( 1199 5 
the volume of the arm will increase as long as the veins are still 
tightly compressed. This will continue till the pressure in the veins 
has become equal to that in the arteries. Consequently, if only we 
work slowly enough, the arterial blood-pressure will at last prevail 
in the veins, i.e. the pressure of the blood-column itself, whilst the 
influence of the arterial wall is of course excluded. 
Not before this pressure in the veins, which must consequently 
be inferior to arterial pressure —+ arterial wall, and is supported 
both by the parietes of the veins and the surrounding tissues, sur- 
passes the pressure in the compression-armlet, the blood under that 
armlet will be able to flow again from the veins to the heart. But 
at that moment the volume of the arm will decrease again, for the 
fall in the veins distal and proximal to the armlet is at that moment 
enormous. 
Now the volume of the arm diminishes in our case at a pressure 
of 127 mm.Hg. The downward move of the vegistered curve proves 
it likewise. 
As we may neglect the parietes of the veins as factor, this pres- 
sure is consequently the real pressure of the blood without the factor 
of the arterial wall. 
A fortiori we may regard the arteries + capillaries + veins as 
a system of communicating vessels, if we take into account LEONARD 
Hirs words: “that there are wider channels connecting the arteries 
and veins through which the pressure is transmitted to the veins. 
The existence of such wide channels is recognised by histologists.” 
(Further advances in physiology, 1909, p. 145). 
In the beginning we simply waited till the lever of the Marny- 
tambour did not move upward any longer. Then we diminished the 
pressure. In this way we obtained as factor for the arterial wall 
with normal persons about 15 mm.Hg. (40 observations). 
Then Lronarp Hitt and Marti FrackK’s article in the Journal of 
Physiology vol. XXXVIII came to our hand. In order to determine 
the exactitude of the palpatory method they proceed from the same 
idea as we, viz. that in the end the same pressure prevails in the 
veins as in the arteries, if the latter are open, and the former tightly 
compressed. Their experiment is best cited in their own words: 
“We place one armlet round the brachial artery, and another 
narrower one round the forearm of the same arm — each connected 
with a manometer. We find the obliteration pressure with the first 
armlet. Suppose it is 150 mm. Hg. We lower the pressure in this 
armlet to say 145 mm. Hg. so that arterial blood can get through 
into the limb, but cannot get out of the veins of the limb until 
