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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



way of thinking, before he abandons Liebig's 

 fertile idea, supported by Gerhardt and others, 

 that the mere organic matter of the air can en- 

 gender fermentative changes in suitable fluids, 

 leading, though it may, among other phenomena, 

 to a new birth of living particles. This, too, the 

 reader will observe, is a very different notion 

 concerning the mode of origin of such new living 

 particles from that which Prof. Tyndall persists 

 in attributing to me — viz., the absurd idea that 

 mere dead particles from the air are themselves 

 " miraculously kindled into living things." 



Now, it is to this first part of the subject that 

 the great bulk of Prof. Tyndall's experiments 

 belong. He has sought to throw light upon such 

 problems as these : what ordinary air contains in 

 the way of solid matter, what air subjected to 

 different kinds of treatment contains, how the 

 contents of the atmosphere differ in various 

 places, how in these different conditions and 

 places it affects previously-boiled fluids ; and, by 

 way of speculation only, as to the exact nature 

 of the material which, falling into organic fluids 

 from the air, incites fermentation therein. He 

 has renewed the proofs of things which were not 

 before doubted, and he claims in addition to 

 have shown that the air contains invisible or 

 "ultra-microscopical particles," which by their 

 subsidence are, like larger particles or debris, 

 also capable of contaminating organic infusions. 

 But I fail to find in this latter fact, however much 

 it may be confirmed, and however frequently it 

 may be reiterated, any proof that such particles 

 are " germs " of bacteria, especially when, on Prof. 

 Tyndall's own testimony, the behavior of these 

 invisible particles in regard to heat is altogether 

 opposed to that of all known visible germs of 

 which I or anybody else have any cognizance. 



Burdach exhibited much sagacity some forty 

 years ago when he said in reference to the invis- 

 ible germs which were also postulated in his 

 time : 



" Les dit-on trop petits pour etre apercus, c'est 

 avouer qu'on ne peut rien savoir de leur existence. 

 . . . Croire que partout ou l'on rencontre des in- 

 fusoires, ils ont 6t& precedes d'oeufs, c'est done 

 admettre une pure hypothese, qui n'a d'autre fon- 

 dement que l'analogie. ... Si c'est seulement par 

 l'analogie qu'on suppose des ceufs chez eux, il faut 

 accorder a ces ceufs des propriety semblables a 

 celles de tous les ceufs connus : car ce serait jouer 

 sur les mots que de supposer qu'ils en ont de par- 

 ticulieres a eux seuls." l 



1 " Traite de Physiologic" Translation by Jour- 

 dan, 1837, t. i., p. 22. 



All this discussion about the nature of the 

 atmospheric dust, visible and invisible, together 

 with elaborate and ingenious experimentation to 

 prove its infective nature, so far as fermentations 

 are concerned, has not really advanced the main 

 question one iota. It is, as we have seen, impos- 

 sible for Prof. Tyndall, by all the refinements 

 which he has introduced into the study of this 

 part of the subject, to get beyond the simple con- 

 clusion of Schwann, long anterior to the la- 

 bors of Pasteur, that the air contains a " some- 

 thing " which is infective ; but we are no more 

 able to say now than Schwann was in 183*1 what 

 is the precise nature of this something. In this 

 view I am, as I shall subsequently show, sup- 

 ported by high authority. 



My more simple experiments with glass ves- 

 sels, from which most of the air had been ex- 

 pelled by boiling, and in which heat was relied 

 upon as the scourge of all antecedent life, had, 

 moreover, thoroughly shown that the essential 

 question does not lie in the direction of Prof. 

 Tyndall's experiments. The verdict in connec- 

 tion with spontaneous generation essentially de- 

 pends on the answer which can be given to 

 another problem. As the late Prof. Jeffries 

 Wyman said, ' " The issue between the advo- 

 cates and the opponents of the doctrine in ques- 

 tion clearly turns on the extent to which it can 

 be proved that living things resist the action of 

 water at a high temperature." 



When any one asks what explanation can be 

 given of the appearance of the lowest forms of 

 living matter in previously-boiled and guarded 

 infusions, only two interpretations are possible. 

 There must have been (1) a survival of organisms 

 or germs, or else (2) a new and independent 

 birth of living particles. Yet, if we look at them 

 merely in the light of previous experience, each 

 of these interpretations seems alike at variance 

 with our actual knowledge. 



Many considerations and much thought will 

 be required before any one would be likely to 

 entertain the conclusion that the forms of living 

 matter which appear in the previously-boiled 

 fluids are primordial, and had arisen indepen- 

 dently, in a mother liquid, somewhat after the 

 fashion of incipient crystals ; and similarly we 

 ought, if our minds are free and unbiased, to 

 hesitate much and long before we conclude that 

 forms of living matter which are so minute as to 

 be beyond the reach of present microscopes not 

 only exist, but have properties totally different, 



1 American Journal of Science and Art, September, 1867. 



