652 Proceedings of the Royal Society 
remark may be made similar to that applied to Smellie’s drawing; 
namely, that the head could not be so placed unless the uterus had 
an anterior obliquity, an obliquity opposite in direction to that 
figured by Smellie and described by Schatz ; an obliquity quite 
incompatible with Nsegele’s own description in his work on the 
female pelvis •* or unless the child maintained an unnatural and 
undescribed left lateral flexion of its head. 
The now generally entertained views, that the axis of the uterus 
coincides with the axis of the brim of the pelvis, and that the 
foetal head presents at the brim directly, f have at least the merit 
of evading such obvious and adverse criticism as the figure of 
Smellie, and the expressed opinions of Schultze, Schatz, and of 
Nmgele, are liable to be subjected to. 
The great authority of Nasgele was long sufficient to give cur- 
rency to his statement that the head of the foetus, as it passed 
through the brim of the pelvis, had its vertical axis in a position 
of anterior obliquity to the plane of the brim, an obliquity which 
is appropriately designated the Nasgele obliquity, in order to dis- 
tinguish it from other obliquities at the same situation. The great 
argument against this view, and the only one having a final charac- 
ter, is, that it is not an accurate description of what takes place ; 
but in addition, it has been argued against it that it is impossible 
to find a mechanism to account for it. Stoltz’s attempt to explain 
its occurrence by mere lateral flexibility of the neck of the child 
is insufficient, because it affords no explanation why the lateral 
flexion is towards the posterior shoulder ; but the now alleged 
posterior obliquity of the uterus, as regards the axis of the brim, 
affords a solution which Nsegele did not foresee when he described 
this obliquity as present and increasing with the increasing height 
of the head in or above the true pelvis. If, adopting the kind of 
nomenclature introduced by Barnes, we describe a curve of the 
natural promontory, produced at the brim of the pelvis by the 
posterior obliquity of the uterus, then this curve, representing a 
deflection of the axis to the extent of about ten degrees, can be 
easily made to account for the alleged Neegele obliquity during the 
first half of the passage of the child’s head through the ligament- 
* F. C. Nsegele. “ Das Weibliche Becken.” Carlsruhe, 1825. 
+ See my “ Researches in Obstetrics,” p. 834, &c. 
