On a Septic Microbe, &c. By G. F. JDowdeswell. 773 



affect the purity of the air, it may be mentioned that Dr. Miquel 

 (Op. cit., J). 240) found micro-organisms twenty times more 

 numerous in the streets of Paris four feet above the ground tban at 

 the summit of the Pantheon at an elevation of 330 feet. 



Important as is the microscopical examination of air, and 

 immeasurably as the subject has been advanced and illustrated 

 by the magnificent work of M. Miquel — certainly by far the 

 most extensive and important as yet made in any branch of 

 micrology — there is as yet one void in it, and tbat is the 

 want of a clear diagnosis of the specih'c characters of the various 

 microbes that occur in different conditions, seasons, and localities. 

 In a general way no doubt the salubrity of any given portion of air 

 corresponds with the paucity of micro-organisms which it contains, 

 but in spite of the innumerable observations and the laborious 

 statistics that have been given, it has not yet been shovvn that 

 there is any direct connection between their number and the 

 prevalence of infectious or epidemic diseases. The reason of this 

 appears obviously to be that we are not as yet generally able, from 

 the mere inspection of the outward characters of any micro- 

 organisms, to say that such an one is fatally infective— the bacillus 

 of tubercle — the micrococcus of pneumonia or diphtheria — that 

 another is merely saprophytic or zymotic, harmless to the animal 

 organism.* 



When we are able to do this, then will it be possible from the 

 mere microscopical examination of a sufficiently large sample of the 

 air of any locality to connect it certainly with the prevalence of 

 infectious diseases. The same considerations apply equally strongly 

 to the examination of drinking water, and now that the chemical 

 analysis of this has lately been shown to be practically useless,! if 

 not even misleading, it appears that microscopical examination 

 must be relied on in future. 



With this object the study of and familiarity with the specific 

 characters of these organisms is one of the most important subjects 

 that can occupy the microscopist. In this view I have brought to 

 notice to-night the diagnostic characters of the microbe now shown, 

 remarkable from the situation where it occurred. A comparison of 

 the preparations under the Microscopes will show that it is not 

 impossible to discriminate by their form alone two microbes 

 somewhat similar, and which to a cursory view might appear 

 identical. 



• Tlie liJihit of growth of tho lower fungi in Holid cultivation.s, wliicli Ima been 

 so mucli dwelt upon of late, iw very uiiroliable and mucli over-rated as a means 

 of Hix;cifie diagnowin, being only at moat of very eecondary utility, as I shall 

 endeavour in dirnouhtrate shortly. 



t Itep. Med. Olf. Loc. Govt. Bd., 1882-3. 



tj.r. '2.— Vol. V. 3 E 



