682 UTERINE CONTRACTIONS. [BOOK iv. 



labour will progress quite naturally while the patient is unconscious 

 from the administration of chloroform, shews that in woman also 

 the whole matter is an involuntary action, however much it may be 

 assisted by direct volitional efforts. That the uterus is capable of 

 being thrown into contractions through reflex action, excited by 

 stimuli applied to various afferent nerves, is well known. The con- 

 traction of the uterus, which is so necessary for the prevention of 

 haemorrhage after delivery, may frequently be brought about by 

 exerting pressure or by dashing cold water on the abdomen, by the 

 introduction of foreign bodies into the vagina, and especially by 

 putting the child to the nipple. And we learn from experiments 

 on animals that rhythmic contractions of the uterus resembling r at 

 least those of parturition may be brought about in a reflex manner 

 by stimulating various afferent nerves. Similar movements may 

 be induced by direct stimulation of the spinal cord along its whole 

 length, as well as of various parts of the brain; but there are 

 reasons for thinking that in these cases, the impulses started in the 

 brain, and upper part of the spinal cord, produce their effects by 

 working upon what may be called a 'parturition' centre in the 

 upper lumbar regions of the cord. And it would appear that' the 

 uterine contractions which are induced by such drugs as ergot as 

 well as those caused by asphyxia, are, at all events in part, brought 

 about by the agency of the same lumbar centre. From this centre 

 the paths for the efferent impulses appear (in the dog) to be two- 

 fold: one along sympathetic tracts, by nerves passing from the 

 inferior mesenteric ganglion to the hypogastric plexus, and the 

 other along spinal tracts by branches of the sacral nerves to the 

 same plexus. It is stated that the characters of the movements 

 induced by stimulating these two tracts are somewhat different 

 and moreover that the sympathetic tract is vaso-constrictor and the 

 spinal tract vaso-dilator in nature; but the matter has not yet been 

 fully worked out. 



We are however hardly justified in considering the rhythmical 

 contractions of the uterus during parturition as simple reflex acts 

 excited by the presence of the foetus. We are utterly in the dark 

 as to why the uterus, after remaining apparently perfectly quiescent 

 (or with contractions so slight as to be with difficulty appreciated) 

 for months, is suddenly thrown into action, and within it may be a 

 few hours or even less gets rid of the burden it has borne with 

 such tolerance for so long a time; none of the various hypotheses 

 which have been put forward can be considered as satisfactory. 

 And until we know what starts the active phase, we shall remain 

 in ignorance of the exact manner in which the activity is brought 

 about. The peculiar rhythmic character of the contractions, each 

 'pain' beginning feebly, rising to a maximum, then declining, and 

 finally dying away altogether, to be succeeded after a pause by a 

 similar pain just like itself, pain following pain like the tardy 

 long-drawn beats of a slowly beating heart, suggests that the cause 



