CHARLES DARWIN—WEISMANN. 433 
of creation was fought out by Geoffroy St. Hilaire and Cuvier in 
the Paris Academy. Cuvier triumphed, and thus it came about that 
an idea so important as that of evolution sank into oblivion again 
after its emergence, and was expunged from the pages of science so 
completely that it seemed as if it were for ever buried beyond hope 
of resurrection. 
Scientific men now turned with eagerness toward special problems 
in all the domains of life, and the following period may well be 
characterized as that of purely detailed investigation. 
Great progress was made during this period; entirely new branches 
of science were founded, and a wealth of unexpected facts was dis- 
covered. The development of individual organisms, of which little 
had previously been known, began to be revealed in all its marvelous 
diversity; first, the development of the chick in the egg; then of 
the frog; then of insects and worms; then of spiders, crustaceans, 
starfishes, and all the classes and orders of mollusks, as well as of 
backboned animals from the lowest fish up to man himself. Within 
this period of purely detailed investigation there falls also the dis- 
covery, in animals and plants, of that smallest microscopically visible 
building stone of the living body, the cell, and this discovery paved 
the way for the full development of the newly founded science of 
tissues, histology. 
In botany the chief progress in this period was in regard to the 
reproduction and development of the lower plants, or cryptogams, 
and the discovery of alternation of generations, a mode of repro- 
duction that had previously been known in several groups of the 
animal kingdom, in polyps and meduse, in various worms, and later 
in insects and crustaceans. 
At the same time it was found that the proposition, which had 
hitherto been accepted as a matter of course, that an egg can only 
develop after it has been fertilized, is not universally valid, for there 
is a development without previous fertilization—parthenogenesis, or 
virgin birth. 
Thus, in the period between the Napoleonic wars and 1859, an 
ever increasing mass of new facts was accumulated, and among these 
there were so many of an unexpected nature that further effort was 
constantly being put forth to elucidate detailed processes in every do- 
main. This was desirable and important—was, indeed, indispensable 
to a deeper knowledge of organic nature. But in the endeavor to 
investigate details naturalists forgot to inquire into the deeper causes 
and correlations, which might have enabled them to build up out 
of the wealth of details a more general conception of life. So great 
was the reaction from the unfortunate speculations of the so-called 
“ Naturphilosophie,” that there was a tendency to shrink even from 
taking a comprehensive survey of isolated facts, which might lead 
to the induction of general principles. 
