THE FEMALE REPRODUCTIVE ORGANS 297 
The Pelvis. 
A study of the dynamics of the female pelvis from an 
evolutionary standpoint may explain some of the diffi- 
culties attending parturition. Starting from the biologi- 
cal law that morphology follows function and that the 
anatomy of a part alters to suit a changed physiology 
with such modifications as are necessary to fit each part 
properly to interact with other structures comprising 
the entire animal, it is evident that two great changes 
have occurred in the evolution of homo — the assumption 
of the upright posture and an increase of intellectual 
power necessitating a larger cranium of modified form. 
To this end also the pelvis would have to change both 
for support and to allow the passage of the enlarged 
head. The functions of the pelvis are (1) to attach the 
legs or hinder limbs to the trunk; (2) to furnish points 
of attachment and fulcra for the great muscles which 
move the limbs, and in the case of man, hold the trunk 
erect; (3) to provide egress and support for the termi- 
nal canals of the intestinal and urinary systems; (4) to 
provide for a birth passage; (5) to act as a shelf and 
support for the abdominal viscera. In quadrupeds the 
first four functions being perfectly served, there are 
fewer abnormalities of reproduction (and in the posi- 
tions of viscera as well — Ed.). In man natural selection 
weeded out narrow pelves, but the present product is as 
yet an imperfect structure for one of its main uses, 
parturition. It should be a funnel-shaped basin of the 
shape of the fetal head and of the same height at all 
points — that is not oblique, there should be no promon- 
tory, the pelvic symphysis should be short and the 
sacrum of the same height. This would obviate internal 
rotation now necessitated by the oblique pelvis ; this does 
not occur in quadrupeds. 
Tracing the evolution of the pelvis, it is to be found 
first in fishes where it is a loose disjointed, variable 
structure not attached to the spine; in some it consists 
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