82 PRELIMINARIES TO FERTILIZATION 



(Bishop, Campbell, Hancock, and Walton, 1954; Bishop and 

 Hancock, 1955; Bishop, 1955). The observation that fluoride in- 

 hibits both fructolysis and motility under aerobic conditions 

 (Lardy and Phillips, 1943) does not invalidate the value of re- 

 spiratory metabolism for motility, because of the nonspecific 

 nature of fluoride inhibition. It is unlikely that the aerobic inhibi- 

 tion of spermatozoon motility by hydrogen peroxide formation, 

 observed under certain conditions in vitro ( McLeod, 1946; Tosic 

 and Walton, 1950) will occur within the female tract, owing to 

 the presence of catalase in the mucosa. 



The importance of glycolytic metabolism is likely to be greatest 

 when the spermatozoa exist together in dense suspension and con- 

 sequently reduce the local oxygen tension. This will occur at the 

 site of deposition of the semen, and it is of course precisely at this 

 point that the spermatozoa are most under the influence of the 

 seminal plasma. The semen of the dog and cat, however, contains 

 no fructose (Mann, 1954). 



As already noted, high dilution of spermatozoa occurs in the 

 female genital tract. A well-known result of dilution in vitro is 

 spontaneous head agglutination — it is shown notably by rat, 

 mouse, and guinea pig speiTnatozoa upon suspension in physio- 

 logical saline, but occurs less readily with bull or ram spermato- 

 zoa. This suggests the presence of surface charges on the heads 

 of the spermatozoon and indeed Milovanov and Selivanova 

 ( 1932 ) have reported that unagglutinated spermatozoa do carry 

 a negative charge and migrate to the anode in an electric field. 

 When the charge is neutralized by electrolytes in the medium, 

 head agglutination occurs and the spermatozoa are not moved by 

 the current. Schroder (1940) went further, claiming that she had 

 separated by electrophoresis the spermatozoa bearing the X 

 chromsome, which migrated to the anode, from those bearing the 

 Y chromsome, which migrated to the cathode. This work still 

 awaits confirmation. The surface charge carried by spennatozoa 

 is held to be associated with the lipoid capsule (Milovanov, 

 1934a,b), which, as mentioned earlier, is readily removed by 

 electrolytes. In the semen or within the female tract, however, 

 head agglutination is not a feature of spermatozoa, presumably 



