PARTURITION ITS NATURE AND CAUSE. 911 



contractions by the dash of cold water on the abdominal surface, by the in- 

 jection of cold water into the vagina, by the ingestion of cold water into 

 the stomach, or even by dipping the hand into cold water, or again by the 

 suctorial application of the infant's lips to the nipple, by the introduction 

 of the hand into the vagina, by violent movements of other parts of the 

 body, and by various other means. This general fact has an important 

 practical bearing ; since there are various occasions on which it is most im- 

 portant to life that the previously flaccid uterus should be excited to vigor- 

 ous contraction, for the sake of accelerating parturition or of suppressing 

 haemorrhage ; whilst, on the other hand, it is often no less important to be 

 able to prevent or to antagonize the operation of causes which would prema- 

 turely induce uterine contractions, to the destruction of the offspring and 

 the danger of the mother. 



TGI. When, in the normal act of Parturition, the head has so far made 

 its way through the os uteri as to begin to distend the lower part of the 

 genital canal, a new kind of expulsive effort is superadded to that of the 

 Uterus itself; the assistance of the Expiratory muscles being then called in 

 ( ")()7>, through the intermediation of the Spinal Cord, which is probably 

 excited to this action by the stimulus thus applied to the afferent nerves of 

 the compressed parts ; and it is chiefly by the instrumentality of these mus- 

 cles that the normal act of parturition is usually completed. The same 

 action which expels the foetus, generally also detaches the placenta ; and if 

 the uterus contract with sufficient force after this has been thrown off, the 

 orifices of the vessels which communicate with it are so effectually closed, 

 that little or no haemorrhage takes place. If, however, the uterus does not 

 contract, or relaxes after having contracted, a large amount of blood may 

 be lost in a short time from the open orifices. For some little time after 

 parturition, a sero-sanguineous discharge, termed the lochia, is poured out 

 from the uterus; and this commonly contains shreds of the deciduous mem- 

 brane which had not been previously detached, together with a quantity of 

 fat-globules, and other products of disintegration of the uterine tissue ( 351 j. 1 

 Within a few weeks after delivery, the uterus regains (at least in a healthy 

 subject) its previous condition ; part of its newly generated muscular fibres 

 seem to disappear altogether, whilst the others shrink to their ordinary di- 

 mensions ; and the portion of its mucous membrane which had been thrown 

 off as Decidua, seems to be to some extent reproduced, according to the 

 researches of Dr. Matthews Duncan and M. Robin, even before delivery 

 occurs, so that the muscular tissue of the Uterus is never left completely 

 denuded. 2 



762. As to the reason why the period of Parturition should be just forty 

 weeks after the occurrence of Conception, we know nothing more than we 

 do of that of similar periodical phenomena in the history of the life of Man 

 and of other living beings; all of which must be considered as occasional 

 manifestations of changes that are constantly in progress, whose rate, being 

 dependent upon the degree of Heat supplied, is so uniform in warm-blooded 



1 In addition to the evidence above referred to, of the rapid occurrence of fatty 

 degeneration of the uterine structure after parturition, the Author may mention that 

 hc'has been informed by Dr. Retzius (Professor of Midwifery at Stockholm) that hu 

 has detected a large number of fat-globules in the urine, of puerperal women. Is it 

 not possible it may be further asked that some of the oleaginous matter so copiously 

 pound forth by the Mammary glands, may be derived from this source? Such an 

 economy of nutrient material would be consistent with what we elsewhere meet with ; 

 and the idea is conformable to the fact that the proportion of butyrin in the milk is 

 much greater in the earlier, than in the later months of lactation. 



2 See Huxley's Elements of Coinp. Anatomy, 1864, p. 107. 



