586 FRAGMENTS OF SCIENCE. 



protoplasm can withstand four, six, or eight hours* boil- 

 ing?" Regarding naked specks of protoplasm I make no 

 assertion. I know nothing about them, save as the crea- 

 tures of fancy. But I do affirm, not as a ' ' supposition," nor 

 an "assumption/ 7 nor a "probable guess," nor as "a wild 

 hypothesis," but as a matter of the most undoubted fact, 

 that the spores of the hay bacillus, when thoroughly desic- 

 cated by age, have withstood the ordeal mentioned. And 

 I further affirm that these obdurate germs, under the 

 guidance of the knowledge that they are germs, can be 

 destroyed by five minutes' boiling, or even less. This 

 needs explanation. The finished bacterium perishes at a 

 temperature far below that of boiling water, and it is fair 

 to assume that the nearer the germ is to its final sensitive 

 condition the more readily will it succumb to heat. Seeds 

 soften before and during germination. This premised, the 

 simple description of the following process will suffice to 

 make its meaning understood. 



An infusion infected with the most powerfully resistent 

 germs, but otherwise protected against the floating matters 

 of the air, is gradually raised to its boiling-point. Such 

 germs as have reached the soft and plastic state immediately 

 preceding their development into bacteria are thus 

 destroyed. The infusion is then put aside in a warm room 

 for ten or twelve hours. If for twenty-four, we might have 

 the liquid charged with well-developed bacteria. To antici- 

 pate this, at the end of ten or twelve hours we raise the in- 

 fusion a second time to the boiling temperature, which, as 

 before, destroys all germs then approaching their point of 

 final development. The infusion is again put aside for ten 

 or twelve hours, and the process of heating is repeated. 

 We thus kill the germs in the order of their resistance, 

 and finally kill the last of them. No infusion can with- 

 stand this process if it be repeated a sufficient number of 

 times. Artichoke, cucumber, and turnip infusions, which 

 had proved specially obstinate when infected with the 

 germs of desiccated hay, were completely broken down by 

 this method of discontinuous heating, three minutes being 

 found sufficient to accomplish what three hundred minutes' 

 continuous boiling failed to accomplish. I applied the 

 method, moreover, to infusions of various kinds of hay, in- 

 cluding those most tenacious of life. Not one of them bore 

 the ordeal. These results were clearly foreseen before they 



