evolution.[44] The preformation of the organism seemed an inevitable deduction from the opinions once universal. It led to many strange, and some absurd conclusions; among them, to the assertion that the original germ of every species contained within it all the countless individuals which in process of time might issue from it; and this in no metaphysical “potential” guise, but as actual boxed-up existences (_emboîtés_); so that Adam and Eve were in the most literal sense progenitors of the whole human race, and contained their progeny already shaped within them, awaiting the great accoucheur, time. 100. This was the celebrated “emboîtement” theory. In spite of obvious objections it gained scientific acceptance, because physiologists could not bring themselves to believe that so marvellous a structure as that of a human organism arose by a series of successive modifications, or because they could not comprehend how it was built up, part by part, into forms so closely resembling the parent-forms. That many and plausible reasons pleaded in favor of this opinion is evident in the fact that illustrious men like Haller, Bonnet, Vallisneri, Swammerdamm, Réaumur, and Cuvier, were its advocates; and if there is not a sigle physiologist of our day who accepts it, or who finds any peculiar difficulty in following the demonstrations of embryologists, how from the common starting-point of a self-multiplying epithelial cell parts so diverse as hairs, nails, hoofs, scales, feathers, crystalline lens, and secreting glands may be evolved, or how from the homogeneous germinal membrane the complex organism will arise, there are very few among the scorners of the dead hypothesis who seem capable of generalizing the principles which have destroyed it, or can conceive that the laws of Evolution apply as rigorously to the animal and vegetable _kingdoms_ as to the individual _organisms_. The illustrious names of those who advocated the preformation hypothesis may serve to check our servile submission to the authorities so loudly proclaimed as advocates of the fixity of species. The more because the two doctrines have a common parentage. The one falls with the other, and no array of authorities can arrest the fall. That the manifold differentiations noticeable in a complex organism should have been evolved from a membrane wholly destitute of differences is a marvel, but a marvel which Science has made intelligible. Yet the majority of those to whom this has been made intelligible still find an impossibility in admitting that the manifold forms of plant and animal were successively evolved from equally simple origins. They relinquish the hypothesis of preformation in the one case, and cling to it in the other. Evolution, demonstrable in the individual history, seems preposterous in the history of the class. And thus is presented the instructive spectacle of philosophers laughing at the absurdities of “preformation,” and