alee td 
DISEASES OF SWINE AND OTHER ANIMALS. 327 
tle which had been heated to red heat. The glass slides and cover- 
glasses were cleaned and burned, the skin of the animal cleaned and 
ineised with a knife that had just been heated in the flame of a lamp. 
The caustic solution and the distilled water for the immersion-lens were 
reboiled on each occasion before using, and tinally the glass rods em- 
ployed to lift the latter were superheated before being dipped in them. 
On different occasions, when the animal was being killed, the blood 
from the flowing vessels was received beneath the skin into a capillary 
tube which had just been purified by burning in the flame of a lamp. 
With these precautions he thinks it might have been possible for one or 
two bacteria to get in from the atmosphere, but this would not account — 
for the swarms found as soon as the blood was placed under the micro- 
scope. 
The most scrupulous care was observed by Dr. Law in his experi- 
ments in inoculation. The isolated and non-infected locality where the 
experiments were conducted offered special advantages for a series of 
experiments of this character, as there were no large herds of diseased 
and exposed swine, and, consequently, no danger of accidental infection 
from other sources than the experimental pens. The number of animals 
subjected to experiment was limited by the necessity for the most per- 
fect isolation of’ the healthy and diseased, for the employment of sepa- 
rate attendants for each, and for the disinfection of instruments used 
for scientific observations, and of the persons and clothes of those neces- 
sarily in attendance. The experimental pens were constructed on high 
ground in an open field, with nothing to impede the free circulation of 
air. They were large and roomy, with abundant ventilation from back 
and front, with perfectly close walls, floors, and roofs, and in cases 
where two or more existed in the same building, the intervening walls 
- were constructed of a double thickness of matched boards, with build- 
ing pasteboard between, so that no communication could possibly take 
place except through the open air of the fields. When deemed neces- 
sary, disinfectants Were placed at the ventilating orifices. On showing 
the first signs of illmess, infected pigs were at once turned over to the 
care of attendants delegated to take charge of these alone. The food, 
utensils, &c., for the healthy and diseased animals were kept most care- 
fally apart. When passing from one to the other for scientific observa- 
tions, the healthy were first attended, and afterward the diseased, as 
far as possible in the order of severity. Disinfection was then resorted 
to, and no visit was paid to the healthy pigs until after a lapse of six or 
eight hours, with free exposure to the air in the interval. In the pens 
the most scrupulous cleanliness was maintained, and deodorizing agents 
used in sufficient quantities to keep them perfectly sweet. 
The experiments of Dr. Law have shown the period of incubation to 
vary greatly, though in a majority of cases it terminated in from three 
to seven days after inoculation. One animal sickened and died on the 
first day, three on the third, two on the fourth, one on the fifth, two on 
the sixth, four on the seventh, and one each on the eighth and thirteenth 
days respectively. ° Referring to experiments of others for determining 
the period of incubation, Dr. Law says that Dr. Sutton, observing the 
result of contact alone in autumn, sets the period at from thirteen to 
fourteen days; his own observations in Scotland, in summer, indicated 
from seven to fourteen days; Professor Axe, in summer, in London, con- 
cluded on from five to eight days; Dr. Budd, in summer, from four to 
five days; and Professor Osler, in autumn, at from four to six days. 
Dr. Detmers gives the period of incubation from five to fifteen days, or 
