90 BACTERIA IN THE AIR 



2. The air in the debating chamber is from a bacteriological 

 point of view remarkably pure (5*8 per litre as average of eleven 

 experiments). 



3. The number of bacteria found in the committee, dining, and 

 smoking rooms was several times greater than in the chamber (32 '3 

 per litre as average of six experiments). 



4. No organisms pathogenic to man were isolated, and only a few 

 which were pathogenic to animals. 



(iv.) Fourthly, in 1902 Andre wes furnished a report to the London 

 County Council on the micro-organisms present in the air of the tube 

 of the Central London Kail way.* The method he employed was 

 in principle that of Frankland, viz., the aspiration by means of a brass 

 syringe (capacity 425 c.c.) of a known volume of air (5 litres), through 

 a plug of glass wool and finely-powdered cane-sugar. The latter 

 retains the micro-organisms, which can be subsequently distributed 

 through a suitable cultivating medium (such as gelatine) in a Petri 

 dish. The gelatine plate-cultures were incubated at 20 C. for four 

 days, when the colonies were counted, examined, and sub-cultured. 

 Special control experiments were made, and search was also made 

 for the presence of anaerobic organisms. The twelve series of 

 experiments yielded results which may be abstracted and tabulated 

 as follow : 



* Examination of the Atmosphere of the Central London Railway, London County 

 Council, 1902. No. 615. F. W. Andrewes, M.D., F.R.C.P. 



