68 



STUDY AND IDENTIFICATION OF BACTERIA. 



FIG. 25. Bacillus tubercu- 

 losis; glycerine agar-agar cul- 

 ture, [several months old. 

 (Curtis.} 



It is important to remember that such 

 organisms have very rarely been reported 

 from pulmonary lesions, and when pres- 

 ent they have been considered as proba- 

 bly causative. Consequently the finding 

 of tubercle bacilli in sputum has practi- 

 cally as great value as it had before we 

 knew of these various acid fast bacteria. 



Tubercle Bacillus (Koch, 1882). 

 This is a rather long, narrow rod, 3 x. 3//.. 

 In the human type it tends to show a 

 beaded appearance, this not being due to 

 spores, however. In the bovine type the 

 staining is .more solid, the organism 

 shorter and thicker, and shows even a 

 more scanty growth than human T. B. 

 It has been established that many of the 

 tuberculous affections of man, especially 

 those of the skin, bone and mesenteric 

 glands, are of the bovine type, while, as a 

 rule, pulmonary and laryngeal lesions 

 are of the human type. Experiments by 

 various commissions in different countries 

 have shown that human and bovine types 

 are very closely related and that not only 

 may a bovine strain affect man, but that 

 human T. B. may infect young calves. 

 It is a question whether the avian type is 

 absolutely distinct; many experiments 

 having indicated the impossibility of in- 

 fecting fowls with human T. B. Nocard, 

 by inserting collodion sacs containing 

 bouillon suspensions of human T. B., 

 claims to have changed these to the avian 

 type. The avian type grows at 43 C. 

 fairly luxuriantly, as a moist, more or 



