158 The Theory of Atmospheric "Germs. [April, 



this dictum, for Pasteur long ago found that if strata of 

 cotton-wool were arranged in series and air were drawn 

 through them, fine particles were absorbed by many of the 

 successive layers. As far, then, as the direct examination 

 of the air, microscopic or otherwise, is concerned, we may 

 conclude that there is at least as much evidence in favour 

 of the germ theory as of the spontaneous generation theory. 



It is at least as easy to conceive the existence of germs 

 so minute that vision, however aided, fails to detect them, 

 as it is to conceive the undemonstrable union of ordinary 

 matter and ordinary forces to produce a living thing which, 

 when produced, overrides the laws of both. Two objections, 

 however, are urged against the germ theory which are of 

 high importance. The first difficulty may be stated thus : 

 the spores or germs of definite fungi are themselves 

 definite : they are not of infinite minuteness ; these fungi 

 nevertheless spring up when it is absolutely certain that their 

 ordinary spores cannot be discovered. The second difficulty 

 is this : the organisms found in putrescible solutions are of 

 many varieties and species ; there must be definite and 

 distinct germs for each of these. You must, therefore, 

 concede that the air contains multitudes of them, that 

 every square inch of it is a magazine of innumerable varieties. 

 The air would be then encumbered with germs. These 

 questions may be styled those of the specificity and the 

 plurality of germs. 



According to the germ theory the essential cause of each 

 variety of fermentation is a cellular fungoid organism. The 

 objective phenomena of fermentation are but the results of 

 the development, growth, and acts of life of the organisms. 

 How, then, does this theory explain the apparently spon- 

 taneous fermentations, i.e., when no determining cellule has 

 been added to the organic solution ? It is proved that a 

 yeast cell can form in a saccharine fluid precisely as other 

 varieties of organisms arise in other putrescible fluids. The 

 fluid in which yeast cells float, and which contains no 

 formed cells whatever, is exceedingly efficient in inducing 

 saccharine fermentations. It follows either that those cells 

 arise from molecules infinitely more minute than the cells 

 themselves, or else the germ theory cannot stand. The 

 careful researches of Dr. Beale have shown that molecules 

 capable of development into perfect yeast cells are of 

 extreme minuteness, many of them being much less than 

 i-ioo,oooth of an inch in diameter. Such germs as these 

 are readily capable of being wafted by the air and could defy 

 the closest means of detection. 



