770 Transactions of the Society. 



requisite temperature. Thus were explained the previous failures 

 to recognize the presence of organisms in the atmosphere, by the 

 circumstance that the cultivating fluids then employed had generally 

 been solutions of mineral salts — the so-termed Pasteur's or Cohn's 

 fluids — and which are here shown to be unsuitable for the develop- 

 ment of most species of these organisms. 



More recently has appeared the remarkable work* carried out 

 during some years past by Dr. Miquel at the Observatory of 

 Montsouris, near Paris, some of the results of which have recently 

 been brought to the notice of this Society by one of our Fellows, 

 himself amongst the earliest investigators in this direction. 



As a branch of this subject, the examination of the air at 

 difierent altitudes has not been neglected : the purity of the atmo- 

 sphere in these situations has ever been a matter of common 

 observation ; and the difi'erent experiments that have been made at 

 various heights, have all, with one exception, tended to show the 

 extreme rarity of organic germs in it. 



Eecently, M. Freudenreich, of Bern, a former pupil of Dr. 

 Miquel, under his auspices and following his exact methods, has 

 made several series of systematic observations upon this point, far 

 exceeding in scope anything previously attempted ; this he has 

 done by aspirating large measured quantities of air on difi'erent 

 mountains at various elevations, with the general result that the 

 rarity of micro-organisms it contains is proportionate to the altitude, 

 for whilst at Bern, at an elevation of 1900 feet 300 to 400 of 

 these bodies occurred in a cubic metre of air, which is less than a 

 tenth part of their numbers in Paris, at higher elevations they 

 became proportionately rarer,t and above 7000 feet were generally 

 altogether absent ; but in one series of these observations on the 

 summit of Mount Niesen in the Bernese Alps, at an elevation of 

 7900 feet, close on the line of perpetual snow, together with three 

 bacteria and one of the moulds, a form of bacillus hitherto unde- 

 scribed occurred in 500 litres of air aspirated ; preparations from 

 the cultivation of this organism which I lately received from 

 M. Freudenrich through Dr. Maddox, are here shown to-night. 



This microbe, in Cohn's classification a bacillus, in form is very 

 similar to the common hay bacillus, B. siibtilis, but is readily dis- 

 tinguished from it by not forming a pellicle on the surface of the 



* ' Les Organismes vivants de 1' Atmosphere,' Paris, 1883. 



t As shown in the following table (' Annuaire de I'Observatoire de Mont- 

 souris,' 1883, p. 538). 



Number of bacteria contained in 10 cubic metres of air in difiPerent situa- 

 tions : — 



1. At altitudes from 6000 to 12,000 ft • 



2. On Lake Thun, 18,000 ft S'O 



3. On land, in the vicinity of the same lake .. .. 25-0 



4. In the park at Montsouris 7,600 • 



5. In the streets of Paris 55,000-0 



