BACTERIA IN THE AIR. 623 
air of the country; the lower strata of the atmosphere contained 
more than the air of elevated localities. 
Von Freudenreich also found that the air of the country contained 
fewer germs than that of the city. Thus in the city of Berne acubic 
metre of air often contained as many as two thousand four hundred 
germs, while the maximum in country air was three hundred. His re- 
sults corresponded with those of Miquel in showing that the number 
of atmospheric organisms is greater in the morning and the evenins, 
between the hours of 6 and 8, than during the rest of theday. Neu- 
mann, whose researches were made in the Moabite Hospital, found 
the greatest number of bacteria in the air in the morning after the 
patients able to sit up had left their beds and the wards had been 
swept. The number of germs was then from eighty to one hundred 
and forty in ten litres of air, while in the evening the number fell to 
four to ten germs in ten litres. 
Miquel has given the following summary of results obtained in 
his extended experiments, made in Paris during the years 1881, 1882, 
and 1883 : 
Number of Germs in a Cubic Metre of Air. 
Air of Laboratory, Air of Park, Mont 
Montsouri. souri. 
Average for 1880.......00c0005 seeeeee cee 215 71 
hig” ETO S Vis woot cten dedi ad ian 348 62 
ae pr ee 550 51 
Rue de Rivoli, average for one year, 750; summit of Pantheon, 28 ; 
Hotel-Dieu, 1880, average for four months, male ward 6,300, female 
ward 5,120; La Piété Hospital, average of fifteen months, 11,100. 
It must be remembered that the figures given relate both to bac- 
teria and to the spores of mould fungi, and that the latter are com- 
monly the most numerous when the experiment is made in the open 
air. Petri has shown that when gelatin plates are exposed in the air 
the relative number of spores of mould fungi deposited upon then: is 
less than is obtained in aspiration experiments. 
The number of colonies which develop on exposed plates does not 
represent the full number of bacteria deposited, for these colonies 
very frequently have their origin in a dust particle to which several 
bacteria are attached, or in a little mass of organic material contain- 
ing a considerable number. 
It is generally conceded that sea air and country air are more 
wholesome than the air of cities, and especially of crowded apart- 
ments, in which the number of bacteria has been shown to be very 
much greater. But it would be a mistake to ascribe the sanitary 
value of sea, country, and mountain air to the relatively small num- 
