44 VETERINARY OBSTETRICS. 
involuntary muscular contractions; the longitudinal 
fibres, in the primary stage of the act, and both 
longitudinal and circular, in the later stages, contracting, 
and thus the expulsion of the foetus is brought about. 
~The umbilical cord is ruptured at the act of 
parturition, or immediately afterwards. Ina state of 
nature, the parent tears the cord with her teeth, if it is 
not ruptured in the act. The foetal membranes, or 
envelopes, may come away with the foetus, or may be 
retained in the uterus for several days, and require to 
be removed by hand. 
Parturition in the Cow may be completed in from 
half an hour to one anda half hours, but sometimes 
may be prolonged for five or six hours, and both 
mother and fcetus do well. In the Mare, how- 
ever, if the act is prolonged beyond two to two and 
a half hours, there is danger of the foetus dying, 
possibly also the parent. 
Parturition, as thus described, requires no assistance. 
Those cases in which mechanical or other inter- 
ference is necessary, is called “ difficult parturition,” or 
“ difficult labor.” 
