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 (Loffler), 55 C., Bacillus gallinarum micrococcus of fowl 

 cholera (Salmon), 56 C. ; Bacillus of diphtheria (Loffler), 60 C. 



In the writer's experiments the micrococcus of gonorrhoea was 

 apparently killed by exposure for ten minutes to a temperature of 

 60 C. 



" Some gonorrhceal pus from a recent case which had not undergone 

 treatment was collected for me by my friend Dr. Rohe 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 WHS entirely negative. For obvi- 

 ous reasons no control 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 microorganism, 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 microorganism 

 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 tfO 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. 1 



" 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, as a 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 3 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 : 



" A 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 u temperature of 60 C., but resists 50. 



