CLEAVAGE PLANE AND ENTRANCE POINT OF SPERM. 245 



The dishes (nos. I to 5) and the slide (no. 6) were examined as 

 the first cleavage furrow appeared. In 95 per cent, of the eggs 

 the first cleavage plane passed through the point of sperm 

 entrance (Fig. 9). Dish no. 7 showed, on the other hand, that in 

 only 50 per cent, of the eggs the first cle.ixa-e furrow passed 

 through the point of sperm entrance. 



FIG. g. First cl<\i\ 



At 2:45 p.m. of the same day, eggs \\rtv in>eininate<l in watch 

 no. 8. Examination revealed that tin- fir>t Hea\a".e plane 



through the point of entrance in No prr cent. ot ej 

 I jgs transferred from india ink ami sea-water to dean fiv-h 

 MM-u.iit-r twenty to thirty minute^ alter insemination >li<>\\r<l 

 per i nt. of first cleavages through the point of entrance. 

 A Mimmarv of the results of Kxperimein - I to s i-, as iollo\\>: 



i > iiiM-iiiin.itr<l in watch ;. i \v.i-ln-'l. -hn\vi-il t'u-t cleavage tlin>ui;li 



i-nti.uii e p< MII! . -i 5 PIT cent. 



6 iiiM-iiiin.iU'd on slide glass, not wa-li>-l. -li-iwf-l tit-t thnni^h -n- 



ti.iiu i- point . <>5 per cent. 



\ - iii-.-niiii.ucd in watch glass. wasln-<l, ln>\vi-il tir-t cli M\ a.i;<- thn'iii;h <-ntrance 

 p. -int. >n p-r cent. 



ii.it.i-il in \\.itrh .ula--. nut \va?>lK-i|. slmwi-il tir-t cleavage thruuKh en- 

 ti.in. < p..int, 80 per cent. 



No i) in-cniinated in wat. h glass, ti.ui-i. rn-<l to slide, slmwc-'l tir-t rlrava.ui- through 

 rntr.mre point, 60 p-r o-nt. 



That tin' ink i> not to\ic to the eggs and, ilietefore, does not 

 inhiliit cleavage I was able to prove by inseminating at the same 

 time t\\o di-lir- of eggs, one with ink and one without; develop- 



