ULTRAVIOLET AND ARBACIA FERTILIZATION. 



431 



more permeable to a viscous substance contained in the 

 sperm, and given off into the sea water. Popa. '27, lias recently 

 described such a substance in Arbacia sperm. 



T.U'.LE XI. 



PERMAXEXCE OF FOAM STRUCTURE ix SPERM SUSPEXSIOXS FOLLO\VIXG 



RADIATION. 



A. Examined after 30 min. 



B. Examined after 90 min. 



Ultraviolet radiation likewise alters the permeability of the 

 sperm surface, producing aggregates of sperm which, however, 

 are not reversible, differing in this respect from the agglutinated 

 masses produced by the action of normal egg-water upon normal 

 sperm. 



Certain of the above-described characteristics of fertilizin sug- 

 gest an enzyme-like nature of the substance. Its high adsorption 

 constant, the retention of some of its activity while in the ad- 

 sorbed state, its displaceability by acids and not by fat-solvents, 

 and an optimum pH range for activity and for adsorption have 

 been described. 



Tchachotine, '21, ascribed a sperm-agglutinating power to the 

 gelatinous egg envelope. Although sperm do attach themselves in 

 large numbers to the jelly layer of Arbacia eggs (if higher con- 

 centrations of sperm are used), this is probably due to the fact 

 that the fertilizin is adsorbed by the jelly, and still retains some 

 of its agglutinating power. A similar condition exists in the ex- 

 periments described above, in which bits of charcoal with their 

 adsorbed fertilizin behaved like artificial eggs, and attracted and 

 held active sperm agglutinated in a film about them. 



Glaser, '140, found that sperm which had been paralyzed could 



