

On the Behaviour of the Nuclei during the Conjugation of Zygnema. 
PE SE LET ae 

8 stage (ig. 5), the “thread” becomes broader, its width being almost equal to that of the body of the 
* nucleus; in this stage, the two nucleoli do not yet come into fusion. ‘Then the “thread,” which may now 
rather be called a “band,” becomes shorter and the two nucleoli approach each other (Jig. 6). When this 
stage is over, two chromatophores pass from each cell into the common canal, which widens and becomes blad- 
= dery ; now, the real fusion of the two nuclei takes place, for both nucleoli become fused into one, and the 
1] | resulting nucleus takes the normal shape (7%9. 7.) For the formation of zygote, it remains then nothing 
dm but to form a thick coat around the whole apparatus of these chromatophores and nuclei. 
6 In short, during the conjugation of this species of Zygnema, after the fusion of the two processes of 
に cells, one of the nuclei produces a thin slender process which advances inwards and meets with that produced 
Mj}! similarly from another and thus the so-called “thread” is formed. The latter then becomes wider, the two 
“ nucleoli approach each other and fuse together, and the nucleus takes the normal shape. This is the whole 
= process relating to the fusion of the two nuclei. 
ン bs It may here be remarked that chromatophores (pyrenoids as well as starch-granules) seem to grow in 
se 
those cells concerned in conjugation. Tor this 1 refer the readers to the /%g. 4a in which cells concerned 
and those not concerned are found both in one and the same filament. 
In conclusion, I have to add that I could follow also almost all successive stages of the behaviour of 
nuclei during the conjugation of a species of Zygnema belonging to the first class above mentioned. I ap- 

