XXV 
ARTIFICIAL PARTHENOGENESIS IN THE EGGS OF THE 
STARFISH 
1. The experiments on artificial parthenogenesis in starfish 
differ in an essential point from those in the sea-urchin. The 
sea-urchin egg undergoes maturation and remains at a state 
of rest while in the ovary. The causation of development 
means, therefore, a transition from the resting state to an active 
state, and this is accompanied by a rapid increase in the rate 
of oxidations. 
The conditions in the starfish egg are different. When these 
eggs are taken out of the ovary they are as a rule immature. 
As soon as they are laid, a number of eggs, which varies with 
the individual starfish, begin to mature. Not until one or both 
polar bodies are thrown out can a spermatozoon enter. As 
soon as this critical stage is reached the egg can be fertilized by 
sperm. If it is not fertilized by sperm at that time it perishes 
in afew hours. There is then this difference between the state 
of the sea-urchin egg and that of the starfish egg at the time 
of fertilization: The starfish egg is in a state of activity since 
the maturation divisions are just completed, while the sea- 
urchin egg is at rest. This finds its expression in the fact that 
Wasteneys and I found that the entrance of a spermatozoon 
into the starfish egg does not increase the rate of oxidations.! 
It harmonizes with this result that the writer found that the 
process of maturation of the starfish egg requires conditions 
similar to those for the development of the sea-urchin egg: If 
oxygen is removed from the sea-water or KCN is added the eggs 
remain immature. Moreover, in an alkaline solution the eggs 
ripen more rapidly than in a neutral or acid solution. 
1 Loeb and Wasteneys, Archiv f. Entwicklungsmechanik, XXXV, 555, 1912. 
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