DIPTERA. 65 
Tn order to examine the interior cavity, Réaumur opened some 
of these tumours, either with a razor or a pair of scissors. He 
found it in a most disgusting state. The larva is lodged in a 
regular festering wound, matter occupying the bottom of the 
cavity, and the head of the worm is continually, or almost con- 
tinually, plunged in this liquid. “It is most likely very well off 
there,” says Réaumur; and he adds that this matter appears to 
be the sole food of the larva. 
‘The pesition of a horned beast,” observes the great naturalist, 
“which has thirty or forty of these bumps on its back, would be 
a very cruel one, and a terrible state of suffering if his flesh were 
continually mangled by thirty or forty large worms. But it is 
probable they cause no suffering, or at least very little, to the 
large animal.” ‘“ Besides,” continues Réaumur, “those cattle 
whose bodies are the most covered with bumps, not only show no 
signs of pain, but it does not appear that they are prejudicial to 
them in any way.” 
Réaumur tried to discover how the larva, when arrived at its 
full growth, succeeds in leaving its abode, as the opening is 
smaller than its own body. 
“Nature,” says Réaumur, “has taught this worm the surest, 
the gentlest, and the most simple of methods, the one to which 
surgeons often have recourse to hold wounds open, or to enlarge 
them. They press tents’ into a wound they wish to enlarge. 
Two or three days before the worm wishes to come out, it com- 
mences to make use of its posterior part as a tent, to increase the 
size of the exit from its habitation. It thrusts it into the hole 
and draws it out again many times in the course of two or three 
days, and the oftener this is repeated, the longer it is able to 
retain its posterior end in the opening, as the hole becomes larger. 
On the day preceding that on which the worm is to come out, 
the posterior part is to be found almost continually in the hole. 
At last, it comes out backwards and falls to the ground, when it 
gets under a stone, or buries itself in the turf; remaining quiet 
and preparing for its last transformation. Its skin hardens, the 
rings disappear, and it becomes black. Thenceforth the insect 
is detached from the outer skin, which forms a cocoon, or box. 
At the front and upper part of the cocoon is a triangular piece, 
F 
