480 



MARIE A. HINRICHS. 



TABLE III. 



THE EFFECT OF RADIATION ON ^ u PER CENT. SPERM WHEN TIME is 



ALSO A FACTOR. 



(Sperm was radiated for five minutes, and immediately thereafter used to 

 fertilize normal eggs.) 



When examined five minutes after exposure, less than I per 

 cent, of the radiated sperm show any motility. Later, however, 

 after about nine hours the sperm may be seen to cluster about 

 the eggs, indicating some degree of recovery of motile power. 

 The recovery of motile power following inhibition by radiation, 

 recalls the assertion made by Glaser, '14, namely, that paralyzed 

 sperm may be reactivated but not reagglutinated. 



Motility is considerably reduced soon after exposure to ultra- 

 violet radiation (see also Lillie and Baskervill, '22) . Sperm in the 

 more dilute suspensions more quickly lose their power of move- 

 ment, and clumping or agglutinating takes place early. The 

 clumps are large and irregular and stable. The higher the dosage, 

 the larger are the clumps of sperm. In viewing an exposed lot 

 of sperm with a microscope, it can be seen that the surface layer, 

 contains immobile sperm, while the layers below (as seen in 

 optical section) have been "shaded" from the ultraviolet radi- 

 ation (or have not been reached because of insufficient penetration 

 of the rays), and are therefore normally active. The extreme 

 bottom layer of the dish again contains inactive sperm which 

 have probably sunk down from the top layer. Clusters of sperm 

 are numerous. In transmitted light, radiated sperm suspensions 

 appear "clear," while.- nonradiated ones appear "milky." 



When sperm in dilutions ranging from 1/300 per cent, to 



1 Time elapsed (in minut' ><>sure to radiation for 5 minutes. 



