140 SECRETS OF ANIMAL LIFE 
frog, artificial parthenogenesis, followed by normal 
development, can be induced in egg-cells which 
invariably require fertilization in the ordinary 
course of nature. Professor Jacques Loeb’s chief 
method is to subject the ova, say of sea-urchin 
or starfish, first to the influence of some fatty acid, 
like butyric, which leads to oxidations in the cortex 
of the egg, the formation of a membrane of fertiliza- 
tion, and so on. The egg is activated, and if the 
process continues it ends in disintegration and death. 
But if at an appropriate time the activated egg 
is subjected to hypertonic sea-water, this acts as a 
corrective of the impending dissolution, and brings 
the egg back to a safe path of normal development. 
Professor Yves Delage’s chief method is to subject 
the ova of sea-urchin or the like to the combined 
action of tannin and ammonia, the former tending 
to coagulate, the latter tending to liquefy, the 
colloid substances which make up the egg. Most 
of the ova, when restored to sea-water, develop 
and form normal larve; in two or three cases the 
adult form has been reached. Bataillon’s chief 
method is to prick frogs’ eggs with a very fine 
stylet of glass or platinum, and then wash them 
with blood. The first event provokes activation; 
the second event allows the entrance of an organic 
center (a blood corpuscle, and not necessarily a 
frog’s!) which initiates a well-balanced ovum- 
segmentation. Two or three parthenogenetically 
developed frogs have been reared; they are normal, 
and of both sexes. 
