H. M. FucHs 270 



VI. Effect of Ciona Blood on the Fertilizing Power of 



Cjona Sperm. 



Trials were next made to see whether there is an agent which 

 increases the fertilizing power of the sperm in the blood, as well as in 

 the eggs of Giona. Owing to lack of time no other tissues of the body 

 were tested, but it will be important to do so in the future. 



The blood was removed from the body by the method already given 

 (see p. 264). In each experiment the blood of one particular individual 

 (given in the Table) was used. After removal from the body it was 

 diluted to varying extents, according to the amount obtained. Given 

 amounts of sperm -suspension were added to (1) 2i cc. water, and 

 (2) 2i cc. blood. T(i each was added 10 cc. water, after which (1) and (2) 

 were poured on to approximately equal numbers of eggs. Each experi- 

 ment was made double, two different amounts of sperm being used. 

 The results of the experiments are given in Table XIX. 



The Table shows that this series is an extensive one, there being 

 22 double experiments, or 44 comparisons in all. The reason for this 

 is not that this investigation is more important than previous ones, but 

 that, as will readily be seen from the Table, the results of each of the 

 Series A, B, C, D and E contradict one another, although the experi- 

 ments within each series agree. For the experiments in Series A and D 

 show an increase in the number of eggs fertilized as a result of the 

 treatment of the sperm with blood, while in Series B, C and E the per- 

 centages are decreased. The only exceptions to this statement are that 

 in Series D, all other experiments of which showed an increase in the 

 percentages as the result of the blood treatment, the second parts of 

 Exps. 10 and 15 gave no change'. Owing to the contradictory results 

 of the different series, the experiments were continued until a reason 

 for this behaviour was found. 



At first it was thought that an explanation of the different effects of 

 the blood on the sperm might be that the behaviour of the former 

 differed according as it was derived from the same animal as the eggs 

 used in the same experiment, or as the sperm, or from a third individual. 

 That this is not the explanation is seen from the fact that Series D, in 

 which the percentages were raised by treatment of the sperm with 

 blood, there are experiments in which the blood was derived from (1) 



• The first parts of Experiments 9 and 13 allow of no comparisons, as too little sperm 

 was used. The same is the case with the second parts of Experiments 20 and '21, where 

 too much sperm was used. 



