roken, at rare intervals, by a more or less useful publication.
'The Pharmacopoeia of the Silkworm,' wrote M. Cornalia in 1860, 'is
now as complicated as that of man. Gases, liquids, and solids have
been laid under contribution. From chlorine to sulphurous acid, from
nitric acid to rum, from sugar to sulphate of quinine,--all has been
invoked in behalf of this unhappy insect.' The helpless cultivators,
moreover, welcomed with ready trustfulness every new remedy, if only
pressed upon them with sufficient hardihood. It seemed impossible to
diminish their blind confidence in their blind guides. In 1863 the
French Minister of Agriculture signed an agreement to pay 500,000
francs for the use of a remedy, which its promoter declared to be
infallible. It was tried in twelve different departments of France,
and found perfectly useless. In no single instance was it successful.
It was under these circumstances that M. Pasteur, yielding to the
entreaties of his friend, betook himself to Alais in the beginning of
June, 1865. As regards silk husbandry, this was the most important
department in France, and it was the most sorely smitten by the
plague.

The silkworm had been previously attacked by muscardine, a disease
proved by Bassi to be caused by a vegetable parasite. This malady was
propagated annually by the parasitic spores. Wafted by winds they
often sowed the disease in places far removed from the centre of
infection. Muscardine is now said to be very rare, a deadlier malady
having taken its place. This new disease is characterised by the
black spots which cover the silkworms; hence the name _pebrine_, first
applied to the plague by M. de Quatrefages, and adopted by Pasteur.
_pebrine_ declares itself in the stunted and unequal growth of the
worms, in the languor of their movements, in their fastidiousness as
regards food, and in their premature death. The course of discovery
as regards the epidemic is this: In 1849 Guerin Meneville noticed in
the blood of silkworms vibratory corpuscles, which he supposed from
their motions to be endowed with independent life. Filippi, however,
showed that the motion of the corpuscles was the well-known Brownian
motion; but he committed the error of supposing the corpuscles to be
normal to the life of the insect. Possessing the power of indefinite
self-multiplication, they are really the cause of its mortality--the
form and substance of its disease. This was well described by
Co