It has been laid down as a fundamental law of biogenesis that ontogeny (the development of the individual) and phylogeny (that of the race) must exactly correspond.... This law which I long held as well founded is absolutely and radically false. Attentive study of embryology shows us, in fact, that embryos have their own conditions suitable to themselves, very different from those of adults. "In a word," M. de Quatrefages continues, "the learned Genevan professor rightly considers that, 'The ontogenesis of all organic beings without exception, is the normal result of all the various influences which operate upon such beings.'" But it must, moreover, be noted that the story which embryology can be made to tell is by no means so plain as we might easily be led to suppose. Thus, although snakes are held to be descended from lizards, and some of them have rudimentary legs even in the adult stage, others have no trace of limbs even in the egg, while they _have_ vestiges of gills, and thus would seem to be visibly linked to ancient water-dwelling ancestors, and not to far more recent land-dwellers. Again;[230] Amphibians (frogs, newts and the like) agree in some respects, as to the development of the germ, with mammals, differing in the same respects from reptiles and birds. But reptiles and birds are supposed to be a more recent development than Amphibia, and therefore should intervene between them and mammals on the genealogical tree. Moreover the eggs of one group of Amphibians are found to exhibit some remarkable resemblances to those of reptiles and birds, from which it would thus appear to have derived them, although on other grounds it is declared to be of an older stock than theirs. Most frogs, toads, and newts come out of the egg as tadpoles, furnished with gills and so breathing in water. This should signify that these creatures are descended from fish or fishlike ancestors. But one frog (_Rana opisthodon_) is never a tadpole even in the egg, from which he gets out by means of a special opener on his snout which he has somehow acquired. On the other hand certain newts[231] breed as tadpoles instead of in their mature form, which looks like an attempt to climb down the tree instead of up. It will be remembered that the latter phrase was that used by Professor Milnes Marshall. Yet even he expressed himself strongly concerning the exaggerations of Professor Haeckel on this subject. In his review of Haeckel's _Anthropogenie_,[232] after observing that many descriptions of human embryology have been based on observations of dogs, pigs, rabbits, or even chickens and dogfish, he thus continued regarding the book before him: