PHENOMENA ACCOMPANYING FERTILIZATION 529 



there a fusion prior to the degeneration of other pronuclei of the 

 stationary pronucleus with one of the "male" pronuclei of which 

 there may be as many as four in each conjugant? Or did the sta- 

 tionary pronucleus degenerate, its place being taken by one of the 



% 



'Z6 



%l %Z %S %, % Vz. 



'ZS 



Fig. 220. — Urolepi us mohilis, cut during conjugation as indicated. In this case 

 the conjugants were in the prophase stage of the first meiotic division. PXI 

 history of reorganization without fertilization. (After Calkins.) 



other pairs of pronuclei? Some evidence that the last alternative 

 was the case is afforded by the fact that the conjugating pairs if cut 

 apart at an early period in conjugation do not undergo the third 

 division, some one of the products of the second division acting as 

 an amphinucleus, thus realizing the condition during "endomixis." 

 34 



