

DETECTION OF THE BACILLUS 345 



tuberculous subjects and sometimes in very large numbers. In order to 

 determine whether these bacilli are tubercle bacilli or no resort must always 

 be had to guinea-pig inoculation.] 



I. Milk. 



Tubercle bacilli occur only in small numbers in milk and the chances of 

 finding them by microscopical examination are far from great. [Moreover 

 non-pathogenic acid-fast bacilli (infra) are of frequent occurrence in cow's 

 milk and no reliance can be placed upon microscopical examination for the 

 detection of tubercle bacilli in milk. ] Several methods have been described 

 for detecting the bacillus in milk. 



(a) Leave the fresh milk to stand for 24 hours and examine the deposit. 



(6) Centrifuge and use the precipitate for making films. 



(c) Coagulate 200 c.c. of milk with a little powdered citric acid, filter, 

 dissolve the precipitate on the filter in a solution of sodium phosphate, pour 

 the liquid into a large test-tube, add a few cubic centimetres of ether, shake 

 for 10 minutes or so, decant the ether with the fat in suspension, centrifuge 

 the aqueous fluid and examine the deposit. 



With milk as with urine the only certain method of ascertaining whether 

 a given specimen contains the tubercle bacillus is to inoculate a few cubic 

 centimetres collected as aseptically as possible into the peritoneum of a guinea- 

 pig. [Stand the milk in the ice chest for 12 hours. Pipette off some of the 

 cream into one sterile centrifuge tube and the deposit into another. Centri- 

 fuge and inoculate 3 c.c. of the cream from the first tube into one guinea-pig 

 and 3 c.c. of the deposit from the second into another guinea-pig.] 



[A. S. Griffith and others have shown that tubercle bacilli are found in the 

 milk of cows suffering from tuberculosis quite independently of whether there 

 is disease of the udder or not. The bacilli cannot however be detected on 

 every occasion on which the milk is tested. F. Griffith suggests in explana- 

 tion of this fact " that the quantity of milk " (50 c.c.) " inoculated was not 

 sufficient to be representative rather than that the elimination of tubercle 

 bacilli was irregular since in several of the animals " (inoculated with the 

 milk) " the slight amount of disease produced showed that only a few bacilli 

 had been inoculated." And this explanation is supported by the fact that 

 if a number of guinea-pigs say eight be each inoculated with the same quantity 

 of the same milk often not more than one animal develops tuberculosis. ] 



THE ACID-FAST, OR PARA-TUBERCLE, BACILLI. 



Besides the leprosy bacillus, the bacillus of verruga and the smegma bacillus 

 there is a number of bacilli which share with the tubercle bacillus the property of 

 resisting the decolourizing action of acids. These organisms, variously described 

 as acido-phile, acid-fast, or para-tubercle bacilli, have been described by Petri, 

 Rabinowitsch, Riibner, Beck, Obermiiller, Coggi, and Moeller as occurring in milk, 

 butter, manure, grass, air, and so on. Moeller, in particular, has described several 

 species of these organisms (the manure bacillus or Misibazillus, the grass bacillus or 

 Grasbazillus, and the Timothy-grass bacillus or Timothee bazillus). Similar bacilli 

 have been found in various pathological conditions in man e.g. in gangrene of the 

 lung (Pappenheim, Meyer, Lydia Rabinowitsch, and others) in conditions of the 

 eye simulating tuberculosis (Guisberg), in various pulmonary diseases (Moeller, 

 Flexner, Ohlmacher, and others) and in diseases of the alimentary canal (Mironescu) 

 etc. The ichthic bacillus described by Dubard also belongs to this group. 



None of these bacilli which morphologically resemble the tubercle bacillus can 

 be distinguished from the latter in microscopical preparations : when stained they 

 are not decolourized by acid and even sometimes not by alcohol. According to 



