MATURATION IN EGGS OF LIMPETS . BY CHEMICAL MEANS. 345 



oxygen or by the addition of either acid or potassium cyanide to 

 the sea water the eggs remain alive a considerable period of time. 

 The eggs in which maturation has already begun, or has just 

 been completed, are also saved from rapid death by these means. 1 



Later, he found that the eggs of a mollusc {Lottia gigantea) 

 when removed from the ovary were always immature and would 

 remain so even if they were kept in water for two days. Such eggs 

 could not be fertilized by sperm. But if they were first treated 

 with a mixture of 50 c.c. sea water and I c.c. 1/10 n NaHO for 

 from four to five hours maturation took place with the result that 

 over 75 per cent, of the eggs would develop into larvae in normal 

 sea water after the addition of sperm. He found also that treat- 

 ment with sea water containing benzol would cause the eggs to 

 become mature very rapiply. 2 



As in the case of the starfish egg the maturation processes in 

 the eggs of Lottia, induced by alkali or benzol can be prevented 

 by lack of oxygen, or by either the addition of acid or potassium 

 cyanide to the sea water. 



The fact that the immature eggs of the starfish and especially 

 those of Lottia could be caused to become mature in this way, 

 suggested experimentation upon the other limpets found at Paci- 

 fic Grove. Four varieties of Acmcea were used by the writer. 

 AcmcEa patina, pelta, persona and scabra. The eggs of the 

 Acmcea studied are all immature when removed from the ovaries. 

 They look very much like those of Lottia (Fig. 1) and are char- 

 acterized by a greenish color, a very irregular outline, and a 

 transparent membrane — a chorion which conforms to the shape 

 of the egg. In maturing the chorion disappears and the egg 

 becomes perfectly spherical in shape and rather more opaque, 

 Fig. 2. Only when this maturation process is completed is it 

 possible to fertilize the egg by the addition of sperm. The eggs 

 of Acmcea remain immature in sea water for two or three days and 

 only occasionally does one find any mature eggs in the culture 

 that has stood for ,-. > ength of time. 



To determine, whether by increasing the alkalinity of the sea 



1 These experiments have recently been repeated and confirmed by A .P. Matthews, 

 Am. Jotirnal of Physiology, 1 907. 



2 Univ. of Cat. Publications, Nov. 17, 1905, Vol. 3, No. I, pp. 1-8. 



