CONDITIONS FAYOURIN& FERMENTATION. 



81 



not take place in a single instance, the inoculated mixture 

 having been boiled as before for ten minutes. 



Further than this I have not gone, at present, though it will be 

 easy, when time permits, to ascertain the exact death-point of 

 the Bacillus-spores, and whether their power of resistance is at all 

 greater than that of the rods and filaments from which they are 

 derived. Had it been found in the foregoing experiments that 

 fermentation invariably occurred in the fluids in which the spores 

 were contained and not in those holding the rods and filaments, 

 we should have had a fair presumption that the spores had sur- 

 vived — since, in face of the possibility of the existence of a chemical 

 ferment in the materials which served as inoculating agents, 

 this would probably have been similar in both. Still this view 

 could not have been certainly held ; the differences in the medium 

 which had led to spore-formation in the one and not in the other 

 liquid might also have entailed a difference in their chemical pro- 

 ducts ; so that, in the face of affirmative results, the possible in- 

 fluence of the medium and its chemical principles must have been 

 diff'erentiated from the influence of the organism alone. 



It remained only to ascertain by similarly exact experiments 

 whether any evidence could be obtained in favour of the state- 

 ment that a previous desiccation enabled spores, in such a state, 

 and when surrounded by thin albuminoid or gelatinous envelopes, 

 to resist for a long time the moistening influence of water, and 

 thereby to withstand for prolonged periods a degree of heat 

 which would otherwise have proved destructive. 



To test this point I proceeded in the following manner. I took 

 a hay-infusion on which there was a well-formed scum containing 

 myriads of the most typical spore-bearing fibres, partly entire 

 and partly breaking up. » This was put into a corked vessel and. 

 shaken vigorously for a few minutes, so as to procure a uniform 

 dissemination of the spores through the liquid. Some of the 

 thick, muddy-looking fluid was then poured upon an ordinary, 

 clean, microscope slip, so as to cover it with a stratum of fluid, 

 which was subsequently allowed to evaporate. In the course of 

 three or four hours, when a dry opaque layer had been left upon 

 the glass, the slip was placed in the dry chamber of an incubator at 

 a temperature of 1 22° F., where it was kept exactly four days. The 

 dry layer was then scraped off" with a clean knife into a clean watch- 

 glass, and to the resulting powdery material about thirty or forty 

 drops of distilled water were added. 



LINN. JOUEN. — ZOOLOGY, YOL. IIY. 6 



