18 C. ISHIKAWA. 



show8 the Hinge \u wliich the nuclei are more clo.sely placed 

 (hail in the one represented in fig. 36, the right smaller one being 

 the eo'f-nuclens and the left laro-er one that of the siDermatozoon. 

 Close to the smaller nucleus is seen a small spherical area with a 

 minute central hody in the middle of it. This evidently corresponds 

 with the central Ixxly with the attractive sphere around it. In fig. 

 38 the nucleus of tlie egg in proportion to that (^f the spermatozoon is 

 relatively larger than tliose shown in figs. 36 and 37, and the four 

 cliromatic elements are more or less distinctly to he seen. The central 

 body seems now to have become divided into two bodies lying still 

 very close to each other. The section represented b}^ fig. 40 did not 

 pass exactly through the plane of the nuclei, but a little obliquely t<3 

 it, so that they are seen overlappirig. One of the central bodies, the 

 lower one in the figure, lies below the spermatic nucleus and is seen 

 throuo'h it. The central bodies are now quite separated from each other. 

 Fio's. 41-45 are made from eggs killed with Flcmmincjs 

 solution of aceto-osmo-chromic acid, the chrcjmatic elements of the 

 copulating nuclei are very faintly stained by haematoxylin, but 

 the contour of tlie nuclei, as well as the attractive spheres are 

 Aery distinctlv to be seen. These are placed in all these eggs, in 

 contradistinction to tlie eggs shown in figs. 37-40, nearer to those 

 nuclei which, from their relati\e position to the second pijlar body, 

 appear to be those of the spermatozoon. In Wg. 41, besides the second 

 polar body, lying in the body of the egg, there is the first })olar l)ody 

 which happened Ijy chance to be carried with the egg into the breeding- 

 sac and came to lie outside the egg-mend )rane, just near the place where 

 the second polar ])odv lies. The nundjer of chromatic elements within 

 the first ])olar body is still distinctly to l)e counted as eight. Figs. 

 42-44 show three successive stages in the nuclear copulation ; and in 

 fiii'. 45 we see two nuclei closely in contact with one another, while the 



