GENITAL SYSTEM. 487 



the verm ior ;anum; it cannot immediately escape along the 

 canal on account of the contraction of the urethra! sphincter. 

 But this muscle cannot long maintain its state of contraction ; 

 it relaxes, and immediately, under the influence of the high 

 pressure which it has acquired, the seminal fluid is precipi- 

 tated, and forcibly precipitated ; then the muscle again con- 

 tracts and arrests the seminal eruption ; again suddenly 

 relaxes and so on, so long as the ejaculation continues. We 

 see thus that the force of the ejaculation is due to the sudden 

 relief of the high pressure, and the rhythm to the alternate 

 contraction and relaxation of the urethral sphincter. 



In this view it is seen that the integrity of the pros- 

 tate is as important to the act of generation, as it is to that 

 of micturition. It is here also the contact of the seminal 

 fluid with the mucous surface which influences the intermittent 

 and tetanic contraction of the urethral sphincter. So, also, dis- 

 ease of the prostatic mucous surface has a great influence over 

 the function of generation, and may cause, either satyriasis, 

 impotence, or seminal emissions. This explains the useful- 

 ness of cauterization (Lallemand) to counteract the last- 

 named disturbance. 



It is interesting to note the circumstances which favor the 

 movements and vitality of the spermatozoids in the ejacu- 

 lated seminal fluid. Cold water, the electric spark (Prevost 

 and Dumas), and acid solutions destroy the spermatozoids; 

 slightly alkaline and neutral solutions are favorable to and 

 increase the activity of their movements. The vaginal 

 mucus destroys them only when it is very acid; under 

 ordinary circumstances the spermatozoids remain living for a 

 long time in the vagina, arid Percy has collected them in a 

 state of activity at the neck of the womb, eight days after 

 the last coitus. 1 Finally, according to Godard, the menstrual 

 blood increases the activity of their movements. 



Moreover, the spermatozoids can live in pus, blood, and 

 various other fluids. Sims has often seen conception take 

 place even during severe suppuration of the neck of the 

 uterus. According to Kb'lliker phosphate of soda is especially 

 favorable to their activity. 



. * See Marion Sims, " Notes Cliniques sur la Chirurgie Ute- 

 rine." Traduct. frangaise, Paris, 1872. 



