lOO E. E. JUST. 



most of the eggs that escaped were collected in dry watch 

 crystals. Bits of tissue were always removed. Such eggs and 

 sperm are "dry eggs" and "dry sperm." 



For a given experiment eggs and sperm were mixed and after 

 an interval of time varying from five to sixty seconds flooded 

 with sea-water. Four kinds of inseminations were made: 



Washed eggs X washed sperm. 

 Washed eggs X dry sperm. 

 Dry eggs X dry sperm. 

 Dry eggs X washed sperm. 



The experiments fall into two groups: "A.M. inseminations" 

 — made the morning after the worms were captured; and "P.M. 

 inseminations" — made during the evening of capture. 



The following table gives a summary of results: 



Table I. 



Eggs. Sperm. Group. Development. 



Washed Washed A.M. and P.M None. 



Washed Dry A.M. and P.M None. 



Dry Dry A.M. and P.M Cleavage and larvae. 



Dry Washed A.M. None. 



Dry Washed P.M. Cleavage and larvae. 



Washed eggs, inseminated with dry or washed sperm, never 

 reach cleavage stages nor do they ever produce swimming forms. 



I have commented above on the dry egg X dry sperm series. 

 These eggs cleave and later produce normal larvae. 



Washed sperm X dry eggs of the A.M. group (191 2) did not 

 yield cleavage or swimming forms. The worms do not thrive 

 well in the laboratory. The practise, therefore, of conducting 

 experiments the morning after capture has been since 1912 prac- 

 tically abandoned. The only test for the vitality of the worms is 

 copulation — a test the very nature of which precludes experiment. 

 Doubtless, therefore, this set of experiments gave no results 

 because the animals were not fit. Study of sections of eggs 

 normally inseminated and laid as early as 5 A.M. shows a large 

 percentage in the germinal vesicle stage. I have made counts in 

 dishes of living eggs to show at the later cleavage stages the pro- 

 portion of eggs still in the germinal vesicle stage. For example, 



