554 



FRANK R. LILLIE 



apparently still producing it vigorously, but that is only because 

 they carried the fertiUzin-saturated jelly with them. Ninety-eight 

 per cent of the B eggs segmented perfectly. 



The result is in accord with the assumption that all free ferti- 

 lizin is fixed at the moment of fertilization, or membrane formation. 

 But I know of no way of absolutely demonstrating that the fix- 

 ation takes place thus rapidly. But if such fixation is the mechan- 

 ism for prevention of polyspermy, as I believe, the fixation of all 

 free fertilizin must take place in a few seconds at most. 



A duplicate experiment was made on August 25. The methods 

 of Experiment 1 were repeated exactly. The eggs were not, 

 however, so good a lot and the membranes did not stand put so 

 far from the eggs. The shaking of lot B removed the jelly from 

 most, but not from all. In this experiment tube B came negative 

 on the sixth and seventh washings; whereas tube ^4 gave a 90-sec- 

 ond reaction, undiluted, on the sixth washing. Over 98 per cent 

 of the eggs segmented and the unsegmented eggs had spindles. 



Both experiments were clear-cut ; there can be no question that 

 after fertilization the eggs cease to produce fertilizin. Two 

 effects are involved; the disappearance of fertilizin, and failure 

 to produce more. The first effect might be due to extrusion of 

 all fertilizin from the eggs; but it seems improbable that this could 

 take place with sufficient rapidity to prove effective as a mechan- 

 ism for preventing polyspermy, and inasmuch as we know that 

 the eggs contain anti-fertilizin capable of occupying the spermo- 



