43O MARIE A. HINRICHS. 



Since the normal agglutinability of sperm suspensions is re- 

 duced by ultraviolet radiation, a stronger concentration of egg-- 



* c> oo 



water is necessary to produce agglutination in radiated sperm. 

 Table X records the results of such an experiment. While the 

 control sperm may be agglutinated with egg-water diluted about 

 6,000 times, sperm radiated for 60 sec. will agglutinate with egg- 

 water diluted only about 30 times. Radiation for 120 sec. reduces 

 agglutination to zero. 



Radiated sperm suspensions show no change in pH detectable 

 by the indicator method. Higher concentrations of sperm show 

 a slight increase in relative viscosity, as measured by a stalag- 

 mometer. This bears out the suggestion made above regarding 

 the increased adhesiveness of sperm heads in aggregations appear- 

 ing in radiated suspensions. Apparently ultraviolet radiation 

 changes the consistency and permeability of the sperm surface 

 causing the sperm to become more " sticky." Sampson, '26, de- 

 scribes a similar change in the consistency of sperm agglutinated 

 by normal egg- water. Glaser, '14^, found that egg extracts in- 

 creased the permeability of cells. Other workers have reported 

 similar results. 



There appears to be a decrease in surface tension following the 

 radiation of sperm suspensions. The relative permanence of foam 

 structure formed the basis, for the above suggestion, following 

 Bartsch, '26. 25 cc. of each of the various sperm suspensions 

 were shaken in small bottles until frothy. Examinations were 

 made after 30 and 90 minutes. It will be seen from Table XI. 

 that the stronger suspensions of sperm had more froth than the 

 more dilute suspensions, and that in both strong and dilute sus- 

 pensions, the number of bubbles was increased by radiation, as 

 indicated by the number of X's in the table. 



General Discussion. From the fact that the degree of viability 

 and fertilizability of Arbacia eggs show a parallelism with the 

 power to produce fertilizin, it may be argued that fertilizin plays 

 an essential role in the fertilization reaction. (See Lillie and 

 Just, '24, p. 486.) There appear to be two distinct substances 

 yielded by the egg to the sea-water, one of which stimulates the 

 sperm to greater activity, while the other agglutinates the sperm, 

 perhaps by so affecting the sperm-head surface as to cause it to 



