THE FEMALE GENERATIVE ORGANS 531 



that stimulation of the medulla caused the movements of the 

 uterus to cease. Moreover, it is to some extent borne out by 

 the fact that the " pains " of labour can often be inhibited by 

 emotions and other contemporary actions of the central nervous 

 system (see below, p. 539). 



It is well known that uterine contraction can be induced by 

 the presence of a foreign body in the uterus, by injections into 

 the rectum, by the appUcation of the child to the breast, and 

 by various other means. According to Kmrdinowski -^ the 

 sensation of any violent pain may cause uterine contraction in 

 animals, and the organ may respond to remote stimulation 

 (e.g. in the ears). These observations alone are sufficient to 

 show that the contraction is often a reflex act. The experimental 

 evidence cited above shows no less clearly that the controlhng 

 centre is in the lumbar portion of the spinal cord. Nevertheless 

 there are many indications, as just mentioned, that the move- 

 ments of the uterus can be brought under the influence of a 

 higher centre situated in the brain. On the other hand, the 

 fact that rhythmical contractions can continue to occur in the 

 absence of all nervous connections is a certain proof that they 

 are primarily independent of the nervous system, although 

 normally they are to a large extent influenced by it. It must 

 be concluded, therefore, that the power to contract and relax 

 rhythmically is an inherent property of the muscular tissue of 

 the uterus. 



The question as to the nature of the mechanism involved 

 in uterine contraction is inseparably connected with the further 

 problem concerning the part played by nervous influence in 

 controlhng the course of parturition. This subject is dealt 

 with below (p. 537). 



The Normal Course of Parturition in the Human 

 Female 



The increased size of the foetus, together with the accumula- 

 tion of the amniotic fluid, causes the uterus towards the end of 

 pregnancy to become considerably distended. The enlarge- 



' Kurdinowski, " Ueber die Eeflectorische Wechsel bezlehung zwisohen 

 der Biustdriisen und dem Uterus," Arch. f. Oynak., vol. Ixxxi., 1907. 



