Journal of Agricultural Research 
Vol. IX, No. 6 
168 
hog’s blood. The animals were then removed from the crate and exer¬ 
cised for a certain length of time, or placed in a small wire pen, exposing 
them to the sun according to the series to which they belonged. Some 
pigs were very easy to exercise, and would drive freely for several minutes 
and would begin to show symptoms of fatigue and a high body temper¬ 
ature io to 15 minutes after the exercise had started. Many pigs, on 
the other hand, were difficult to drive; it is difficult to get them to move 
at a faster gait than a walk, and with such animals it usually requires 
about one-half hour of exercise before they show fatigue and an increase 
in body temperature. Immediately after the exercise or sun exposure 
the various blood examinations were again determined. 
In a number of animals dry spreads were made at certain intervals, 
covering a period of 24 to 48 hours or longer, following the exercise or 
exposure to the sun. In this manner the leucocytic curve was estab¬ 
lished. 
The methods of technic were similar to those used in our studies on 
the blood of normal pigs. ' The temperature throughout each experiment 
was recorded. 
I.—EFFECTS OF MUSCULAR EXERCISE 
A.—EFFECTS ON THE RED CORPUSCLES 
It is well established that exercise in man causes an increase in the num¬ 
ber of red corpuscles. Tomow 1 found in experiments on soldiers after 
long marches an increase of about 9 per cent in the number of red cor¬ 
puscles. Hasselbalch and Heyerdahl (2) in two experiments found an 
increase of 13 and 17 per cent. Boothby and Berry (2) found an aver¬ 
age increase of 19 per cent, but the increase occurred only when sweating 
was marked. Willebrand (5) found in 12 young men during gymnastic 
work an increase which varied between 2.9 and 23.4 per cent; and the 
length of time consumed in returning to normal was quite variable. 
Zuntz and Schumberg (5, 7), in a study of German soldiers during 
marches, obtained an average increase of 9 per cent. Hawk (5), in his 
studies of college athletes, found an increase from 7.3 to 26,7 per cent. 
Schneider and Havens (7), in their studies on college athletes, found an 
increase which varied between 3.2 and 22.8 per cent. 
In animals Cohnstein and Zuntz (5) examined the blood of rabbits, 
after subjecting the animals to a systematic harassing for several min¬ 
utes. They found a slight decrease in the number of red corpuscles and 
an accompanying leucytosis. 
In the blood of 15 pigs studied in this laboratory there were practically 
no changes in the number of red corpuscles (Table I). There were slight 
individual variations in the counts before and after exercise; in some 
cases there was an increase and in others a decrease following the exer¬ 
cise. These variations, however, were no different than those found in 
1 Reference is made by number to "literature cited," p. 182. 
