508 



TEE POPULAR SCIENCE MONTELY.— SUPPLEMENT. 



resolve themselves iuto spores. This resolution, 

 as proved by Cohn and Koch, is conspicuously 

 illustrated by the Bacilhcs subtilis of hay, and the 

 Bacillus anlhracis of splenic fever. Both these 

 organisms propagate themselves by spores which 

 may be rendered as plain to the eye of the micro, 

 scopist as peas in a pod. 1 



This premised, let the reader place before his 

 mind one of the sealed chambers described in the 

 January number of this review; let him figure 

 its series of test-tubes, charged with infusions 

 which, exposed to optically pure air, have re- 

 mained sweet and clear for six months in a warm 

 room. Let the reader now suppose the door of 

 the sealed chamber to be opened, and a bunch of 

 dry hay to be shaken in the moteless air of the 

 chamber. A beam sent through that air now 

 shows it to be laden with dust. Forty-eight hours 

 after this dust has been let loose, the infusions 

 are found to have a fatty, corrugated scum upon 

 their surfaces, it may be with a clear or it may 

 be with a turbid liquid underneath. When this 

 scum is examined, it is found to consist of count- 

 less multitudes of the hay-bacillus matted to- 

 gether. What are we to conclude? Whence 

 have these organisms come ? I say there is but 

 one interpretation possible, and this is the par- 

 ticularly obnoxious phrase that my respondent 

 has italicized as marking my scientific bigotry and 

 narrowness of view. The interpretation is that 

 the organisms have come from the germs of Ba- 

 cillus subtilis, which have been shaken from the 

 hay. In giving this interpretation, and in assert- 

 ing it to be the only one, I am not, I submit, 

 arbitrarily setting my seal upon the possibilities 

 of Nature, but loyally and dutifully following her 

 teachings as an obedient son. But, my respon- 

 dent might urge, you forget the other interpreta- 

 tion, that I made so clear to the reader at page 

 267 of my " reply " — the interpretation, namely, 

 that the dust of the hay is dead organic matter in 

 a state of motor decay. This dead dust falls into 

 the infusions, and, although it does not commit the 

 "absurdity" of becoming "itself" alive, it does 

 go through the perfectly reasonable process of 

 making the dead infusions alive. The value of 

 logic leading to this issue has been duly appraised 

 by our highest scientific authorities ; its survival 

 among the general public cannot, I think, be 

 long. 



" What present warrant," asks my respondent, 



1 A few days ago I had an opportunity of seeing 

 matted together and dotted with spores some magnifi- 

 cent examples of Bacillus anthracis, which had been 

 cultivated by Mr. Ewart, of University College. 



" is there for supposing that a naked, or almost 

 naked, speck of protoplasm can withstand four, 

 six, or eight hours' boiling?" To which he 

 adds, "I can only answer none." Regarding 

 naked specks of protoplasm I make no asser- 

 tion. I know nothing about them save as the 

 creatures of my respondent's fancy put into words. 

 But I do affirm, not as a " supposition," nor an 

 "assumption," nor a "probable guess," nor, to 

 use a more strenuous stigma of my respondent, 

 "a wild hypothesis," but as a matter of the most 

 undoubted fact, that the spores of the hay-bacil- 

 lus, when thoroughly desiccated by age, have, in 

 special cases, 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' boil- 

 ing, or even less. This needs explanation. The 

 finished bacterium, as the reader of my January 

 article knows, 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 con- 

 dition the more readily will it succumb to heat. 

 Reeds soften before and during germination. 

 This premised, the simple description of the fol- 

 lowing 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 anticipate this, at the end of ten or 

 twelve hours we raise the infusion a second time 

 to the boiling temperature, which, as before, de- 

 stroys all germs then approaching their point of 

 final development. The infusion is again put aside 

 for ten or twelve hours, and the process of heat- 

 ing is repeated. We thus kill the germs in the 

 order of their resistance, and finally kill the last of 

 them. No infusion can withstand this process if 

 it be repeated a sufficient number of times. Arti- 

 choke, 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, 

 including those most tenacious of life. Not one 



