STUDIES OF FERTILIZATION 415 
b c 
Text fig. 1 Three photographs of eggs of Nereis in ink; a, before insemination; 
b, three minutes after insemination; c, twelve minutesafter insemination. aand 
b were taken with direct sunlight and short exposure (one second), ¢ Wiis 
light and longer exposure (ten seconds). See text for description. \ 
\ 
The formation of the jelly may be most readily observed if the 
eges are inseminated in sea-water, into which India-ink has been 
ground so as to make a black suspension. I here reproduce three 
photographs showing the formation of the jelly under such cir- 
cumstances (text fig. 1, a, b, c); ais an egg taken before insemina- 
tion; the germinal vesicle and the oil globules stand out very 
distinctly; the cortical layer may be seen on the left side of the 
figure, but it does not come out very distinctly because it 1s seen 
through a layer of ink between the cover slip, which touches the 
