y three-quarters of all diseases were
caused by "itch struck in," and yet it had been demonstrated long before
his day, and can be demonstrated any time, that itch is simply a local
skin disease caused by a small parasite.

JENNER AND VACCINATION

All advances in science have a bearing, near or remote, on the welfare
of our race; but it remains to credit to the closing decade of the
eighteenth century a discovery which, in its power of direct and
immediate benefit to humanity, surpasses any other discovery of this or
any previous epoch. Needless to say, I refer to Jenner's discovery
of the method of preventing smallpox by inoculation with the virus of
cow-pox. It detracts nothing from the merit of this discovery to say
that the preventive power of accidental inoculation had long been
rumored among the peasantry of England. Such vague, unavailing
half-knowledge is often the forerunner of fruitful discovery.

To all intents and purposes Jenner's discovery was original and unique.
Nor, considered as a perfect method, was it in any sense an accident. It
was a triumph of experimental science. The discoverer was no novice in
scientific investigation, but a trained observer, who had served a long
apprenticeship in scientific observation under no less a scientist than
the celebrated John Hunter. At the age of twenty-one Jenner had gone to
London to pursue his medical studies, and soon after he proved himself
so worthy a pupil that for two years he remained a member of Hunter's
household as his favorite pupil. His taste for science and natural
history soon attracted the attention of Sir Joseph Banks, who intrusted
him with the preparation of the zoological specimens brought back by
Captain Cook's expedition in 1771. He performed this task so well that
he was offered the position of naturalist to the second expedition, but
declined it, preferring to take up the practice of his profession in his
native town of Berkeley.

His many accomplishments and genial personality soon made him a favorite
both as a physician and in society. He was a good singer, a fair
violinist and flute-player, and a very successful writer of prose and
verse. But with all his professional and social duties he still kept up
his scientific investigations, among other things making some careful
observations on the hibernation of hedgehogs at the instigation of
Hunter, the results of which were laid before the Royal Society. He also
made quite extensive in