Normal Parturition 517 



expulsion of the first and the second fetus. In the cow, where 

 the act of parturition is more deliberate, there is a greater interval, 

 sometimes 20 or 30 minutes. Under abnormal conditions the 

 interval between the expulsion of the two fetuses may be much 

 greater. The birth of the second of a pair of twin fetuses may 

 be delayed for hours or even days after the birth of the first. 

 Any great delay in the expulsion of the second fetus is usually 

 due to some exhaustion in the contractile power of the uterus, 

 resulting from the expulsion of the first fetus and the advent of 

 a subsequent period of rest before the renewal of labor pains for 

 the expulsion of the second fetus. 



In multiparous animals, the entanglement of two fetuses during 

 parturition cannot well occur. No fetus, or parts of a fetus, nor- 

 mally occupies the uterine body. The fetuses are wholly lodged 

 within the two cornua. The body of the uterus is actually nar- 

 rower, when labor sets in, than are the two gravid cornua, so that 

 it is quite impracticable for a fetus from each horn to enter simul- 

 taneously the body of the uterus. One fetus enters at a time and 

 it is assumed that they enter alternately from the two cornua, so 

 that the two are emptied nearly together, that is to say, that one 

 horn is not completely emptied of its fetuses until the other is 

 also emptied of all but one. 



Symptoms of Parturition. Preliminary to the completion 

 •of pregnancy there appear certain signs which indicate to us, 

 with more or less certainty, the near approach of labor. 



One of the most conspicuous of these is the increased func- 

 tional activity of the milk glands. In all of our domestic animals 

 there is a tendency for the glands to become gradually enlarged 

 and ten.se as the period for giving birth to young approaches. 

 The date at which this enlargement appears varies, being of 

 longer duration in primipara than in those which have previously 

 given birth to young. Usually a few weeks before birth there 

 appears in the udder at first a watery secretion, which may be 

 pressed from the teat, but which bears only a faint resemblance 

 to milk. Later the secretion becomes more milk-like and assumes 

 the characters of colostrum, which some claim is essential to the 

 well-being of ^the young. When parturition is near, the milk 

 secretion may be so profuse that it escapes from the teat in drops, 

 or in streams. 



