50 THE DOCTRINE OF DESCENT. 
germ at a period when the type has not yet manifested 
"itself. This led him to the question, “Whether, at the 
beginning of development, all animals are not essen- 
tially alike, and whether a common primordial form 
does not exist for all?” “It might,” he finally thinks, 
“be maintained, not without reason, that the simple 
cyst-like form is the common fundamental form from 
which all animals are developed, not merely in idea, but 
historically.” 
When the barrier which it was formerly thought 
necessary to erect between asexual multiplication and 
multiplication caused by fecundation had been recog- 
nized as non-existent, and it was perceived that all 
development amounts to the multiplication and meta- 
morphosis of the primitive germ or egg-cell, the cell 
was necessarily regarded, in the acceptation of the older 
investigators, as the common fundamental form. But 
although the descriptive history of evolution does not 
go back to this elementary organism, and considers 
even the bifurcation as merely a preparation for actual 
development, at any rate the earliest rudimentary larval 
conditions of different types may be compared with 
each other. 
The discoveries of the last ten years with reference 
to this subject are so numerous, and such striking 
analogies have been advanced, that we must needs go 
much further than, at that time, was possible for Von 
Baer. It is not merely a question of those general 
analogies in the segregation of tissues from an indiffer- 
cnt rudimentary mass, but of homologies in the distri- 
bution, form, and composition of the embryos and larvae, 
of which the after effects are of profound importance 
