:256 CONTAGIOUS diseases of domesticated animals. 



the experiments, for reasons stated in my last report, did not meet 

 "witb satisfactory results, and Some unavoidable mistakes were com- 

 mitted. So, for instance, I inoculated a Texas cow, wbicli undoubtedly 

 possessed immunity, but was the only animal at my disposal, and as I 

 had to remain in Texas I delegated that part of my experiments, of 

 which success migLt have been expected, because to be carried out in the 

 North, where the cattle do not possess immunity, to a friend. It also 

 miscarried for reasons stated in my last report. Another experiment, 

 made by myself in the North, was made on very young animals, and too 

 late in the season, and besides this, some other mistakes, partly un- 

 avoidable, and known to be mistakes when made, and partly due to a 

 want of facilities and inexperience, were committed, which it will not 

 be necessary to enumerate, for they will be avoided in the future. All 

 this combined, however, amply accounts for the want of success, which, 

 therefore, has not decided anything. Besides it is to me exceedingly 

 doubtful whether a disease not known to have ever been directly or 

 indirectly communicated by a diseased animal to a healthy one can at 

 all be inoculated in the usual way. At any rate no well authenticated 

 case of any direct infection or communication of the disease from a 

 diseased animal to a healthy one is on record, while many cases are 

 known in which animals took sick with southern cattle fever and died 

 of it in the midst of healthy herds and none of the heathy animals, 

 unless previously infected, ever contracted the disease. Neither is it 

 positively known that Northern cattle or cattle themselves susceptible 

 to an infection ever infected northern pastures, «&c. Still, whether under 

 certain circumstances they are able to do so is another question. North- 

 ern or susceptible cattle, grazing on premises or drinking out of water- 

 holes infected by Southern cattle, almost invariably contract the 

 disease and die of it before the system becomes accustomed to the 

 action of the pathogenic principle (the bacteria), and charged with the 

 same to such an extent that the latter will be present, and be con- 

 stantly reproduced in the mucous secretions of the mouth and in the 

 juices of the })aunch. 



But it stands to reason, if they (the Northern cattle) gradually ac- 

 quired immunity like the Texans, and then continued for a certain 

 length of time to occupy infected premises and to take up the infec- 

 tious i)rinci[)le, or if it were j)0ssible to charge their syst(,Mn with the 

 pathogenic principle, as just indicated, before they contract the dis- 

 ease and die of it, then these Northern cattle, if driven to uninfected 

 pastures, would probably infect the latter just as effectively and just 

 as soon as Southern cattle, particularly if the Northern cattle were 

 first driven like a herd of Texans, and thus caused to shiver. That 

 suscei)tible cattle, or such as will contract the disease, do not com- 

 municate it to otiicrs, strange as it may seem, probably also admits an 

 .exi)lanation., if all known facts are taken into due consideration. 



In the first place, tlie pathogenic princii)le (the bacteria) of south- 



