H. M. FucHS 265 



The Table shows that in each of the experiments more eggs were 

 fertilized in the water containing the egg-extract than in plain sea- 

 water. The suggestion at once arose — were the eggs in the egg-extract 

 developing in part parthenogenetically { This was ruled out of court 

 by controls of unfertilized eggs in egg-extract, none of which segmented- 



The egg-extract present at fertilization and during the early stage 

 seems to have no baneful effect on development. Table I shows that in 

 Exps. I and II the eggs in plain water completed the 4-cell division 

 simultaneously with those in the egg-extract. Moreover, in a further 

 experiment (17.29.1) in which the eggs B were fertilized by sperm a in 

 (1) water, (2) B egg-extract, (3) A egg-extract, (4) C egg-extract, the 

 resulting larvae all developed equally well. 



Evidently some substance extracted from the eggs by breaking them 

 up in sea-water so affects the eggs or the sperm or both that more eggs 

 are fertilized than is the case in plain sea-water, when other conditions 

 are equal. 



An experiment (22.7.2) was then made, in which equal quantities of 

 A eggs were put simultaneously into (1) fouV dishes, each containing 

 12 cc. sea-water, (2) four dishes, each containing 12 cc. B egg-extract. 

 At given successive intervals one drop of b sperm was added, at the 

 same moment, to (1) a dish of water containing A eggs and (2) a dish of 

 B egg-extract containing A eggs. Each was then well mixed. 



TABLE II. 



(The numbers in brackets give the time in minutes after fertilization at which the 

 first 4-celI division was completed.) 



Eggs tried out into dishes containing (1) water, (2) extract at 12.20. 



(1) Water (2) Extract 



Cross: A/b, B extract. Fertilized 12.20 62 (88) 91 (88) 



Fertilized 12.40 53 (89) 57 (89) 



Fertilized 10 31 (89) 57 (89) 



Fertilized 1.20 24 (84) 52 (84) 



This experiment was, in the first place, a confirmation of the previous 

 ones, in that the eggs fertilized in the egg-extract all showed higher 

 fertilization percentages than those fertilized after a corresponding 

 length of time in water. In this case the egg-extract was obtained from 

 the same individual from which the sperm was used. 



The Table also shows that although the fertilization percentages 

 decreased with each fertilization, the length of time taken to attain the 

 4-cell stage became shorter in the last fertilization (see Part I). As 



