LN HLL LULLUTS UL DEA Determination 397 
“overripe.”” Only a small number of them segmented. The 
next table gives the results : — 
Normally laid eggs, Culture B go females 78 males 
Normally laid eggs, Culture C 21 females 89 males 
Normally laid eggs, Culture D 84 females 189 males 
Overripe egg, Culture E 13 females 317 males 
The excess of males is much greater in the overripe set. Hert- 
wig concludes from these data that the overripe condition favors 
male production, because the nucleus undergoes an increase 
in size during the period of overripening. The improbability 
of this assumption is manifest when we recall that when the eggs 
have reached the uterus, the nucleus has disappeared as such, 
and the second polar spindle has formed in the egg. In regard 
to the results from the eggs prematurely fertilized, Hertwig thinks 
that they can be accounted for by assuming that the cytoplasm 
has not fully developed at this time; but this assumption also 
seems improbable, since the eggs of the frog reach their full 
growth in the autumn of the year preceding their deposition. 
Hertwig’s attempt to bring these results —as well as others 
relating to the influence of temperature as a sex-determining 
factor in the frog’s egg — seems forced, and his general theory 
finds little support, I think, in the outcome of his experiments. 
The Extrusion of the Polar Bodies, and the Analogous Process 
in the Sperm-cells 
The fact that the egg throws off two polar bodies before it 
begins its development has led to much ingenious speculation 
in modern times. Amongst other views that have been suggested 
as to the meaning of this “‘maturation”’ process it has been urged 
that in one or both of the polar bodies the male or the female 
element is ejected. This view was first proposed by Minot in 
1877, and adopted later by Balfour, 1879, and by van Beneden, 
1883. More recently Castle has offered a more elaborate hy- 
pothesis that rests on the same foundation. 
The discovery that most eggs extrude two polar bodies was 
