itchell of
Philadelphia, in the year 1869, made the original and remarkable
observation that if a part of the body of a frog be immersed in simple
syrup, there soon occurs in the crystalline lens of the eyeball an
opaque appearance resembling the disease called cataract. He extended
his observations to the effects of grape sugar, and obtained the same
results. He found that he could induce the cataractic condition
invariably by this experiment, or by injecting a solution of sugar with
a fine needle, subcutaneously, into the dorsal sac of the frog. The
discovery was one of singular importance in the history of medical
science, and explained immediately a number of obscure phenomena. The
co-existence of the two diseases, diabetes and cataract, in man had been
observed by France, Cohen, Hasner, Mackenzie, Duncan, Von Graafe, and
others, and Von Graafe had stated that after examining a large number of
diabetic patients in different hospitals, he had found one-fourth
affected with cataract. Before Mitchell's observation there was not a
suspicion as to the reason of this connection, and a flood of light,
therefore, broke on the subject the moment he proclaimed the new
physiological fact. Still more, Mitchell showed that the cataract he was
able to induce by experiment was curable also by experiment, a truth
which will one day lead to the cure of cataract without operation. Then,
but not till then, the splendid character of this original
investigation, and the debt that is due to one of the most original,
honest, laborious workers that ever in any age cultivated the science
and art of medicine, will be duly recognized." Upon receiving
intelligence of this discovery, Dr. Richardson undertook experiments to
discover the cause of this dependence of cataract upon diabetes. He
found that whenever the specific gravity of the blood was raised to ten
degrees above the normal standard, and remained so for a short time,
cataract followed. He also found that the disease so produced could be
cured by removing the salts which had been introduced into the blood.
This certainly points to a cure for cataract which shall be really
radical, and adds another to the results which justify, even upon
humanitarian grounds, physiological experiments, at the expense of the
animal creation, within prescribed limits.

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--Mr. Sorby has lately made some calculations of the probable size of
the invisible atoms whi