DISEASES OF SWINE AND OTHER ANIMALS. 13 



wlieretwo or more existed in the same building, the intervening -walls 

 were constructed of a double thickness of matched boards, \rith build- 

 ing pasteboard between, so that no communication could possibly take 

 l)lace 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 illness, 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- 

 fully 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 scruimlous cleanliness was maintained, and deodorizing agents 

 used in sufficient quantities to keep them i)erfectly sweet. 



The exijeriments 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. Eeferring to experiments of others for determining 

 the period of incubation, Dr. Law says that Dr. Sutton, observing the 

 residt 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 foiu-teen days ; Professor Axe, in siunmer, in London, con- 

 cluded on from five to eight days ; Dr. Budd, in summer, from four to 

 five days ; and Professor Osier, in autumn, at from four to six days. 

 Dr. Detmers gives the period of incubation from five to fifteen days, or 

 an average of about seven days. A comparison of these results would 

 seem to indicate that both extremes have been reached. 



In experimenting in this direction. Dr. Law first sought to ascertain 

 the tenacity of life of the dried virus. Some years ago Professor Axe 

 had successfully inoculated a pig with virus that had remained dried 

 upon ivory points for twenty-six days. In order to carry this experi- 

 ment still further, Dr. Law inoculated three pigs Avith virulent products 

 that had been dried on quills lor one day, one with virus tUied on a quill for 

 four days, one for five days, and one for six days. These quills had been 

 sent from Xorth Carolina and New Jersey, Avrappcd in a simple paper 

 covering, and were in no Avay specially protected against the action of 

 the air. Of the six inoculations, four took effect. In the two exceptional 

 cases the quills had been treated with disinfectants before inoculation, 

 so that the failure Avas anticipated. 



Three pigs were inoculated with diseased intestine which had been 

 dried for tln-eo and four days respectively. The intestine Avas dried in 

 the free air and sun, and the process was necessarily slower than in the 

 case of the (juills, where the virus Avas in a very thin layer, hence there 



