382 EEPORT OF I'EE COMMISSIONES OF AGRICULTUSE. 



and on other food-plants of field and pasture, and in that way Trere 

 conveyed from one place to another. Such a rising in tlic air, and such 

 a conveyance of the bacillus gerips from one place or locality to another, 

 cannot be accomplished at all, or only to a very limited extent, while 

 everything is frozen or covered with snow, because in that case all the 

 moisture and watery parts, which otherwise might have evaporated, are 

 locked up by frost — have become solid. 



3. It was fiu'ther observed that swine plague spread the most rapidly, 

 and was the most malignant, among herds in which the animals had 

 external wounds, sores, or lesions, caused by recent ringing, castration, 

 &c., and in all those swine-yards or hog-lots in-which an old straw-stack 

 served as shelter and sleeping place, wounds, sores, and scratches con- 

 stitute a port or entree for the disease-producing germs, and partly 

 rotten and constantly damp old straw-stacks not only catch the organic 

 particles, such as the bacilli and their germs, that may be floating in the 

 air, but also shelter and protect them agaiust destructive influences, 

 and favor and promote their development, proi)agation, and dissemina- 

 tion, first by being warmer, in the winter at least, than the surrounding 

 atmosphere, and secondly, by absorbing and causing to evaporate, 

 in consequence of their porous condition, a great deal of moisture. 

 Clinical observations have convinced me that an old straw-stack may 

 preserve the infectious principle for several months. The above facts, 

 too, if looked upon in a j^ropcr light, will go far to show that the infec- 

 tious principle must be something endowed with vitality and means of 

 Ijropagation. 



4. When resuming my investigation in May, I went again to Cham- 

 l)aign. Champaign County, Illinois, because I had been informed of the 

 existence of swine-plague in the immediate vicinity of that place. Ar- 

 riving there I found my information to be correct, but found also that 

 the disease, which had never entirely ceased to exist in that county 

 since July a year ago (1878), was spreading very slowly, and made a 

 temporary stoj), or ceased to spread immediately after ea(;h heavy or 

 pouring rain, and during the spring most rain-storms in the West are of 

 this character. I found, further, that even its propagation within the 

 herd became visibly slower or stopped altogether for several days after 

 each violent or pouring rain in aU such herds as were kept in a pasture 

 or a hog-lot sufficiently drained to enable the water to flow ofTj but the 

 spreading was not visibly interrupted in such herds as were kei)t in a 

 timber-lot or in a pen under roof. So I have necessarily come to the 

 conclusion that each pouring rain brought down the hacilli and bacillus 

 germs floating in the air and washed them away at once, not only from 

 the grass and herbage, but also from the surface of tbe ground. In 

 timber lots, however, it was diflerent ; there the force of the rain was 

 broken l)y the trees and tlie usually rank vegetation beneath, and there 

 the water does not run off as fast as from a pasture, or from a bare hog 

 lot. Besides, the drainage in the timber, as far as Illinois is concerned 

 at least, is usually very indifferent. 



As to the nature of the infectious principle there can be, in my opinion, 

 no more doubt ; and in regard to its spreading my recent observations 

 have corroborated the conclusions arrived at last summer and fall. To 

 sum nj), swine plague spreads and is communicated to healthy animals: 

 first, by an introduction of hadlli and bacillus germs into the digestive 

 canal with the food and water for drinking; and, second, through 

 wounds, sores, and. scratches, or by direct inoculation. "\Vhether they 

 can also ent*-r (and communicate the disease) through the whole skin, 

 and through the whole respiratory mucous membrane, free from any 



