306 NATURAL EUTOCIA. 



These assertions of the German professor ought to be taken into 

 consideration, not that they are perfectly correct, for even provided 

 the very numerous observations collected at the Paris Maternile could 

 not be cited as proofs of the contrary, the form of the pelvis and the 

 specific gravity of the foetus would alone prevent the admission of 

 such an opinion, until its correctness had been irreversibly demon- 

 strated by multiplied facts; but they should be taken into considera- 

 tion, because it appears certain, that when the occiput reaches the 

 bottom of the excavation, it does, in fact, in some instances turn to- 

 wards the acetabulum instead of proceeding towards the posterior 

 median line. I have already observed and pointed out to many stu- 

 dents the reality of this phenomenon, so as to leave no doubt upon 

 the subject. Upon passing the pelvic circle, the head by degrees in- 

 clines to one side, and places itself exactly cross-wise, soon after it 

 descends into the excavation. This pivot motion continues, under 

 the influence of the uterine contractions; if it be the fourth position, 

 the posterior fontanel gradually reaches the arch of the pubis, by 

 gliding from behind forwards, and from right to left, along the right 

 anterior inclined plane, and on the other hand from left to right for 

 the fifth, &c. 



748. I am ignorant of the causes to which such anomalies ought 

 to be attributed; I have never found any thing peculiar in the con- 

 formation of those women who have exhibited them; the labors have 

 progressed regularly, and there was nothing unusual in the weight 

 of the children; I think I have only noticed that from the very begin- 

 ning of the labor, the antero-poslerior diameter of the head was much 

 nearer to the bis-iliac than to the sacro-pubic line of the strait, and 

 that the pubis, being slightly depressed above, seemed to favor the 

 anterior rotation, by the hoUowness of the arch, and by the distance 

 to which the acetabula were separated.* 



749. The knowledge of these conversions ought not to be over- 

 looked in practice: in the first place, because, as they are favorable, 

 we may in some instances be enabled to promote, and even to enforce 

 them whenever such a thing is possible; in the next place, because 

 they afford a very natural explanation of the mistakes, which we 

 have been heretofore compelled to attribute to the ignorance of those 

 who committed them. For example, it pretty often happens that 



* I have in a good many instances observed the fetal head to change its posi- 

 tion during labor, so as to bring the occipital fontanel from the left acetabulum 

 quite over to the right one, and then go back again to the original position. 

 In an ample pelvis the child has power to change the position of its head very 

 readily, until it is fairly within the vagina, where it is held too firmly to admit 

 of such spontaneous rotations. — M. 



