438 
George Arnold 
It must not be forgotten tbat the cell from the time it leaves the 
resting stage up to tliis, is steadily growing, and tbe nucleo-plasmic 
ratio increases even more rapidly. Whetber tbe view advanced by 
Hertwig and Popoff tbat tbe tvvo synapses represent suppressed 
attempts at nuclear division is correct or not, there can be no doubt 
tbat in tbe svnaptic stage, tbe nucleus bas enormously increased in 
volume, quite out of proportion to tbe increase whicb bas taken place 
in tbe cytoplasm. Tbe nucleus is in a condition of tension Avitb regard 
to tbe cytoplasm, but its contents are in a state of stress, and tliis 
is quite sufficient to bring about a marked condensation of all tbe 
beavier particles (chromatin) embedded in tbe lighter nuclear sap. It 
is not suggested tbat auy importance is to be ascribed to tbe synapsis 
qua synapsis, but I bave endeavoured to show tbat the synapsis is 
a normal condition of tbe cell at a certain period of its history, and 
not au artifact. 
In Planaria lactea, as in Planaria gonocephala, tbe number of 
somatic cbromosomes is 16. And just before tbe svnaptic clirnax, as 
in Fig. 7, it is possible to trace eacb Segment, and ascertain tbe 
number of Segments, which is 8. 
It Yvould be difficult to find cells sbowing tbe longitudinal 
split more clearly tban tbe oocytes and spermatocytes of Planaria 
lactea. 
Even before tbe synapsis bas reached its culminating point 
(Fig. 5) it is noticeable in tbe arc of one or two Segments. Eacb 
segment bas tbe appearance of a simple band of linin, with tbe chro- 
matic granules arrauged on eacb side (Fig. 8 a and b). Tbe diver- 
gence of tbe split halves of eacb segment is greatest at tbe period 
of greatest condensation (Fig. 8), and is continued for some time 
after. I bave not seen any synapses comparable to tliose figured by 
Mattiesex for PL torva. His figures 8 and 9 seem to indicate a 
real contraction, brought about by too sudden dehydration. Tbe split 
closes up sooner in tbe oocytes tban in the spermatocytes, for in tbe 
latter traces of the split may be seen in tbe late prophase fdiaki- 
nesis, Häcker) see Fig. 33. 
At tbe commencement of tbe synapsis (Fig. 7), yolk globules 
begiu to appear in tbe cytoplasm. At tbe same time, while tbe 
nucleolus in tbe nucleus becomes increasingly fainter, but no smaller, 
tbe cliromatic granules in tbe cytoplasm (Figs. 7, 9 and 11), become 
larger, and are stained yet more deeply tban before by tbe basic 
stains. 
