230 FERTILIZATION 



failed when semen alone was used, the addition of hyaluronidase from bull testis 

 to the semen produced successful fertilization (Leonard and Kurzrok, '46). 



b) Secretions Related Specifically to the Fertilization Reac- 

 tions. The substances mentioned in the preceding paragraphs are related to 

 the general fertilization process, but they may not be related specifically to 

 the reactions which bring the sperm in direct contact with the egg. In the egg 

 we have observed the presence of fertilizin which stimulates a series of sperm 

 activities directed to this end. Similarly, in the male gamete, sperm of various 

 species seem capable of producing "androgamic substances which neutralize, 

 in part, the action of the gynogamic substances and thus assure the precise 

 mechanism necessary for precise fusion of the gametes" (J. Brachet, '50). 



An introductory study by Frank ('39) suggests the presence of a sperm 

 substance which reacts directly with the fertilizin complex of the egg. It was 

 shown by this investigator that an extract from the sperm of the sea urchin, 

 Arbacia, is: 



( 1 ) able to destroy the sperm agglutinating factor when added to a solution 

 of fertilizin derived from the sea-urchin egg, and 



(2) possesses the power to agglutinate eggs of the same species. 



Other students of the problem have found a similar substance associated 

 with the sperm. (See Hartmann, Schartau, and Wallenfels, '40; Southwick, '39; 

 Tyler, '40.) The general term "sperm antifertilizin" has been given to this 

 substance (or substances) by Tyler and O'Meiveney ('41). Sperm antiferti- 

 lizin unites with fertilizin produced by the egg, with the result that the sperm 

 is entrapped at the egg's surface. Tyler and O'Meiveney ('41) regard the 

 reaction between antifertilizin of the sperm and fertilizin of the egg to be the 

 "initial (perhaps essential) step in the union of the gametes whereby the 

 spermatozoon is entrapped by the . . . fertilizin, on the egg." 



c) Secretions Which Induce the Spawning Reaction in the Female. 

 Galtsoff ('38) has shown that the presence of sperm of the oyster, Ostrea 

 virginica, "easily induces spawning in oysters." He also found that the spawn- 

 ing reaction is specific in that sperm of different species cannot provoke it. 

 The active principle of the sperm suspension is thermolabile and insoluble 

 in water. However, it may be readily extracted in 95 per cent ethyl alcohol 

 and benzene. 



To what extent spawning-inducing substances may be present in other animal 

 species is questionable, but it may not be an uncommon phenomenon, espe- 

 cially in sedentary species, such as the oyster and other mollusks. In the ver- 

 tebrate group, surface contact of the male and female bodies is an important 

 factor in many cases. 



2) Relation and Function of Sperm Number in Effecting the Contact of 

 the Sperm with the Egg. In the preceding chapter, sperm transport is con- 

 sidered. This transportation journey is an efficient one with regard to the end 



