27 



There are some Indications that the central "body is not 

 firm hut a plastlo, semiflnld euhstance. This Is supported hy 

 the fact that It sometimes glides out through the Inner tubule 

 at stages such as that shown In Pig. 76 and adheres to the 

 surface of the everted tuhule In one or more amorphous masses 

 (Pigs. 77,g.» 79 and 82). This condition may have heen brought 

 about by a degeneration of the body as a result of keeping 

 the sperms in the serum of the blood or in salt solutions. 

 Sometimes in unexploded sperms the central body adheres to one 

 side of the tubule instead of standing in the center, and it 

 may be that it was only in such cases as this that it adhered 

 to the everted wall of the tubule. 



5. Dynamics of Ever si on. 



We may now consider the forces Involved in the turning 

 of the tubule and capsule inside out. We may divide this in- 

 quiry Into two questions: (l) what are the external conditions 

 necessary to initiate and csirry on the process? (2) What eire 

 the internal conditions that respond to the external ones and 

 determine the nature of the process? 



As stated above a decrease In the osmotic pressure of the 

 medium in which the sperms lie, will oause the everslon. Un- 

 exploded sperms taken from blood serum and placed in 5% KlOg 

 do not explode; placed in 3% to A% ZSOg they take the forms 

 shown in Pigs. 67 to 70; in 2?5 to 3^ KHO3 the forms in Pigs. 

 70 to 72 and 77 are obtained; in 1.5^ to 1^ KNO3 the everslon 

 proceeds to the stages shown in Pigs. 77 to 82. Like results 



