AUTO-PARTHENOGENESIS IN ARBACIA AND ASTERIAS. 399 



it follows, not that the fertilizin theory is inapplicable to these 

 cases, but only that it does not apply exactly as F. R. Lillie has 

 supposed. 



2. The Block by Means of Groups Split from the Sperm and the 

 Egg- Secretion. The prevention of both fertilization and auto- 

 parthenogenesis in eggs previously treated with boiled sperm 

 infusion, as well as the parthenogenetic block in eggs subjected 

 to the action of boiled secretion, seem at first sight to have little 

 in common. In reality however there is an element of identity 

 in all three cases, for suspensions of sperm as well as the egg- 

 secretion give on boiling a characteristic color reaction due to 

 the formation of a purple substance which may be looked upon 

 as a chemical cleavage product split off from a mother substance. 

 In an earlier paper ('i4 2 ) I suggested on other grounds, and in 

 complete ignorance of its role in parthenogenesis, that this 

 purple material might prove to be significant, as it seems to be 

 specific for Arbacia. This suggestion now appears almost cer- 

 tainly correct, and I therefore propose for this substance, pro- 

 visionally at least, the name "Purple X." 



An attempt to understand the part played by Purple X in 

 these reactions must begin with the proof that this substance 

 and not some other cleavage product is really the effective one. 

 Such proof would be found if the block to both parthenogenesis 

 and fertilization could be removed with the removal of the 

 Purple X. To accomplish this and at the same time not render 

 the solutions toxic by the addition of precipitating agents, called 

 for methods which had first to be discovered. 



The Purple X is either in a state of very fine suspension, 

 bordering on solution, or is actually in solution. Since now a 

 precipitable colloid frequently carries other bodies with it when 

 thrown down, I added the albumen of hen's egg to the Arbacia 

 egg-secretion, and boiled the mixture. The expectation that 

 the purple compound might be removed at least to a considerable 

 extent, proved correct, as the white coagulum of hen's egg al- 

 bumen was quite markedly discolored by the purple substance. 

 After filtration the secretion was tested for its parthenogenetic 

 effect. The method of separation however is not quantitative 

 and so the results were not perfectly clear cut. Nevertheless it 



