400 OTTO GLASER. 



remains true that the only boiled secretion that ever induced 

 parthenogenesis was one from which the Purple X had been 

 removed by coagulating white of hen's egg. This result, I may 

 add parenthetically was obtained only after a very remarkable 

 effect of the egg-white itself had been investigated. Even in 

 the dilutions in which it is present in the sea-water after boiling, 

 the white of a hen's egg produces very regular and curious dis- 

 tortions of the eggs which may even be divided into pseudo- 

 cleavage products. However the effect does not seem to be 

 analogous to parthenogenesis, and I shall therefore deal with it 

 separately at another time. 



In the course of these experiments a very much better and 

 simpler method was found, for the Purple X is a relatively un- 

 stable compound and readily disappears. Thus a concentrated 

 sperm-suspension boiled on one day and giving a color as deep 

 as port wine, may on the next be golden yellow. With such a 

 solution eggs were treated for one hour and five minutes. At 

 the end of that time the addition of living sperm resulted in the 

 fertilization of practically every egg. The experiment was 

 repeated, the eggs being exposed for two hours and forty minutes, 

 and again fertilization occurred. 



As a counterpart to these experiments with sperm, the parthe- 

 nogenetic effect of boiled secretion which had lost its purple 

 color was tried. Such solutions contrast sharply with the newly 

 boiled secretion, for whereas the latter very effectually blocks 

 auto-parthenogenesis, development can be induced without dif- 

 ficulty after the spontaneous disappearance of the Purple X. 



Since the Purple X-block occurs in the presence as well as in the 

 absence of sperm, we can be certain that it is not the result of an 

 effect upon the male sex cells or, in the language of the fertilizin 

 theory, of occupancy of the sperm receptors. Which particular 

 one of the remaining three blocks theoretically possible we are 

 dealing with however must for the present remain an open 

 question, although if the immediate effect of the egg-secretion is 

 really identical with the immediate effect of any other partheno- 

 genetic agent, occupancy of the egg-receptors is indicated. If 

 this is true, then Purple X should block parthenogenesis no 

 matter how induced. That this process should be blocked by 



