77/ /v HXl'i:LLISn POWERS IX I'lnTlTRITIOX. Ti\ 



seKiiiont of one of the cornua nearest the cervix, then the next segment, 

 and so on until tlie one in proximity to tlie ovary is reached, so as to 

 j^'et rid of all successively — one cornu expelling a fcetus alternately with 

 the other ; the uterine contractions, although general, being most ener- 

 getic at the portions intermediate to the fcetuses. 



The uterine contractions are very powerful, as anyone can testify 

 who has had occasion to introduce his hand into the uterus of one of the 

 larger animals during parturition ; and their force is not always related 

 to the general physical power of the animal — though they are always 

 m: ire energetic in the Mare than the Cow, as well as more continuous. 

 .\ )t iufrecjuently they are more powerful in weak-looking animals than 

 in those wliich are robust and vigorous ; and their energy depends 

 evidently upon the development of the muscular structure of the uterus, 

 and the potency of the sympathetic ganglia which stimulate it. Their 

 energy and frequency also often depend upon the duration of the 

 pains, and the existence of mechanical obstacles to the birth of the 

 fu'tus. 



After the complete dilatation of the os, the third stage of delivery 

 begins, and the manner in which the uterus contracts is modified. 

 The resistance is no longer at the cei'vix, but in the uterus itself, being 

 due to the presence of the fcetus ; and now the circular as well as the 

 longitudinal fibres come into action simultaneously, in order to diminish 

 the uterine cavity and quite expel its contents. In this they are 

 greatly aided by the abdominal muscles and the diaphragm, which 

 until now could assist but little ; though the participation of these 

 does not appear to be absolutely indispensable, for birth may take 

 place without it. Nevertheless, it is a fact that, in diminishing the 

 abdominal cavity and pressing on its contents, these muscles concur 

 in pushing the fcetus in the direction in which least resistance is 

 offered — towards the pelvic cavity ; and as their contractions are 

 effective, so do those of the uterus, which are coincident with them, 

 become increased in power and frequency. The animal '* strains," as 

 in defecation or micturition, but with all its force ; and these throes, 

 which are involuntary to a great extent, and in which nearly all the 

 muscles of the trunk share, soon bring tlie act to a termination. 



The fcetus itself has been sometimes regarded as the chief agent in 

 parturition, from the fact that this act is longer and more dilVicult 

 when the creature is dead, and that it has been expelled after the 

 mother has ceased to live. But it must be remembered that the move- 

 ments of the fcL'tus are very trifling, and of little importance when com- 

 pared with the resistance to be overcome at birth ; so that the young 

 creature must remain almost, if not quite, passive during the act. And 

 if this act is tardily accomplished when the fcetus is dead, the delay 

 may be due to the absence of stimulation or irritation in the organ, to 

 the uterus not having a fixed point to act upon, or perhaps even to a 

 local septosis or paralysis from the decomposition of the foetus. 



With regard to expulsion of the futus after the death of the mother, 

 it must also be remembered that all the organs do not cease to live at 

 once, and that many continue to contract for some time after the 

 mother's heart has ceased to pulsate. Leroux has felt this organ con- 

 tracting a quarter of an hour after death, and after gastro-hysterotomy 

 on the dead human body it has been seen to contract as in the living 

 woman ; Haller has witnessed the contraction of the cornua of the 

 Cat's uterus, even when the organ was detached from the body ; and 



