“ A few hairs of leaves of plants and fibres, similar in ap-. 
pearance to flax, were seen, and as might have been expected 
in this city, cotton filaments, some white, others coloured, 
were numerous ; red and blue being the predominant 
colours. A few granules of starch, seen by the aid of the 
poloriscope, and several long elliptical bodies, similar to the 
pollen of the lily, were noticed. After this dust from the 
atmosphere had been kept quiet for three or four days, ani- 
malculse made their appearance in considerable numbers, 
the monads being the most numerous. Amongst these were 
noticed some comparatively large specimens of paramecium 
aurelia, in company with some very active rotiferse; but 
after a few days the animal life rapidly decreased, and in 
twelve days no animalculse could be detected. 
“For the purpose of obtaining a rough approximation of 
the number of spores or germs of organic matter contained 
in the fluid received from Dr. Smith, I measured a quan- 
tity by the pipette, and found it contained 150 drops of the 
size used in each examination. Now I have previously 
stated that in each drop there were about 250,000 of these 
spores, and as there were 150 drops the sum total reaches 
the startling number of 37 J millions.” 
After these examples, the first being twenty-four years 
earlier than the last, I need not add that my certain know- 
ledge is that particles both organic and inorganic are found 
in air. 
Further, that some of the organic particles are organized. 
Lime, soda, sulphates, and chlorides have been mentioned 
in another paper as being found, coal ash and of course car- 
bon, and to some extent the amount measured. In railway 
carriages we even breathe rolled plates of metallic iron 
which are large enough to be seen by the naked eye. 
Some of the most difficult particles to remove are those 
of coal smoke, they are oily or tarry or both. These are in- 
stances of organic and not organised particles. 
