JOURNAL A. M. A., Nov. 1, 1913, p. 1634.] showed that altitude
increases the red blood cells from 4 to 11.5 percent, and the
hemoglobin from 7 to 10 percent The greatest increase in these
readings is in the first few days. It has also been shown that with
every 100 mm. of fall of atmospheric pressure there is an increased
hemoglobin percentage of 10 percent over that at the sea level.
[Footnote: Blood and Respiration at Moderate Altitudes, editorial,
THE JOURNAL A. M. A., Feb. 20, 1915, p. 670.]

Schneider and Havens [Footnote: Schneider and Havens: Am. Jour.
Physiol., March, 1915.] find that in low altitudes abdominal massage
increases the red corpuscles, and the percentage of hemoglobin in
the peripheral vessels. While there is thus apparently a reserve of
red corpuscles while the individual is in a low altitude, in a high
altitude they find such reserve to be absent; in other words,
abdominal massage did not cause this increase in red corpuscles in
the peripheral vessels. This absence of reserve is easily accounted
for by the fact that after one reaches the high altitude there is an
increase in red corpuscles and hemoblogin in the peripheral blood.

Schneider and Hedblom [Footnote: Schneider and Hedblom: Am. Jour.,
Physiol., November, 1908.] showed that the fall in systolic pressure
at altitudes is greater and more certain than the fall in diastolic,
some individuals even having a rise in diastolic pressure. This rise
in diastolic pressure is probably caused by dyspnea.

Schrumpf, [Footnote: Schrumpf: Deutsch. Arch. f. klin. Med., 1914,
cxiii, 466] on the other hand, finds that normal blood pressure is
not much affected by an ascent of about 6,500 feet, while patients
with arteriosclerosis and hypertension, without kidney disease, have