The Influence of Extraneous Factors 55 



and de Quatrefages were fully aware of the fact that sodium chloride 

 and various other sodium and potassium salts, are able to stimulate 

 or inhibit sperm motility, according to concentration and specific 

 experimental conditions. Their results were soon confirmed and 

 extended by others, including Koelliker (1856) whose paper on 

 'Physiologische Studien liber die Samenfllissigkeit' still remains the 

 most comprehensive survey of its kind, and includes observations 

 on spermatozoa of the bull, stallion, dog, rabbit, pigeon, frog and 

 fish. Koelliker pointed out that spermatozoa rendered motionless by 

 dilution with water can be revived by prompt addition of salts or 

 concentrated solutions of certain organic substances such as sucrose, 

 glucose, lactose, glycerol, urea and various proteins. He investi- 

 gated in some detail the activating influence of blood serum, male 

 accessory gland secretions, and of a variety of inorganic and organic 

 substances on sperm motility. It was he who found that cyanide is 

 not an inhibitor of sperm motility and established that acids are, 

 on the whole, more harmful to the sperm than alkalies. 



Furthermore, Koelliker noticed that if a drop of a fairly concen- 

 trated solution of potassium hydroxide is mixed with a drop of 

 semen on a microscopic slide, there is usually a sudden outburst of 

 activity before the spermatozoa are rendered motionless. Such a 

 period of short-lived stimulation which precedes the terminal loss 

 of activity, is rather characteristic of various sperm-paralysing 

 agents including distilled water. Schlenk (1933) aptly named the 

 phenomenon 'Todeszuckung'. Not all investigators, however, seem 

 to have realized the fundamental difference between short and pro- 

 longed activation phenomena, and many of them tended to confuse 

 a transient increase in initial motility with the state of activity essen- 

 tial for the maintenance of continuous motility and for sperm sur- 

 vival. Only too often substances have been pronounced as beneficial 

 to spermatozoa merely because they were observed to stimulate 

 motility and metabolism, no heed being paid to the fact that this 

 very stimulation may have shortened, rather than prolonged, the 

 life of spermatozoa. Similarly, many a substance has been declared 

 detrimental to spermatozoa solely because it appeared to reduce the 

 speed of movement and metabolic rate. However, quite often the 

 lowering of activity tends to prolong the life of spermatozoa, and 

 favours, rather than hinders, their survival. 



