462 ALVALYN E. WOODWARD 



Just ('15 a) found that it was difficult or impossible to initiate 

 development in Nereis eggs which had been washed. The eggs 

 of Platynereis, also, are very sensitive to an excess of sea-water 

 ('15 b). From these facts he concluded that a substance formed 

 by the egg and necessary for development had been removed. 



Fuchs found that the fertilizing power of the sperm of Ciona, 

 Arbacia pustulosa, Ascidia mentaul, and Strongylocentrotus 

 lividus could be increased by treatment with egg secretions of the 

 same species. Moreover, the fertility of Ciona sperm could be 

 enhanced by treatment with the egg secretion of Phallusia, Arba- 

 cia, or Stronglyocentrotus. Likewise, Strongylocentrotus sperm 

 are made more effective by the secretions of Ciona, Echinus, 

 Sphaerechinus, and Asterias eggs. The egg extract, obtained 

 by crushing the eggs, had the same effect as the secretion, except 

 in the case of Asterias. In this instance, the secretion stimulates, 

 while the extract poisons, Strongylocentrotus sperm. The 

 method followed by Fuchs prevented the observation of sperm 

 agglutination. He concluded that the secretions affected sperm 

 only. 



Asterias eggs, Glaser found ('14 b), form a secretion similar to 

 that of Arbacia, except in color and a few minor points. More- 

 over, Asterias sperm are directed, activated, agglutinated, and 

 paralyzed as well by Arbacia secretion as by that from their 

 own species. Arbacia sperm react similarly to Asterias secretion. 

 The writer has been able to confirm these observations and to 

 demonstrate the reactions to colleagues. 



While mature Arbacia eggs in a healthy condition are easy to 

 •obtain and always secrete a sperm agglutinin, the conditions 

 differ in the case of Asterias. It was difficult, during the summers 

 of 1915 and 1916, to obtain Asterias which contained many ferti- 

 lizable eggs. In a good batch 10 per cent would produce larvae. 

 Therefore, it was difficult to obtain the agglutinin in any usable 

 amount. In June, 1914, however, Asterias at Woods Hole were 

 in the best condition I have ever known. It was almost impos- 

 sible to keep them in the laboratory three or four hours without 

 their shedding eggs or sperm. Mr. Gray reported that the live- 

 <;ars in which they were kept, though very open, were always 



