488 ALVALYN E. WOODWARD 



then, should result in increased metabolism. With this assump- 

 tion in mind, let us examine the methods of artificial partheno- 

 genesis. 



Lipoid solvents, such as butyric acid, chloroform, chloral 

 hydrate, and ether, can remove the fatty inhibitor by dissolving 

 it, and thus allow the enzymes to act more rapidly. Bases sapon- 

 ify fat. The third large class of chemicals used for this purpose 

 includes the halogen salts. These are usually used in hyper- 

 tonic solutions, but still sufhciently dilute so that there is con- 

 siderable dissociation. The basic radical, as before, can saponify 

 the fat. But the halogen radical is the more important, for that 

 can saturate the acid, which no longer inhibits enzyme action 

 after saturation (Jobling and Petersen). The compounds of 

 bromine and iodine are more effective than the chlorides as par- 

 thenogenetic agents, just as they more easily saturate fatty acids. 

 Such a solution must be hypertonic to allow the salt to penetrate 

 a membrane tuned to normal sea-water. Finally it must not be 

 forgotten that lipolysin is both a fat solvent and a parthenoge- 

 netic agent. 



That these parthenogenetic agents act by removing an in- 

 hibitor is indicated by experiments of R. S. Lillie ('12), who found 

 that 'resistant' Asterias eggs at the close of the season would 

 give a much greater percentage of cleavages if treated with a very 

 dilute solution of lipoid solvent or halogen compound before 

 fertilization with sperm. 



Early in June, 1915, I found few Asterias eggs mature, and 

 those in which the germinal vesicle had broken down failed to 

 attract sperm in any visible numbers. Some of these eggs were 

 treated with solutions of lipoid solvents and other compounds 

 (tables 14 and 15). In the treated eggs, mature ova and cleav- 

 ages were subsequently found in much larger percentages than in 

 the controls. The treatment not only enabled the sperm to 

 fertilize more mature eggs, but enabled more eggs to form polar 

 bodies. 



Sperm to which had been added resistant Asterias eggs were 

 neither more nor less active than before and did not collect around 

 the eggs. They became very active, however, if the eggs had 



