656 Proceedings of the Pioyal Society 
to be solved, is to make out from this angle on the surface of the 
spheroid what is the corresponding deflexion of the axis of the 
spheroid ; and since the angle, as measured low down on the sur¬ 
face of the abdomen lies in a plane nearly parallel to that in which 
the axis of the uterus is deflected from the antero-posterior mesial 
plane, the deflexion of the axis may be regarded as nearly iden¬ 
tical in amount with the angle measured on the surface. It is 
probable that this angle of deviation of the axis of the uterus from 
the axis of the brim of the pelvis has important physiological and 
practical bearings; but as yet little has been made out regarding 
them. It has been looked upon as affording some explanation of 
the alleged comparative frequency of laceration of the cervix on 
the left side in ordinary labour.* But the most interesting appli¬ 
cation of it is to assist in accounting for the production of face 
cases.f It has been shown how, under certain conditions, and 
supposing a right lateral deviation of the uterus, the part of 
the head on the left side of the brim—that is, the seat of the con¬ 
cavity of the curvature, will have a greater tendency to descend— 
that is, to be more powerfully pushed downwards than the part 
on the right side of the brim. Of this there can be no doubt; and 
the probability of this being a true theory or explanation of face 
cases is highly increased by remarking the apt manner in which 
other things, known in regard to face presentations, adapt them¬ 
selves to it. 
Another ingenious dynamical theory of face presentation has 
been started by Schatz. He states it as follows:—“ When the 
uterus alone is in action, or when there is also acting uniform 
resistance around by the walls of the pelvis, a cranial presentation 
always occurs, if the occipital foramen of the foetal head at the 
time of the first more important shortening of the long axis of the 
uterus lies backwards from this towards the back of the foetus, 
but a face presentation, if it deviates forwards from this towards 
the breast side of the foetus. With the co-operation of non- 
uniform resistance by the walls of the pelvis, cranial presentation 
is produced if the occurring positive or negative distance of the 
great occipital foramen towards the back of the foetus from the 
* Edinburgh Medical Journal, June 1871, p. 1061. 
t Edinburgh Medical Journal, May 1870. 
