io6 Artificial Parthenogenesis 



layer probably of the nature of a superficial cytolysis. 

 The question remains: What could be the physico- 

 chemical nature of this cytolysis? The writer had 

 suggested in former papers that in the cytolysis under- 

 lying membrane formation lipoids were dissolved, and 

 he supposed that the substance to be dissolved might 

 be a calcium-lipoid compound which might form a 

 continuous layer under the surface of the egg. 1 v. 

 Knaffl, working on the cytolysis of eggs in the writer's 

 laboratory, gave the following idea of the process : 



Protoplasm is rich in lipoids; probably it is mainly an 

 emulsion of these and proteins. Any physical or chemical 

 stimulus which can liquefy the lipoids causes cytolysis of 

 the egg. The protein of the egg can really only swell or 

 be dissolved if the condition of aggregation of the lipoid 

 is altered by chemical or physical agencies. The mechan- 

 ism of cytolysis consists in the liquefaction of the lipoids 

 and thereupon the lipoid-free protein swells or is dissolved 

 by taking up water. . . . Hence this supports Loeb's view 

 that membrane formation is induced by the liquefaction 

 of lipoids. 2 



The writer suggested that the destruction of an 

 emulsion in the cortical layer might possibly be the 

 essential feature of the alteration leading to membrane 

 formation and development. It had been long ob- 

 served that unfertilized starfish eggs may begin to 



1 Loeb, J., Uber den chemischen Charakter des Befruchtungsvor gangs, 

 etc., Leipzig, 1908. 



2 v. Knaffl, E., Arch. f. d. ges. PhysioL, 1908, cxxiii., 279. 



