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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



spondent invented the theory referred to in my 

 January article, according to which sound tins 

 do, in the first instance, ferment, the associated 

 organisms committing suicide by the pressure of 

 the gases developed by their own vital actions. 

 This is the very first point to which his " reply," 

 if he meant it, to be a real one, ought to have 

 been directed. Why did he, when dealing with a 

 question described by himself as " lying at the 

 root of the most fatal class of diseases to which 

 the human race is liable," commit the levity of 

 enunciating so easily tested a theory without hav- 

 ing carefully verified it experimentally ? Why, 

 after its character has been exposed, does he still 

 leave his medical brethren in the dark regarding 

 his views by neglecting to confess his error, and 

 to retract it ? The reply that we have a right 

 to demand of him ought to direct itself to such 

 points as this. 



In my January article I also refer to sixty 

 flasks prepared in the .Royal Institution, and 

 transported in warm July weather to the Alps. 

 On their arrival fifty-four of these flasks were 

 found transparent and void of life. Six of 

 them were charged with organisms, and these 

 particular six were found on examination to 

 have had their fragile sealed ends broken off. 

 Here is a question for my respondent which he 

 does not attempt to answer. I described accu- 

 rately the way in which the flasks were charged 

 and sealed, and gave him, moreover, a represent- 

 ative drawing of one of them. He does not of- 

 fer a word of explanation of the sterility of the 

 fifty-four flasks, prepared according to his own 

 prescription, and which ought, according to his 

 prediction, to have " swarmed with bacteria and 

 allied organisms." With reference to his press- 

 ure-theory, which he has also applied to explain 

 Gruithuisen's experiments, he was, moreover, in- 

 formed that animal and vegetable infusions had 

 been subjected by me to mechanical pressures far 

 more than sufficient to produce the bactericidal 

 effects which his theory ascribes to pressure, and 

 that bacteria nevertheless grew and multiplied to 

 countless swarms under such pressure, but he has 

 not a word of answer to the fact, or of acknowl- 

 edgment of what it involves. He had claimed a 

 power for the " actinic rays " as aiding in the de- 

 velopment of organisms. By observations con- 

 ducted in the powerful sunlight of the Alps, and 

 at the temperatures which my respondent declared 

 to be most efficient, the alleged power was proved 

 to be a delusion. I pointed out the fundamental 

 mistake contained in his communication to the 

 Royal Society, where an observation made with a 



mineral solution is unwarrantably extended to an 

 organic infusion, a demonstration of the de novo 

 generation of living organisms being founded on 

 this illegitimate process; but the " reply " does 

 not contain an allusion, much less an answer, to 

 my counter-demonstration. He passes without 

 notice my remarks about positive and negative 

 results, his " misunderstanding " of which, to use 

 the words of Dr. William Roberts, " makes him 

 blind to the overwhelming cogency of the case 

 against him." In reply to one of his arguments, 

 I ask : " Why, when your sterilized organic in- 

 fusion is exposed to optically pure air, should 

 this generation of life de novo utterly cease ? 

 Why should I be able to preserve my turnip-juice 

 side by side with your saline solution for three 

 hundred and sixty-five days of the year in free 

 connection with the general atmosphere, on the 

 sole condition that the portion of that atmosphere 

 in contact with the juice shall be visibly free from 

 floating dust, while three days' exposure to that 

 dust fills it with bacteria ? " There is no answer. 

 These are but a fraction, and by no means the 

 weightiest fraction, of the points urged upon his 

 attention, but which he systematically avoids. 

 He expands, with a " wonderful efflueuce of 

 words," on Medkago and such like things. He 

 deflects the discussion from the question of spon- 

 taneous generation to the totally different ques- 

 tion whether the bacterial matter of the air exists 

 there as germs or as finished organisms. But he 

 leaves absolutely untouched the main facts and 

 the most conclusive arguments of my article. 



As to any bias, or prejudice, or foregone con- 

 clusion, that may beset me in this matter, I have 

 only to remind the reader that few persons at the 

 present day have more distinctly avowed belief 

 in the " potency of matter," and that few have 

 paid more dearly for the avowal, than myself. 

 The criticism of high-minded scholars and cul- 

 tivated gentlemen, as well as the vituperation of 

 individuals who have not yet reached that " place 

 in Nature " where gentlemanly feeling comes into 

 play, have been liberally bestowed upon me. In 

 a letter recently received from my excellent friend 

 Mr. Oliver Wendell Holmes, he justly remarks 

 that I should probably have been well satisfied 

 had my inquiries in relation to the present ques- 

 tion justified Pouchet instead of Pasteur. With 

 the views, indeed, which I entertain upon this 

 subject, it specially behooves me to take care that 

 no theoretic leaning shall taint my judgment of 

 experimental evidence. I have always kept apart 

 the speculative and the proved. Before Virchow 

 laid down his canons I had reduced them to prac- 



