298 NATURAL EUTOCIA. 



from right to left, and takes the place of the bi-parietal diameter; dur- 

 ing the act of rotation its extremities slide upon the right anterior, 

 and left posterior inclined planes, to conduct the occiput under the 

 arch of the pubis, and the forehead in front of the sacrum. 



735. At the inferior strait and vulva there is not the least differ- 

 ence remaining betwixt the two positions; but after the escape of 

 the head, the occiput in its act of restitution turns to the right in- 

 stead of inclining itself towards the left; the left shoulder, and not 

 the right, comes under the symphysis pubis, the right side, and not 

 the left, slides along the sacro-perineal curve; the face and whole 

 anterior surface of the foetus look towards the inside of the woman's 

 left thigh, instead of turning towards the right; but nothing of all 

 this process changes the proportional relations of the foetal head to 

 the maternal pelvis. 



736. This variety is considered as less favorable than the other; 

 some have said that it renders tlie labor slower and more fatiguing; 

 when the forehead is turned towards the right sacro-iliac symphysis 

 it is separated from the parietes of the pelvis only by fat and a layer 

 of peritoneum, on which it slides without any difficulty, while in the 

 second position, the rectum shortens the opposite oblique diameter 

 a little. When in the first position, the occiput and forehead rest on 

 two regular planes, equally solid and smooth; while in the second, 

 the anterior part of the head depresses the rectum from above down- 

 wards, pushes it along before it, and folds it so as soon to form a 

 kind of cushion, whose thickness is also increased bjT^ the foscal mat- 

 ters contained within it; it at least follows, that the left posterior 

 surface of the basin is too soft to allow the head to glide rapidly 

 down into the lower part of the excavation. The foetus might here, 

 to a certain extent, be compared to a solid straight stick, one end 

 of which is applied upon a smooth hard plane, as for example a 

 plate of glass, or on the other hand upon an uneven or spongy sur- 

 face, such as a woollen cloth or a mattress. In the former case, 

 the stick would slide along without tlie least obstacle and under the 

 slightest impulse, while in the latter it would not slide at all, or with 

 difficulty. Further, it may be conceived that this state of the plane, 

 on which the forehead is obliged to descend, may in the same way 

 interfere with the act of rotation or the pivot motion, &c. All this 

 may doubtless be true, but upon looking at the subject a little closer, 

 we soon perceive that much is to be retracted of these pretended 

 difficulties; for, 1. The thickness of the rectum when compressed 

 by the head is reduced to a very small degree; 2. The matters with 

 which it is filled are or may be evacuated at the very beginning of 

 labor; and 3. The forehead in every case presses on the rectum, 

 through the parietes of the womb, which does not rise in folds. 



