70 G- W. SALISBURY 



dilution of end products of metabolism which increase on storage 

 resulting in an increased osmotic pressure (Salisbury et al., 1948). 



For optimum preservation of spermatozoa and conservation of 

 intracellular reserves the evidence suggests that the proper osmotic 

 pressure is greater than that of fresh seminal plasma, the level in 

 the epididymis being at a milliosmole equivalent of about 350. On 

 the other hand, for optimum resistance to freezing to the tempera- 

 tures of solid C0 2 or liquid N 2 , the glycerol and other constituents 

 in the diluent should exert a A F.P. of about — 3.0°C, equivalent to 

 about a 1.6 molal concentration. 



Apart from these considerations is the large number of interactions 

 possible among the variables to which spermatozoa may be naturally 

 and experimentally subjected. Such interacting items include not 

 only osmotic pressure, mineral cations, and the anions already men- 

 tioned, but also H ion concentration, other cations, anions, substrates, 

 protein and amino acids, and other constituents of seminal plasma. 

 Most experiments published have dealt with the influence of such 

 factors one, or at most two or three, at a time, so that physiological 

 interactions which might have occurred in the ideal experiment in- 

 cluding all such variables at once have not been tested statistically. 

 The published data on the effect of pH on spermatozoan motility, 

 livability, and metabolism illustrate the fact of, if not the degree of, 

 such interactions. 



Hydrogen Ion Concentration 



While the pH of male and female mammalian reproductive tract 

 fluids upon removal from the tract has been extensively studied in 

 some species, the question needs reexamination in situ by modern 

 electronic equipment using microelectrodes so as to eliminate ex- 

 posure of the fluids to air and thus tO rapid gaseous exchange. For 

 example, about twenty years ago Davis and Cole (1939) found that 

 semen of the stallion increased rapidly in pH on exposure to air. 

 Could this have been due to loss of CO a from the semen to the at- 

 mosphere on ejaculation? 



In general, one may say that in the larger mammals the evidence 

 suggests that the pH in the epididymis is low, pH 6.0 or even less 

 in cattle, and that it is increased by admixture of the accessory fluids 

 on ejaculation to near neutrality, depending on the sperm cell con- 



