564 FRANK R. LILLIE 



zation by opening the animal and removing the ovaries so that 

 the eggs are contaminated by blood or tissue secretions, and it is 

 evident that the latter in some way inhibit the fertilization re- 

 action, though they could hardly be supposed to have any direct 

 injurious effect upon either sex element. 



The necessity of washing the eggs carefully before fertilization, 

 had been forced upon my attention by the poor results of certain 

 experiments; and after some of the results recorded in the first 

 part of the paper had been obtained, the phenomenon appeared 

 to possess great significance, because the failure to fertilize in 

 the case of unwashed eggs was clearly due to the presence of blood 

 of the species. Some element of the blood must block the mechan- 

 ism of fertilization, and it was clear that the analysis of the 

 phenomenon must aid in understanding the mechanism. 



The first experiments were undertaken to ascertain the extent 

 of the inhibiting action of the blood of the sea-urchin. The 

 nature of the effect may be seen from the protocol of the following 

 experiment : 



July 7, 1913: The blood of several males and females was obtained 

 by cutting open the shell near the oral membrane and pouring out the 

 perivisceral fluid (blood) in a finger-bowl. After the usual loose clot 

 was formed the plasma was filtered through a soft filter-paper. The 

 eggs used in the experiment came from one female and were washed in 

 sea-water. The experiment was then set up as follows: 



1 Quantity of eggs x plus 25 cc. sea-water plus 4 drops 1 per cent sperm 



2 Quantity of eggs x plus 12.5 cc. filtered blood plus 12,5 cc. sea-water plus 



4 drops 1 per cent sperm 



3 Quantity of eggs 2/5 X plus 10 cc. filtered blood plus 4 drops 1 per cent sperm 



The fertihzations were made about the same time and the result 

 was that in 1 practically all divided, in 2 only a fraction of 1 per cent 

 divided, in 3 none divided. Moreover in 2 and 3 no fertilization mem- 

 branes wdre formed in the undivided eggs and the egg nucleus remained 

 intact; no spindles were formed. And this in spite of the fact that 

 the spermatozoa were very active, so abundant that they formed 'halos' 

 around the eggs by penetrating the jelly, and many reached the surfaces 

 of the eggs. 



This experiment was followed by a considerable number carried 

 out in more detail. Four of these experiments are tabulated in 

 table 8. The left-hand column gives the percentage of blood in 



