CAMBRIDGE, July 8, 1853.

. . .I have been lately devising some method of learning how far animals are truly autochthones, and how far they have extended their primitive boundaries. I will attempt to test that question with Long Island, the largest of all the islands along our coast. For this purpose I will for the present limit myself to the fresh-water fishes and shells, and for the sake of comparison I will try to collect carefully all the species living in the rivers of Connecticut, New York, and New Jersey, and see whether they are identical with those of the island. Whatever may come out of such an investigation it will, at all events, furnish interesting data upon the local distribution of the species. . .I am almost confident that it will lead to something interesting, for there is one feature of importance in the case; the present surface of Long Island is not older than the drift period; all its inhabitants must, therefore, have been introduced since that time. I shall see that I obtain similar collections from the upper course of the Connecticut, so as to ascertain whether there, as in the Mississippi, the species differ at different heights of the river basin. . .

TO PROFESSOR S.S. HALDEMAN, COLUMBIA, PENNSYLVANIA.

CAMBRIDGE, July 9, 1853.

. . .While ascending the great Mississippi last spring I was struck with the remarkable fact that the fishes differ essentially in the different parts of that long water-course,—a fact I had already noticed in the Rhine, Rhone, and Danube, though there the difference arises chiefly from the occurrence, in the higher Alpine regions, of representatives of the trout family which are not found in the main river course. In the Mississippi, however, the case is otherwise and very striking, inasmuch as we find here, at separate latitudes, distinct species of the same genera, somewhat like the differences observed in distinct water-basins; and yet the river is ever flowing on past these animals, which remain, as it were, spell-bound to the regions most genial to them. The question at once arises, do our smaller rivers present similar differences? I have already taken steps to obtain complete collections of fishes, shells, and crayfishes from various stations on the Connecticut and the Hudson, and their tributaries; and I should be very happy if I could include the Susquehanna, Delaware, and Ohio in my comparisons. My object in writing now is to inquire whether you could assist me in making separate collections, as complete as possible, of all these animals from the north and west branches of the Susquehanna, from the main river either at Harrisburg or Columbia, and from the Juniata, also from the Schuylkill, Lehigh, and Delaware, and from the Allegheny and Monongahela. I have Swiss friends in the State of New York who have promised me to collect the fishes from the head-waters of the Delaware and Susquehanna within the limits of the State of New York. I cannot, of course, expect you to survey your State for me, but among your acquaintance in various parts of your State are there not those who, with proper directions, could do the work for me? I would, of course, gladly repay all their expenses. The subject seems to me so important as to justify any effort in that direction. Little may be added to the knowledge of the fishes themselves, for I suppose most of the species have been described either by De Kay, Kirtland, or Storer; but a careful study of their special geographical distribution may furnish results as important to zoology as the knowledge of the species themselves. If you cannot write yourself, will you give me the names of such persons as might be persuaded to aid in the matter. I know from your own observations in former times that you have already collected similar facts for the Unios, so that you will at once understand and appreciate my object. . .

He writes in the same strain and for the same object to Professor Yandell, of Kentucky, adding: "In this respect the State of Kentucky is one of the most important of the Union, not only on account of the many rivers which pass through its territory, but also because it is one of the few States the fishes of which have been described by former observers, especially by Rafinesque in his "Ichthyologia Ohioensis," so that a special knowledge of all his original types is a matter of primary importance for any one who would compare the fishes of the different rivers of the West. . .Do you know whether there is anything left of Rafinesque's collection of fishes in Lexington, and if so, whether the specimens are labeled, as it would be very important to identify his species from his own collection and his own labels? I never regretted more than now that circumstances have not yet allowed me to visit your State and make a stay in Louisville."

In 1854 Agassiz moved to a larger house, built for him by the college. Though very simple, it was on a liberal scale with respect to space; partly in order to accommodate his library, consisting of several thousand volumes, now for the first time collected and arranged in one room. He became very fond of this Cambridge home, where, with few absences, he spent the remainder of his life. The architect, Mr. Henry Greenough, was his personal friend, and from the beginning the house adapted itself with a kindly readiness to whatever plans developed under its roof. As will be seen, these were not few, and were sometimes of considerable moment. For his work also the house was extremely convenient. His habits in this respect were, however, singularly independent of place and circumstance. Unlike most studious men, he had no fixed spot in the house for writing. Although the library, with the usual outfit of well-filled shelves, maps, large tables, etc., held his materials, he brought what he needed for the evening by preference to the drawing-room, and there, with his paper on his knee, and his books for reference on a chair beside him, he wrote and read as busily as if he were quite alone. Sometimes when dancing and music were going on among the young people of the family and their guests, he drew a little table into the corner of the room, and continued his occupations as undisturbed and engrossed as if he had been in complete solitude,—only looking up from time to time with a pleased smile or an apt remark, which showed that he did not lose but rather enjoyed what was going on about him.

His children's friends were his friends. As his daughters grew up, he had the habit of inviting their more intimate companions to his library for an afternoon weekly. On these occasions there was always some subject connected with the study of nature under discussion, but the talk was so easy and so fully illustrated that it did not seem like a lesson. It is pleasant to remember that in later years Mr. Ralph Waldo Emerson revived this custom for his own daughters; and their friends (being, indeed, with few changes, the same set of young people as had formerly met in Agassiz's library) used to meet in Mr. Emerson's study at Concord for a similar object. He talked to them of poetry and literature and philosophy as Agassiz had talked to them of nature. Those were golden days, not to be forgotten by any who shared their happy privilege.

In the winter of 1855 Agassiz endeavored to resume his public lectures as a means of increasing his resources. He was again, however, much exhausted when spring came, and it seemed necessary to seek some other means of support, for without considering scientific expenses, his salary of fifteen hundred dollars did not suffice for the maintenance of his family. Under these circumstances it occurred to his wife and his two older children, now of an age to assist her in such a scheme, that a school for young ladies might be established in the upper part of the new and larger house. By the removal of one or two partitions, ample room could be obtained for the accommodation of a sufficient number of pupils, and if successful such a school would perhaps make good in a pecuniary sense the lecturing tours which were not only a great fatigue to Agassiz, but an interruption also to all consecutive scientific work. In consultation with friends these plans were partly matured before they were confided to Agassiz himself. When the domestic conspirators revealed their plot, his surprise and pleasure knew no bounds. The first idea had been simply to establish a private school on the usual plan, only referring to his greater experience for advice and direction in its general organization. But he claimed at once an active share in the work. Under his inspiring influence the outline enlarged, and when the circular announcing the school was issued, it appeared under his name, and contained these words in addition to the programme of studies: "I shall myself superintend the methods of instruction and tuition, and while maintaining that regularity and precision in the studies so important to mental training shall endeavor to prevent the necessary discipline from falling into a lifeless routine, alike deadening to the spirit of teacher and pupil. It is farther my intention to take the immediate charge of the instruction in Physical Geography, Natural History, and Botany, giving a lecture daily, Saturdays excepted, on one or other of these subjects, illustrated by specimens, models, maps, and drawings."

In order not to interrupt the course of the narrative, the history of this undertaking in its sequence and general bearing on his life and work may be completed here in a few words. This school secured to him many happy and comparatively tranquil years. It enabled him to meet both domestic and scientific expenses, and to pay the heavy debt he had brought from Europe as the penalty of his "Fossil Fishes" and his investigations on the glaciers. When the school closed after eight years he was again a free man. With an increased salary from the college, and with such provision for the Museum (thanks to the generosity of the State and of individuals) as rendered it in a great degree independent, he was never again involved in the pecuniary anxieties of his earlier career. The occupation of teaching was so congenial to him that his part in the instruction of the school did not at any time weigh heavily upon him. He never had an audience more responsive and more eager to learn than the sixty or seventy girls who gathered every day at the close of the morning to hear his daily lecture; nor did he ever give to any audience lectures more carefully prepared, more comprehensive in their range of subjects, more lofty in their tone of thought. As a teacher he always discriminated between the special student, and the one to whom he cared to impart only such a knowledge of the facts of nature, as would make the world at least partially intelligible to him. To a school of young girls he did not think of teaching technical science, and yet the subjects of his lectures comprised very abstruse and comprehensive questions. It was the simplicity and clearness of his method which made them so interesting to his young listeners. "What I wish for you," he would say, "is a culture that is alive, active, susceptible of farther development. Do not think that I care to teach you this or the other special science. My instruction is only intended to show you the thoughts in nature which science reveals, and the facts I give you are useful only, or chiefly, for this object."