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Show 256 EXPLANATIONS. depends; for have we not seen Mr. Uwen on th: last page affirming that the human embryo is first vermz~m·m? -this meaning the form of the worms, a portion of the class Annelides, in one of these lower divisions. That all these divisions or sub-kingdoms are 'not represented in t~1e .human embryo is an objection perfeetly visionary, for It Is net necessary that all should be involved in the ancestry, and therefore analogies to all are not to be looked for. It may be said, then, there is no true difficulty in this quarter. Perhaps no part of the arguments for the development theory has been more misapprehended, or misrepresented, thaTt this. It is continually said that the embryo. at any of its particular stages, is not in reality the animal repre'sented by that stage. The Edinburgh reviewer remarks with regard to the fish stage, " ~r ere the embryo of ~ mammal thrown off at that time into the V\~ater (of its own temperature), it could not support life for a moment." The brain of a child in the seventh month is also said to 9e not the brain of any of the inferior animals, but a true numan brain. The truth is, no one ever pretended that there ·was such an identity. It is only saici that there is a resemblance in general character between the particular embryotic stage of being, and the mature condition and form of the appropriate inferior animal. The particular adaptations, and the character of vital maturity, are all wanting, and therefore it is that the ernbryo could not live, as the inferior animal represented, if separated from the parent, and really is not that iuferior animal. It may be well, before leaving this part of the subject, to advert to a special charge which this writer, and at least one other,* have brought forward: it is, that I assume, not only that the organic germs of all creatures are alike, but that they are identical. The Edinburgh Review brings a contradiction to this proposition from Dr. Clark. It is wholly unneces!.'ary, for no such assumption was ever made by me. The phrase used in the book was, "Its primary positions [meaning the doctrines of embryonic develqpment] are that the ""mbryos of all animals are not distinguishably different from each other;" which is a very different proposition. In sev,"rur other instances, pt·opositions are thus misrepresented tfl 't-~ord the glory of a visionary refutation. For exampl~, tho • North American Review, ArrJ, 1845. GERMS NOT IDENTICAL. 257 idea that there being light in the planets, any inhabitants of thas~ orbs ~ay b~ presumed ~o have eyes, as eyes bear a relatwn to ltght, Is met by h1m very gravely with the ract, left for him to discover, that animals have eyes before thev are born! I have now reviewed the vestiges of creation, presented in both the geological ~nd physiological records, the former presenting memonals of the actual proO'ression of species, in nearly such a conformity with the general ar~ an7ements of the organic ki':lgdoms as we might expect In tne present state of the scwnce, and the latter afiorlling us proofs-proofs, at least, satisfactory to many of the best anatomists of our age-of a plan of individual development, which may be called the living picture of the advance of species during the vast ages chronicled by the sedimentary rocks. A third series of vestiges now remains for consideration-namely, those which hint at originations and modifications of organic beings in the current era. The objections to the occasional production of organic beings, otherwise than ea: ovo, do not appear to have been / softened by the publication of my former volume. All reviewers, with the single exception of the British and Foreign Medical Review, have intimated their continued Rkepticism on this point. The experiment of Professor Shulze, of Berlin, with decaying organic matter floating in a flask to which common air was admitted, after pass ... ing through sulphuric acid, thereby bein.g deprived of all animal admixtures-an experiment which ended in the non-production of any animalcules or mould-is pointed to as conclusive. Explanations more or less plausible have also been otlerecl for the origin of the entozoa, the parasites of civilization, the pimelodes cyclopum, &c. I should fear to weary the reader with a new discussion of all these particulars: for the sake of brevity, let me meet the call which the opponents of the development theory usu~lly make, to give it the direct proof which would be afforded by showing one instance, either of the origin of life or the transmutation of species. The objection of the Edinburgh reviewer to the alleged ~ransrnutation of oats into rye, is that he believes it a fable. This is the opinion of one person, advanced with· out fact or argument to support it. Let us see, on the other hand, what a greater authority on b0tanical subjects |