88 Specificity in Fertilization 



membrane formation does not create such a block al- 

 though it puts an end to the "fertilizin" reaction. In 

 the egg of piirpuratus the ' ' f ertilizin " reaction ceases 

 when the jelly surrounding the egg is dissolved by an 

 acid and the eggs are repeatedly washed; yet such eggs 

 can easily be fertiHzed b}'' sperm. 



Lillie does not assume that the ' ' f ertilizin " causes 

 an agglutination between egg and spermatozoon — we 

 should assent to such an assumption — but that the 

 *'fertilizin" acts like an "amboceptor" between egg 

 and spermatozoon, the latter being the complement, 

 the former the antigen. The pathologist would prob- 

 ably object to this interpretation since no "ambocep- 

 tor" is needed for agglutination. The writer has had 

 some doubts concerning the value of Ehrlich's side- 

 chain theory which, besides, can only be applied in a 

 metaphorical sense to the mechanism of the entrance 

 of the spermatozoon into the egg.'^ 



^ Loeb, J., Am. Naturalist, 1915, xlix., 257. 



The writer may be permitted to illustrate by a special case his reason 

 for declining to accept Ehrlich's side-chain theory. Ehrlich and Sachs 

 found that if to a given mass of toxin small quantities of antitoxin are 

 added successively the first fraction added neutralized more than the 

 later fractions; and on the basis of this reasoning Ehrlich concluded 

 that ten different toxins were contained in the diphtheria toxin. Ar- 

 rhenius showed that the same phenomenon can be obtained when a 

 weak base like NH4OH is neutralized by a weak acid {e. g., boric 

 acid); hence we should assume that NH4OH consists of ten different 

 forms of ammonia. Both cases, the saturation of toxin with anti- 

 toxin and ammonia with boric acid are equilibrium phenomena. 

 (Arrhenius, S., Quantitative Laws in Biological Chemistry^ London, 



1915-) 



