STUDIES IN ARTIFICIAL PARTHENOGENESIS. 2OI 



those balancing them, and the membrane is as a result pushed 

 away from the egg. 



5. Cytolysis is not due to a simple swelling of egg proteins 

 for these can be shown to coagulate rather than to swell, it is 

 due to a continuation of the same process as that which results 

 first in membrane elevation. 



6. The sperm produces membrane elevation by lowering the 

 surface tension of the vitelline membrane. This it accomplishes 

 by causing the membrane to swell at the point where it strikes 

 the egg. 



7. Experimental evidence is presented to show that this 

 membrane swelling produced by the sperm is due to the action 

 of an acid. 



8. The fact that potassium cyanide does not prevent initiation 

 of development by hypertonic sea-water, is taken as evidence 

 against the oxidation theory of artificial parthenogenesis. 



9. All initiation of development involves the gelatinization 

 or coagulation of some substance within the egg. This coagu- 

 lative change can be demonstrated to take place before the egg 

 interior shows any other signs of the approach of development. 



The above summary covers only the more important points 

 of the paper. 



I desire to thank Professor F. R. Lillie, and also Professors 

 Child and Tower, for their kind criticism of the manuscript. 

 To Professor Lillie I am also indebted for the use of a table at 

 the Woods Hole Marine Biological Laboratory, where all of the 

 experimental work was done. 



V. REFERENCES. 



Albrecht, E. 



'98 Untersuchungen zur Struktur des Seeigeleies. Sitzungsber. d. Ges. f. 



Morph. u. Physiol. in Miinchen, 1898, pp. 133-141. 

 Czapek. 



'n Ueber cine Methode zur direkten Bestimmung der Oberflachenspannung 



der Plasmahaut von Pflanzenzellen, Jena, 1911, G. Fischer. 

 Delage, Y. 



'07 L'oxygene, la pression osmotique, Jes acides et les alcalis dans la partheno- 



genese experimentale. C. R. Acad. Sci. Paris, T. 145, pp. 218-224. 

 Delage, Y. and Goldschmidt, M. 



'13 La parthenogenese naturelle et experimentale, Paris, 1913. 



