806 Proceedings of the Boyal Society 
incipient tubule. All primitive ampullae exhibit (a) large, granular 
cells with round nuclei, and (b) smaller cells with more oval nuclei, 
in regard to which the possibility is suggested that the narrowed 
nuclei form the round. At a later stage two distinct layers are 
observed ; the narrow nucleated cells form for a while an outer 
epithelium, but afterwards disappear ; this is succeeded by a stage 
where the lumen is apparently lined by large conical cells with two 
nuclei, of which the inner are long and granular, while the outer are 
round and homogeneous. The inner oval nuclei bud off externally 
a large number of round spermatoblast nuclei, first regularly and 
then irregularly grouped. These are enclosed within the conical 
mother-cell, and are separated from the ampulla wall by the large 
oval nucleus of the “ Deckzelle,” in regard to whose origin, from a 
modification of an outer layer of spermatoblast nuclei, or from the 
outer narrow-nucleated cells of the primitive ampulla, Semper 
remained undecided. The sixty or so spermatoblast nuclei, elongate 
to form the heads of the spermatozoa, which lie originally near the 
“cover-cell”; the -whole mass forms a bundle filling the greater part of 
the mother-cell, from which they are expelled by the swelling up of 
the “cover-cell.” 
The important series of researches by Yon la Valette St George 
was meanwhile leading up to a quite different view of spermato- 
genesis. In his fifth communication, in 1875, he distinguishes 
within the seminal tubule, two kinds of cells — (a) epithelial cells, 
homologous with primitive ovules, and dividing to form spermato- 
gonia which lie close to the tunica propria ; and ( b ) small round 
cells lying between the spermatogonia, and having no other function 
than that of enveloping the spermatogonia and their successors. 
Each spermatogonium forms by division a multinuclear cyst or 
spermatogemma , consisting of a mass of daughter-cells or spermato- 
cytes. These spermatocytes may either (a) all develop into 
spermatozoa (Mammals), or (b) a single spermatocyte may become 
modified as a basilar cell (Plagiostome Eishes), or (c) a number may 
form an envelope round the others (Amphibians and Eishes). In 
comparing these divergent results with those of Merkel and Sertoli 
on the one hand, and those of Yon Ebner on the other, he regards 
his primitive spermatogonia, lying round the tunica propria , as 
equivalent to Yon Ebner’s “Keimnetz” and the base of Merkel’s 
