xiv] BACILLUS TUBERCULOSIS 357 



spores of other bacilli withstand much higher temperatures. 

 Tubercular sputum distributed in salt solution does not 

 lose in the least its virulence by being kept at 100° C. 

 from one to two minutes. Nor does a solution of per- 

 chloride of mercury kill the tubercle bacilli in the way it 

 does sporeless bacilli. Dr. Lingarcl found (Report of 

 Medical Officer of Local Government Board for 1S85-S6, 

 p. 183) that solution of perchloride of mercury, one grain 

 of mercuric bichloride to 960 grains of water, that is to say, 

 about one in 1,000, although it kills the bacilli in human 



Fig. 140. — From the Juice of Lui'us-Tissue prepared akter the Koch- 

 \VErGERT Method of drying a thin Layer on a Cuvek-glass. 



Magnirying power about 700. 



tubercular matter when acting on it for four hours, does not 

 do so in the case of bovine tubercular matter, since not 

 even eight hours' exposure to the solution is sufficient to 

 neutralise the infective power of that material. This also 

 shows what has been mentioned already on a former page, 

 viz., that bovine tubercular matter is of a higher degree 

 of virulence than human tubercular matter. 



The Royal Commission on Tuberculosis issued in 1S95 

 their Report (Part L) and from the evidence given before 

 them and the extensive researches made for them by 



