No. 581] ENTRANCE OF THE SPERMATOZOON 



285 



off during the process of membrane formation. The 

 writer has pointed out in former papers that the cortical 

 layer of the egg which undergoes liquefaction in the 

 process of membrane formation behaves towards reagents 

 very much like the jelly which surrounds the egg. 32 But 

 since in the egg of purpuratus the loss of this auulut inn- 

 ting power on the part of the egg is not necessarily accom- 

 panied by the loss of the power of being fertilized— e. g., 

 in the HC1 experiment— we are inclined to believe that 

 there must be another reason that an egg fertilized by 

 sperm can not be fertilized a second time. 



As far as the statement is concerned that the egg can 

 no longer be fertilized after artificial membrane forma- 

 tion by butyric acid the writer can not admit the correct- 

 ness of this statement (see Chapter III). In the eggs in 

 which artificial membrane formation has been called forth 

 by butyric acid the main if not the only block to a subse- 

 quent fertilization is the membrane itself. 



This can be proved by a very simple experiment. If 

 we call forth the membrane formation in the egg of 

 purpuratus in a neutral or faintly alkaline solution of m/2 

 (NaCl + KC1 + CaClo) (instead of in sea water) a very 

 thin membrane is formed, which is easily torn and offers 

 no resistance to the spermatozoon. All the eggs treated 

 in this way can be fertilized by sperm. The agglutinin 

 reaction of such eggs is, however, permanently lost. 



The facts thus far known seem to force us to the conclu- 

 sion that no adequate proof has been offered thus far for 

 the connection between the power of an egg of being fertil- 

 ized by sperm and its power of causing a cluster formation 

 of the sperm. The writer has pointed out in a previous 

 paper that it is difficult to see why there should exist 

 such a relation, since sperm agglutination can only in- 

 hibit the entrance of the spermatozoon into the egg. 



""Artificial Parthenogenesis and Fertilization," Chicago, 1913, pp. 

 210-14. University of California publication, Physiology, Vol. 3, p. 1, 1905. 



