184 EXPERIMENT STATION RECORD. 



iiKK-iilutcil int.) ni])l)it.s in .luantities varying from 1 to S rr., phmIuccmI within 15 .lays 

 lyi>ical (•asc.u.s processes with giant cells and with stainable tubercle bacilli. All 

 animals inoculated in this manner showed a pronounced decrease in weight. Non- 

 virulent tubercle bacilli which had been subjected to the same temperature and later 

 inoculated into the body cavity or hypoderinically produced no changes in the 

 experimental animals. Inoculations with the tubercle bacilli from tish in quantities 

 of from 2 to 4 cc. had no effect, the health of the animals remaining good, and no 

 changes were revealed by a microscopic study. From these experiments the author 

 concludes that virulent tubercle bacilli are not killed by subjection to a temperature 

 of 120° C. 



Tlie author studied the prol>lem of variation in reaction to tuberculin on tlie part 

 of animals which had l)een inoculated with tubercle bacilli of different degrees of 

 virulence. It was found that animals inoculated with from 0.1 to 0.25 mg. of virulent 

 tul)ercle bacilli, after a period of from 2 to 4 weeks, reacted ]jy a rise in temperature 

 of from 1 to 1^°. Animals inoculated with the same amount of nonvirulent tuljercle 

 bacilli usually showed an elevation of only a fraction of a degree when tested with 

 tuberculin. Animals which were inoculated with tubercle bacilli from fish did not 

 react to the tuberculin test. 



In order to determine the reaction of tuberculous guinea pigs to tul)erculins i)re- 

 pared from tubercle bacilli of different degrees of virulence, the author made a num- 

 ber of inoculation experiments. During this study it was found that tuberculous 

 guinea pigs which received from 0.1 to 3 mg. of tuberculin, prepared from virulent 

 tubercle bacilli, showed an elevation of temperature which constantly exceeded 1°. 

 Tuberculous guinea pigs when tested with from 0.2 to 3 mg. of tuberculin from non- 

 virulent tubercle bacilli of human origin, from fishes, or from tubercle l:)acilli which 

 had been subjected to a high temperature, reacted Avitli a rise of temperature which 

 never reached 1°. 



The period of incubation of tuberculosis in cattle and the ag-e of tubercular 

 lesions, Nocard (AVc. Med. Vet., Paris, S.ser., 7 {1900), No. £.3, pji. S11-S15).— The 

 results of the author's experiments may be stated as follows: Ingestion of tubercu- 

 lous material rarely causes tuberculosis, while inhalation is believed to l>e the ordi- 

 nary method by which the disease is a(;quired. Enormous quantities of tuberculous 

 material were fed to 4 cows, with the result that 1 resisted infection entirely and no 

 lesions could be found in the other 3, although they responded slightly to the tuber- 

 culin test. Experiments indicated that tuberculous material could be inhaled in a 

 state of dry, impalpable dust or in fine particles held in suspension. 



The period of incubation of tuberculosis in experimental animals varied from lU to 

 32 days. Direct inoculation into the trachea did not give uniform results. The 

 lungs entirely escaped infection. Even in cases infected by inhalations of dry tuber- 

 cular material the pulmonary alveoli were not attacked, the tubercular lesions being 

 confined to the pleura or periphery of the pulmonary lobes. The nmcous layer of 

 the bronchial tubes and active mammary glands showed very slight resistance to 

 infection, and were nearly always centers of tubercular lesions. The author believes 

 that the mannnary glands may occasionally be the primary focus of tuberculosis. 

 Intravenous inoculations with virulent tubercle bacilli uniformly gave the most 

 malignant and rapid form of tuberculosis; but since this method of infection can 

 hardly Vje realized under natural conditions, it is of no great practical importance. 

 The interesting fact was noted in connection Avith experimental tuberculosis that the 

 tubercles in no case became caseous or calcified. 



The growth of tubercle bacilli on acid media, G. Jochman.x (Hyg. Itmtd- 

 aclmu, 11 (1900), Xo. 1, jip. 1, ;?).— During culture experiments it was found that a 

 medium with an acid reaction had a favoral)le effect upon the growth of the tubercle 

 V)acillus. The author continued his experiments along this line, in order to deter- 

 mine the conditions most suitable for producing a rapid growth of the bacillus. 



