308 NATURAL EUTOCIA. 



table obstacle to the sixth position. It must therefore be admitted, 

 at least, as a possible shade, if not as a real variety. 



752. Its mechanism, moreover, scarcely differs from that of the 

 two oblique varieties; the posterior surface and occiput of the 

 foetus being, from the beginning, turned directly backwards, there 

 is no occasion for the head to perform its pivot movement in the 

 excavation, so as to engage in the inferior strait; the shoulders pass 

 through the superior strait parallel to the bis-iliac diameter, and there 

 is no act of restitution without, any more than there is an act of ro- 

 tation within the pelvis, and if the face comes at last to turn towards 

 one of the thighs and the occiput towards the other, it happens so be- 

 cause the trunk, in revolving on its vertical axis to place the shoul- 

 ders in an antero-posterior attitude, necessarily carries the bi-parietal 

 diameter in the same direction. 



It is less favorable than the corresponding oblique positions, only 

 because it renders the forehead and face more liable to be turned 

 downwards, and to permit the great diameters of the head to become 

 parallel to the smallest ones of the pelvis. When they attributed 

 the difficulties accompanying it to the friction of the face behind 

 the pubis, accoucheurs of past ages, doubtless, had not reflected 

 on the state of flexion in which the head is found to be placed; for 

 it would have been easy for them to see that it is the anterior ex- 

 tremity of the oceipito-bregmatic diameter, and not that of the occi- 

 pito-frontal diameter, that must rest upon the hinder part of the pubic 

 articulation. 



753. Remarks. Besides these six varieties, there would be a great 

 many intermediate ones, provided the occiput were obliged, in each 

 of them, to correspond to some indicated point of the pelvic circle: 

 in effiect, if there be some of them that we can bring in relation with 

 the extremities of the four principal diameters of the strait, I cannot 

 perceive why eight others might not be established betwixt those just 

 now mentioned; and this number once agreed upon, there is no rea- 

 son why we might not add sixteen others, and so on ad infinitum. 

 But it is quite enough to make a particular position of all the cases 

 where the occiput looks towards any portion of the left anterior quar- 

 ter-circle of the pelvis, another for the right, and a third and fourth 

 for the posterior half of the pelvis; since these varieties, which dif- 

 fer more in degree than reality, ought, after all, to be considered as 

 mere shades, constantly changing, before the close of labor, into 

 occipilo-anlerior, and occipito-posterior positions: so that, in fact, the 

 four diagonal positions of the superior strait, when reduced to the 

 two antero-posterior ones of the inferior strait, constitute the whole of 



