SPERMATOGENESIS IN MYXINE GLUTINOSA. 181 
plication of the germ-cell gives rise to the spermatoblasts. It 
may be that each capsule originally contains but a single germ- 
cell, but I am not sure of this. Possibly two or more may 
sometimes be enclosed in a single developing capsule. The 
remaining stroma-cells are differentiated into the fibrous con- 
nective tissue which forms the walls of the capsules and the 
intermediate tissue of the testis. 
Thus Nansen’s conjecture, that originally each capsule 
contains a single large cell or spermatogonium, is to some 
extent verified by the condition seen in the germinal proli- 
ferating tissue, where the separate germ-cells may be seen 
surrounded by stroma-cells. I have never seen a capsule with 
fibrous walls containing only a single spermatogonium; by 
the time the walls of the capsule are definitely formed the 
original germ-cell has increased to several. 
The existence of the germinal proliferating tissue is by no 
means confined to the earliest stage of development of the testis. 
I have found it in portions of the surface of the testis at all 
stages, even in ripe testes, although in the older organ it is in 
small quantity, and occurs only at scattered points. The rest 
of the testis is not bounded by a definite flat epithelium, but 
simply by irrregularly arranged small cells. 
Theoretical Considerations. 
So far as I have been able to discover, the spermatogenesis of 
Myxine is in many respects unique, not resembling closely 
that observed in any other form, either vertebrate or inverte- 
brate. I am not, however, in a position on the present occa- 
sion to discuss the facts I have described above in the light of 
all the various theories of spermatogenesis that have been 
recently brought forward, or to attempt to compare the sper- 
matogenesis of Myxine with the complicated history of the 
spermatozoa in other Vertebrates, such as Elasmobranchs, 
Birds, and Mammals. Such a discussion demands a more 
extensive and more detailed acquaintance with both the litera- 
ture and the phenomena than I yet possess. I will therefore 
confine myself to the fundamental features of the process. 
