130 DEPARTMENT OF AGRICULTURE. 



high as 106 Fahrenheit. It is, however, remarkable how difficult it is in healthy animals 

 to cause any great deviation from a normal standard, even during the hottest days of a 

 western summer. Comparative observations on a number of animals at the same time 

 constitute a valuable and essential test. It was, however, striking and strange that in 

 examining Texan cattle caught with the lasso, the temperatures obtained were the same 

 as those among work cattle of the same herds, which, could be handled readily near the 

 wagons. Observations of this kind are referred to in the report on splenic fever. 



The bes.t part and the only one which should be chosen for the insertion of the 

 thermometer, is the rectum. The instrument must be introduced as nearly as possible to 

 the same extent in all cases, and retained in situ at least three minutes. Animals are apt 

 to defecate soon after the thermometer is passed in, and the rectum then remains passive 

 for a time. This necessitates the withdrawal and reintroduction of the instrument, and 

 the time required for the observation must be taken from the second intromission. 



By this means animals in apparent health, grazing and moving in perfect comfort, 

 are often found sick; and in the case of a contagious disease like pleuropneumonia this 

 timely warning is of the highest moment. 



In relation, however, to the nature of a malady, much is taught us by the thermome 

 ter. The periodic fever of southern cattle begins, like the rinderpest, with an increased 

 heat of the body. The local changes appear secondary to the general fever, though it is 

 difficult to estimate the time that elapses from the first exaltations of temperature to the 

 local manifestations. In pleuropneumonia it is probable, and indeed our observations are 

 almost conclusive on the point, that there is first a local change and commencing deposit. 

 A material grows and penetrates, charged with and dependent on the presence of a specific 

 poison, and when it has sufficiently involved any important parts and become complicated 

 with ordinary inflammatory changes, the general fever sets in. An elevated temperature 

 is, however, observed in this disease long before a farmer or dairyman suspects that an 

 animal is affected. This is the only way in which some latent cases of pleuropneumonia 

 are recognized. 



Scientific men have hitherto failed in tracing the distinctive characters of organic 

 poisons which differ from each other, and are only recognized, by the very different effects 

 produced on the animal economy. Some attack a single species of animal ; others induce 

 the same disease in a number of species. The lung-plague poison induces its characteristic 

 effects on cattle; the poison of hydrophobia, most readily communicated among feline and 

 carnivorous animals, is deadly to the omnivora and vegetable feeders. Of the peculiar 

 principles which tend to the diffusion of those diseases which are known to us as indigenous 

 in certain latitudes, and which we must distinguish at all times, in classifying diseases, 

 from the contagious maladies of no known primary source, we have two equally remark 

 able instances in the splenic fever of the South and the charbon or anthrax of many parts 

 of the world. The one passes from cattle to cattle; the other is deadly to men, horses, 

 dogs, pigs, and other warm-blooded animals. 



It is evident that principles which exert such a variety of definite influences must 

 have fundamental characters to distinguish them that the virus of smallpox may some 

 day be capable of distinction in its virus form from the virus of rinderpest or the lung- 

 plague. 



