240 



NORMAL PARTURITION. 



sideration of which is, nevertheless, very important from 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 

 positions 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. Allusion 

 has been repeatedly made to the position of the foetus in the uterus 

 during gestation, and to the fact that this position is changed as par- 

 turition 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 foetus to assume, towards 



Fig. 71. 

 Normal Position of the ra:TDs in the Make at Parturition (First Stage). 



the termination of pregnancy, the position most favourable for its exit 

 through the pelvic cavity ; though it is indeed very questionable whether 

 the instinctive faculties of the young creature are already sufficiently 

 developed to bring about this result, which may, after all, be due to 

 some reflex action. However this may be, it is certain that the foetus 

 is very far from being always in this favourable situation, and that the 

 resources of art are often needed to remedy the false positions the 

 young creature may have assumed at the termination of pregnancy. 



In studying the various positions and attitudes the foetus assumes 

 at birth, and the consequent presentations it offers towards the anterior 

 opening of the pelvis, there are to be considered: (1) the region of its 

 body which is first presented to the pelvic inlet, and (2) the relations 

 of, or correspondence between, this region and the shape and dimen- 

 sions of the pelvic cavity itself. 



The first has been designated the presentation, and the second the 

 position of the foetus ; and the inlet, instead of the outlet, of the pelvis 



