INNERVATION OF THE GENERATIVE ORGANS 579 



are being suckled and the mother becomes pregnant the implantation 

 of the embryos is retarded for about nine clays, and until suckling- 

 ceases, and that a corresponding prolongation of the period of 

 gestation occurs, as compared with that of non-suckling females. 

 In other cases of suckling mice, according to Kirkham, ovulation 

 is inhibited or postponed. These phenomena are interpreted as 

 being of a protective nature to the parent organism, since mice whose 

 litters are removed at birth usually produce young so frequently 

 that they die of exhaustion before reaching their climacteric. 



THE PUERPERIUM 



In multiparous women the uterus continues to contract and relax 

 at more or less regular intervals after the expulsion of the placenta 

 which marks the termination of the third stage of labour. The 

 contractions which occur at this period give rise to the sensations 

 commonly known as the " after-pains." These may last several days, 

 but are not generally very severe after the first day. They are 

 particularly liable to occur when the child is put to the breast, a 

 fact which seems to indicate a nervous connection between the 

 uterus and the mammary glands. In primiparous women the tonicity 

 of the puerperal uterus is usually greater than in multiparous ones, 

 so that the uterus is capable of remaining during this period in a 

 state of almost uninterrupted retraction unless blood clots or other 

 foreign bodies are present in the cavity, in which case the organ 

 undergoes movements in attempting to expel them. 



This tonic retraction of the uterus is an important factor in 

 closing the blood sinuses, and so preventing bleeding. If, owing to 

 any circumstance, the normal contraction and retraction of the 

 uterus are interfered with, post-partum haemorrhage is liable to 

 occur. This is not infrequently the case with white women who 

 have migrated to the tropics, or with ill-nourished women in the 

 slums, in whom, owing apparently to an inefficiency in the uterine 

 nerve supply, the organ tends to become inert. 1 It follows from 

 what has been said that multiparous women are more liable to 

 post-partum haemorrhage than primiparous ones. 2 



According to Longridge the anaemic condition of the normal 

 puerperal uterus is due partly to the effacement of the ovarian and 

 uterine arteries which occurs when the uterus contracts. "The 



1 Longridge, The Puerperium, London, 1906. 



2 Longridge has pointed out, however, that the amount of post-partum 

 discharge in multipart is not as a rule in proportion to the severity of the 

 "'after-pains," and consequently that the latter cannot be ascribed simply to 

 defective retraction on the part of the uterus. He suggests, therefore, that 

 the "after-pains" in multipart are largely due to the uterus suffering from 

 cramp resulting from the excessive exertion involved in discharging the child. 



