156 INFLUENCE OF PHYSICAL AGENTS. 
ogenic organisms have been made by the authors named : Bacillus 
anthracis (Chauveau), 54° C.; Bacillus mallei—the bacillus of glan- 
ders—(Léffler), 55° C., Bacillus gallinarum—micrococcus of fowl 
cholera—(Salmon), 56° C. ; Bacillus of diphtheria (Léffler), 60° C. 
In the writer’s experiments the micrococcus of gonorrhcea was 
apparently killed by exposure for ten minutes to a temperature of 
60° C. 
“Some gonorrheeal pus froma recent case which had not undergone 
treatment was collected for me by my friend Dr. Rohé in the capillary 
glass tubes heretofore described. A microscopical examination of stained 
cover-glass preparations showed that this pus contained numerous ‘ gono- 
cocci’ in the interior of the cells. Two of the capillary tubes were placed 
in a water bath maintained at 60° C. for ten minutes. The pus was then 
forced out upon two pledgets of cotton wet with distilled water. Two 
healthy men had consented to submit to the experiment, and one of these 
bits of cotton was introduced into the urethra of each and left in situ for 
half an hour. As anticipated, the result was entirely negative. For obvi- 
ous reasons no controi experiment was made to fix the thermal death-point 
within narrower limits. 
‘‘In connection with these experiments upon the thermal death-point of 
known pathogenic organisms, it is of interest to inquire whether the viru- 
lence of infectious material, in which it has not been demonstrated that this 
virulence is due to a microérganism, is destroyed by a correspondingly low 
temperature. Evidently, if this proves to be the case, it will be a strong 
argument in favor of the view that we have to deal with a microdrganism 
in these diseases also. We have experimental proof that a large number of 
pathogenic organisms are killed by exposure for ten minutes to a tempera- 
ture of 55° to 60° C. But, s» far as I am aware, this low temperature would 
not be likely to destroy any of the poisonous chemical products which might 
be supposed to be the cause of infective virulence, leaving aside the fact that 
such chemical products have no power of self-multiplication, and, there- 
fore, could not be the independent cause of an infectious disease.! 
“ Vaccine Virus.—Carstens and Coert have experimented upon the tem- 
perature required to destroy the potency of vaccine virus. In a paper read 
at the International Medical Congress in 1879 they report, asa result of 
their experiments, that the maximum degree of heat to which fresh vaccine 
virus can be exposed without losing its virulence probably varies between 
52° and 54°C. Fresh animal vaccine heated to 52° C. for thirty minutes 
does not lose its virulence. Fresh animal vaccine heated to 54.5° for thirty 
minutes loses its virulence. 
‘‘ Rinderpest.—According to Semmer and Raupach, exposure for ten 
minutes to a temperature of 55° C. destroys the virulence of the infectious 
material in this disease. 
“* Sheep-pox.—The authors last mentioned have also found that the same 
temperature—55° C. for ten minutes—destroys the virulence of the blood of 
an animal dead from sheep-pox. 
‘* Hydrophobia.—Desiring to fix the thermal death-point of the virus of 
hydrophobia, I obtained, through the kindness of Dr. H. C. Ernst, a rabbit 
which had been inoculated, by the method of trephining, with material 
which came originally from Pasteur’s laboratory. The rabbit sent me 
showed the first symptom of paralytic rabies on the eighth day after inocu- 
lation. It died on the eleventh day (March 2d, 1887), and I at once pro- 
ceeded to make the following experiment : 
‘CA portion of the medulla was removed and thoroughly mixed with 
1 Since this was written Brieger has isolated a toxalbumin from cultures of the 
diphtheria bacillus which is destroyed by a temperature of 60° C., but resists 50°. 
