VETEEINARY MEDICHSTE. 383 



barns for the purpose of obtaining their offspring. The main milking herd was 

 then distributed among four separate disinfected barns, which held from 12 

 to 48 animals each. In the majority of cases the milking animals were tested 

 every 6 months until 2 negative tests were obtained and then yearly thereafter. 

 Calves intended for future introduction into the milking herd were immunized 

 with human tubercle bacilli intravenously injected. All new cows purchased 

 were placed in quarantine ITtO ft. from the main barns. 



In the spring of 1905 the milking herd, which then consisted of 120 animals, 

 was again tested and showed 13, or 10.8 per cent,, of reactors. Five months 

 later (November, 1905), out of 136 animals 7, or 5.1 per cent, reacted. In 

 April, 1906, 150 animals were tested and of these 13, or 8.4 per cent, reacted, 

 and in the following November out of 137 animals tested 5, or 3.6 per cent, 

 gave the test. In April, 1907, 201 animals and in October of the same year 

 137 animals were tested, but no reactions were found. During 1908, in the 

 months of April and November, 145 and 169 animals, respectively, were ex- 

 amined. In the first case the reactors present amounted to 1.4 per cent and in 

 the latter to 1.8 per cent, which shows a reinfection of the herd. In April, 

 1909, no reactors were present in the herd, but about a year after this, out of a 

 herd of 151 animals, 5 animals or 3.7 per cent reacted. The author accounts for 

 the reinfection of the herd the second time as due to the fact that 2 valuable 

 animals which reacted in November, 1908, were retained in the herd for a 

 retest. " The history and cycle of the tuberculin test for these 2 animals and 

 a few others are dealt with in detail in the original. 



" [In the vaccination experiments which were conducted] since 1904 there 

 were 184 calves vaccinated, of which 46 are in the main milking herd at the 

 present time. Of the 143 animals that were sold for breeding purposes, for 

 beef, or that died from lung worms, etc., post-mortem examinations were ob- 

 tained on approximately 100 head and no lesions of tuberculosis were found in 

 any except those aforementioned following the tuberculin test of 1911." 



The vaccine used was made from the human type of tubercle bacillus, which 

 was never more than 36 hours old. 



Report on an experiment to produce a tolerance in cows to tubercle bacilli 

 after injection of various products, A. J. Smith and H. Fox (An». Rpt. 

 Comr. Health Penn., 4 (1909), pt. 1, pp. 251-268). — In these experiments 3 

 definitely tubercular cows, 2 which were highly suspicious, and 2 which were 

 almost certainly free from the disease were used. The latter 2 animals served 

 as controls, and one received no vaccine. All of the rest of the animals were 

 given a pretreatment with tubercle bacilli in order to determine their degree 

 of resistance toward the products. The products injected, either under the skin 

 or intravenously, in the experiments proper were made from dead degreased 

 tubercle bacilli used in a standardized emulsion and a salt solution extract of 

 living tubercle bacilli in which the fat had been softened with ether. 



After giving the clinical autopsical and microscopical findings the authors 

 show that none of the above animals lived long enough to overcome the acute 

 effects of injecting a large number of bacteria into the circulation. The animals 

 which had tuberculosis before beginning the experiment, particularly those 

 where the lesions were more retrogressive, stood the injections better and 

 showed a more increased tissue resistance than those which were markedly 

 tubercular and the remainder which had only slight lesions or none at all. 

 The animals with- active lesions are not able to accommodate much extra toxin 

 or to stimulate to any great extent the power of antibody formation. 



An active immunity is therefore very difficult to attain. The methods em- 

 ployed here seem only to increase the power of the tissues to passive resistance. 



