XII 
THE EFFECT OF THE AGENCIES OF ARTIFICIAL PAR- 
THENOGENESIS UPON THE OXIDATIONS. THE CY- 
TOLOGICAL CHANGES IN THE PARTHENOGENETIC 
EGG 
I 
1. The experiments thus far considered have shown that it 
is possible to imitate the activating effect of the spermatozoon 
upon the egg of the sea-urchin approximately by submitting 
the egg to two different processes. The first process consists 
in calling forth the membrane formation in the egg by a 
fatty acid (or as we shail see later by a number of other 
chemicals). This process seems to be the essential feature in 
the activation of the egg, since it suffices to set in motion the 
whole apparatus of nuclear and cell division. The second 
process has only a corrective effect, since the membrane forma- 
tion alone leads to a rapid disintegration of the egg, unless the 
temperature is very low. The prevention of this disintegration 
is brought about by the second process. This second process 
consists in submitting the egg for a short period to a hypertonic 
solution containing oxygen (or for a longer period to sea-water 
free from oxygen). 
We will now consider the effects of these two processes upon 
the oxidations in the egg, and afterward gain an insight into 
the cytological changes produced in the egg by these agencies. 
We will first consider the effect of the membrane formation. 
The reader will remember that I had shown that the disinte- 
gration of the egg which follows the artificial membrane forma- 
tion at room temperature (if the egg is not treated also with a 
hypertonic solution or lack of oxygen) can be retarded for a 
long time if the egg is kept without oxygen. From this fact [ 
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