UTERUS (FUNCTIONS). 



677 



woman was entirely ignorant of what had 

 occurred. Scanzoni and Chaussier relate simi- 

 lar examples of birth taking place notwith- 

 standing complete paralysis of the sensitive 

 and motor functions of the lower half of the 

 body. In Chaussier's case the pressure was 

 occasioned by a hydatid cyst which involved 

 the chord on a level with the first dorsal 

 vertebra.* 



On the other hand, that the uterine move- 

 ments are also capable of being influenced by 

 spinal fibres, appears from the following con- 

 siderations. Uterine contractions may be ex- 

 cited by the application of cold to the general 

 surface of the body, or by placing the child at 

 the breast ; by injecting warm and stimulating 

 fluids into the rectum, and in other like modes. 



Again : the uterus, under various circum- 

 stances of health and disease, is observed to 



* Cases of paraplegia have sometimes occurred in 

 which artificial aid appears to have been needed to 

 complete the delivery, as in a case cited by Brachet 

 (Fonctions du Systeme nerveux ganglionaire, p. 266. 

 1830). By those who contend for a preponderance 

 of spinal influence over labour, such cases are cited 

 in proof. It is said that notwithstanding the com- 

 plete loss of sensation and motion in the extremities, 

 independent reflex operations may still be preserved 

 in the uninjured portion of the chord. But the 

 motions which may be occasionally excited by irri- 

 tating paralysed limbs are " disorderly and pur- 

 poseless," and are in no way comparable with those 

 co-ordinated actions that characterise natural la- 

 bour. Moreover, the argument is entirely inappli- 

 cable to the case cited in the text, in which no 

 reflex action whatever could be produced. It has 

 also been supposed that an essential distinction ma}' 

 be drawn between cases in which the disease is 

 situated high up, and those in which it occupies a 

 lower situation: in the latter cases the portion of 

 chord supposed to furnish spinal nerves to the 

 uterus being involved in the disease, and in the 

 former not. But such conclusions can be of little 

 value until the precise limits of the chord, whence 

 spinal fibres can be derived to the uterus, have been 

 anatomically determined. (See the account of the 

 origin of these nerves at p. G41.) 



For like reasons it does not appear that in the 

 present state of neural physiology in relation to the 

 uterus, satisfactory conclusions can always be drawn 

 from experiments upon animals. For although it 

 might seem probable that in a case of mixed nerves, 

 by destroying the centre or origin of one of the 

 sets, the functions of the other might be left unim- 

 paired ; or by stimulating one of the nerve centres 

 alone, their actions would be exclusively called 

 forth, while the rest would remain passive ; still, 

 absolute conclusions cannot always be arrived at, 

 even in these ways. For in the latter case, on ac- 

 count of this very intermixture of nerves, whenever 

 we attempt to stimulate ganglionic centres, or 

 plexuses, we are dealing at the same time with the 

 spinal fibres which pass through them. Or con- 

 trariwise, when we endeavour to destroy extensive 

 tracks of spinal centres, we do not know if the 

 arrest of labour that may follow is not due to the 

 violence which, in most "of these experiments, has 

 caused the death also of the animal within a few 

 hours or days after, rather than to the destruction 

 only of the portion of spine whence uterine fibres 

 are supposed to be derived. In this way, perhaps, 

 we can explain those discordant results of experi- 

 ments, in some of which labour has been arrested, 

 and in others has not apparently been interfered 

 with, so far as uterine action alone is concerned, 

 after greater or less injury or destruction of the 

 chord. 



react upon all or several of the parts just 

 named. 



Hence it appears that a mutual relationship 

 is established, by virtue of which the uterus 

 may be either the excitor of actions in these 

 parts, or may through them be itself excited 

 to action. And there can be no doubt that 

 the spinal cord is the agent through whose 

 reflex operations these several effects are pro- 

 duced. 



From this evidence it may be concluded 

 that the double supply of nerves answers dif- 

 ferent purposes. That the spinal system fur- 

 nishes nerves for the purpose of bringing into 

 harmonious relations all those organs whose 

 cooperation with the uterus is essential or ac- 

 cessory to various steps of the reproductive 

 process. While the organ deriving also a simi- 

 lar or even larger supply from the ganglionic 

 system, these nerves serve to regulate the 

 functions which the uterus itself is capable of 

 discharging without cooperative aid. In this 

 view the offices of the spinal system, as a 

 system of relations, and of the ganglionic, as a 

 system presiding over the direct acts of the 

 parts which it supplies, may be separately ex- 

 hibited. It is doubtless also a chief office of 

 the ganglionic system to regulate and control 

 the action of the blood-vessels with which the 

 uterus is so largely supplied. 



What is the exciting cause of labour? This 

 question carries us only one stage further in 

 the preceding course of inquiry : and the reply 

 to it will be nearly found in the facts already 

 stated. For if these serve to throw light upon 

 the causes of the rhythmic and peristaltic 

 movements of the uterus, then the conditions 

 which determine the first rhythm and first 

 peristalsis, or, in other words, the beginning 

 of labour, cannot lie very remote from these. 



Many circumstances may evoke the first 

 rhythm, which being followed by others, labour 

 becomes established. Thus, irritation of in- 

 cident nerves in various parts and organs may 

 so force those sympathies with the uterus 

 which, for other uses, are established by the 

 spinal system of nerves, as to bring on an un- 

 natural and premature form of labour ; but 

 this is not the present question. 



The determining causes of natural labour 

 can be only satisfactorily sought among that 

 class of phenomena which causes the separa- 

 tion of the ripe fruit from the stem which 

 bears it : in a perfecting, namely, of the fruit 

 or product of conception, so that it becomes 

 fitted for an independent existence, and as a 

 step preparatory to this, in a gradual meta- 

 morphosis of those tissues which, having 

 served for a time the purpose of connecting 

 the two together, are now no longer required 

 by either. This connecting medium in the 

 human subject is the decidua, which lines the 

 whole uterus. Its metamorphoses during preg- 

 nancy have been described. Already as early 

 as the middle of that period, the preparation 

 has begun for a new tissue, which, after labour, 

 is to reconstruct the lining membrane. The 

 old attenuating and perishing decidua, now no 

 longer needed, except at the spot where it 

 x x 3 



