XVI 
ANALYSIS OF THE ORIGINAL METHOD OF PRODUCING 
ARTIFICIAL PARTHENOGENESIS BY HYPERTONIC 
SOLUTIONS ALONE 
1. We are now able to undertake the analysis of the purely 
osmotic method of artificial parthenogenesis by which the 
writer first obtained parthenogenetic larvae of the sea-urchin 
(see chapter vii). The reader will notice that this method ap- 
parently contradicts the statement that artificial partheno- 
genesis is due to the influences of two agencies, one of which 
causes the membrane formation, the second the correcting 
effect, which protects the egg against the disintegration in- 
duced by the artificial membrane formation. The apparent 
contradiction is abolished by the realization of the fact that 
in this method the hypertonic solution acts simultaneously in 
two capacities: first, as a cytolytic agency causing a change 
in the cortical layer (the formation of a gelatinous film), and 
second, as a corrective agency. This latter effect is sufficiently 
intelligible from what has been said before. The cytolytic 
effect of a hypertonic solution, however, needs to be demon- 
strated, and, moreover, proof must be furnished that the two 
agencies active in artificial parthenogenesis may act simultane- 
ously instead of in succession. 
It must first be stated that this method also leads to a kind 
of stunted membrane formation; only such eggs can be caused 
to develop by this method which form a membrane. 
But the hypertonic solution is not a reliable agency for the 
causation of membrane formation, and this is the reason that 
this original, purely osmotic method of artificial parthenogenesis 
gives such poor results with the eggs of S. purpuratus and 
not very good results with the eggs of Arbacia. The direct 
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