I'HYsiuLouy OF I'.urrrjuTiox. 227 



BOOlv IV. 



XUKMAl. PAKTUKITIUN. 



Xoii.MAL, natural, physiological, or spontaneous parturition or birth, is 

 the expulsion of the fcctus from the uterus through the maternal 

 passages, by natural forces, when it is suf!iciently developed to live 

 external to its parent. This act is designated " foaling," when occurring 

 in the Mare, " calving " in the Cow, " lambing " in the Sheep, " pup- 

 ping " in the Bitch, etc. It receives the designation of "normal," 

 " natural," etc., when it is accomplished in a manner favourable to the 

 parent and offspring without extraneous assistance, and by natural 

 forces alone ; and " abnormal," " pathological," or " dillicult," when it 

 cannot be so accomplished, and when the aid of man is required to 

 relieve ilie parent and release the progeny. Though eminently a 

 physiological act, it is nevertheless one of the most difficult ; the 

 inter\'al between normal and pathological parturition is sometimes 

 extremely brief, the one being often transformed into the other in a 

 remarkably short time. It is also said to be " premature " when it 

 occurs before the usual period, and the young creature is bcrn in a 

 viable condition; while it is "prolonged" birth when pregnancy 

 extends beyond the ordinary term. We have already spoken of these 

 terms, and alluded to their diversity ; and we have only now to note 

 that these variations do not appear to have any influence on the physio- 

 logical act of parturition. 



CHAPTER I. 

 Physiology of Parturition. 



The act of parturition, notwithstanding its special object, is dis- 

 tinguished from all other physiological acts or functions by certain 

 peculiarities ; for while the latter are normally accompHshed without 

 disturbing in any way the well-being of the individual, parturiticm, on 

 the contrary, even when natural, is accompanied by pain, general dis- 

 turbance and uneasiness, and violent efforts. And during birth nature 

 does not appear to obey those in)nmtable laws so strictly as in the 

 accomplishment of other physiological acts, but makes frequent and 

 wide deviations ; though these do not often compromise the final result. 

 We never find two births exactly alike, but each otTers something pecu- 

 liar when attentively observed. We need only refer to the duration of 

 the act as a whole, as well as to each of its periods or stages. Some- 

 times it only occupies a few minutes, in other instances days are 

 required to complete it ; in some cases the first stage is long and the 

 second short, and in others it is the reverse. The " labour pains," or 

 utero-abdominal contractions, present as notable differences with regard 

 to intensity, duration, and frequency, as well as in the pain they cause 

 and the influence they exercise on the other parts of tlie body ; while 

 the amount of allantoid or amniotic fluid is as variable, though no ill 

 effects may result from this. And, finally, the foetus may present itself 

 for expulsion in a variety of positions, which, though they may not 

 impede birth, yet prove that parturition is an extremely variable act, 

 while its phenomena are highly complex. 



