No. 2.] THE ORIGIN OF THE SEX-CELLS. 215 
as degenerate, and that the gonophore represents a retrograded 
umbrella, rather than a step in the phylogenetic history of the 
more perfect medusa. 
Weismann considers the “Keimstatte’’ as existing in four 
different positions, due to a shifting process: first, the sex- 
cells originating from the ectoderm of the manubrium; second, 
from the ectoderm of the bell nucleus; third, from the 
endoderm of the manubrium; and fourth, from the endoderm of 
the blastostyle. Assuming that the first state is the primitive 
condition, we have the ova of Podocoryne belonging to the 
third, those of Hydractinia to the fourth. While the sperma- 
tozoa of Podocoryne are still found in the first state, those of 
Hydractinia according to Weismann are found in the fourth, 
while as a result of my studies, I place them in the second 
state. Thus Weismann looks upon this shifting of the germinal 
states as a proof of the origin of Hydractinia from Podocoryne,. 
That the sex-cells when mature are found in the ectoderm 
of the manubrium and spadix in Podocoryne and Hydractinia 
respectively, proves, Weismann thinks, that this was phylo- 
genetically their origin and position of complete development, 
thus for Hydractinia he says: “So kann z. B. bei der weib- 
lichen Hydractinia diese Wanderung ins Ektoderm des Manu- 
briums schwerlich noch einen andern Sinn haben, als den einer 
phyletischen Reminiscenz, einer ontogenetischen Wiederholung 
der Stammesgeschichte.”’ 
THE UNSEGMENTED EGG. 
In Hydractinia it was found that the ova and spermatozoa 
were discharged about the same time, namely from 9.30 to 
10.30 P.M. The ovum while in the gonophore has a well 
defined nucleus situated above the center of the egg, which 
fades from view when the ovum is deposited. The mature eggs 
when observed by reflected light have a greenish tint, and are 
not surrounded by a vitelline membrane. Sections of the egg 
show deutoplasm spheres distributed throughout the proto- 
plasm, with the exception of an outer rim which is composed 
entirely of protoplasm. 
