162 
POPULAR SCIENCE REVIEW. 
AIR BENEATH THE MICROSCOPE. 
By the EDITOR. 
PLATE CIX. 
T HE world may be said to consist — from one point of view 
at least — of an earthly soil and two great seas : one the 
aqueous ocean, and the other the atmosphere. Fish and a few 
other vertebrate, and many invertebrate, animals live in the 
watery ocean; but man, most mammalia, birds, and a very 
large number of invertebrate animals, inhabit the aerial one. 
And just as in the seas there are a certain number of animals 
that are compelled to inhabit the bottom alone, so in the 
aerial ocean we find the same state of things — one group of 
animals having to do with the land, while another set have the 
wide range of the atmosphere in which to carry on their lives. 
Of course this division is well enough known already ; but the 
fact is by no means so familiar, that the very air we breathe is 
laden with inhabitants of both the animal and vegetable king- 
doms, and in reality is very thickly populated and planted, 
although we have not ordinarily the power of recognising that 
this is so. 
However, the microscope introduces us to quite a novel 
world; and now that its powers have reached almost the 
highest mark, now that practical art has nearly realised the all 
that is possible in the theoretical world of microscopy, now that 
microscopically the whole Bible might be written out — every 
verse in every chapter — about six or seven times within the 
space of a single square inch, in these days of objectives not 
only of Jg-th or ~th, but even of the yg-th* of an inch, we are 
by instrumental means introduced to an entire world of which 
a couple of hundred years ago we had not the faintest idea. 
The researches which we are about to describe, however, have 
not been conducted with the highest powers, and from that 
circumstance they are liable to serious error ; inasmuch as it may 
* It is worthy of note that not only have Powell and Lealand brought 
out a 7— object-glass of really wonderful definition, but this has also been 
achieved by the American workers, Messrs. Tolies and Stodder. 
