no E. E. JUST. 



pointed out^ experimental evidence must be amassed testing the 

 meaning of each of these stages. 



1. Concerning insemination, as Lillie has shown, the egg plays 

 an important part through the production of agglutinins. ^ For 

 both Arbacia and Nereis it has also been shown that chemotaxis 

 plays a part in insemination. (Lillie, '12, '13a, '13&, and '14). 



I believe that Platynereis belongs to this class. I may, how- 

 ever, be permitted again to point out the great difficulty attending 

 the use of Platynereis eggs on this phase. All the phenomena are 

 extremely rapid, the reactions must be very nice. The material 

 is unfavorable for any intensive study of agglutination and che- 

 motaxis. When one stops to think of the extremely precise 

 reactions of the eggs, one gets a hint of the task. The carrying 

 over of the smallest drop of sea-water above the maximum to eggs 

 from vigorous females within the shortest time after capture will 

 prohibit cleavage in every egg. 



To answer the general question whether or not eggs secrete 

 substances that activate the spermatozoa, I believe forms whose 

 eggs are inseminated normally in sea-water should be used. So 

 far as Platynereis is concerned, agglutination or not, chemotaxis 

 or not, the egg must lose a substance or substances when in 

 sea-water whose presence is necessary for fertilization. 



2. Study of the normal fertilization of Platynereis indicates that 

 as in Nereis the egg plays the active r61e in the penetration of the 

 spermatozoon for it actually draws in the passive spermatozoon. 

 After sea-water treatment I have not, as mentioned above, found 

 the early stages of penetration in eggs fixed at three minute 

 intervals after insemination. Either the sperm penetration is 

 unlike that after normal insemination or penetration takes place 

 with extreme rapidity. In the later stages of penetration it is 



1 Lectures to classes in embryology, Woods Hole, Mass. 



2 Apparently Buller did not realize that he obtained iso-agglutination of sea- 

 urchin sperm, although he speaks of the sperm forming "balls" and although the 

 phenomena of agglutination were well known at that time. Landsteiner the year 

 before had secured sperm agglutinating sera. Nougouchi's work on Nereis sperm 

 is of interest: he demonstrated agglutination with snake venom. The experiments 

 of Schiicking, von Dungern, de Meyer, and others are well known. An observation 

 of Walker's ('lo) is likewise worthy of mention — the agglutination of the sperm of 

 the rat when mixed with the seminal vesicle secretion of the same animal. 



Chemotaxis of sperm has been demonstrated for mammals — see for instance. Low. 



