318 UNNATURAL EUTOCIA. 



latation of the os uteri, if the position is regular and the pains good, 

 the foetus will, indeed, pass out without running much more risk 

 than in a delivery by the head; but if the membranes give way 

 very early, if the least traction be employed under the pretext of 

 hastening the delivery, it is certain that difficulties will be infi- 

 nitely multiplied, and the life of the child seriously compromitted. 

 This is a point which young students, as well as practitioners, ought 

 never to lose sight of. This, also, is one of the motives that have 

 induced me, both in my lectures and in this work, to deviate from 

 the ideas generally received among us in relation to pelvic presenta- 

 tions of the foetus. 



759. Previously to the time when de la Motte, Petit and Bau- 

 delocque had demonstrated that the somerset motion described by 

 their predecessors was a mere chimera; as long as it was supposed 

 that the fostus naturally remained squatting on the sacro-vertebral 

 angle until the end of the seventh month of pregnancy, there was 

 no difficulty in accounting for the presentations of the breech, knees 

 or feet; to explain their occurrence, it was sufficient to say that 

 something had prevented the somerset from taking place; that the 

 child, either through forgetfulness, weakness, or something else, had 

 allowed the opportune moment for performing this pretty feat to 

 elapse; but at present, when we cannot resort to this subterfuge, we 

 are brought to confess that the causes of presentations of the pelvis 

 are but little known. 



770. It is probable that, about the period when the length of the 

 occipito-coccygeal diameter of the foetus begins to exceed that of the 

 transverse or horizontal diameter of the womb, it may happen that 

 the head of the child, being carried upwards by some sudden move- 

 ment, by the decubitus of the woman; or some other cause, cannot 

 resume its original position. It has been observed at the Maison 

 d'Accouchmens at Paris, and I have had occasion myself to notice 

 it, that presentations of the pelvic extremity are much more common 

 in abortions and in twin pregnancies than in simple labors occurring 

 at full term; and this remark might perhaps be used to sustain the 

 above explanation; but how can we refer the cause of this anomaly 

 to the foetus, or to mere peculiarities of attitude in the mother, in 

 those tolerably numerous cases, where all the deliveries of one in- 

 dividual terminate in this way, and when it is well understood that 

 a woman having once been delivered of a breech presentation, war- 

 rants us in fearing that it will happen so to her again? Would it 

 not, rather be reasonable to seek for this cause in the conformation 

 of the womb or pelvis in such a case? 



771. The positions of the pelvic extremity may, like those of the 



