OTHER DISEASES OF DOMESTIC ANIMALS. 151 
young, and those which survive the fourth moult 
shrink and shrivel away; they can hardly creep on to 
the heather to spin their cocoon, and produce scarcely 
any silk. 
On an examination of the worms which have died 
of this disease, De Quatrefages ascertained the presence 
of minute stains on the skin and in the interior of 
the body, which he compared to a sprinkling of 
black pepper; hence the name pebrine. Under the 
microscope these stains assume the form of small 
mobile granules like bacteria, which Cornalia termed 
vibratile corpuscles, on account of their movements. 
Finally, Osimo and Vittadini ascertained the existence 
of these corpuscles in the eggs, and consequently 
showed that the epidemic might be averted by the 
sole use of healthy eggs, of which the soundness 
should be established by microscopic examination. 
It was at about this date, 1865, that Pasteur under- 
took the exhaustive study of pebrine; but Béchamp 
was the first to pronounce the disease parasitic, 
resembling muscardine in this respect, and caused by 
the attacks of a microbe—or microzyma, to adopt 
Béchamp’s name—of which the germ or spore is derived 
from the air, at first attacking the silkworm from 
without, but multiplying in its interior, and developing 
with its growth, so that the infected moth is unable 
to lay its eggs without depositing the spores of the 
microbe at the same time, and thus exposing the 
young grub to attack as soon as it is born. Pasteur’s 
