ESSENTIAL FEATURES OF SEXUAL PROCESS 1355 



eggs various modes of treatment will lead to the appearance of attrac- 

 tion spheres in the cytoplasm, and even to division of the non-fertilised 

 egg. Loeb has suggested that the action of the spermatozoon is essen- 

 tially chemical in character. By alteration of the medium in which 

 the eggs are contained, Loeb has succeeded in imitating exactly the 

 changes which normally need the entrance of a spermatozoon for their 

 occurrence. On immersing the eggs in a weak solution of formic or 

 lactic acid, a membrane is formed. The eggs are then taken from the 

 acid, placed in concentrated sea-water for a short time, and then 

 removed to ordinary sea-water. Division rapidly occurs with the 

 production of a normal larva. He suggests that the spermatozoon 

 brings with it ferments, or other chemical substances, which excite the 

 egg-nucleus and cytoplasm in the same way as the chemical measures 

 adopted for this artificial induction of segmentation. 



