48 MAROUS M. HARTOG. 
This confirms our interpretation of the rejection-nuclei in 
general, as gametonuclei that have failed to find cytoplasm. We 
must admit that the fusion of the gametes in Vorticellines, 
externally resembling a true sexual process, is only derived 
from the peculiar temporary conjugation of the free Ciliata. 
B. Merazoa. 
The gametogenic processes in the Metazoa are strangely 
uniform as compared with the wide range of organic differen- 
tiation they present; and it is easy to see that workers 
impressed by the latter fact should have laid undue stress on 
the former. In my introductory remarks I have pointed out 
that, as most of our biological thought has been largely 
moulded, nay, created by the Metazoan zoologists, a reverence 
for great teachers has impressed itself in provinces where they 
had neither the knowledge nor the training to guide theory 
aright. 
1. Spermatogeny.! 
The spermatozoa may be formed in one of the three follow- 
ing ways. 
(a) The most primitive mode, existing in some Sponges, 
Coelenterates, Vermes, and possibly other groups, is this: a 
germinal cell or spermatogonium undergoes segmentation to 
form a more or less coherent mass of cells, not inaptly termed 
a “ sperm-morula’’ by comparison with the morula of ajholo- 
blastic oosperm. Each brood-cell (‘‘ spermatocyte” of La 
Valette, St. George’s) develops usually into a uniflagellate 
spermatozoon. One of the simplest cases occurs in Ascaris 
megalocephala, an organism which, for researches on Meta- 
zoan gametogeny and karyogamy, has taken the place 
occupied by the classic Frog in the physiological laboratory : 
here, the spermatogonium by two divisions forms four sperma- 
tozoa; but the simplicity is probably derived, not primitive ; 
1 Here, as elsewhere in the paper, I have omitted the proper ontogeny of 
the spermatozoa, or the modifications by which it arises from the spermatocyte, 
its youngest stage, as foreign to the scope of the inquiry. 
