SPERM ATOGENES IS INSEMINATION 181 



action on the part of the latter organ. The os uteri, which is 

 situated above the ventral wall of the vagina, was observed to 

 dip down into the seminal fluid at the bottom of the vagina, and 

 then to be withdrawn again in conjunction with a peristaltic 

 contraction of the uterus. These movements were repeated at 

 intervals. Moreover, it was found that the sucking action 

 could be induced artificially by stimulating the erectile tissue of 

 the vulva. It is probable, however, that the spermatozoa, 

 after once entering the uterus, proceed to their destination un- 

 assisted, and that the direction of their movement is deter- 

 mined by the capacity they possess to respond to the stimuli 

 set up by opposing currents. Moreover, pregnancy has been 

 known to follow imperfect coition in Man, so that there can be 

 no doubt that under certain circumstances the spermatozoa are 

 capable of passing inward by their own unaided efforts. 



INSEMINATION 



The act of copulation results in the introduction of seminal 

 fluid through the generative aperture of the female. The 

 mechanism by which this is effected in the higher animals is 

 described in a future chapter, where the functions of the acces- 

 sory male organs are dealt with. The introduction of the fluid 

 into the female generative passages is known as insemination 

 (as distinguished from impregnation, which is the term used in 

 reference to the female when fertilisation takes place l ). 



It is obvious that in those animals which ovulate spon- 

 taneously during the oestrus periods it should be possible to 

 induce pregnancy at such times by the artificial introduction of 

 spermatozoa into the vagina or into the uterus. That this 

 could actually be effected was probably first demonstrated by 

 Spallanzani, 2 though there is evidence that the practice of 

 artificial insemination was not unknown to the Arabs many 

 centuries ago. 3 The following is a description of Spallanzani's 



1 That is to say, the animal is inseminated when the spermatozoa are 

 introduced, and it is impregnated when the ovum becomes fertilised by a 

 sperm. See Heape, " The Artificial Insemination of Mammals," Proc. Roy. 

 Soc., vol. Ixi., 1897. 



2 Spallanzani, Dissertations, vol. ii., London, 1784. 



3 Gautier, Le Fecondation artificielle, &c., Paris, 1889. 



