66 BOVINE OBSTETRICS 



from being sufficient. After the cervix is once open- furUier 

 dilatation is continued from within the uterus, and therefore is 

 a passive one. 



By the contractions of this stage, a portion of the chorion, 

 which lies close to the inner opening of the cervix uteri, is 

 detached from the maternal placentae and is pushed forward in 

 the shape of a bladder by the allantoic fluid, which is under 

 high pressure. As a result of the pressure exerted by this 

 bladder against the internal uterine opening and its adaption 

 to the form of the cervical canal, dilatation slowly pro- 

 gresses. 



Anatomy teaches us that the mucous folds (palmss plicatse) 

 of the cervix uteri lie in such a way that the uterus may be 

 probed from within to without, but not vice versa. As soon as 

 the cervix uteri is somewhat dilated, the secretion of the palmse 

 plicatse advances into and beyond the vagina, — thus corrobor- 

 ating the anatomical peculiarity just mentioned. In this stage, 

 therefore, we see long viscid streams of mucus appear at the 

 vulva. The cervix is gradually dilated by that segment of the 

 envelopes filled with the foetal liquor. An examination per 

 vaginam at this stage reveals the globular fluctuating foetal 

 envelope, completely filling the whole vagina. 



We term it the water-bag, since it contains foetal fluids. 

 This water-bag is composed of the chorion and allantois con- 

 taining the allantoic fluid, but since the chorion is less elastic 

 than the allantois, and held firmly by the placentae, the former 

 ruptares already on passing through the cervical canal, so that 

 the water bag finally consists only of the allantois. 



At the end of this stage the cervix uteri has widened to such 

 an extent that the vagina and uterus form a common cavity. 

 At the end of this stage the intensity of the coutrartions 

 increise. The previous statements permit of the deduction 

 that the water-bag must necessarily advance as far as the 

 vagina — yes, even beyond the vulva — to sufficiently dilate the 

 genital canal. It does not only dilate the cervix uteri, but also 

 the vagina ; therefore it prepares the canal for the passage of 

 the foetus. 



