592 
J. BRONTE GATENBY. 
The Genesis of the Sperm. 
In the Roman figures to the right I have indicated the sort 
of male cell generation in which no spermatogonia! divisions 
take place. (See also Text-fig. 5.) 
I. Earlier stage than drawn in any other figures. 
II. Progerminative cell (PI. 31, fig. 19). 
III. Mitochondria appearing in spermatogonium. Rare 
kind of Nebenkern (PI. 31, fig. 20). 
IV. Spermatocyte, with Nebenkern just appearing (PI. 32, 
fig. 23). Usual Nebenkern. 
V. End of growth stage. Cytoplasm differs greatly in 
size in different examples (PI. 32, fig. 25- TV.). 
VI. Maturation division. Spindle curiously orientated 
with relation to cell, first maturation. (Second 
maturation drawn in PI. 32. fig. 22- TV.). 
VII. Spermatid (PI. 32, fig. 26). 
VIII. Later spermatid (PI. 32, fig. 24 a- TV.). 
It will be noted that on the left bottom region at the 
Arabic numbers 1 and 2, there is another source of male cells. 
The two sources of cells, marked in Arabic and in Roman 
numerals respectively, are often mixed indiscriminately and 
later stages are hard to distinguish. Thus the bouquet stages 
marked 3 a are certainly derived from such a source as 1, 2, 
on the left, because in the generation derived directly as 
shown at the Roman numerals the contraction figure and 
other stages up to the beginning of growth take place directly 
on the wall (see PI. 32, fig. 21, which was stuck on the wall, 
and Text-fig. 3, i). 
In the case of the cells marked V 4 it was not possible to 
tell whether they were derived as in the Roman numerals or 
as in the Arabic. Thus the Roman numerals beyond VI are 
probably of uncertain derivation. VI itself, on account of its 
great size, is probably of the Roman numeral generation. 
Almost invariably the two generations, derived respectively 
from the bottom left corner at 1 and 2, and from the bottom 
right at the Roman numerals have a Nebenkern formed of 
