Still another zoölogist of the eighteenth century was a Lamarck, a French author, who, although he did not begin the study of zoölogy until after he was fifty years old, is regarded as one of the greatest authorities by the student of to-day.

Lamarck's principal work was devoted to the study of intervertebrates, or animals which have no backbone, and he raised this branch of zoölogy to a very important place. He was the first master to insist upon a thorough acquaintance with the lower forms of life as a preliminary study to the higher forms, and so minute and exact were his studies of the lower animals that his works have become the text-books for all time.

Lamarck was among the few zoölogists who taught that the lower animals were first formed, and that the vertebrates or back-boned animals are of much later origin, a view that has been confirmed by the discoveries in zoölogy, and by the greatest modern naturalists.

And thus the study of zoölogy was led on step by step, one naturalist making a discovery and another using it as a basis for a new ground-work of belief, until the nineteenth century found the scientific world possessed of a tolerably clear idea of the resources of the animal kingdom, and its history from the earliest times. And then the story was taken up again by others interested in the great wonder-book of nature, and thus we find that time cannot interrupt, but only make more complete, the work of those who give their lives to science. Among the worthy successors of Linnĉus, Lamarck, and Cuvier may be counted Louis Agassiz, whose name is familiar wherever the student of science is found.

Agassiz was born at Motier, in Switzerland, in 1807, exactly one hundred years after the birth of Linnĉus, and his early life very closely resembled that of the illustrious child of the North. Like Linnĉus, his childhood was passed in a quiet country parsonage, situated on the borders of a lake, and embracing a view of a region of such picturesque beauty, that it could not fail to impress itself upon the mind of the child.

The home-life of the parsonage was very simple, and the children of the family were early taught to regard only those things as valuable which were independent of wealth, and their childish pleasures were all such as could be found in any of the unpretentious little homes that surrounded them.

Unlike many of the great naturalists who only took up their special work late in life, Agassiz may be said to have begun his life-work in his early childhood, though he himself was unconscious of it.

For, like Linnĉus and Cuvier, his first impressions of nature were received form the games and employments of his country home; and in his boyish taste for collecting nests, eggs, birds, and other pet animals, and in the little aquarium, supplied with specimens from the lake, could be traced the small beginnings of his scientific career.

Thus the love of nature, and the finding out of her secrets, began with the boy's first consciousness, and in all his out-of-door sports he was laying up stores of valuable information. To him, as to all country children, the different seasons of the year brought each its offering of gifts and laid them at his feet; and from the first spring blossom to the fall of the snow all nature seemed a harmonious whole, and the wide earth but a treasure-house where one might gather largess at his will. And as the years passed, Agassiz learned more and more of the great forces which linked him with the world of nature around him, and began to understand the sympathy which the genuine naturalist feels for all forms of life.

Besides these lessons, learned in the fields and woods and by the shores of the lake, where nature herself was the teacher, Agassiz had a few simple tasks out of books, his father and mother being his teachers, and, up to his tenth year, he received no instruction outside of his home.

But a boy so intelligent and observing as Agassiz could not fail to learn many things not included in his daily hours of study, and the home-life of Motier, which was in many respects very primitive, furnished the boy many a self-imposed but not the less instructive task.

From the shoemaker who came twice a year to fit the family out with boots and shoes, the boy learned how to make a tiny pair of shoes for his sister's dolls, from the tailor, who was a guest in the house while making the spring and winter outfits, he learned to fashion a suit of clothes, and when the cooper arrived to put the barrels and hogsheads in order for the vintage, he found an apt pupil in the boy to whom nothing seemed uninteresting, and who gained, in these childish amusements, much of that training of the eye and hand which were invaluable to him later on when dexterity and delicacy of touch were so necessary to his scientific pursuits.

And the times of seed-sowing and harvest and vintage, when all the members of the family took an unusual interest in the farming affairs, were also made to contribute their share toward the education of the future naturalist, who learned many practical, useful lessons about growing plants at a time when the learning seemed only childish pastime.

The vintage was the great annual holiday season, when almost the entire population gave themselves up to the business of gathering the grapes and making the wine, and the merry-making attendant upon such a festival. Here all ages and classes met together, the very old and the very young being alike able to give their share of work and fun, and it was amid such scenes that Agassiz early learned to sympathize with the tastes and interests of everyday-life, and imbibed that generous love for humanity which was such a distinguishing trait of his character.

When he was ten years old Agassiz left home to attend school at Bienne, twenty miles away, where he remained five years, coming home only for the vacations.

They were years full of pleasure to the boy, who developed a great taste for study, and made a lasting impression upon his mind; for long before their close he had learned the great lesson for all scientists, to love knowledge for its own sake, and not merely as the means to an end.

During this time his taste for natural history was confirmed, and the little collections he had made at Motier gave place to others more in keeping with his ambitions. He did not have the benefit of a teacher in these pursuits, and the pages of manuscript filled with notes were written on a plan entirely his own. He made at first no attempt at classification, being content to give all the plants and animals for which he knew Latin names, with the design of extending the list gradually until it should include the entire animal and vegetable kingdoms.

Although this design may seem childish enough, it yet shows the birth of the true scientific spirit, which begins with inquiry into the familiar, and never ceases until the unknown has been explored as widely as possible.

And although Agassiz's attempts at studying natural history were at this time so desultory, and included only general observations on the appearance and habits of the specimens, they yet were fruitful in laying the foundations for those accurate studies from nature which distinguished the work of this naturalist.

Meadow, field, forest, and stream were haunted by the boy, who thought no living thing uninteresting, and his room was gradually turned into a small museum of natural history. Birds, insects, and fishes were collected with great care, and their modes of life so carefully studied that the knowledge thus gained became a storehouse of useful facts when Agassiz became interested in the graver problems of natural history. He raised caterpillars form the eggs and studied with minute care the different kinds, describing their habits and differences of diet, and the length of time passed in the chrysalis state, and accurately noting the characteristics of the great variety of butterflies and moths, with which he soon became familiar.

The songs of the birds, their twitterings, scolding, changes of position, habits, and instincts were all as well understood by the boy-naturalist as the voices of his friends; and in his autobiography he says that what he knew of the habits of the fresh-water fishes of Central Europe was almost entirely learned at that time, it being a matter of great surprise to him when he became acquainted with the works of the principal authorities on fishes, to find how little they knew of their habits and life, things which Agassiz himself had been familiar with since boyhood.