250 ShidieH hi the Phjiaiolofiji of Fertilization 



products had been removetl into the sea-water. The details and results 

 of the experiment are recorded in Table XI, and it will be noticed that 

 the experiment is the same as that given in Table V, Exp. 5. In 

 addition, the cross Kjp was made, and is tabulated here only, as the 

 percentages of eggs fertilized were immaterial to the matter under 

 discussion in the previous section. 



TABLE XI. (14.18.1.) 



For explanation of headings of Colamns see Table X. 



Eggs A', croes-fertilized, Kjp 



Self-fertilization, Kjh 



Sperm k, cross-fertilized, Ljk 



The variations in the segmentation times of the eggs fertilized at 

 different intervals in any of the three crosses were small. It is seen by 

 comparing Kjk with Ljk that there is practically no difference in the 

 rate of early segmentation of eggs self- and cross-fertilized. The four 

 fertilizations Kjp took rather longer to divide than the other two com- 

 binations. The results further emphasize the fact that the rates of 

 segmentation do not depend on the percentages of eggs fertilized. 



As was explained in the Introduction, the original scheme of work 

 has not yet been carried out, namely that of rearing reciprocal cross- 

 fertilized families to maturity, in order to find the degi'ee of cross- 

 fertility of sisters inter se and of members of one family with those of 

 the reciprocal. This has not yet been attempted owing to the many 

 preliminaries to be settled first, the investigation of which forms the 

 substance of this paper. A number of families were, however, reared, 

 partly in order to settle the optimum conditions of food, etc., (G), but 

 more especially to compare the later development of animals derived 

 from cross- and from self-fertilized eggs. The details of two t3'pical 

 experiments are given below. 



