312 NATURAL EUTOCIA. 



chanics, therefore, in accordance with facts, permit us to class face 

 cases among the spontaneous labors. 



759. According to Deventer, the causes of this presentation are 

 to be sought for in the obliquities of the uterus, which, from the very 

 beginning of its action, cause the extremity of the occiput to lodge 

 upon the margin of the strait, and thus oblige the face to descend 

 first. According to M. Gardien, the cause lies much more in the 

 inclination or obliquity of the foetus itself, than in that of the organ 

 which contains it. Madame Lachapelle, who rejects both of these 

 hypotheses because she saw the face presenting at the upper strait 

 in two women who died previously to labor, attributes it to the cir- 

 cumstance that the anterior obliquity of the womb being very com- 

 mon, the weight of the occiput must in such cases prevent the chin 

 from remaining applied against the sternum, and must bring the 

 mento-bregmatic diameter into parallelism with the sacro-pubic 

 diameter from the very commencement of labor. It seems to me 

 that all these opinions have some foundation, but that none of them 

 suffice to explain all the facts, and that it is for the most part impos- 

 sible to say why the face and not the occiput presents. 



760. The face positions being in fact only reverted vertex posi- 

 tions, it is plain that we must for both admit the same number of 

 species and varieties. Authors, however, have generally described 

 only four; and they have rarely agreed as to the manner of arrang- 

 ing them. Some make them correspond to the four oblique posi- 

 tions of the vertex; others, as Smellie, Stein, Baudelocque, and 

 MM. Gardien and Desormeaux, dispose them transversely, and from 

 front to rear, and admit a right mento-iliac and a left mento-iliac 

 position, as well as a mento-pubic, and a mento-sacrcd position. 



Perhaps, in studying the subject, there is some advantage in this 

 latter mode of classifying them; but it is important in practice to 

 know, 1. That the antero-posterior positions are rare, so much so, 

 that Madame Lachapelle has never seen a single case of that kind, 

 although Rcederer, Deleurye, Stein, &c. admitted them as very 

 common, and as the easiest; 2. That if they do sometimes occur at 

 the commencement, as in one case that I saw, they soon become 

 converted into lateral positions; 3. That the mento-sacral position, 

 which Stein gives as the best, and of which one case is related by 

 Smellie, is altogether impossible without this conversion; and, 

 4. That in the iliac positions, the fronto-mental diameter is more 

 frequently directed obliquely than transversely. 



761. It ought also to be known that the face does not always 

 present in full; that the forehead often sinks lower than the chin; 

 that the contrary obtains in other cases; that in some instances, 



