MATURATION IN EGGS OF LIMPETS BY CHEMICAL MEANS. 347 



ture for one hour. Practically all become mature and the larvae 

 resulting are excellent. 



If, however, the eggs are under-exposed or over-exposed to 

 the solutions they either break up or segment irregularly and it 

 is not very long before these latter eggs too, break up, and dis- 

 integrate. The number of disintegrating eggs is smaller when 

 the eggs are treated for one hour with the mixture of 50 c.c. sea 

 water and 1.5 c.c. njio NaHO than with any of the other solu- 

 tions used. When sperm was added to the eggs which had not 

 been treated with alkaline sea water, not a single egg became 

 mature or developed into a swimming larva. 



Next I tried the effects of lack of oxygen on maturation. The 

 alkaline sea water (50 c.c. sea water -f 1.5 c.c. n/io NaHO) was 

 placed in a bottle and connected with the hydrogen generator, 

 and a stream of hydrogen was passed through the solution for 

 two hours. The eggs were then quickly introduced and left for 

 one hour in the solution, with a good stream of hydrogen still 

 passing through. The eggs were then transferred to normal sea 

 water and sperm added. The following table shows the result : 



Table II. 



Solution. Treatment for i hr. 



So c.c. sea water -f- 1.5 c.c. All mature and swimming. 



n/10 NaHO with oxygen. Few eggs disintegrating. 



50 c.c. sea water-]- 1,5 cc. About half a dozen mature eggs. 



n/ 10 NaHO without oxygen. Two larvae. 



No disintegration. 



This shows that, as in the case with Lottia, the alkali can only 

 cause the maturation of the eggs of Acmcea if oxygen be present. 

 If the eggs that had been kept from becoming mature by lack 

 of oxygen were subsequently treated with akaline sea water in 

 the presence of oxygen, practically all became mature, and would, 

 upon the addition of sperm, develop into larvae. 



By stopping the oxidative processes in the eggs through the 

 presence of potassium cyanide, maturation can also be inhibited. 

 Thus, if to alkaline sea water a little potassium cyanide be added 

 no maturation occurs. 



