572 THE PHYSIOLOGY OF REPRODUCTION 



in which the spinal lesion was apparently in the lumbar region of the 

 cord. In this case the uterus failed to make the normal contractions* 

 and the child was eventually extracted with forceps. The placenta 

 also had to be removed by hand. It is clear, therefore, that a spinal 

 lesion in the lumbar region may result in materially weakening the 

 action of the uterus, and so may hinder the normal course of labour. 

 On the other hand, in those cases in which the lesion was in the 

 dorsal part of the cord, the possibility of spinal reflexes in the lumbar 

 region could not be excluded.^ 



The, following general conclusions regarding the nervous mechanism 

 of parturition are based largely on those of Eouth. (1) The act of 

 parturition is partly automatic and partly reflex, these actions 

 corresponding in the main to the first and second stages of labour 

 respectively, the spinal reflexes usually commencing as soon as the 

 membranes have ruptured. (2) Direct communication with the brain 

 is not essential for the proper co-ordination of iiterine action, but 

 the brain appears to exercise a controlling influence of some kind. 

 Thus, emotions often become a hindrance to the progress of parturition. 

 It would seem possible that this inhibition of uterine contractions is 

 brought about by an inhibition of a centre in the brain (see above, 

 p. 564). (3) Direct communication between the utervis and the 

 lumbar region of the cord is generally essential for the occurrence of 

 those rhythmical contractions which take place during the progress 

 of normal labour. There is experimental evidence upon animals, 

 however, that the uterus is sometimes able automatically to expel its 

 contents, at least as far as the relaxed portion of the genital cord, 

 even when entirely deprived of all spinal influence.^ 



Changes m the Maternal Organism 

 The influence of parturition upon the metabolism of the maternal 

 organism is dealt with by Sellheun.^ There is a slight rise of 

 temperature during the process, and the pulse rate is also affected, 

 being much quicker during the pains, bu!t slower between them, the 

 difference amounting to as much as thirty-six beats a minute. The 

 blood shows a marked leueocytosis, and the blood pressure is higher. 

 Urine is secreted in smaller quantities, and is liable to contain traces 

 of renal epithelium, red and white blood corpuscles, and albumen. 



' Eouth also discusses post-mojiem parturition, but points out that in most 

 of those cases wherer it occurred, the expulsion of the foetus was caused by 

 increased abdominal pressure due to putrefactive gaseous distension during a 

 condition of muscular relaxation. There are some facts which go to prove that 

 uterine contractility and retraction may continue or even commence after death, 

 possibly resulting from the movements of the imprisoned child. 



2 For further references to the literature of the nervous mechanism of 

 parturition, see Bechterew, Die Funktionen der Nervencentra, Weinberg's 

 German translation, vol. i,, Jena, 1908. 



^ Sellheim, loc. cit. 



