6 DISEASES OF SWINE AND OTHER ANIMALS. 



bmed, the Commissioner deemed it best to devote the greater portion of 

 the limited sum placed at his disposal to an investigation of the fatal 

 diseases affecting this class of farm animals. 



The preliminary investigation instituted and conducted under the 

 supervision of this department, in the fall and winter of 1877-'78, estab- 

 lished the fact that diseases prevail among these animals much more ex- 

 tensively din-ing the late summer and early fall months than at other 

 seasons of the year, and for this reason the examiners selected to con- 

 duct the investigation were employed for periods ranging from one to 

 three months. It was assumed, and the subsequent history of the dis- 

 ease proved the assumption to be well founded, that the reduced tem- 

 perature of the late fall and early winter months w^ould cause an abate- 

 ment of the disease, and in a measure deprive the examiners of subjects 

 with which to continue their experiments. While, therefore, the very 

 severe weather of the past winter caused a great reduction in the num- 

 ber of animals affected, the disease was not eradicated, nor did its 

 fatality seem to be lessened. The spread of the infection from one herd 

 to another was greatly diminished ; but^ in infected herds, where the 

 malady was still prevailing when cold weather set in, there appeared 

 but little difference in the rapidity of the transmission of the disease, 

 from one animal to another, iu the same herd. Dr. H. J. Detmers, V. 

 S., of Chicago, who conducted his investigations and made his experi- 

 ments in one of the worst infected of the many krge hog-growing dis- 

 tricts in Illinois, writing under date of January 7th last, speaks as follows 

 of the effects of severe frosts on the spread of the disease : 



Since my last letter tlie weatlier lias continued extremely cold. Where I now am, 

 in Lee County, some five or six miles west of Dixon, tlie thermometer indicated at 

 seven o'clock on tlie morning of January 2, 28° below zero, and on the next momiug 

 24° below zero. At present — to-day, yesterday and day before — tho weather is a 

 little milder. To-day it tried to snow a little ; otherwise the sky has been clear 

 every day. The wind is, and has been, west, except yesterday afternoon, when it was 

 almost due south. Swine-jilague diuing this cold Aveather does not seem to spread 

 either so readily or so rapidly from one farm to another as a few mouths ago ; but as to 

 its spreading from one animal to anoihcr iu the same herd in which it i^reviously ex- 

 isted no difference can be observed. It seems to be just as fatal as in August, and its 

 course, on the whole, is probably more acute, as severe aftections of the lungs .and of 

 the heart are more frequent, a fact easily explained in the habits of swine crowding 

 together and lying on top of each other in their sleejiing places when the temperature 

 is very low. 



Dr. Jauios Law, of Ithaca, !N". Y., whose investigations were solely 

 confined to experiments intended to further establish the contagious 

 and infectious character of the disease, the i)eriod of its incubation, 

 &c., conlirms the statement of Dr. Detmers, i. c, that the severe frosts 

 of winter do not destroy the germs of the malady but simply retard 

 their (;on\'eyance from one herd to another. In a letter of recent date, 

 forwaixled since his report Avas completed, Dr. Law says : 



I hiiAL- demon straied that the freezing of the virulent matter does not destroy its ac- 

 tivity, and lliiit the virus loses nothing in potency by preservation for one or two 



