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in growing arteries, the umbilical, for instance, which is to be expected, 
for the peripheral bed is enlarging. After the vessels cease to grow the 
area of the vascular bed is about the same from the ascending aorta to 
the smallest arteries; the bed enlarges in the capillaries. Under such 
conditions (homonomous ramification) the average rate of the current is 
equal in all of the arteries. 
Whether the ramification is homonomous or heteronomous appears to 
me to be of little consequence, and I have pointed out the uncertainty of 
Thoma’s statements for my own measurement, which are quite nu- 
merous, and decidedly in favor of a heteronomous ramification. 'Thoma’s 
assumption of homonomous ramification is based largely upon the meas- 
urements upon the aorta and its branches. From now on, however, the 
vascular bed enlarges, at first slowly, and more rapidly as the capillaries 
are approached. The bed has doubled itself in the arteries one millimeter 
in diameter and has increased about fivefold in arteries .05 mm. in 
diameter. A change so slight as this could barely be detected when the 
_ measurements are made in adjoining internodes. In order to obtain re- 
liable figures the measurements must be made farther apart. For in- 
stance, it is easy to lay the intestine of the dog into a series of anatomical 
units to correspond with the arteries—mesenteric arches, arches to the 
submucosa and arteries to the vilh. If the area of the superior mesen- 
teric artery is 7 sq. mm. and that of the ends of the main branches but 
12 sq. mm., it will be seen that when a trunk divides into two branches 
the change in area will be but slight. But when we compute the number 
of villi, and this is easily done, we determine at the same time the num- 
ber of terminal arteries to the villi, all of which are about of the same 
size. At this point, as Table I shows, the artery is .0225 in diameter 
and the bed is nearly 60 times the area of the superior mesenteric artery. 
If the ramification were homonomous down to the arteries of the villi 
there should be but 17,000 villi, the number which can be counted upon 
10 sq. em. of mucous membrane. No matter how the following tables 
are compared, it is seen that there is a gradual widening of the vascular 
bed from the branches of the aorta to the capillaries. 
