[SHANLY] HEAT RESISTANCE OF BACTERIAL SPORES 135 



heat-resisting properties as do the endospores of bacteria. It is not 

 a little remarkable that scarcely any attention seems to have been 

 given this question. I have found only one reference to the matter 

 in the course of my reading, and that, merely the vague passing state- 

 ment that the thermal resistance of the spores of forms like Mucor and 

 Pénicillium is distinctly less than that of bacterial endospores. It 

 seemed worth while, therefore, to study this matter in its broader 

 aspect to observe what is the resisting power of the gonidia of the lower 

 moulds, and to compare this with the resisting power of the presumed 

 spores of the tubercle bacillus. 



Having obtained luxuriant growths of two fungi. Pénicillium glau- 

 cum and Mucor Sp.K ?) on bread exposed to the air of the laboratory, 

 we subjected them- under the same conditions to the test of heating in 

 broth. After the required period of heating, the broth was cooled 

 and poured upon sterile bread in test-tubes. The first experiment was 

 that of heating for sixty minutes at 100°C. then 60°C. Following 

 these were a series decreasing both in the degree of heat, and in the 

 length of the time of exposure, until at length it was found that the 

 gonidia would not germinate after heating for ten minutes at 40°C. 

 This is a confirmation of the preceding statement that they are dis- 

 tinctly less resistant to heat than are endospores. Evidently with a 

 very moderate heat the spore case of these large gonidia becomes 

 ruptured when they are immersed in fluid. 



THE THERMAL DEATH POINT OF THE PRESUMED SPORES OF 

 B. TUBERCULOSIS. 



The method used for testing the tubercle bodies was varied to 

 the extent that all growths of this bacillus were planted upon either 

 Dorset's egg medium or upon glycerine agar, which media are known 

 to be much more satisfactory for this organism than plain agar-agar; 

 the Diphtheroid bacillus of Hodgkin's disease was transferred to hy- 

 drocele agar. As showed years ago by Prudden and Hodenpyl,^ 

 the intravenous inoculation of tubercle bacilli killed by heat, results 

 in the production of characteristic tubercles around the clumps of the 

 dead bacilli where they become arrested in the capillaries. While 

 these tubercle-like growths eventually become absorbed and disap- 

 pear, and normally no progressive infection is set up, these "pseudo- 

 tubercles" nevertheless by their presence delay a sure diagnosis re- 

 garding the vitality of inoculated bacilli. It is therefore inadvisable 

 to employ animal inoculation as the test, in researches upon the ther- 



^ This was a mucor having the general characters of Mucor mucedo though the 

 Sporangia were smaller than is usual with this species. 

 2 New York Med. Jour., June 6th and 20th, 1891. 



