CHAPTER XXIII. 

 Bacteria in Air, Earth, and Water. 



Spores in the Air in Hospitals — Effects of Currents and Altitude^Direction 

 of Wind — Nature of Country over which it passes — Frankland's, Car- 

 nelley's, Haldane's and Petri's Experiments — Few Bacteria in the Air of 

 Sewers — Tyndall's Glycerine Chamber — Examination of Air — Koch's 

 Method — Miquel's Method — Hesse's Apparatus — Modified Hesse's 

 Apparatus — Miquel's Sugar Method — Bacteria in Water — Effect of 

 Standing — Sluggish Movement — Oxidation of Organic Matter in Water 

 ■ — Organisms carried by Sewage — Number of Organisms in Water — 

 Method of Procedure in Analysing Water — Pfuhl's Flasks — Petri's 

 Dishes — Petruschky's Flask — Plate Cultivations — Cooling Apparatus — 

 Von Esmarch's Tulje Cultures — Effect of Rains, Frosts and Thaws — 

 Relation of Bacteria to Ammonia — Basis on which to determine 

 whether water is fit for Drinking or not — Filtration — Method of 

 Examination of Soil. 



As will have already been gathered from what has been- 

 stated in connection with the distribution of the cholera 

 bacillus, tubercle bacillus, anthrax bacillus, and similar 

 organisms, there are marked differences in the facility 

 with which organisms may be carried even by currents of 

 air. Those organisms that do not produce spores, and that 

 are easily killed by drying, are very seldom contained in 

 the air, at any rate in a condition capable of growing, whilst 

 it is found that those which resist dr3dng, and especially 

 those which form resting spores, may be carried about from 

 place to place, either alone or adhering to dust or other 

 particles. 



In connection with this question of micro-organisms in 

 air, there are certain general rules that should always be 

 borne in mind. Their presence must, we are afraid, be 

 looked upon as inevitable in those hospital wards in which 

 patients suffering from infective diseases are gathered to- 

 gether for treatment ; tubercle bacilli, for example, are found 

 in the air of wards where phthisical patients are collected, 



