610 THE PHYSIOLOGY OF REPRODUCTION 



The method adopted by gynaecologists who have practised 

 artificial insemination is to inject seminal fluid into the uterus 

 by means of a syringe, the fluid in most cases being obtained 

 from the vagina of the same individual shortly after coitus. 

 In this way it has been found possible to overcome such 

 structural defects as constriction or undue rigidity of the cervix 

 or hypertrophy of the Ups of the external os uteri. By modify- 

 ing 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 inabihty 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 sterihty, 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 hps of the external os, and the 

 formation of false membranes which may effectually close the 

 orifice ; inabihty to retain spermatozoa in the vagina, owing to 

 abnormal shortness of the organ or to violent muscular con- 

 traction after coitus ; a want of sufficient muscular power ; 

 abnormal structure or size of the cervix or os uteri, which pre- 

 vent 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 kiU or deleteriously affect the spermatozoa, &c., 

 may be overcome by artificial insemination." ^ Heape, and 

 more recently Iwanoff,^ have cited numerous cases in which 

 mares have been got in foal successfully 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 



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



' Iwanoff, loc. cil. This important memoir, besides containing descrip- 

 tions of the author's own experimehts, gives a very fnll account of the 

 literature of artificial insemination. 



* See also a booklet edited and published by Huish, The Cause and 

 Remedy for Sterility in Mare, Cows, and Bitches, London. 



