So again as to the phenomena of embryology. No doubt they are very striking and impressive. That the most highly developed creatures, and man himself, should in the first stages of existence exhibit the characteristics of lower forms, is an exemplification of development no less signal than the succession of ascending types witnessed to by the rocks. It is not easy to see, however, why it should be taken for granted that this can only signify genetic descent from all such forms, and that these embryo animals are engaged in climbing up their genealogical trees. Yet this is usually assumed as a matter of course, and any one who ventures to question the validity of such an inference, must be prepared to find himself accused of dogmatizing. And yet, after all, upon what grounds does the assumption rest? That such a recapitulation of racial experiences forms no essential feature of Evolution is sufficiently evident from the case of the vegetable world,--for plants do not climb _their_ genealogical trees, or pass in the seed through a series of botanical phases. And as to animals, since through all varieties of form, each always arrives at the required term, it is obvious that, apart from any archaic associations, and on Darwinian principles themselves, these forms must be the best for the purpose at each respective stage,--perhaps the only ones by which the term could be reached. It is therefore, to say the least, quite conceivable, that we have here the whole explanation and need go no further. In certain instances this obvious consideration is strikingly illustrated. Thus the salamander, an Amphibian of the newt family, brings forth its young in adult condition without gills.[228] But previously to birth they have gills relatively large. The experiment having been tried of bringing some of them forth by artificial means before their time, and placing them in water, the first thing they did was to cast off these big gills, which were speedily replaced by new ones of much smaller size, and evidently better suited for the work required, as they lasted as long as a fortnight. Here, in the first place, it is quite impossible to suppose that the large gills would continue to appear unless they were of advantage during the period of gestation. It is equally evident that it is not from a previous aquatic condition that they are inherited, for in such a condition they are useless. Finally, as Mr. Mivart observes, the new gills, suitable for unwonted conditions, were developed "not in a struggle for existence against rivals, but directly and spontaneously from the innate nature of the animal." This view of the matter commended itself on mature consideration to so ardent an evolutionist as Carl Vogt, with whom we may couple M. de Quatrefages, who cites his words with approval as follows:[229]