May 7,1917 Effects of Exercise and Sun on Normal Pigs 173 
D.—EFFECTS ON SPECIFIC GRAVITY 
The specific gravity of the blood of man in muscular activity has been 
studied by Jones (6). He found that it usually varied directly with the 
red corpuscles. He reports, however, that gentle exercise is accompanied 
by a fall, while the more prolonged or violent forms of exercises are 
accompanied by a rise in the specific gravity. Zuntz and Schumberg 
(5, 7) constantly obtained an increase in the specific gravity of the 
blood. Schneider and Havens (7) found that exercise invariably caused 
a rise. 
In pigs we did not find an increase in specific gravity when the entire 
experiment was considered. 
E.—EFFECTS ON CLOTTING TIME 
As one would naturally expect, the clotting time was greatly increased. 
The clotting time seems to be varied in a rough way with the body 
temperature of the pig. 
CONTROL EXPERIMENTS 
■ Several control ^experiments were carried out, whereby blood counts 
were made on normal resting pigs at various intervals. In making the 
wet counts the same pipette was used in each experiment, and the 
blood samples were obtained from a fresh vein in either ear. The dry 
spreads were obtained in a similar manner—that is, a fresh clean vein 
was used in making each spread. 
Results of this work showed that, although in some pigs the results 
are quite uniform both in the wet and dry counts, it is often found 
that the blood of the pig is subject to considerable variation at different 
times. 
In some pigs the wet counts were very uniform and showed no varia¬ 
tions other than normal. In others there was sometimes as much as 
1,000,000 red corpuscles per cubic millimeter difference in two examina¬ 
tions on the same animal. The differential count of leucocytes also 
showed similar results. In some pigs the differential count covering a 
period of 24 hours was quite uniform and showed very slight changes, 
varying between zero and 2 to 3 per cent. In others, however, there 
was marked variation. The individual leucocytes varied at different 
times, and the greatest variation occurred in the polymorphs and lym¬ 
phocytes. Five experiments dealing with the differential counts were 
made in normal resting pigs and covering a period of 24 hours (12 counts 
made). 
