176 
stimulating effect of chocolate was attributed 
to the high fat content of this beverage. Wery 
ripe fruit increased the catalase of the blood 
quickly and extensively, while less ripe fruit 
did not. This was attributed to the fact that 
the very ripe fruit contaimed much sugar, 
which was quickly absorbed, taken to the liver, 
and stimulated this organ to an increased out- 
put of catalase, whereas the less ripe fruit 
contained less sugar and hence did not stimu- 
late the liver so strongly. The meat digest in- 
ereased the catalase of the blood very quickly 
and extensively, whereas meat, eaten as such, 
did not act so quickly, due presumably to the 
time taken for digestion. The meat extract 
and beef juice produced a small increase in 
catalase. 
Dogs were used in studying the effect of 
moderate exercise on catalase. The animal 
was placed in a treadwheel and by a little 
coaxing was induced to run and thus turn the 
the wheel at a rate of about five miles per 
hour. The catalase in 0.5 c.c. of blood taken 
from the external jugular was determined be- 
fore the exercise as well as at 15-minute inter- 
vals during the exercise. It was found that 
the effect of moderate exercise was to increase 
the catalase of the blood from 15 to 20 per 
cent. in most of the dogs used. 
Domestic rabbits were used in studying the 
effect of strenous exercise and fatigue on 
catalase. The rabbits were also placed in the 
wheel, which was turned slowly by hand so 
that the direction in which the wheel was 
rotated could be changed to suit the direction 
in which the rabbit took a notion to run. A 
few slow turns of the wheel was sufficient to 
tire and fatigue the rabbit. Every precaution 
was taken not to abuse or injure the animal 
in any way. It was found that the strenuous 
exercise and fatigue decreased the catalase of 
the blood in some eases by as much as 30 per 
cent. and that during rest for an hour, the 
catalase returned to the normal amount and in 
fact above normal in several instances. 
We had already shown that the output of 
catalase from the liver was increased by stimu- 
lating electrically the nerves (splanchnics) 
. distributed to the liver. The explanation that 
x 
SCIENCE 
[N. S. Vou. XLVIII. No. 1233 
suggested itself for the imcrease in catalase 
during moderate exercise was the stimulation 
‘of the liver over the splanchnics to an in- 
creased output of this enzyme, while the de- 
erease in catalase during violent exercise and 
fatigue was due to the using up of catalase 
in the oxidative processés of the muscles more 
rapidly than it was being replenished by the 
liver. The increase in catalase during the 
periods of rest after hard exercise was at- 
tributed to the fact that the liver was putting 
out catalase in the blood more rapidly that it 
was being used up in the muscles. 
According to the chemical theory as set 
forth by Ranke,* fatigue is due to the accu- 
mulation of substances, acid in nature, such as 
lactic acid, which inhibits or depresses the 
power of the muscles to contract. It is rec- 
ognized that the accumulation of these acid 
substances is due to incomplete or defective 
oxidation. The decrease in catalase observed 
in the experiments reported in this paper is 
offered as the cause for the defective oxidation 
during hard muscular work and fatigue while 
the helpful effect of moderate exercise is at- 
tributed, in part at least, to the increase in 
catalase produced in this type of exercise. 
From the. experiments reported in this 
paper, the conclusion is drawn that food and 
exercise produce an increase in catalase with 
resulting increase in oxidation by stimulating 
the liver to an increased output of this enzyme. - 
W. E. Burce 
PHYSIOLOGICAL LABORATORY OF THE 
UNIVERSITY OF ILLINOIS 
4 Ranke, ‘‘Tetanus,’’ Leipzig, 1865. 
SCIENCE 
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