ORDER V. COLEOPTERA.— THE SPANISH FLY. 291 
from the joints of the feet, which is caustic and of a penetrating odor. The 
most important group of the Cantharidia is the genus 
Cantnaris. — The Cantharides of commerce (Cantharts vesicatoria) 
are of a beautiful green, attain to a size of four fifths of an inch, and 
are found on ash trees, lilacs, and other shrubs. Commerce, for a long 
time, brought them from Spain, and some still come from that country : 
hence the common name of Spanish Fly. As they live in great numbers 
together, collecting them is easier and less expensive than would be that of 
other species of the same family which are not gregarious, but which have 
the same medicinal properties. The presence of the Cantharides is mani- 
fested by the strong odor which they diffuse to some distance. When, by 
aid of this smell, they are discovered, generally settled on an ash, they are 
collected in the following manner: Very early in the morning, a cloth of 
light tissue is stretched out at the foot of the tree, and the branches are 
shaken, which causes the insects to fall. These, numbed by the cold of the 
night, do not try to escape. When there is a sufficient quantity, the four 
corners are drawn up, and the whole plunged into a tub of vinegar diluted 
with water. This immersion causes the death of the insects. They then 
carry them to a loft, or under a very airy shed. To dry them they spread 
them out on hurdles covered with linen or paper; and, from time to time, 
to facilitate the operation, they are moved about, either with a stick, or with 
the hand, which is more convenient ; but it is then necessary to take the pre- 
caution of putting on gloves; for, if touched with the naked hand, they 
would cause more or less serious blisters. The same precaution must be 
observed in gathering them. 
When the Cantharides are quite dry, they put them into wooden boxes, 
or vessels of glass or earthen ware, hermetically sealed, and preserve them 
in a place protected from damp. With these precautions they may be kept, 
for a long while, without losing any of their caustic properties. Dumeril 
made blisters of Cantharides which had been twenty-four years in store, and 
which had lost none of their energy. When dry, they are so light that a 
kilogramme contains nearly thirteen thousand insects. Aretius, a phy- 
sician who flourished in Rome in the first century of our era, seems to have 
been the first to employ Cantharides, reduced to powder, as a means of ves- 
ication. Hippocrates administered them internally in cases of dropsy, 
apoplexy, and jaundice. But it is pretty nearly established that the Can- 
tharides of the ancients were not the same species used at the present day. 
They were probably a kindred species —the Mylablis chicortt. A_ blister- 
ing principle has been extracted from these insects, called “ Cantharidine.” 
This organic product presents itself under the form of little shining flakes, 
without color, soluble in ether or oil. One atom of this matter applied to 
