THE NORTHERN MICROSCOPIST, 
AND 
MicroscoricaL News. 

No. 23. NOVEMBER. 1882, 



THE ELEMENTS OF MICROSCOPY. 
By GerorcE E. Davis, F.R.M.S. 
i 
THE HUMAN EYE. 
A paper read before the Manchester Microscopical Society. 
@ all studies, whether it be of pure Microscopy as a Sciehce, or 
4 whether it be of one of those departments of Natural History 
in which the microscope is brought in as an aid to vision, we must, 
at the outset, recognise the importance of a study of the human eye. 
Constructed as this organ is of a delicacy ’twere sheer folly to 
attempt to describe, it has, we know, many imperfections, pro- 
duced, no doubt, by misuse, but which are apt to modify the con- 
clusions we may draw from our observations, unless we are careful 
to study well into what lines such imperfections may lead us. 
Nature has given us in this organ a means whereby all objects 
may be compared with each other, the more especially as to size, 
colour, and general characters, and it must astonish the student, 
should he ever think so deeply, to find that so little is known de- 
finitely as to How we are able to appreciate magnitudes, colours, 
and forms. It is easy to say that the eye lenses focus a picture of 
the object upon the retina, and the irritations are carried by the 
optic nerve to the brain, but do we practically realize what this 
means ? 
Then again, without more of our senses than one are brought to 
bear upon a matter under consideration, we can scarcely form a 
true opinion upon our subject. 
Take something which greets our vision for the first time. We 
know not what it is; we can see it, it is true, but we have to bring 
in the aid of other senses ere we can be correct in our judgment ; 

