( 1193 ) 
the pressure in the veins rises above 145 mm. Hg. Allowing time 
for the veins to fill, we then measure the pressure in one of the 
superficial veins and find that it does finally reach this pressure. 
We raise the pressure in the second armlet, observe the pressure 
at the moment when the vein fills from below. One of us watches 
the vein and signals the moment of filling, the other reads the 
manometer. We repeat the observation several times. If we find 
the pressure in the vein reaches 145 mm. He, we know that the 
obliteration pressure was correct within 5 mm. Hg. To carry out 
this method a vein must be chosen which does not fill from above 
or at any rate quickly. With such high pressures in the veins the 
valves leak, and this makes quick working necessary. In cases of 
high pressure it is necessary to give a rest between each test as 
the maintenance of the first armlet at a pressure close to the obli- 
teration pressure is rather painful. 
From the above observations we conclude that the obliteration 
method of measuring the arterial pressure is correct within 5 mm. 
Hg, even in cases where the arterial wall is markedly changed from 
pathological causes. 
One sees what startling similarity there is between this method 
and ours, with regard to the point of issue. And at the same time 
one sees that Leonard Hint and Martin Frack’s experiment has 
proved that — when working in this manner — one may consider 
arteries ++ capillaries + veins as a system of communicating vessels. 
Though Hnr’s determination of the “obliteration pressure” is made 
after the palpatory method and consequently has the incorrectnesses 
of subjectivity, described in our first chapter; and though, as one 
can read in the description, the determination of the pressure in the 
veins is connected with some difficulties, yet there was in this pu- 
blication an incitation for us to make a new series of experiments, 
in which we proceeded still slower. Though we shall afterwards 
revert to the general conclusions, yet we can now already state that 
in the beginning the factor of the arterial wall was most likely 
valued too high by us, but at the same time that the arterial wall 
may not entirely be neglected. 
To return to our case we may thus give as figures there: 
MBp + Aw between 140 and 135 = 137 mm. Hg. 
MByp between 130 and 127 =128 mm. He. 
Consequently : Aw aa Domi! Hie. 
That the fall of the plethysmographic curve is in reality caused 
by the veinous blood being pressed from below the compression-armlet 
to the heart appears from a peculiar behaviour of the oscillatory 
