104 ^- ^- JUST. 



by the sea-water since it combines but feebly with the sperm 

 The ether as in Asterias renders the Platynereis egg irritable since 

 as shown by the low percentage of maturation more fertilizing 

 substance must be secreted. 



i^CiV.— Inseminations made with washed or dry eggs during 

 or after treatment with KCN (i per cent. KCN and sea-water 

 made in various proportions) gave only maturation. But the 

 eggs will maturate in KCN alone while in the solutions. (Cf. 

 Allyn on Chcetopterus.) 



CaCh. — Newman found that CaCU inhibits fertilization in 

 Fundulus through a precipitation effect. I thought that in 

 somewhat the same way calcium chloride might through action 

 on the cortex inhibit the loss of the fertilizing substance in Platy- 

 nereis. M/2 CaCU added to sea-water in different quantities 

 does not inhibit the loss of the substance since after the calcium 

 chloride treatment the egg does not fertilize. 



Cooled Sea-water. — Sea-water was cooled to 10.5° C. and dry 

 eggs after 30, 60 and 90 seconds' treatment in 5 c.c. were insemi- 

 nated at this temperature or after the cooled water was pipetted 

 off. In some experiments the female was kept at the low tem- 

 perature for several minutes before the eggs were cut out. 5 c.c. 

 of sea-water were used in each experiment. The eggs never 

 cleave, but more form jelly and maturate than controls insemi- 

 nated in ordinary sea-water. This would seem to indicate a 

 slowing down of the secretion. The effect of cold is just the op- 

 posite of the effect of ether. Unfortunately, only few of these 

 experiments were made. Perhaps they should be repeated at 

 lower temperatures. 



Concerning the nature of this substance, some of my earliest 

 notes are of interest. After insemination in sea-water I found 

 some time later (forty minutes in one case) "sperm dancing above 

 the eggs." In 1914, I found the sperm of sea-water insemination 

 active after twelve hours. One does not find this after dry in- 

 semination, even with excess of sperm. Sperm in the dishes of 

 successfully inseminated eggs are profoundly changed. Study 

 of the movements of Platynereis sperm reveals the circular swim- 

 ming of echinid spermatozoa, as shown by Duller, Gemmil, 

 Winslow, and others (see also Dewitz, Ballowitz, etc.). They 



