16 C. ISHIKAWA. 



a small notch at the surf'ice of the latter shows clearly the point where 

 it entered. Both the ])oIar spindle and the spermatic nucleus lie in a 

 common protoplasmic mass. Fig.i. 32 and 33 are drawn from eggs 

 in the same breeding sac as that from which fig. 31 is drawn. In 

 l)oth eggs the polar spindle is nearly in the same stage as in the egg 

 represented by fig. 31, the only difference being that in fig. 33 it lies more 

 in the centre of the egg, and that the chromosomes are more elongated 

 than in the (jther. The position of the spermatic nucleus is, however, 

 in botli cases difierent. In fig. 32 it lies in the same pole of the egg 

 as that in which tlie ])<>lar spindle is found, while in fig. 33 i^ has 

 penetrated an opposite pole of the egg. although the path of its penetra- 

 tion is not to be seen in the figure. 



The two nuclei resulting from the di^ ision of the second polar 

 spindle, the nucleus of the second polar body, and the egg-nucleus, show 

 o-reat différences in appearance. That of the second polar body re- 

 mains small and its four chromosomes coalesce into a single mass, stain 

 xevy deeply bv picrocarmine, haematoxylin, etc., while the nucleus 

 of rlie egg soon l)ecomes greatly enlarged, and its chromosomes show 

 distinctlv as four thread-like. A'^-shaped ])odies (figs. 34 and 35). 

 At first their number is (piite distinct, but so(3n the chromosomes 

 elongate, become twisted and send out many ])rocesses which an- 

 astomose witli one another, and their innnber becomes indistinct (fig;?. 

 36-40). In figs. 34 and 35 the four chromosomes are still cpiite dis- 

 tinctly to be seen. In figs. 36, 37, and 40 they have begun already 

 to send out processes, and in figs. 38 and 39 they appear as if broken 

 up into a great number of elements. (The nucleus on the left of 

 the fig-ure is in both cases the ea-g- nucleus). 



The changes which the spermatic nucleus goes througli after it 

 has entered into the l)ody of an egg and before its copulation with 

 the e""'-nucleus, are ahnost the same as those of tlio latter, except 



