23 
than those which characterized the spermatogonial generations. On the 
equatorial plate they are again closely massed together (fig. 1, e and f). 
In side view the equatorial plates of the first meiotic division are dis- 
tinguishable from those of the spermatogonial by their smaller dia- 
meter. The equatorial plates of those dividing nuclei nearest the central: 
cayity, presumably those of the second meiotic division, are again smal- 
ler (fig. 1, g). 
The newly formed spermatids are round (fig. 1, k), and the chro- 
matin is mostly peripheral. Gradually they lengthen; the deeply staining 
(07 
d 
aa’, Prophases of spermatogonial cells showing 8 and 10 chromosomes respectively; 
b, Side view of spindle of spermatogonial cell; e, An equatorial plate from cell in 
intestine; d, Prophase of first meiotic division, showing 4 chromosomes; e, Side view 
of spindle of first meiotic division; f, Equatorial plate of first meiotic division; g, Side 
view of equatorial plate of second meiotic division; h, Newly formed spermatids; 
î, Young spermatozoan. Magnification about 3500. 
chromatin of the newly formed spermatozoa being very conspicuous 
(fig. 1, 2.) The spermatozoa finally contract somewhat and lose their 
intense staining capacity. 
Spermatogenesis in male D. pulex is, thus, perfectly typical. The 
spermatogonial cells contain the diploid number of chromosomes; reduc- 
tion ensues; two meiotic divisions follow, the first and second sperma- 
tocyte cells containing the haploid number. The eggs which develop 
into male daphnia must contain the diploid number of chromosomes, in 
which respect they resemble those summer eggs which have developed 
parthenogenetically into female daphnia. 
