52 BACTERIA IN DAILY LIFE 



degree of infection possessed by dust in such sur- 

 roundings must, of course, depend upon the degree 

 of cleanliness which characterises the management 

 of any particular institution ; and such investiga- 

 tions as the above can only help to emphasise the 

 immense importance of common cleanliness and 

 the reasonableness of taking every precaution 

 possible in the disinfection of utensils, etc. 



Some years ago Messrs. Carnelley, Haldane, 

 and Anderson carried out an elaborate series of 

 investigations on the air of dwelling-houses in 

 some of the poorest parts of Dundee. The 

 samples were taken during the night, between 

 12.30 a.m. and 4.30 a.m., and in their report the 

 authors state that the one-roomed tenements were 

 mostly those of the very poor ; " sometimes as 

 many as six or even eight persons occupied the 

 one bed," whilst in other cases there was no bed 

 at all. As regards the number of bacteria present 

 in the air in these one-roomed houses, an average 

 of several examinations amounted to sixty per 

 quart ; in two-roomed houses it was reduced to 

 forty-six, and in houses of four rooms and up- 

 wards only nine micro-organisms in the same 

 volume of air were discovered. 



On comparing the mortality statistics with the 

 composition of the air of dwelling-houses of 

 different dimensions, the authors arrive at the 



