64 
accuracy. They have taken forms which no geometer, no ana- 
lytical integrator, could divine —forms which, even arrived at 
approximately by our imperfect mathematical analysis, we could 
not imitate mechanically. Possessing, too, just those refractive 
indices which are adapted, in combination with those forms, to 
secure a minimum, indeed, for aught I know, a perfect degree 
of absence of spherical and chromatic aberration. Possessed, 
again, with an inexplicable power of adapting their form to 
the perfect vision of a star in infinite space, and to an object 
removed but a few inches from them. Supplied, again, with a 
self-acting diaphragm sensitive to fight— not for vision, but 
for contracting and expanding — so as to adapt the rays ol 
light admitted into the marvellous camera obscura m such 
quantities only as are adapted to secure the proper impression 
on the retina. Need I refer to the black pigment for absorbing 
superfluous light; to all the accessories of the wondrous 
camera obscura ; to the muscles which move it with mechanical 
design and contrivance ; to the lids which veil it from ligh 
too injurious to be admitted into the dark -chamber ; to the 
contrivances for preserving the transparency of the external 
surface of the transparent cornea with a never-failing supply ol 
moisture ? , 
Where am I to seek for the architects of this wondrous ex- 
hibition of skill and contrivance ? Is it in the blood corpuscles 
or in the fluid in which they swim? The blood certainly was 
the agent by which all this structure was built up, with fault- 
less, unerring accuracy, by no law of natural selection by the 
destruction of less perfect instruments. If I ask modern 
physiologists as to the structure of my eye, I am told it is like 
a fountain, which preserves its general form amid the unceas- 
ing motion of the particles which form it. The atoms which 
form my eye are constantly being laid down and taken up 
again. Constantly deposited from the vital stream of blood 
flowing through my body ; as constantly taken up again into 
the general stream. Let this stream stop, and the marvellous 
structure from that instant commences to fall into irretrievable 
ruin. Where, I may ask, is the formative nisus which erected 
this skilful structure" ? Where dwells the constant formative 
nisus which preserves this structure when once it is built up f 
What architect endows the atoms which constitute the structure 
with such marvellous powers ? Why do the same corpuscles 
which form the ear, with its marvellous auditory purposes, 
when they reach another part of the body, become such skilled 
artists in optical wisdom ? Why in one part of the organ form 
lenses possessed with one refractive index, in another part ol 
another, and then a third, every one mutually adapted amid a 
