THE MICROBES OF THE AIR 275 



air, ' yet there can be no doubt that, in the imme- 

 diate vicinity of the foci of disease, such microbes 

 are present, and that their distribution and convey- 

 ance in the air will take place in just the same 

 manner as in the case of non-pathogenic microbes. 

 The investigations on aerial microbia, so far as they 

 have as yet been carried, are of service in indicating 

 how, we may escape from all microbes, whether 

 harmful or harmless ; and secondly, how we may 

 avoid the conveyance of microbes into the atmo- 

 sphere from places where pathogenic forms are 

 known or likely to be present. This acquaintance 

 with the distribution of microbes in general, and 

 the power of controlling their dissemination which 

 it confers, is really of far wider practical importance 

 than discovering whether some particular pathogenic 

 form is present in some particular sample of air. 

 It is this knowledge which has led to the vast 

 improvements in the construction and arrangement 

 of hospital wards and of sick-rooms generally, and 

 which has directed attention to the importance of 

 avoiding all circumstances tending to disturb and 

 distribute dust. It is, moreover, this knowledge of 

 the distribution of microbes in our surroundings 

 which has formed one of the foundations for the 

 antiseptic treatment of wounds that great step in 

 surgery with which the name of Sir Joseph Lister 

 is associated.' 1 



1 For further information see Frankland's papers in Journal 

 of Society of Arts, vol. xxxv. p. 485; Proc. Roy. Soc., 1885-86; 

 Miquel's Les Organismes Vivants de I' Atmosphere; Prudden's 

 Dust and its Dangers ; and Griffiths' Researches on Micro - 

 Organisms. 



