THE MICROBES OF HUMAN DISEASES. 165 
and Belleville, crowded and populous quarters, in which 
are also cemeteries and slaughter-houses. 
It has long been established that the air is much 
purer on high mountains or on the sea, than in plains 
and in the vicinity of inhabited places. If glass flasks 
which have been previously sterilized and deprived 
of air are taken to a great height on the Alps or 
Pyrenees, and then filled with air, it will be difficult 
to detect any microbes, and the few which may be 
found are possibly brought by the observer. So 
again, on the top of the Pantheon, a cubic metre of 
air only contains 28 microbes, while 45 are found in 
the park of Montsouris, and 462 in the centre of 
Paris. 
The Microbes of Running and Drinking Water.— 
Water, whatever be its source, contains many more 
microbes than air. They are even found in spring- 
water taken from its source, which shows that they 
exist in the interior of the earth. The following is 
Miquel’s estimate, which will give an idea of the 
quantity of microbes found in Paris water, taken from 
‘different places :— 
Source of water. No. of microbes 
to the litre, 
Condensed aqueous vapour ... oa age eee ine 900 
Water from drain, Asni@res ... va we aie ses 48,000 
Rain-water... we Sei ne des a wee 64,000 
Vanne water (Montrouge basin)... _ nee aoe 248,000 
Seine water (from Bercy, above Paris)... wee ee 4,800,000 
Seine water (from Asniétres, below Pari-) ... ae ses 12,800,000 
Sewer-water (from Clichy) ... er ses vee .« 80,000,000 
