FERTILIZATION REACTION IN ECHINARACHNIUS PARMA. 37 



agglutination produced by a substance distinct from the iso- 

 agglutinin ; it is found in Arbacia blood. Likewise the agglutinin 

 in Arbacia egg-water for Echinarachnius sperm is separate from 

 the iso-agglutinin. These points could be better determined 

 by the microscopic method, by examining the agglutination 

 after diluting the egg-water, attenuating the agglutinin by wash- 

 ing the eggs, etc. The macroscopic method of studying the 

 agglutination would fail. It may be, farthermore, that Arbacia 

 blood is generally toxic. Thus, I have found that it will induce 

 jelly-formation, maturation, and if allowed to act too long cytol- 

 ysis in the Nereis egg. We may readily understand that when 

 cross fertilization is possible between forms in one direction only 

 the fact that an agglutination takes place in the opposite direction 

 does not- invalidate the fertilizin theory of fertilization if the 

 agglutination is a toxic hetero-agglutination. 



Finally, the activation of sperm by egg-water may be of great 

 importance in fertilization as Loeb ('15) points out. Thus, 

 Echinarachnius egg- water activates Arbacia sperm which are 

 capable of fertilizing Echinarachnius eggs. In Asterias if at the 

 moment of insemination by immobile sperm more sperm be 

 added they are greatly activated. In Nereis agglutination is 

 only possible with very active sperm; such sperm spontaneously 

 form aggregations when mixed with sea-water alone. Sperm 

 that do not form these spontaneous aggregations will not agglu- 

 tinate. Also in both Arbacia and Echinarachnius the first stage 

 in the agglutination reaction is activation. Probably in those 

 Echinarachnius eggs normally resistant to fertilization there 

 exists a membrane condition that masks the presence of fertilizin. 

 In addition, therefore, to the farther study of activation we must 

 approach the investigation of just such conditions. By these 

 analyses the fertilizin theory may prove of wider application. 



LITERATURE CITED. 

 Delage, Yves 



'01 Etudes experimentales sur la maturation cytoplasmique et sur la partheno- 

 genese artificielle chez les Echinodermes. Archiv. de Zool. Exper. et Gen., 

 Ser. 3, T. G. 

 Fuchs, H. M. 



'14 The Action of Egg-secretions on the Fertilizing Power of Sperm. Arch. 

 Entw'mech., Bd. 40. 



