648 THE PHYSIOLOGY OF REPRODUCTION 



The method adopted by gynsecologists who have practised 

 artificial insemination is to inject seminal fluid into the uterus by 

 means ol a syringe, the fluid in most cases being obtained from 

 the vagina of the same individual shortly after coitus. In this 

 vi^ay it has been found possible to overcome such structural defects 

 as constriction or undue rigidity of the cervix or hypertrophy of 

 the lips of the external os uteri. By modifying the method by 

 which the semen is obtained, it has proved possible to induce 

 pregnancy in cases of abnormal vaginal secretion where the 

 spermatozoa are ordinarily killed before they can effect an entrance 

 into the uterus, and in other cases where there is an inability on 

 the part of the vagina to retain the semen after coitus. 



Artificial insemination has frequently been practised on mares 

 with a view to overcoming certain forms of sterility, and considerable 

 success has been attained. " Such defects as flexion or constriction 

 of the canal of the cervix ; rigidity of the cervix ; hypertrophy of 

 the lips of the external os, and the formation of false membranes 

 which may effectually close the orifice; inability to retain sper- 

 matozoa in the vagina, owing to abnormal shortness of the organ 

 or to violent muscular contraction after coitus ; a want of sufficient 

 muscular power; abnormal structure or size of the cervix or os 

 uteri, which prevent the free .action of the functions of the cervix ; 

 occlusion of the os owing to spasmodic contraction of the muscles 

 of the cervix during coitus ; abnormal or excessive vaginal secretions, 

 which may kill or deleteriously affect the spermatozoa, etc., may be 

 overcome by artificial insemination." ^ Heape, and 'more recently 

 Iwanoff,^ have cited numerous casQs in which mares have been got 

 in foal sucoessfully by artificial insemination. 



The actual methods employed are described by these writers.^ 

 The most usual plan is to allow the stallion to serve the mare in 

 the ordinary way, and then, immediately afterwards, to insert a 

 syringe into the vagina, and draw up into it some of the seminal 

 fluid which is caused to collect in a depression or pocket made in 

 the vaginal floor by the pressure of the flnger tips. The same mare 

 can then be inseminated by injecting the fluid so obtained into the 

 uterine cavity, or the semen can be utilised for impregnating other 



' Heape, "The Artificial Insemination of Mares," Veterinarian, 1898. In 

 the writer's experience incapacity to retain the semen after service is a 

 common cause of sterility. It is sometimes possible to catch the fluid as it 

 is evacuated from the vagina with a beaker, and then to inject it through 

 the OS uteri. 



2 Iwanoff, loc. cit. This important memoir, besides containing descriptions 

 of the author's own experiments, gives a very full account of the literature of 

 artificial insemination. See also lwa.no3, Jour, of Agric. Sci., vol. xii., 1922. 



^ See also a booklet edited and published by Huish The Cause and Remedy 

 for Sterility in Mares, Cows, and Bitches, London. 



