( 1194 ) 
curve, as it can often be seen and controlled at the manometer. If 
we look at curve II (D. M., normal individual, 31 years, 6 11911) 
we see the oscillatory curve rise at 107 mm. Hg. This is occasioned 
by the veins beginning to press the blood under the compression- 
armlet, so that the pressure in it increases, for the volume of the 
arm at the place of compression augments. We see consequently the 
mercury in the manometer rise a few mm. And if now we lower 
the pressure in the armlet, the passage under it is forced by the 
veinous blood, and the oscillatory curve goes down again (in our 
case at 106 mm. Heg). 
It is clear that, if Pacnon is right, namely that under the broad 
compression-armlet the pulse-wave can be annihilated at a certain 
pressure, and yet the blood continue to ooze under the armlet, (comp. 
p. 1184) that in that case the palpatory method for dertermining the 
MBp + Aw fails; our method however does not, as the oozing of 
the blood will likewise swell the arm and consequently make the 
plethysmographic curve rise. 
After these elucidations it appears to us that our method enables 
us to determine the MBp + Aw exactly and to estimate the factor 
of the Aw. 
One remark must still be made. We found like Hitt and Frack 
that at high bloodpressure — but only then — the slow operation 
could become painful for tbe patient. And as it is admitted that pain 
can raise the bloodpressure it might be possible that our determination 
of the Aw consequently became incorrect (too small). This objection 
also holds for Hint, and FLack’s experiments. In such cases it is 
therefore necessary to raise the pressure again quickly to just a little 
above the Mbp + Aw that has been determined before, and to see 
if the pulsation has disappeared. If not, then it is necessary to deter- 
mine the pressure at which the plethysmographic pulse disappears 
again. This method however gives less beautiful results. It seems 
that occasionally at very high Ap, the Ap rises a few mm. during 
the slow phase of the experiment. At lower Lp the pain is not felt. 
After having noted a few times more the curve at lower pressure 
(120, 115, 110 mm.) in order to state that now really, when lowering 
the pressure,a gradual fall takes place, we open, in order to deter- 
mine the mp, the valve of the plethysmographic apparatus for a 
short moment, and let the surplus pressure escape from it. We repeat 
this at every further diminution of pressure in order to have in this 
way the following curves registered at the same level. This is neces- 
sary for the following reason. 
