FOWL-TUBERCULOSIS. 275 



losis thus treated. Behring is of the opinion that tuber- 

 culin R is less well adapted for therapeutic employment in 

 the case of human beings than for the fundamental inocu- 

 lation of animals for the purpose of further immunization. 

 His own experiments, in connection with von Lingelsheim, 

 in the preparation of a serum for tuberculosis, according to 

 his statement read before the Fifteenth Congress for In- 

 ternal Medicine, appear promising. Behring and von Lin- 

 gelsheim in their experiments employed dry, highly viru- 

 lent, pure cultures of tubercle-bacilli. According to Beh- 

 ring, the tubercle-bacilli contain various substances, but 

 only one of the tuberculosis-toxins appears to possess im- 

 munizing properties. With the aid of this toxin it may be 

 hoped that a curative serum or an antitoxin will be pro- 

 duced, as in the case of diphtheria and of tetanus ; but ac- 

 cording to Behring, years may elapse before this serum will 

 prove sufficiently powerful to be introduced into general 

 practice. 



FOWL-TUBERCULOSIS. 



The bacillus of fowl-tuberculosis is closely related to the 

 bacillus of human and mammalian tuberculosis. It is somewhat 

 longer and thinner, and exhibits more frequently bulbous and 

 branched variations. It is more easily stained, but it retains the 

 stain with similar tenacity. It is not so fastidious with regard to 

 culture-media, and it develops upon ordinary agar and upon or- 

 dinary bouillon. The addition of glycerin, however, materially 

 favors its growth, which, on the whole, is more rapid than that 

 of the bacillus of mammalian tuberculosis. The cultures are 

 not so dry, but more moist, and on solid media they form a 

 coherent coating that bridges over the water of condensation. 

 All cultures constantly exhibit a yellowish discoloration. At 

 temperatures of 42 C. (107.6 F.), 43 C (109.4 F.) or 45 

 C. (113 F. ) the bacilli of fowl-tuberculosis thrive as luxur- 

 iantly as at a temperature of 37 C. (98.6 F.). This is their 

 most radical distinguishing feature as compared with the bacilli of 

 human tuberculosis, which will not develop at this temperature. 

 If the two varieties are considered identical, this difference 

 must be explained by the fact that by reason of their residence 

 in the body of birds, which naturally have a higher temperature 

 (41 .105.8 F., or 42 . 107.6 F.), the bacilli have 

 adapted themselves to a higher temperature. The bacilli of 

 fowl-tuberculosis are even more resistant to heat than those of 

 human tuberculosis, being -destroyed by exposure for fifteen 

 minutes to a temperature of 70 C. (158 F.). 



