18 
In respect of the circumstances under which they now affect 
our olfactory organs, they are exhalations from the several 
substances that produce them, whether organic or inorganic, 
consisting of inconceivably small particles of matter, the quantity 
and quality depending, in some measure, on the temperature of 
the bodies from which they emanate, while the distance to 
which the odour is carried would depend upon the state of the 
wind that wafts them about. This distance is sometimes very 
remarkable. Darwin speaks of the air being “tainted over 
“miles of space by certain offensive animals and yet strongly 
“ affecting the olfactory nerves,”* 
And with this last remark I might end what I have to say in 
immediate connection with the title of this paper. But the 
subject to which it relates, bound up, as it is, with the proved 
existence of matter in its simplest state—so microscopically small 
as to be hardly made known to us except when arising from 
odoriferous substances; bound up also with the fact of living 
germs in the air being almost everywhere mixed up with the 
material particles, leads me on irresistibly to the consideration of 
a question of the deepest interest and importance; viz., the 
question as to the origin of life on this earth ? 
I stated above that before our earth, with all its varied 
productions, had taken shape, matter must have existed, though 
in its most elementary state ; indeed it has been recently stated 
by high authority that “in atoms we have something which has 
“existed either from eternity, or at least from times anterior 
“to the existing order of nature.”+ There must also have been 
from the beginning the living germs themselves, from which— 
according to the teaching of evolution now so generally accepted 
—were to be evolved in after ages all the various forms of animal 
and vegetable life we meet with at the present day. Now the 
* “Variation of Plants and Animals,” vol. ii., p. 403. 
+ See the new Encyclopedia Britannica, Art. Atom. 
