CONTAGIOUS DISEASES OF DOMESTICATED ANIMALS. 385 



those of his next neighbor south, Mr. Hadeler's, became affected next. 

 Mr. Hadeler lost one hundred head, and saved nine. His hogs aifected 

 those of Mr. Lawrence, who lives a little further south, close to the 

 northern bank of Eock Eiver. From Mr. Lawrence's farm the disease 

 traveled west half a mile, and invaded Mr. MuUer's herd. I was at his 

 place on January 3, soon after the plague had made its appearance. 

 Mr. MuUer had his herd divided, and kept one part in one yard, and the 

 other in an adjoining one separated from the former by a board fence. 

 The disease was prevailing only in one yard, in the one toward the east. 

 Five animals had died. Owing, probably, to tlie severe cold, and to the 

 15 or 18 inches of snow covering the ground and preventing evaporation, 

 the plague remained confined to the eastern yard, and the animals in 

 the western yard escaped. 



I could cite many more cases illustrating the peculiarities of swine 

 plague in its spreading or propagation, but those given, I think, may 

 suffice. The mortality, all other conditions being equal, is always 

 greater the larger the herd and the younger the animals. 



In my first report I stated that the vitality of the bacilli and their 

 germs is not very great, except where circumstances and surroundings 

 are favorable. This opinion has been confirmed by further observations 

 and experiments. In all animal substances the hacilli and their germs 

 are destroyed, or at least disappear, as soon as putrefaction sets in ; or, 

 to be more definite, they begin to disappear in animal fluids and other 

 animal substances as soon as the putrefaction bacteria make their ap- 

 pearance (see drawings), and cannot be found after the putrefaction bac- 

 teria have become numerous. On the other hand, if contained in a 

 fluid that does not undergo putrefaction, or in which bacterium termo 

 does not appear, the vitality of the bacillus suis is a great one. On the 

 27th of January last I put some filtrated pulmonal exudation (of a pig 

 that died of swine plague) swarming with bacillus germs, but consisting 

 of about one-half of water, which had been added by moistening the 

 filtering papers in a 1-ounce vial with a tight-fitting glass stopper, and 

 left it untouched until the 12th of April, when I examined it again, and 

 found numerous bacilli suis, some of them moving very lively. The vial 

 and its contents, meanwhile, had been exposed to a variety of temper- 

 ature, ranging from the freezing point to nearly 100° F. 



On June 10 I took two perfectly clean 4-ounce vials, and put in each 

 three ounces of clean well-water in which no bacteria nor any other 

 living thing could be found. In one vial, marked No. 1, 1 put half a drop 

 of the fresh pulmonal exudation of a pig that had died of swine plague 

 (Mr. Coffee's), and in the other vial I put one drop of the same pul- 

 monal exudation and three drops of pure carbolic acid. Both vials were 

 immediately closed with new corks, and sealed perfectly air-tight with 

 asphaltum. Both vials were o]iened and their contents examined on 

 July 24. The water in vial No. 2 was examined first, and contained a 

 few motionless bacilli and some clusters of bacillus germs. The water in 

 vial No. 1, which was examined next, contained a few moving and several 

 motionless bacilli, numerous germs, single and double, several clusters, 

 and a few (two or three on a slide) well-preserved blood-corpuscles. 



As has been stated in the chapter on "Morbid Changes" (cases 7 and 

 8), I had an opportunity on January 22 to make Shpost mortem examina- 

 tion of two hogs which had been down with swine plague in the early 

 pfirt of November, and had recovered two months ago, and had thus a 

 chance to see to what extent the morbid changes had been reduced by 

 melting and absorption of the morlud products, and retrogressive pro* 

 25 Aa 



