FERTILIZATION REACTION IN ECHINARACHNIUS PARMA. 



II 



of maximum fertilization capacity be inseminated in ccelomic fluid, 

 the per cent, of cleavage is decreased. Thus equal parts of 

 ccelomic fluid and sea-water may cut down the per cent, of cleavage 

 to zero; higher proportions of ccelomic fluid, 75 to 100 per cent., 

 invariably permit no fertilization. 



In practice it was found extremely difficult to use large quanti- 

 ties of blood owing to its scarcity. Since, however, eggs from one 

 female only were used in any given experiment, this was found no 

 great difficulty, since the number of eggs used was very small in 

 each case. 



The method used is about as follows : Equal parts of ccelomic 

 fluid and sea- water made solution No. 1. To half of No. 1 was 

 added a like quantity of sea- water to make No. 2. Thus a series 

 of half dilutions was made. One half of the last member in the 

 series was discarded in order that all numbers would contain the 

 same quantity of solution. Uninseminated eggs were placed in 

 each solution — one drop of an egg suspension to each. Likewise 

 a drop of uninseminated eggs was placed in normal sea-water equal 

 in amount to that of mixture of ccelomic fluid and sea-water. The 

 eggs in all dishes were then inseminated with the same amount of 

 sperm from one male. In general, inseminations were made first 

 in 100 per cent, and in 50 per cent, blood. Unless these gave 

 high percentages of inhibition, I made no further dilutions. 



The appended summary (Table I.) gives the results of six 

 experiments made in 1919 : 



Table I. 



The Inhibitory Effect of Specific Blood on Fertilization of the Egg op 



Echinarachnius parma as Revealed by the Per Cent, of 



Cleavage in Various Concentrations of Blood in 



Sea-water in 6 Experiments of 1919. 



