31 
is justifiable to assume that if 60° C. for twenty minutes is sufficient 
to destroy the infectiveness of such milk when injected into the peri- 
toneal cavity of a guinea pig, any ordinary market milk after such 
treatment would be quite safe for human use by the mouth so far as 
tubercle bacilli are concerned. 
It is difficult, if not impossible, to summarize the work of- others 
upon the thermal death point of the tubercle bacillus. The follow- 
ing table necessarily leaves out many factors : 
Showing the thermal death point of the tubercle bacillus as found by various investigators . 
Investigator. 
Killed at— 
Not killed at — 
Martin, 1882 
May, 1883 
Sormani, 1884 
Schill and Fisher, 1884 
Voelsch, 1887 
Yersin, 1888 
Bitter, 1890 
Bang, 1891 
Bonhoff, 1892 
Grancher and Ledeux-Le- 
bard, 1892 
Forster, 1892 
De Man, 1893. . 
Schroeder, 1894, 
Woodhead, 1895. 
Marshall, 1899 
Th. Smith, 1899 
Morgenroth, 1900. 
Kobrak, 1900 
Beck, 1900 
Galtier, 1900.: 
Russell and Hastings, 1900. . . 
Herr, 1901 
Hesse, 1901 
Levy and Bruns, 1901 
Barthel and Stenstrom, 1901.. 
Bang, 1902. . ..' 
Tjaden, 1903 
Rullmann, 1903 
Barthel and Stenstrom, 1904.. 
Russell and Hastings, 1904. . . 
Zelenski, 1906 
Rosenau, 1907 
By cooking 
Boiling, 5 minutes. 
160°, 10 minutes (—spores) 
\60°, 10 minutes (+ spores) 
68°, 20 minutes 
[70°, 5 minutes (enfeebles) 
)60°, 5 minutes (sometimes enfeebles). 
80°, (sometimes kills) 
185° (always kills) 
60°, 20 minutes 
/60°, 5 minutes (attenuates) 
\70°, 1 minute (kills) 
(60°, 6 hours 
\95°, momentary 
/ 55°, 4 hours 
\60°, 1 hour 
60°, 15 minutes 
50°, 15 hours 
60°, 8 hours 
60°, 45 minutes 
70°, 45 minutes 
.70°, 2\ minutes 
68°, 20 minutes 
60°, 15 to 20 minutes 
55°, 3 hours 
50°, 4 hours 
100°, 3 hours 
60°, 20 minutes. 
65°, 15 minutes. 
60°, 20 minutes. 
65°, 15 minutes. 
85°, 1 to 2 minutes 
65°, 30 minutes 
80°, 1 minute (uncoagulated) . 
71°, 1 minute 
80°. 
90° for 10 minutes. 
100 °. 
100°, boiling twice. 
60°, 20 minutes. 
50°, 60 minutes. 
55°, 3 hours. 
60°, 45 minutes. 
80°, momentary. 
60°, 45 minutes. 
90° (results contradictory). 
60°, 10 minutes. 
(70°, 10 minutes. 
\100°, momentary. 
fl00° 
\80°, 30 minutes. 
85°, 6 minutes. 
80°, 5 seconds. 
70°, 15 minutes. 
60°, 15 minutes. 
60°, 20 minutes. 
80°, 1 minute (coagulated). 
76°, 20 minutes. 
The above tabular statement shows that my results agree with the 
work of Yersin, Bonhoff, Schroeder, Th. Smith, Russell and Hastings, 
and Hesse in that 60° C. for twenty minutes and less is sufficient to 
kill the tubercle bacillus. 
I am now conducting a further series of experiments upon the 
thermal death point of the tubercle bacillus in butter and milk, nat- 
urally and artificially infected, and while this work is not yet com- 
pleted, the indications again are that 60° C. for twenty minutes is 
quite sufficient to kill the organism under these conditions. 
