2O E. E. JUST. 



tion. Some years ago I observed similar behavior in Asterias. 

 Eggs cut from ovaries may or may not fertilize: if they do cleave, 

 subsequent development may be uncertain. Eggs naturally 

 shed on the other hand, may be inseminated at once, fertilize 

 easily, and develop perfectly, giving rise to larger and more 

 vigorous larvae. It would be a mistake to reach conclusions 

 concerning the behavior of eggs and sperm unless these products 

 have also been studied as they are normally shed. And I am 

 disposed to believe that a great deal of the variability of eggs, 

 so called physiological condition met with by workers, is due to 

 the use of eggs not perfectly ripe. Dry eggs give powerful 

 agglutinative suspensions. 



2. Washed Eggs. 



It is generally known that eggs lose their capacity for fertiliza- 

 tion through remaining in sea-water, though the resistance to 

 sea-water may vary within very wide limits depending upon the 

 species of egg. Thus, the Platynereis egg can no longer be fer- 

 tilized after six to ten seconds in sea-water, whereas the Arbacia 

 egg may still be fertilized after several hours. In Echinarachnius 

 the power to withstand sea-water varies with the kind of egg 

 ("ovary egg" or dry), the time of season, the temperature, 

 amount of mechanical shock, amount of sea-water used, etc. 

 The most important factor is the condition of the egg since the 

 most perfectly ripened eggs, i. e., shed eggs, lose fertilization 

 capacity earliest. There is an optimum period for fertilization 

 and this gradually passes off as the eggs lie in sea-water. Eggs 

 may lose their fertilization capacity in from two to fifteen hours; 

 washing the eggs repeatedly will hasten this loss. Thus, 



(a) i c.c. of eggs, samples of which when tested were fertiliz- 

 able, was suspended in 99 c.c. of sea-water at 4:30 P.M., July 6. 

 The supernatant sea-water gave on 1/800 dilution an 8-second 

 reaction. Next day at 9 A.M. these eggs were unfertilizable 

 before or after washing in 100 c.c. of sea-water. The superantant 

 sea-water was negative to Echinarachnius sperm when tested 

 throughout the day. 



(&) The following is typical of a large number of experiments. 

 On July 6 at 8 A.M., 2 c.c. of eggs were collected from three fine 

 females washed in 5 c.c. of sea-water and strained. They were 



