394 EXPEEIMENT STATION RECORD. 



to inmiuiiize cattle. The Ijest results were obtained from the use of bacilH of human 

 origin whi(;li have been cultivated on artificial media for about 6 years. As a rule 

 young cattle, from 5 to 7 months old, were selected for the experiments. Eacli ani- 

 mal received intravenously 1 mg. of a serum culture 4 to B weeks old; after 4 weeks 

 the animal received 25 mg. of the same culture. Tlie effect of the first inoculation 

 was usuall\' noticed in an elevation of temperature, slight loss of flesh, coughing in 

 some instances, and a susceptibility to tnberculin reaction. The animals, however, 

 recovered usually within a week or 10 days and did not react to tuberculin there- 

 after. The second inoculation produced milder symptoms and the reaction per- 

 sisted for a shorter time. After this treatment, which in some cases was repeated 

 a larger number of times, the animals proved to be immune to inoculation with viru- 

 lent cnltures which were sufficient to kill the control animals within a few weeks. 

 The immunized animals also proved resistant t(j infection by natural methods, as 

 shown by exposure to i-attle suffering from advanced tuberculosis. 



The authors consider their method of innnunization to be strictly analogous to 

 vaccination in man for smallpox. The term, however, was rejected on account of 

 its association with smallpox and on account of the derivation of the word. The 

 term "jennerization" is chosen fur the method adopted by the authors for immu- 

 nizing cattle. The process which takes place in the jennerization of cattle is there- 

 fore considered as an isopathic autoimmunization. 



Many of the animals which have been inmiunized at the Marburg institute have 

 been exposed for a number of years to natural infection, and have all shown perfect 

 resistance to the disease. It is considered, however, that the method has not been 

 tested sufficiently to determine with certainty whether immunization against artifi- 

 cial infection is an easier or more diflicult matter than immunization against natural 

 infection. This question ^^ ill be tested more extensively in future experiments. In 

 a number of experimental cattle which had been jennerized evidence of apparent 

 infection was obtained upon post-mortem examination, but this apparent infection 

 persisted for a short time only, when the attenuated bacilli died or became encap- 

 suled. In the cases in which small tuberculous foci were produced in the lungs as 

 the result of jennerization the authors used much more virulent cultures than were 

 actually required for producing immunity. This was done in order to gain some 

 knowledge of the limits of virulence of cultures which could safely be used. The 

 authors believe that young cattle may be imnninized against tuberculosis by the use 

 of cultures of tubercle bacilli, w'hich will not produce any bad effects in the animals. 

 It is the intention of the authors to conduct further experiments for the purpose of 

 deteniiining whether inoculation of fresh cultures of human origin may not be pre- 

 ceded by inoculation with tubercle bacilli cultivated in vacuum, with bacilli attenu- 

 ated according to Arloing's method, or even with tubercle bacilli from fowls. Sub- 

 sequent experiments must also determine whether the dose of 25 mg. is sufficient in 

 all cases to produce a permanent innnunity, and whether any danger would attend 

 the use of larger doses. 



The comparative virulence of the tubercle bacillus from human and bovine 

 sources, M. P. Ravenel {Pnnm/Ivania DejA. Agr. Rpt. 1901, pi. 1, pp. 286-324; Jour. 

 Com. Med. and Vet. Arch., 2S {1902), Nos. 2, pp. 65-81; 3, pp. 138-156).— The experi- 

 ments which are reported in this pa])er involved 2 lines of work, the isolation and 

 study of pure cultures of tubercle bacilli from various sources in man and cattle, and 

 the testing of the pathogenic power of tubercles of human and bovine origin. A con- 

 siderable variety of animals was employed in these experiments for testing the viru- 

 lence of pure culture and tuberculous material. The exi)erimental animals included 

 guinea pigs, rabbits, dogs, cats, horses, goats, calves, sheep, and pigs. Detailed notes 

 are given on the technical methods employed in securing pure cultures of the tul)ercle 

 bacillus from l)ovine tubercles and from human sputum. The conditions surround- 

 ing the various inoculation experiments and the subsequent fate of all such experi- 



