mosphere, however
obnoxious otherwise, will not produce the disorder. But, if the germs
be present, defective drains and cesspools become the potent
distributors of disease and death. Corrupted air may promote an
epidemic, but cannot produce it. On the other hand, through the
transport of the special germ or virus, disease may develop itself in
regions where the drainage is good and the atmosphere pure.

If you see a new thistle growing in your field, you feel sure that its
seed has been wafted thither. Just as sure does it seem that the
contagious matter of epidemic disease has been transplanted to the
place where it newly appears. With a clearness and conclusiveness s
not to be surpassed, Dr. William Budd has traced such diseases from
place to place; showing how they plant themselves, at distinct foci,
among populations subjected to the same atmospheric influences, just
as grains of corn might be carried in the pocket and sown. Hildebrand,
to whose remarkable work, 'Du Typhus contagieux,' Dr. de Mussy has
directed my attention, gives the following striking case, both of the
durability and the transport of the virus of scarlatina: 'Un habit
noir que j'avais en visitant une malade attaquee de scarlatina, et que
je portai de Vienne en Podolie, sans l'avoir mis depuis plus d'un an
et demi, me communiqua, des que je fus arrive, cette maladie
contagieuse, que je repandis ensuite dans cette province, ou elle
etait jusqu'alors presque inconnue.' Some years ago Dr. de Mussy
himself was summoned to a country house in Surrey, to see a young lady
who was suffering from a dropsy, evidently the consequence of
scarlatina. The original disease, being of a very mild character, had
been quite overlooked; but circumstances were recorded which could
leave no doubt upon the mind as to the nature and cause of the
complaint. But then the question arose, How did the young lady catch
the scarlatina? She had come there on a visit two months previously,
and it was only after she had been a month in the house that she was
taken ill. The housekeeper at length cleared up the mystery. The
young lady, on her arrival, had expressed a wish to occupy a room in
an isolated tower. Her desire was granted; and in that room, six
months previously, a visitor had been confined with an attack of
scarlatina. The room had been swept and whitewashed, but the carpets
had been permitted to remain.

Thousands of cases could probably be cited in which t