2 26 NORMAL PARTURITION. 



secundines of the last puppy, devours them, and returns to the other 

 puppies. 



With animals usually uniparous, but which sometimes bring forth 

 two or mqre young, the envelopes of each foetus are expelled immedi- 

 ately after it is born, so long as they do not offer an obstacle to the 

 passage of the next foetus ; so that in a double birth in the Cow or Ewe, 

 a foetus being lodged in each horn, the second may be born without the 

 envelopes of the first having been discharged. 



We may here note the strange instinct which impels not only carnivor- 

 ous and omnivorous, but also herbivorous animals — Bitch, Cat, Sow, Cow, 

 and even sometimes the Mare — to devour the membranes as soon as they 

 are expelled, if they are not quickly removed from beyond their reach ; 

 at times they even devour them as they are being extruded, and the work 

 of delivery is thus hastened. However unnatural and disgusting this 

 propensity may appear, and though the cause for it is unknown, it does 

 not occasion any visible inconvenience to the creature. 



It has been already remarked, that when the young creature is expelled 

 in its intact envelopes, the mother, if at large, frees it from them by 

 gnawing them through ; more rarely does the progeny release itself by 

 its own efforts. If the mother should chance to be tied up, as in a stall, 

 assistance may be required to cut the umbilical cord and extract the 

 young animal from its imprisoning membranes, as it may become as- 

 phyxiated. This peculiarity is most frequently observed in the Mare, 

 with which birth is always rapid, and the chorion strong and easily de- 

 tached from the uterus. Rueff states that it is not unusual in the Sow. 



CHAPTER II. 



Presentations of the Fcetus and Mechanism of Parturition. 



In addition to, and to a certain extent independent of, the physiological 

 phenomena of gestation and parturition, there are in the latter certain 

 physical and mechanical acts which have been, as Saint Cyr truly re- 

 marks, hitherto very imperfectly studied in veterinary medicine, but 

 whose consideration is, nevertheless, very important in a practical point 

 of view. 



These acts are related to the manner in which the foetus presents at 

 the pelvic inlet for passage through the outlet, and the way in which this 

 passage is effected; they belong, in fact, to the presentations and posi- 

 tions of the foetus, and the mechanism of parturition. 



The presentations and positions of the foetus during parturition, as well 

 as the mechanism of that act, are of much practical importance to the 

 veterinary obstetrist, and demand careful consideration. We have re- 

 peatedly alluded to the position of the foetus in the uterus during gesta- 

 tion, and have stated that this position is changed as parturition draws 

 near. What the agency or influence may be which induces this change, 

 has not been ascertained ; but it has been surmised that it is due to an 

 instinctive tendency of the fcetus to assume, towards the termination of 

 pregnancy, the position most favorable for its exit through the pelvic cav- 

 ity ; though it is indeed very questionable whether the instinctive facul- 



