STUDIES OF FERTILIZATION 555 



phi'e group of the fertilizin, it is more reasonable to conclude that 

 the disappearance of sperm-agglutinating power from the wash- 

 ings of fertilized eggs deprived of jelly is due to neutralization of 

 the substance remaining in the egg. In this connection it is 

 instructive to note that eggs commonly lose pigment on insemi- 

 nation; I always have found the anti-fertiHzin "accompanied by 

 pigment ; it is, therefore, natural to suppose that anti-fertilizin 

 is carried to the surface of tlie egg on insemination, thus afford- 

 ing the opportunity^ for combination with the fertilizin and its 

 neutralization. 



The other possibility that the sperm combines with all the 

 free fertilizin in the egg appears to me inadmissible, because (1) 

 the surface of the egg is relatively so enormous, and (2) the amount 

 of fertilizin which the sperm is capable of binding is very small 

 relative to the amount produced by the eggs even at a single 

 washing (cf. sec. 3, p. 538). The bulk of the sperm actually 

 used for insemination is insignificant compared to the bulk of 

 the eggs, and only a small proportion of the sperm used actually 

 fertilizes so that the amount fixed by the sperm itself is excessively 

 minute compared to the quantit}" contained in the egg. 



We have seen (p. 529) that 1 cc. of eggs charges 5 cc. of sea- 

 water to 1600 units. We have also seen that such eggs contain 

 or produce many times this quantity in successive washings; 

 and that it takes 1 cc. of 3 per cent sperm to fix 1 cc. of 64 power 

 agglutinating solution. Thus it would require 1 cc. X 1600/64 X 5 

 or 125 cc. of 3 per cent sperm to neutralize the agglutinating 

 substance produced by one washing of 1 cc. of eggs in 5 cc, of sea- 

 water. But a single drop of 3 per cent sperm would be much more 

 than sufficient to fertilize the same amount of eggs. The dis- 

 proportion is even greater than indicated in this rough calcula- 

 tion, w^hich is, however, sufficient to show the absurdity of ex- 

 plaining neutralization of the agglutinating substance of the 

 fertilized eggs by the sperm used in fertilization. 



Theories of prevention of polyspermy, or of the non-fertiliz- 

 able character of eggs already fertilized, proceed along two lines: 

 (1) that the membrane formed on fertilization is impermeable to 

 spermatozoa, (2) that the protoplasm of the fertilized eggs has 



THE JOURNAL OF EXPERIMEXT VL ZOOLOGY, VOL. 16, NO. 4 



