286 BULLETIN No. 161 [November, 



external injurious agencies such as heat, drying, light, chemicals, 

 and putrefaction. This, in general, is found not to be the case. 

 Rosenau 123 says, "The tubercle bacillus may be classed with the 

 nonspore-bearing organisms so far as its viability is concerned." 

 This statement is surely correct with respect to heat and light. 

 The thermal death point of the tubercle bacillus, as determined by 

 the more careful investigators (Herr 56 , 1901; Hess 57 , 1901; Rus- 

 sell and Hastings 127 , 1904; and Rosenau 121 , 1908), is given at 

 60 C., with an exposure of from fifteen to twenty minutes. This 

 is practically the same as the thermal death point determined for 

 most other nonspore-bearing organisms. (Sternberg 145 , Smith 130 ). 



As regards desiccation, and more especially the antagonism 

 offered by decay and foul matter, tubercle bacilli appear rather to 

 take an intermediate position between spore- and nonspore-bearers. 

 Rickards, Slack and Arms 119 found that tubercle bacilli in sputum 

 resisted drying for 88 days; LeNoir and Camus 83 found these 

 organisms alive after 33 days ; Kuss 77 found them alive from 20 

 to 30 days, and killed in 40 to 60 days; Noetel 105 found them yet 

 living after 35 days. Maffucci 90 shows that pure cultures of avian 

 tubercle bacilli dried on silk threads live for 14 days. Kirstein 09 

 finds pure cultures dried in dust living from 3 to 8 days. In my 

 own experiments they lived 8 days. Other nonspore-bearing organ- 

 isms die in a very short time, as B. violaceus, i day; B. typhoid, 

 3 days; and B. coll, 3 days. There are reported in the litera- 

 ture cases where nonspore-bearing organisms have resisted drying, 

 under special conditions, for a very long time. Rosenau 123 finds 

 B. pestis to live over four months on a piece of dry sponge. 

 Sirena and Alessi 135 report that the pneumonia diplococcus, when 

 dried on silk threads kept in a moist room, did not die until after 

 192 days. More comparative work must be done with cultures of 

 different nonspore-bearers and with tubercle bacilli exposed under 

 the same conditions before definite conclusions can be drawn. 



In the presence of foul material tubercle bacilli live from a 

 month to a year and more (see Table 7). In my own experi- 

 ments they were always found to live in water for 202 days and 

 as long as 441 days. In this work much care was taken to deter- 

 mine that the tuberculosis produced in the test animals was by 

 living germs. Careful workers like Jordan, Russell and Zeit 65 have 

 found B. typhosus living in sewage from 3 to 4 days only ; Russell 

 and Fuller 126 report from 8 to 10 days. It would be expected 

 that tubercle bacilli protected by the mucoid material, as found in 

 sputum and diseased tissues, in which these germs more frequently 

 occur, and also by their abundance of naturally waxy constituents, 



