INFLUENCE OF CARBONIC ACID GAS 85 



Similar experiments liave been carried out by Frankland, Flligge, 

 Delalivesse, Neisser, Chick, Andrewes, and others.* The last named 

 ^conducted some experiments in London streets in 1902, and reported 

 his results to the Pathological Society. He found the number of 

 organisms varied greatly, but no pathogenic species were detected. 

 The four species he isolated were staphylococci, saroinse, strepto- 

 thricese, and moulds. 



Carnelly, Haldane, and Anderson found the ratio of organisms 

 in the air increased according to whether the air was examined on 

 still damp days, windy damp days, still dry days, and windy dry 

 days, and in brief this expresses the findiags of most investigators. 



Some new light has been thrown upon the subject of pathogenic 

 organisms in air by Neisser in his investigations concerning the 

 amount and rate of air currents necessary to convey certain species 

 through the atmosphere. He states that the bacteria causing 

 diphtheria, typhoid fever, plague, cholera, and pneumonia, and 

 possibly the common Streptococcus pyogenes, are incapable of being 

 carried by the molecules of atmospheric dust which the ordinary 

 insensible currents of air can support, whilst Bacillus anthracis, B. 

 pyocyaneus, and the bacillus of tubercle are capable of being aerially 

 conveyed. This work will require further conJGirmation before being 

 entirely accepted. 



Finally, some mention may be made of the relationship alleged 

 to exist between the presence of a considerable degree of carbonic 

 acid gas in an atmosphere and the number of bacteria contained in 

 the same atmosphere. As far as may be judged, it would appear 

 that the relationship is but slight. But to illustrate the subject as 

 well as other points of importance in the bacteriology of air, four 

 separate investigations may be mentioned. 



(i.) Haldane and Osborn, in their inquiry into the ventilation of 

 factories and workshops, made a number of bacteriological examina- 

 tions.-f The determinations of bacteria were made by a slightly modified 

 form of Frankland's method. The air was drawn through a sterilised 

 plug of glass wool by means of a brass syringe of known capacity. 

 The glass tubes containing the glass wool plugs were each enclosed 

 in a separate outside sterilised glass tube, with an asbestos plug. 

 In taking the sample of air the inside tube was attached directly to 

 the pump by means of a short piece of stout rubber tubing. The 

 plug was afterwards transferred with the necessary precautions to a 

 shallow, flat-bottomed flask, containing a small quantity of liquefied 

 gelatine, which was shaken so as to disintegrate and spread the glass 



* See also Jour, of Sanitary Institute (Oct. 1902), vol. xxiii., pt. iii., p. 209-236. 

 The Dust Problem, by Sir J. Crichton-Browne, F.R.S. 



t First Report of the Departmental Committee appointed to inquire into the 

 Ventilation of Factories and Workshops, 1902. J. S. Haldane, M.D., F.R.S., and 

 E. H. Osborn. 



