280 
PHYSIOLOGY: LUNDSGAARD AND VAN SLYKE Proc. N. A. S. 
was given there because the patient has become more deaf at the higher 
pitches as shown by Curve 2, figure 1, since the first curve was taken. 
It would seem, therefore, even in the case of the complete modification of 
the internal-ear mechanism that a person can hear in a normal manner, 
provided the tones are sufficiently intense and provided there has not been 
a complete destruction of the nerve endings or of the nerves themselves 
in which case we should expect complete deafness. Only one such case 
has as yet been found and in this case the patient was unable to hear at 
any pitch in either ear with as much as 5X 10^ times as much current pass- 
ing through the receiver as was required by a normal ear. 
* Nationai, Research Fei.i.ow in Physics 
THE QUANTITATIVE INFLUENCES OF CERTAIN FACTORS 
INVOLVED IN THE PRODUCTION OF CYANOSIS 
By Christen Lundsgaard and Donald D. Van Slyke 
Hospital of The Rockefeli^ER Institute for Medicai, Research, New York 
Communicated July 7, 1922 
Lundsgaard has shown that the appearance of cyanosis depends on the 
mean concentration of reduced hemoglobin (C) in the capillary blood. 
This concentration he estimated as 
C=^ (1) 
2 
where A is the arterial, V the venous concentration of reduced hemoglobin. 
The effect of certain physiological factors contributing to C is estimated as 
follows. We let T represent the total hemoglobin concentration in the 
blood, I the fraction of total hemoglobin passing in reduced form through 
the aerated parts of the lungs, D the concentration of reduced hemoglobin 
formed by deoxygenation of the blood as it passes from arteries to veins 
through the tissue capillaries. In certain pathological conditions a frac- 
tion of the venous blood reaches the arteries without traversing aerated 
parts of the lungs and therefore carries reduced venous hemoglobin di- 
rectly into the arterial blood. This fraction we designate as a. A, T, and 
C have the significance indicated above. 
When a = 0, only aerated blood entering the arteries, A = I T. When 
however, a has a positive value, the reduced hemoglobin of the arterial 
blood represents the sum of that in the fraction a, of venous blood entering 
