Xn] THE MALE GENERATIVE ORGANS 161 



applicable in those species in which ovulation can take place 

 spontaneously (that is irrespectively of the occurrence of coition ; 

 see p. 183) but this fortunately is the case normally with all farm 

 animals. As Heape has pointed out undue rigidity of the cervix 

 uteri (see p. 166), constriction of the canal, occlusion of the os 

 uteri, or other similar defects may prevent the passage of the 

 spermatozoa into the uterus, while the presence of an abnormal 

 acid secretion in the vagina may kill or deleterioush^ affect the 

 spermatozoa before they can effect an entr}'. In such cases the 

 defect may be overcome by inserting the end of a s^'ringe or in- 

 seminator into the mouth of the uterus and so injecting the semen 

 directly into the body of that organ. The semen can be obtained 

 either from the vagina of the same mare (or other female animal 

 in suitable cases) or from the vagina of another mare which has 

 just been served, the method being to cause the fluid to collect 

 in a little pocket or depression made by the finger tips and then 

 to draw the semen into the sjTinge bj' relaxing the rubber bulb 

 which is held in the hand at the other end of the inseminator 

 and had been previously compressed. In our own experience 

 a not uncommon cause of sterility in mares is evacuation of the 

 semen immediately after service. In such cases the fluid can be 

 caught in a beaker or other vessel on emission from the vagina 

 and then injected. Another method of insemination is to collect 

 the fluid in gelatine capsules which ma}^ be placed in the vagina 

 before copulation, and then to remove them after they have been 

 filled, close their lids and insert them into the uterus, either of the 

 same or of another female, when the heat of the body melts the 

 gelatme and sets free the spermatozua. By this means a number 

 of mares may be impregnated as a result of one service b}' a 

 stallion. 



The possibility of transporting semen from a distance and then 

 utilising it for purposes of insemination is uell worth}' of con- 

 sideration, but so far few experiments have been carried out. It 

 has been found however that the spermatozoa of the rabbit retain 

 their vitaHty within the male generative passages for at least ten 

 days, and that those of other animals can live in suitable artificial 

 media (e.g. glucose and various salt solutions) for two daj^s 

 especiall}- ■i\hen kejit at a temperature sufficiently low to inhibit 

 bacterial multiplication and consequent change in the composition 

 of the fluid. 



