No. j 
0. 419.] ONISCUS ASELLUS LINN. 
NN. 92I 
being now 
E. 8s compactly pressed together (cg. Their devel- 
progresses until, having become mature spermatozo 
a, 
they pass i 
y pass into the vas deferens ; the spermatogonia again fill 
the apical region and the cycle is repeated 
II. SPERMATOGENESIS. 
I. Maturation. 
E i 
E. 2 crate aros x m in the history of the chromatin 
gent ipie 2 e bis maturation division separates 
eae an deo therefore reducing. 
EE ae rate by following the changes in the 
synapsis stage through the first matura- 
“4 E In the anaphase of the last 
i E division the chromatin threads 
E ogether near the center of the cell 
other a almost indisti guishable from each 
boss ^ Lo sess spread apart and are 
E. r the most part V-shaped (Fig. 2a). 
Eu gg an elongation of the threads, 
bitrate g this preces the granules of which 
n D divide into two, so that 
"on osome becomes longitudinally split 
) Of the entire number of chromo- 
somes r EUM 
£e be . * 
present it is difficult to be certain, owing to 
number, however, is 
rmatogonia and not 
the number of 
therefore, at this stage 
o the approximation 
to form a bivalent one. 
codi each other so closely. The 
E uu than that present in the spe 
D. an sixteen. The reduction in 
icm au apparently takes place, 
ioo of | ape so prevalent is due t 
The Coins chromosomes t¢ 
Mo $ ecome more and more à 
COR sis are transformed into the nucl 
med gma The fact that the ¢ 
TRR tients just before the forma 
M on : toa maintenance of their in 
meshes of n preparing for the 
the nuclear network 
tion of the 
dividuality in the rest- 
first maturation 
become coarser, the 
Ae 
cA 
Fic. 2.— a, cell in the 
synapsis stage. å, bi- 
of the chromatin gran- 
ules; nel, nucleolus. 
the fact that 
the 
of 
ttenuated, and finally by 
ear reticulum 
hromosomes remain 
of the 
nuclear mem- 
division, the 
he granules 
