STUDIES OF FERTILIZATION 431 
spheres not stained by the osmic acid or haematoxylin, inter- 
spersed with basophile granules larger than those of zone 2. The 
penetration and rotation phenomena appear in the hyaline zone 
even more clearly than in the normal egg, hence most of the figures 
illustrating these phenomena are taken from the hyaline zone. 
2. The effects on the spermatozoa 
a. Before the beginning of penetration. The effects of the re- 
moval of the jelly on the spermatozo6n have been studied especi- 
ally on stages shortly before penetration begins, both because these 
are the stages most affected as shown by the effects on cleavage 
Text fig. 3 The zones of the centrifuged egg of Nereis 
(stages 16.3 and 16.4, in the preceding table) and also because 
spermatozoa injured at this time would presumably have a better 
chance to enter, being so near to the actual time of penetration. 
Figs. 18 to 23 show successive degrees of injury to spermatozoa 
from a single experiment (6.5 of 1911). The eggs were preserved 
immediately after centrifuging 7200 revolutions at a radius of 6 
em. in thirty-five seconds, fifty minutes after insemination, on 
June 19, 1911, when the temperature of the water was still quite 
low and the processes correspondingly slow. In fig. 18 the entire 
