258 
MRS. G. C. FRANKLAND AND DR. P. F. FRANKLAND 
In some papers on the micro-organisms present in air, previously communicated to 
the Royal Society by one of us," the relative abundance of microbes in the air of 
different places has been called attention to and the methods of experiment fully 
described. As these investigations were carried out with the aid of solid nourishing 
media, we were able to obtain a collection of pure cultivations of a number of micro¬ 
organisms derived directly from the air. It appeared to us, therefore, desirable to 
utilise the opportunity which these experiments furnished for minutely characterising 
some of the principal forms which are thus obtainable from the atmosphere. There 
are many reasons which render it of importance that the task in question should be 
undertaken. Thus, in the methods of cultivation employed by bacteriologists, the 
experimenter may at any moment be brought face to face with organisms from the air 
which have accidentally contaminated his cultivations, and it is obvious, therefore, 
that an intimate acquaintance with the various forms which may thus invade culture- 
media must be both of interest and importance to all practically engaged in experi¬ 
ments on micro-organisms. 
It is not unnatural that the brilliant discoveries in connection with the etiology of 
infectious diseases should have absorbed the lion’s share of the attention of investi¬ 
gators in the field of bacteriology, and that the non-pathogenic organisms should have 
come to be regarded as comparatively uninteresting by the side of their more formid¬ 
able brethren. It must, however, be remembered that the functions of the non- 
pathogenic organisms in the economy of nature are as yet but very imperfectly under¬ 
stood, and that as far as these functions have been investigated they do not yield in 
point of importance to those of the most virulent pathogenic forms. 
Thus the conversion of sugar into alcohol, the decomposition of nitrogenous organic 
matter with elimination of ammonia, the oxidation of ammonia to nitrous and nitric 
acids, besides many other natural transformations which are effected through the 
agency of such micro-organisms, are certainly not second in importance to the results, 
terrible as they often are, achieved by the pathogenic forms. The organisms producing 
the above-mentioned changes are known to be present in the air, and there can be 
little doubt that the numerous other aerial varieties will in the future be found to 
discharge important duties in the laboratory of nature. 
The exactness with-which bacteriological research can now be carried out, thanks 
to the beautiful methods of cultivation which have been developed during the past 
six years, renders it imperative that all future investigations on the chemical and 
physiological action of micro-organisms should be made with specific organisms and 
not with mixtures, as has so often hitherto been the case. On this account the 
* “ The Distribution of Micro-organisms in Air,” ‘ Roy. Soc. Proc.,’ vol. 40, 1886, p. 509. 
“ A New Method for the Quantitative Estimation of the Micro-organisms present in the Atmosphere,” 
ibid., vol. 41, 1887, p. 443 ; ‘ Phil. Trans.,’ 1887, B, p. 113. 
“ Further Experiments on the Distribution of Micro-organisms in Air (by Hesse’s Method),” ‘ Roy. 
Soc. Proc.,’ vol. 42, 1887, p. 267. 
