heterogenetic generation, and of a metamorphosis of germs. To this class belong especially Oswald Heer--"Urwelt der Schweitz" ("Antediluvian World in Switzerland"), Zuerich, 1865, p. 590-604; Koelliker--"Ueber die Darwin'sche Schoepfungstheorie," ("Darwin's Theory of Creation"), Leipzig, 1864; "Morphologie und Entwicklungeschichte des Pennatulidenstammes nebst allgemeinen Betrachtungen zur Descendenzlehre," {57} ("Morphology and History of the Development of the Stem of the Pennatulidae, together with General Remarks on the Descent Theory"), Frankfurt, 1872; and Heinrich Baumgaertner--"Natur und Gott" ("Nature and God"), Leipzig, Brockhaus, 1870. Heer has introduced into scientific language the term "new-modeling of the species," Koelliker that of a "heterogenetic generation," and Baumgaertner that of a "transmutation of the types through a metamorphosis of germs." Baer also is not averse to adopting the latter. The botanist, Albert Wigand, of Marburg, takes a peculiar position. On one hand, the observation of the relationship of organic beings with one another leads him to adopt a common genealogy, a descent; on the other, the objections to adopting a descent of the species one from another appear to him insurmountable. In the first place, he sees all the species everywhere strictly limited--although in the second volume of his work, which appeared after the preceding lines were written, he again warns against a one-sided emphasizing of the invariability of species. In the second place, he sees so clearly, through the whole organic world, the differences, nay, the contrasts, of the species, in their building plan, in the numbers and conditions and positions of their parts, and in their mode of development, that it appears to him impossible to assume in the perfected organism a production of germs which in a course of generations, by a process even as gradual as possible, would grow into such an entirely new phenomenon as a new, even closely related, species would be. But if we adopt the theory of a heterogenetic generation, we explain by it the variety but not the similarity of species; {58} for a heterogenetic generation would in the new species make everything different from the old one--a conclusion, the necessity of which it would be difficult to show. For these reasons, he refers the descent of the organic beings, not to the series of the species, with their individuals already specified and defined, but to the series of _primordial cells_ living free in the water. The earliest primordial cells represented only the common character of the _whole organic world_, and out of them the primordial cells of the _animal_ and those of the _vegetable kingdom_ were produced by dividing the cells; so that the first ones embraced only the general and primitive characteristics of the whole animal, the last ones those of the whole vegetable kingdom. Out of these primordial cells of the two kingdoms, those of the _main types_