Staining 351 



(saurefest) micro-organisms. But it is not improbable that 

 we have been led into error by the assumption, upon inade- 

 quate grounds, that this is a constant and uniform quality 

 of the tubercle bacillus and similar micro-organisms. The 

 interesting observations of Much* have shown that many of 

 the parodoxes of tuberculosis can be accounted for by the 

 fact that during certain stages, or in certain conditions, the 

 bacilli are not acid-proof at all. Thus, examinations of 

 caseous masses from the lungs of cattle show complete 

 absence of tubercle bacilli when examined by the usual 

 method, yet cause typical tuberculosis when implanted into 

 guinea-pigs, with typical bacilli in the lesions, recoverable 

 upon culture-media. This is certainly due to the inability 

 of the bacilli in the bovine lesions mentioned to endure the 

 acids, for when the same tissues are stained by Gram's 

 method, many organisms can be found. This shows that 

 Gram's method is really a more useful method for demon- 

 strating the bacillus than those in which acids are employed. 

 Naturally, Gram's method, not being differential, is inappro- 

 priate for sputum, cavity contents, and tissues in which many 

 other species of bacteria might be present. Much has found 

 two forms of the tubercle bacillus, one rod-like, the other 

 granular, that are not acid-proof, and has succeeded in 

 changing one into the other by experimental manipulation. 

 He believes that the acid-proof condition has some bearing 

 upon virulence, and speculates that the more acid-proof 

 the organisms are, the less virulent they will be found. 



In this connection the work of Maher,f who claims to be 

 able, by appropriate methods of cultivation, to make many 

 of the ordinary saprophytic bacteria (B. coli, B. subtilis, etc.) 

 thoroughly acid-proof, must be mentioned. 



Staining the Bacillus in Sputum. As the purpose for 

 which the staining is most frequently performed by the 

 physician is the diagnosis of the disease by demonstrating 

 the bacilli in sputum, that method will be first described. 



If one desires to make a very careful examination, it is 

 well to have the patient cleanse the mouth thoroughly upon 

 waking in the morning, and after the first fit of coughing 

 expectorate into a clean, wide-mouthed bottle, the object 

 being to avoid the presence of fragments of food in the 

 sputum. 



* "Berliner klin. Wochenschrift," April 6, 1908, p. 691. 



t "International Conference on Tuberculosis," Philadelphia, 1907. 



