VETERINARY SCIENCE AND PRACTICE. 925 



the injections rangin<i' from lit to 2.") minims, 20 minims, or a two-thirds 

 dose, being em})loyed for a cow of average size. 



It is pointed out that all oases showing an undoubted reaction indi- 

 cate the presence of tuberculosis, that tuberculosis can not be eradi- 

 cated without the slaugliter of animals reacting doubtfully, and that 

 the law of temperature tluctuations is not well enough understood to 

 form accurate inferences relative to the presence and extent of reac- 

 tions. Further, it is stated that good care of animals will not strengthen 

 them so as to enable them to withstand an exi)Osure to the germs, and 

 that in large herds it is to be presumed, until the contrary is pioved 

 by the tuberculin test, that tuberculosis is present. 



Sumnuirizing the work so far as it has been carried, the author states 

 that — 



"(1) Absence of leactLou nuder the Koch test is not t-ertaiu jiroof of the abseuce 

 of tuberculosis. Cows may I'ail to nact at the tirst or second injection and on sub- 

 Bequeut injection give the fever reaction, indicating the presence of tuberculosis. 



•'(2) Repeated injection of tuberculin made on a sound animal did not seem to 

 ali'ect its health, and, above all, did not ]iroduce in her any apparent tendency to 

 react to the later injections; therefore, if a cow which has failed to react in previous 

 tests does react subseciuently, such reaction is evidence of a tuberculous condition, 

 and not due to the etfect of tuberculin alone. 



"(3) Eachrepetitionof the injection ou an animal that has given a reaction is, unless 

 a long time intervenes, accompanied by a lower reaction than in the previous test. 

 The power to react, or the sensibility to injected tuberculin, is rapidly reduced by 

 repeated injection. Therefore, whenever an animal gives a doubtful reaction during 

 the application of the Koch test, the uncertainty is only increased by repeating the 

 injection. The repeated test may dispose the veterinarian to declare the animal to 

 be sound, even when tubercles are undoubtedly present. 



''(4) The temperature of the air influences a cow's temperature in some instances 

 very markedly, and must be taken into account in interpreting temperature sheets, 

 especially in summer. Humiditj'^ seems to have no eftect." 



"NTitli reference to cases originally indicated by the test as sound but 

 subsequently found suspicious, the author affirms that either the 

 animals had latent tuberculosis when lirst tested, or they were after- 

 wards infected. He favors the lirst explanation, and states that it is 

 an error to assume, when on an autopsy a tuberculous lesion is found, 

 even in an old cow, that infection is recent, and that cows 9 to 14 years 

 old may have been tuberculous all their lives and still the disease have 

 gained headway only at special intervals. The great variation in the 

 extent of reaction is taken as proof that susceptibility is developed 

 progressively, but inasmuch as susceptibility has no relation to the 

 extent of disease, it is believed probable that the sensitiveness may 

 vary periodically. In support of his statement regarding the extent 

 of tuberculosis in a latent condition, he cites the experience of Stalker 

 and Xiles' and of L. Tarson^ and adduces the case of the autoi)sy of a 

 cow already mentioned. In this animal, which had reacted to the 



' Iowa Sta. Bui. 29 (E. S. R., 7, p. 804). 



2 Pennsylvania Sta. Rpt. 1894 (E. S. R., 7, p. 9S7). 



