Louis Agassiz: His Life and Correspondence

by Louis Agassiz

In the following July we find him again upon the glacier. But the campaign of 1843 opened sadly for the glacial party. Arriving at Meiringen they heard that Jacob Leuthold was ill and would probably be unable to accompany them. They went to his house, and found him, indeed, the ghost of his former self, apparently in a rapid decline. Nevertheless, he welcomed them gladly to his humble home, and would have kept them for some refreshment. Fearing to fatigue him, however, they stayed but a few moments. As they left, one of the party pointed to the mountains, adding a hope that he might soon join them. His eyes filled with tears; it was his only answer, and he died three days later. He was but thirty-seven years of age, and at that time the most intrepid and the most intelligent of the Oberland guides. His death was felt as a personal grief by the band of workers whose steps he had for years guided over the most difficult Alpine passes.

The summer's work continued and completed that of the last season. On leaving the glacier the year before they had marked a network of loose boulders, such as travel with the ice, and also a number of fixed points in the valley walls, comparing and registering their distance from each other. They had also sunk a line of stakes across the glacier. The change in the relative position of the two sets of signals and the curve in their line of stakes gave them, self-recorded, as it were, the rate of advance of the glacier as a whole, and also the comparative rate of progression in its different parts. Great pains was also taken during the summer to measure the advance in every twenty-four hours, as well as to compare the diurnal with the nocturnal movement, and to ascertain the amount of surface waste. The season was an unfavorable one, beginning so late and continuing so cold that the period of work was shortened.

CHAPTER 12.

1843-1846: AGE 36-39.

Completion of Fossil Fishes.
Followed by Fossil Fishes of the Old Red Sandstone.
Review of the Later Work.
Identification of Fishes by the Skull.
Renewed Correspondence with Prince Canino about Journey
to the United States.
Change of Plan owing to the Interest of the King of Prussia
in the Expedition.
Correspondence between Professor Sedgwick and Agassiz on
Development Theory.
Final Scientific Work in Neuchatel and Paris.
Publication of "Systeme Glaciaire."
Short Stay in England.
Farewell Letter from Humboldt.
Sails for United States.

In 1843 the "Recherches sur les Poissons Fossiles" was completed, and fast upon its footsteps, in 1844, followed the author's "Monograph on the Fossil Fishes of the Old Red Sandstone, or the Devonian System of Great Britain and Russia," a large quarto volume of text, accompanied by forty-one plates. Nothing in his paleontological studies ever interested Agassiz more than this curious fauna of the Old Red, so strange in its combinations that even well-informed naturalists had attributed its fossil remains to various classes of the animal kingdom in turn, and, indeed, long remained in doubt as to their true nature. Agassiz says himself in his Preface: "I can never forget the impression produced upon me by the sight of these creatures, furnished with appendages resembling wings, yet belonging, as I had satisfied myself, to the class of fishes. Here was a type entirely new to us, about to reenter (for the first time since it had ceased to exist) the series of beings; nor could anything, thus far revealed from extinct creations, have led us to anticipate its existence. So true is it that observation alone is a safe guide to the laws of development of organized beings, and that we must be on our guard against all those systems of transformation of species so lightly invented by the imagination."

The author goes on to state that the discovery of these fossils was mainly due to Hugh Miller, and that his own work had been confined to the identification of their character and the determination of their relations to the already known fossil fishes. This work, upon a type so extraordinary, implied, however, innumerable and reiterated comparisons, and a minute study of the least fragments of the remains which could be procured. The materials were chiefly obtained in Scotland; but Sir Roderick Murchison also contributed his own collection from the Old Red of Russia, and various other specimens from the same locality. Not only on account of their peculiar structure were the fishes of the Old Red interesting to Agassiz, but also because, with this fauna, the vertebrate type took its place for the first time in what were then supposed to be the most ancient fossiliferous beds. When Agassiz first began his researches on fossil fishes, no vertebrate form had been discovered below the coal. The occurrence of fishes in the Devonian and Silurian beds threw the vertebrate type back, as he believed, into line with all the invertebrate classes, and seemed to him to show that the four great types of the animal kingdom, Radiates, Mollusks, Articulates, and Vertebrates, had appeared together.* (* Introduction to the "Poissons Fossiles de Vieux Gres Rouge" page 22.) "It is henceforth demonstrated," says Agassiz, "that the fishes were included in the plan of the first organic combinations which made the point of departure for all the living inhabitants of our globe in the series of time."

In his opinion this simultaneity of appearance, as well as the richness and variety displayed by invertebrate classes from the beginning, made it* (* Introduction to the "Poissons Fossiles du Vieux Gres Rouge" page 21.) "impossible to refer the first inhabitants of the earth to a few stocks, subsequently differentiated under the influence of external conditions of existence.". . .He adds:* (* Introduction to the "Poissons Fossiles de Vieux Gres Rouge" page 24.) "I have elsewhere presented my views upon the development through which the successive creations have passed during the history of our planet. But what I wish to prove here, by a careful discussion of the facts reported in the following pages, is the truth of the law now so clearly demonstrated in the series of vertebrates, that the successive creations have undergone phases of development analogous to those of the embryo in its growth and similar to the gradations shown by the present creation in the ascending series, which it presents as a whole. One may consider it as henceforth proved that the embryo of the fish during its development, the class of fishes as it at present exists in its numerous families, and the type of fish in its planetary history, exhibit analogous phases through which one may follow the same creative thought like a guiding thread in the study of the connection between organized beings." Following this comparison closely, he shows how the early embryonic condition of the present fishes is recalled by the general disposition of the fins in the fishes of the Old Red Sandstone, and especially by the caudal fin, making the unevenly lobed tail, so characteristic of these ancient forms. This so called heterocercal tail is only known to exist, as a permanent adult feature, in the sturgeons of to-day. The form of the head and the position of the mouth and eyes in the fishes of the Old Red were also shown to be analogous with embryonic phases of our present fishes. From these analogies, and also from the ascendancy of fishes as the only known vertebrate, and therefore as the highest type in those ancient deposits, Agassiz considered this fauna as representing "the embryonic age of the reign of fishes;" and he sums up his results in conclusion in the following words: "The facts, taken as a whole, seem to me to show, not only that the fishes of the Old Red constitute an independent fauna, distinct from those of other deposits, but that they also represent in their organization the most remarkable analogy with the first phases of embryonic development in the bony fishes of our epoch, and a no less marked parallelism with the lower degrees of certain types of the class as it now exists on the surface of the earth."

It has been said by one of the biographers of Agassiz,* (* "Louis Agassiz: Notice biographique" par Ernest Favre.) in reference to this work upon the fishes of the Old Red Sandstone: "It is difficult to understand why the results of these admirable researches, and of later ones made by him, did not in themselves lead him to support the theory of transformation, of which they seem the natural consequence." It is true that except for the frequent allusion to a creative thought or plan, this introduction to the Fishes of the Old Red might seem to be written by an advocate of the development theory rather than by its most determined opponent, so much does it deal with laws of the organic world, now used in support of evolution. These comprehensive laws, announced by Agassiz in his "Poissons Fossiles," and afterward constantly reiterated by him, have indeed been adopted by the writers on evolution, though with a wholly different interpretation. No one saw more clearly than Agassiz the relation which he first pointed out, between the succession of animals of the same type in time and the phases of their embryonic growth to-day, and he often said, in his lectures, "the history of the individual is the history of the type." But the coincidence between the geological succession, the embryonic development, the zoological gradation, and the geographical distribution of animals in the past and the present, rested, according to his belief, upon an intellectual coherence and not upon a material connection. So, also, the variability, as well as the constancy, of organized beings, at once so plastic and so inflexible, seemed to him controlled by something more than the mechanism of self-adjusting forces. In this conviction he remained unshaken all his life, although the development theory came up for discussion under so many various aspects during that time. His views are now in the descending scale; but to give them less than their real prominence here would be to deprive his scientific career of its true basis. Belief in a Creator was the keynote of his study of nature.

In summing up the comprehensive results of Agassiz's paleontological researches, and especially of his "Fossil Fishes," Arnold Guyot says:* (* See "Biographical Memoir of Louis Agassiz" page 28.)—"Whatever be the opinions which many may entertain as to the interpretation of some of these generalizations, the vast importance of these results of Agassiz's studies may be appreciated by the incontestable fact, that nearly all the questions which modern paleontology has treated are here raised and in great measure solved. They already form a code of general laws which has become a foundation for the geological history of the life-system, and which the subsequent investigations of science have only modified and extended, not destroyed. Nowhere did the mind of Agassiz show more power of generalization, more vigor, or more originality. The discovery of these great truths is truly his work; he derived them immediately from nature by his own observations. Hence it is that all his later zoological investigations tend to a common aim, namely, to give by farther studies, equally conscientious but more extensive, a broader and more solid basis to those laws which he had read in nature and which he had proclaimed at that early date in his immortal work, 'Poissons Fossiles.' Let us not be astonished that he should have remained faithful to these views to the end of his life. It is because he had SEEN that he BELIEVED, and such a faith is not easily shaken by new hypotheses."