocks there is at first a tendency to increase the spiral of the shell due to a deepening of the lower at the expense of the upper umbilicus, thus eventually producing more or less trochiform shells. Hyatt states that the Steinheim shells develop similar species in many separate and distinct genetic series, and these parallelisms he ascribes to the fact that all lived in one and the same environment and were subjected to similar external influences. His genealogical series differ considerably from those of Hilgendorf, and the Steinheim shells must be restudied by some unbiased investigator before we can be certain of the facts in the controversy. Hyatt found that the young shells are always smooth, but in one race transverse ridges appear on the outer whorl and finally affect the inner whorls of their descendants. Uncoiling also appears first in the outer whorl and finally the inner whorls also uncoil, and in another stock a keel-like ridge forms first on the outer and afterwards extends to the inner whorls. Thus these characters are accelerated, i. e., appear earlier and earlier in the lives of the descendants. Hyatt concludes that the modifications of the Steinheim shells are due to the law of heredity with acceleration, and are not controlled by natural selection, although natural selection may have caused the dying out of the hybrids between the four original varieties. He also believes that gravity produces modifications of structure, and that unfavorable conditions cause uncoiling, produce transverse ridges and diminish the size of the shells. He states also that "the tendency to earlier and earlier inheritance in successive generations is apparently the result of disturbing and modifying agencies acting from without."
For the last twenty years of his life Hyatt studied the mutations and migrations of those most interesting of variable snails the Achatinelidæ of the Hawaiian Islands, and, indeed, he was upon the point of ​visiting Hawaii when overcame him in 1902. It it very unfortunate that he never fully wrote out the results of his studies upon these shells, the manuscript which was found after his death being very incomplete, especially upon specific points, and although many of his descriptions of the species themselves were completed, yet his conclusions respecting their relationship and migrations are only vaguely referred to. He did, however, published a short paper in Science in 1898 in which he finds that there are about 280 species of land snails on the island of Oahu, with three leading genera, Bulimella, Achatinella and Apex. All of these are probably descended from the recently extinct Achatinella phæzona of Kiliouou valley, whenc they migrated northward, and are now found chiefly on the western sides of the range of mountains which extends along the eastern shore of the island.
Only a very few Achatinella crossed the broad lowlands in the middle of the island, and reached the range along the western coast. Species of Apex,however, crossed these lowlands and now thrive on the western range, but do not live well on the seaward face of either the eastern or the western range of the mountains. but have not crossed the lowlands,and are not found on the western range of the mountains. Hyatt saw that the Achatinellidæ of the Hawaiian Islands afforded a preeminently favorable opportunity for the study of the effects of physical conditions on structure. He knew the stock from which he could trace the migrations of the various descendant races, and he became familiar with the different physical surroundings to the effects of which these races were subjected. Thus he felt that he could demonstrate conclusively the effects of environment upon the structure of the shells, and perhaps upon the soft parts of the animals. This research would, had he completed it, have been his masterpiece, and would have added greatly to the world's store of knowledge.
In 1888 Hyatt published in the Proceedings of the Boston Society of Natural History, his final paper upon the "Larval Theory of the Origin of Cellular Tissues," in which he maintains that the metazoa are descended from colonial forms of protozoa, and the metazoa may be regarded as complexes of multicellular colonies in which growth by sexual union and resulting fission of the ovum leads to the formation of three primary body layers enclosing an archeteron. Volvox or Eudorina are forms intermediate between metazoa and protozoa, and may be called mesozoa, being multicellular colonies composed of only one layer of closely connected cells forming a primitive tissue.
Hyatt's scientific papers and published discussions cover a wide range of subjects and include such titles as the temperature of caves and wells; the absence of distinct marks of glaciation in Alaska; rock ruins at Niagar Falls; the chasms of the Colorado; a disintegrating ​rock at Salem, Mass.; Atlantic shore changes; a raised beach at Marblehead Neck; the porphyries of Marblehead; geological survey of Essex County, Mass.; moulting of the lobster; malformation in lobster's claws; and biographical notices of George H. Emerson, Lucretia Crocker, Spencer F. Baird, Jules Marcou and T. T. Bouvé. Unfortunately, his style is confused, for he uses too many adjectives and subjunctive clauses, and rarely presents summaries of his conclusions. The complexity of his elaborate terminology also tends to deter the general reader, and he never sought to present his theories in simple language.
His productive period began immediately after the publication of Darwin's "Origin of Species" and ended just before the rediscovery of Mendel's law of heredity; thus he was one of the leaders in that active discussion of evolution during that speculative period which has now been superseded by direct experimental tests of the theory itself.
His last published papers are upon fossil cephalopods. In 1900, he completed the revision of the nautiloids and ammonoids for Eastman's translation of Zittel's "Handbuch der Paläontologie"; and after his death a manuscript upon "Pseudoceraties of the Cretaceous" was found lying upon his desk practically completed, he having written upon it on the last day of his life. This work was edited by Dr. T. W. Stanton and published as Monograph No. 44 of the U. S. Geological Survey in 1903. The last paper bearing his name was in cooperation with Professor James Perrin Smith upon the "Triassic Cephalopod Genera of America" and was published by the U. S. Geological Survey in 1905, consisting of 394 pages and 85 plates composed of photographic reproductions from the specimens themselves. For many years Hyatt was paleontologist upon the U. S. Geological Survey and these later papers were the results of his labors in this field.
He was elected to membership in the American Academy of Arts and Sciences at Boston in 1869 and was one of its vice-presidents at the time of his death. In 1875 he became a member of the National Academy of Sciences, and in 1895 of the American Philosophical Society of Philadelphia. He was also a foreign member of the Geological Society of London, and was associated with other leading scientific societies both at home and abroad. In 1898 he received the degree of LL.D. from Brown University, and he was one of the founders and the first president of the American Society of Naturalists.
His broad interest in all departments of knowledge, and his generous heart and kindliness to all about him caused him to be surrounded by a host of warm friends whose regard for him increased as years passed by. Thus it was that he was a prominent member of those remarkable social clubs of Boston which strove for the uplifting of humanity, and for the refining and perfecting of ideals of culture. Such were the Chestnut Street Club, a literary association numbering Longfellow, ​Emerson and Holmes among its members; the Examiner's Club composed of intellectual and clerical men who met to discuss religious and scientific topics; The Thursday Club, a social and intellectual organization; and the Bound Table Club, which was for years presided over by Colonel Thomas W. Higginson and met for the discussion of sociological, educational and political subjects. Another organization of intellectual men was known simply as "The Club" and met for discussions of many interesting topics at the houses of the various members, all of whom were Cambridge men, such as "William James, Horace and Samuel Scudder, Putnam, Trowbridge, Oilman, Dr. Hildreth, Thomdike and Justin Winsor.
Hyatt was keenly appreciative of the natural beauty of the primeval American landscape which man had done so much to desecrate, and he was deeply interested in the conservation of the forests which still clothed our mountainous regions. Thus he was one of the original members of the Appalachian Club, and served as its president in 1887.
On January 15, 1902, he died suddenly of gout of the heart while he was standing in Harvard Square intending to leave Cambridge to attend a meeting of the Boston Society of Natural History. As Professor "William H. Dall says in his biography published in 1902:
No one who had the privilege of Hyatt's acquaintance but will join in testimony to his high-minded scientific integrity; the infectiousness of his hearty enthusiasm; the fertility of his imagination, which yet was always controlled by constant reference to experience and obsenation; and the general atmosphere of good-fellowship which he diffused. Unpretentious, open-minded, a constant example of clean living, high thinking and unassuming kindness to all about him, an ideal husband and father, a steadfast friend; we shall not soon look upon his like again.
He lived in a large wooden house built in the New England Colonial style on Francis Avenue in Cambridge. This place he named "Norton's "Wood," for it was adjacent to the forest which still remained upon the old estate of Professor Charles Eliot Norton. The open-handed hospitality of his home was a heritage from his youthful years at "Wansbeck" in Baltimore, his house being a center for that delightful intellectual social life of the days when Cambridge still retained its traditions as a college town apart from the overwhelming influence of Boston. None of his three children sought to follow him in the study of science, although it may be of interest to observe that both of his daughters became sculptors, the scientific accuracy of their work being remarkable even apart from its artistic merit.
After his death, biographies were written by C. E. Beecher in the American Journal of Science, W. O. Crosby in the Bulletin of the Geological Society of America, Samuel Henshaw in Science, William H. Dall in The Popular Science Monthly, and the Boston Society of Natural History published an account of the proceedings of its Hyatt Memorial ​meeting, all of these appearing in 1902. In 1903, Professor A. S. Packard wrote an appreciative biography in the Proceedings of the American Academy of Arts and Sciences, and in 1904 T. W. Stanton wrote a sketch in the Proceedings of the Washington Academy of Sciences, and finally the late Professor William K. Brooks published a memoir of Hyatt in the "Biographical Memoirs" of the National Academy of Sciences, Volume 6, 1909, this paper containing a chronological list of the titles of his published papers. In 1885 a contemporaneous biography of Hyatt was published by Ralph S. Tarr in volume 28 of The Popular Science Monthly.