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SCIENCE 



[N. S. Vol. XXXVIII. No. 980 



fertilized the production of this substance 

 suddenly ceases absolutely. 



The total disappearance of fertilizin from 

 fertilized eggs can not be demonstrated unless 

 the fertilizin-saturated jelly with which the 

 eggs are surrounded be first removed. This is 

 very easily done after membrane formation by 

 six vigorous shakes of the eggs in a half -filled 

 test tube. Three or four washings then are 

 sufficient to remove the remains of the jelly, 

 and the naked eggs no longer produce the 

 substance. 



Such disappearance may be due either to 

 complete discharge from the egg, or to fixation 

 of all that remains by union with some sub- 

 stance contained in the egg itself. That such 

 a substance — anti-fertilizin — exists in the egg 

 can be shown by a simple test-tube experi- 

 ment : If eggs deprived of jelly are washed 

 34 times in sea water during three days, they 

 are so exhausted that they produce but little 

 fertilizin; the supernatant fluid may be 

 charged only to the extent of 2 to 10 units. 

 The eggs are now on the point of breaking up. 

 If they are then vigorously shaken and broken 

 up so that the fluid becomes colored with the 

 red pigment of the eggs, it will be found that 

 agglutinating power has entirely disappeared 

 from the solution. The fertilizin present has 

 been neutralized. The same phenomenon may 

 be demonstrated also by treating eggs, de- 

 prived of jelly in order to get rid of excess of 

 fertilizin, with distilled water which lakes the 

 eggs and extracts the anti-fertilizin. 



It is probable, therefore, that any excess of 

 fertilizin remaining in the egg not bound to 

 the sperm is neutralized by this combination, 

 and polyspermy is thereby prevented. 



We have noted (1) the secretion by unfer- 

 tilized, eggs in sea water of a sperm agglutina- 

 ting substance, fertilizin; (2) the extreme 

 avidity of the sperm for it as shown by dilu- 

 tion tests; (3) in my previous papers the fixa- 

 tion of this substance in sperm-suspensions of 

 the same species (quantitative measurements 

 will be given in the complete paper) ; (4) the 

 sudden cessation of fertilizin production by 

 fertilized eggs; (5) the existence of an anti- 



fertilizin in the egg; (6) in eggs submitted 

 to a series of washings decrease of the fer- 

 tilization capacity with reduction of the fer- 

 tilizin. The fact that fertilized eggs can not 

 be refertilized is associated with the absence 

 of free fertilizin in them; (7) I may add that, 

 similarly, eggs in which membrane formation 

 has been induced by butyric acid can not be 

 fertilized by sperm and they contain no free 

 fertilizin. 



It is therefore very probable that the sub- 

 stance in question is essential for fertilization. 



It may be maintained that these facts do 

 not constitute demonstrative evidence of the 

 necessity of this substance for fertilization, 

 for the presence or absence or diminution of 

 this material associated with presence or ab- 

 sence or decrease of fertilizing power could 

 always be regarded as a secondary phenome- 

 non. However, the second part of this paper 

 dealing with the other, or ovophile side-chain 

 of the fertilizin, strongly reinforces the argu- 

 ment. 



Before passing on to this, I may be allowed 

 to note some other properties of the fertilizin : 

 In my previous papers I noted the extreme 

 heat-resistance of the fertilizin, being only 

 slowly destroyed at 95° C. I also noted that 

 strongly agglutinating solutions of Arhacia 

 may contain a substance which agglutinates 

 Nereis sperm and stated that this was prob- 

 ably different from the iso-agglutinating sub- 

 stance. This turns out to be the case and the 

 two can be readily separated. The substance 

 must possess great molecular size, as it is 

 incapable of passing through a Berkefeld 

 filter. It is also non-dialyzable; it does not 

 give the usual protein reactions, a fact for 

 the determination of which I am indebted to 

 Dr. Otto Glaser. 



2. The Ovophile Side-chain. — Assuming, 

 then, that the union of this substance with 

 the spermatozoon enters in some significant 

 way into the process of fertilization, the prob- 

 lem was to ascertain in what way. The sim- 

 plest idea, viz., that the union is in itself the 

 fertilization process, was soon shown to be 

 untenable, for the reason that the perivisceral 



