STUDIES OF FERTILIZATION 535 



decrease in bulk is due to loss of jelly, mB and C simply to further set- 

 tling. C was kept for control. A and B were submitted to repeated 

 washings as in table 3, p. 536. 



This experiment positively decides the question as to produc- 

 tion of fertilizin. It continues to be produced by the unfertilized 

 eggs without jelly as long as they live. The jelly is, naturally, 

 saturated with fertilizin, and it seems probable that it may act 

 to prevent too rapid exhaustion of the secreting mechanism of the 

 egg. It is of course possible that all that the egg gives off is pre- 

 formed, but it is more probable that loss of this substance by the 

 egg acts as stimulus to regeneration of more. 



Apparently the eggs do not secrete the fertilizin in such a series 

 of washings after they have settled in a mass at the bottom of the 

 tube ; for it will be noticed that the concentration of the substance 

 in the successive washings is not a factor of the time intervals. 

 On the contrary, a long time interval between washings is often 

 associated with a temporary decrease in concentration, as may be 

 noted, for instance, in the interval of 15 hours between 14 and 14a 

 in table 2. In this case 14 and 14a are actually the same body 

 of supernatant fluid and the concentration is much decreased 

 in the second test 15 hours after the first, as though the eggs were 

 gradually destroying the fertilizin. This subject is fully treated 

 in section 6 (anti-f ertilizin) . 



3. THE BINDING OF FERTILIZIN BY SPERM 



In my previous paper (Lilhe '13) I showed that the sperma- 

 tozoa fix the agglutinating substance, and assumed as a work- 

 ing hypothesis that the fixation was due to chemical union. 

 The fact on which the statement was based was the disappear- 

 ance of the agglutinating substance from a sperm suspension when 

 not present in excess. No attempt was made, however, to make 

 quantitative determinations, so the matter was taken up again 

 in 1913 in a more exact manner. The amount of the agglutinating 

 substance actually fixed by the sperm is surprisingly small when 

 the great avidity of the sperm for it is taken into account. 



