Bee: 
508 Remarks on the Morphology of Arteries, [May, 
mary and epigastric). In the lumbar and sacral regions a similar 
arrangement can be made out, somewhat obscured by the modifi- 
cations of the abdominal wall. This gives strong support to the 
theory of the segmentation of the human skeleton. (Plate X.) 
What can be said as to the limb-trunks? Let us examine 
their plan. It will be observed that their bifurcations have a defi- 
nite relation to the segments of the body. Thus for the pelvic 
extremity we have first, at the sacro-iliac joint, a division of the 
common iliac into internal and external iliac ; below the hip-joint 
the main trunk divides-into superficial and deep femoral; below 
the knee another bifurcation gives us anterior and posterior tibial; 
on reaching the foot there is a division into external and internal 
plantar, whence radiate branches to the toes. 
In the thoracic limb a similar law can be discovered, although 
the enormous preponderance of the cephalic extremity modifies 
the vascular supply. The subclavian gives off the thyroid axis 
after passing the sterno-clavicular joint; the superior profunda 
represents profunda femoris; the next bifurcation is into radial 
and ulnar; then the division of ulnar into deep ulnar and super- 
ficial palmar arch, whence digital branches. Here again we have 
a dichotomous division corresponding to segments of the limb, i 
the main trunk dividing after passing the joint. eo 
As far as I am aware no attempt has been made to explain this 
law morphologically. The conditions of nutrition might be met 
by a single axial trunk extending from the aorta to the phalanges 
giving off branches irregularly. i: 
If it is urged that simplification of trunks is desirable ee 
movable joints, the numerous examples of high division show : 
that the advantage is not great. ; 4 
The existing RE eh of muscles might be ee 1 
causing the peculiarities in the vessels. Itis true that me d 
muscles are segmented in accordance with the divisions seg- a 
limbs, but the superficial layers frequently extend from one © 
ment to another or even to a third. Besides, this segmen de- r 
also requires explanation, and it is conceivable that it pe de | 
pend upon the same causes that affect the bifurcation o 
arteries. 
May it not be possible to explain the division 
arteries by deducing a general law dependent upon tic a 
dent morphological condition? The arteries of the @ — 
ATED Py ESAT E EE 
of the limb- 
