Translated from the German by W. S. DALLAS, F.L.S. Assistant Secretary to the Geological Society of London WITH ILLUSTRATIONS LONDON: JOHN MURRAY, ALBEMARLE STREET 1869 Mr. DARWIN'S WORKS A NATURALIST’S VOYAGE ROUND THE WORLD; being a Journal of Researches into the Natural History and Geology of Countries visited. Post 8vo. 9 shillings. THE ORIGIN OF SPECIES, BY MEANS OF NATURAL SELECTION; or, the Preservation of Favoured Races in the Struggle for Life. Woodcuts. Post 8vo. 15 shillings. THE VARI

My principal reason for undertaking the translation of Dr. Fritz Müller’s admirable work on the Crustacea, entitled ‘Für Darwin,’ was that it was still, although published as long ago as 1864, and highly esteemed by the author’s scientific countrymen, absolutely unknown to a great number of English naturalists, including some who have occupied themselves more or less specially with the subjects of which it treats. It possesses a value quite independent of its reference to Darwinism, due to the n

It is not the purpose of the following pages to discuss once more the arguments deduced for and against Darwin’s theory of the origin of species, or to weigh them one against the other. Their object is simply to indicate a few facts favourable to this theory, collected upon the same South American ground, on which, as Darwin tells us, the idea first occurred to him of devoting his attention to “the origin of species,—that mystery of mysteries.” It is only by the accumulation of new and valuable

When I had read Charles Darwin's book ‘On the Origin of Species,’ it seemed to me that there was one mode, and that perhaps the most certain, of testing the correctness of the views developed in it, namely, to attempt to apply them as specially as possible to some particular group of animals. such an attempt to establish a genealogical tree, whether for the families of a class, the genera of a large family, or for the species of an extensive genus, and to produce pictures as complete and intelli

A false supposition, when the consequences proceeding from it are followed further and further, will sooner or later lead to absurdities and palpable contradictions. During the period of tormenting doubt—and this was by no means a short one—when the pointer of the scales oscillated before me in perfect uncertainty between the pro and the con , and when any fact leading to a quick decision would have been most welcome to me, I took no small pains to detect some such contradictions among the infer

If the absence of contradictions among the inferences deduced from them for a narrow and consequently easily surveyed department must prepossess us in favour of Darwin’s views, it must be welcomed as a positive triumph of his theory if far-reaching conclusions founded upon it should subsequently be confirmed by facts, the existence of which science, in its previous state, by no means allowed us to suspect. From many results of this kind upon which I could report, I select as examples, two, which

Our Tanais, which in nearly all the particulars of its structure is an extremely remarkable animal, furnished me with a second fact worthy of notice in connection with the theory of the origin of species by natural selection. When hand-like or cheliform structures occur in the Crustacea, these are usually more strongly developed in the males than in the females, often becoming enlarged in the former to quite a disproportionate size, as we have already seen to be the case in Melita. A better know

Among the numerous facts in the natural history of the Crustacea upon which a new and clear light is thrown by Darwin’s theory, besides the two forms of the males in our Tanais and in Orchestia Darwinii, there is one which appears to me of particular importance, namely, the character of the branchial cavity in the air-breathing Crabs, of which, unfortunately, I have been unable to investigate some of the most remarkable ( Gecarcinus, Ranina ). As this character, namely, the existence of an entra

Scarcely less striking than the example of the air-breathing Crabs, is the behaviour of the heart in the great section Edriophthalma, which may advantageously be divided, after the example of Dana and Spence Bate, only into two orders, the Amphipoda and the Isopoda. In the Amphipoda, to which the above-mentioned naturalists correctly refer the Caprellidæ and Cyamidæ (Latreille’s Læmodipoda ), the heart has always the same position; it extends in the form of a long tube through the six segments f

Let us first glance over the extant facts. Among the Stalk-eyed Crustacea ( Podophthalma ) we know only a very few species which quit the egg in the form of their parents, with the full number of well-jointed appendages to the body. This is the case according to Rathke [1] in the European fresh-water Crayfish, and according to Westwood in a West Indian Land Crab ( Gecarcinus ). Both exceptions therefore belong to the small number of Stalk-eyed Crustacea which live in fresh water or on the land,

Less varied than that of the Stalk-eyed Crustacea is the mode of development of the Isopoda and Amphipoda, which Leach united in the section Edriophthalma, or Crustacea with sessile eyes. The Rock-Slaters ( Ligia ) may serve as an example of the development of the Isopoda. In these, as in Mysis, the caudal portion of the embryo is bent not downwards, but upwards; as in Mysis also, a larval membrane is first of all formed, within which the Slater is developed. In Mysis this first larval skin may

The section of the Branchiopoda includes two groups differing even in their development,—the Phyllopoda and the Cladocera. The latter minute animals, provided with six pairs of foliaceous feet, which chiefly belong to the fresh waters, and are diffused under similar forms over the whole world, quit the egg with their full number of limbs. The Phyllopoda, on the contrary, in which the number of feet varies between 10 and 60 pairs, and some of which certainly live in the saturated lie of salterns

Perhaps some one else, more fortunate than myself, may be able, even without Darwin, to find the guiding clue through the confusion of developmental forms, now so totally different in the nearest allies, now so surprisingly similar in members of the most distant groups, which we have just cursorily reviewed. Perhaps a sharper eye may be able, with Agassiz, to make out “the plan established from the beginning by the Creator,” [1] who may have written here, as a Portuguese proverb says “straight i

From this scarcely unavoidable but unsatisfactory side-glance upon the old school, which looks down with so great an air of superiority upon Darwin's “intellectual dream” and the “giddy enthusiasm” of its friends, I turn to the more congenial task of considering the developmental history of the Crustacea from the point of view of the Darwinian theory. Darwin himself, in the thirteenth chapter of his book, has already discussed the conclusions derived from his hypotheses in the domain of developm

According to all the characters established in the last paragraph, the Prawn that we traced from the Nauplius through states analogous to Zoëa and Mysis to the form of a Macrurous Crustacean appears at present to be the animal, which in the section of the higher Crustacea (Malacostraca) furnishes the truest and most complete indications of its primitive history. That it is the most complete is at once evident. That it is the truest must be assumed, in the first place, because the mode of life of