8o INTRODUCTION TO SEXUAL PHYSIOLOGY 



the foetus may appear first (breech presentation), or the foetus 

 may be presented crosswise. In such cases skilled assistance 

 is necessary in order to bring about a satisfactory delivery. 



The Nervous Mechanism of Parturition. — The uterus is 

 innervated from the lumbar part of the spinal cord, the fibres 

 coming by the second to the fifth lumbar nerves and from the 

 hypogastric. The process of parturition depends normally on 

 the integrity of the spinal cord which co-ordinates the various 

 muscular movements. The uterus, however, even in the virgin, 

 undergoes more or less rhythmical contractions, independently 

 of its nerve connections. Thus the uterus of a bitch or other 

 animal will do so after removal from the body, provided the organ 

 is maintained at the normal temperature and suspended in a suit- 

 able saline fluid. Goltz showed that the bitch may give birth 

 to pups after the complete exsection of the spinal cord in the 

 lumbo-sacral region, the unco-ordinated contractions of the 

 uterine muscles being sufficient to induce expulsion. An experi- 

 ment by Sir James Young Simpson, the distinguished discoverer 

 of the anaesthetic properties of chloroform, on a pregnant sow, 

 provided a curious demonstration of incomplete parturition 

 after the experimental destruction of the posterior part of the 

 spinal cord. The entire litter of young pigs, excepting for the 

 last, was expelled by uterine contraction alone, the abdominal 

 muscles taking no part in the action owing to the absence of 

 nervous connection. The last young one, however, remained 

 in the vagina, owing to the abdominal muscles not acting, there 

 being no other young ones in process of being pushed out of the 

 uterus to propel the remaining pigling through the external 

 opening. The various cases on record (Brachet's, Routh's, etc.) 

 in which conception took place in women suft'ering from para- 

 plegia (spinal paralysis) and was followed in due course by 

 parturition illustrate further the possibility of the process occur- 

 ring in the absence of co-ordination by the central nervous system. 

 Under such a condition parturition is attended with difficulty 

 and yet may be successfully accomplished. 



The Cause of Parturition 



As regards the immediate cause of parturition, various theories 

 have been put forward in past times, but none of them have 



