of Edinburgh, Session 1885 - 86 . 
811 
which the spermatocytes are associated. The spermatocytes divide 
indirectly to form spermatides or undifferentiated spermatozoa. 
After this notice of some of the more important accounts of 
invertebrate spermatogenesis, it is necessary to return to the much 
more complicated and debated spermatogenesis of vertebrates. 
Eenson (1882) described small round granular cells at the periphery 
of the canal adjacent to the tunica propria, which he regarded as 
the germinative cells of Sertoli and Krause, the granular cells of 
Yon Ebner’s Keimnetz, and the follicular cells of La Yalette. 
These segment into multinuclear cysts — the “ spermatoblasts ” of 
Krause, or the spermatogemmse of La Yalette, — and from the 
resulting cells the young sperms or nematoblasts result. The im- 
mature nematoblasts, however, group themselves round the ex- 
tremity of certain large projecting epithelial cells (cellules de 
soutien), — obviously the spermatoblasts of Yon Ebner, — and actually 
sink into their protoplasm to complete their development. When 
fully developed, the heads of the young spermatozoa have attained 
the base of the supporting cell, but this now elongates and bears 
them anew in the lumen of the duct into which they are expelled. 
The researches of Herrmann (1882) on the spermatogenesis 
of Elasmobranchs are essentially confirmatory of those of Semper. 
The “ male ovules ” within the “ male tubes of Pfliiger,” multiply 
by the transformation of small flattened cells round about them, 
and within each ovule 50 to 60 “ spermatoblasts ” are produced by 
endogenous formation, preceded, however, by a segmentation. 
According to Sabatier, spermatogenesis always occurs in two 
generations of cells. Erom the nuclear division and germination 
of mother-cells or spermatospores, claviform stalked cells (proto- 
spermoblasts) arise. These are detached, increase in size, divide, 
and produce on their surface deutospermoblasts, or the spermato- 
cytes of Yon la Yalette. The protospermoblasts thus form the 
biastophore of the deutospermoblasts, from which the spermatozoa 
directly originate. In Plagiostome fishes Sabatier describes how 
the epithelial cells form culs-de-sae, in which some of the cells 
increase in size, and form spermatospores or male ovules. In the 
peripheral protoplasm of these spermatospores, endogenously formed 
nuclei appear — the protospermoblasts. The nucleus of each of these 
divides to form numerous deutospermoblasts, which are for the 
