172 DADD'S VETERINARY MEDICINE AND SURGERY. 
at length, these muscles appear to act involuntarily on the slightest 
touch of any body whatever. 
THE ESTRUS EQUI. 
5. The newly-hatched bev, 
6. The bot full-grown. 
7. The head of a bot magnified. 
%. The chrysalis. 
1. The female fly, about to deposit an egg. 
3. The male fly. 
8. The egg; its natural size. 
4, The egg magnified, 
The inside of the knee is the part on which these flies are most 
fond of depositing their eggs, and next to this on the side and back 
part of the shoulder, and less frequently on the extreme ends of the 
hairs of the mane. But it is a fact worthy of attention that the 
fly does not place them promiscuously about the body, but con- 
stantly on those parts which are most liable to be licked with the 
tongue, and the ova, therefore, are always scrupulously placed 
within its reach. 
The eggs thus deposited I at first supposed were loosened from 
the hairs by the moisture of the tongue, aided by its roughness, 
and were conveyed to the stomach, where they were hatched; but 
on more minute search, I do not find this to be the case, or, at 
least, only by accident; for when they have remained on the hairs 
four or five davs, they become ripe, after which time the slightesi, 
application of warmth and moisture is sufficient to bring forth, is 
an instant, the latent larve. At this time, if the tongue of the 
horse touches the egg, its operculium is thrown open, and a smal} 
active worm is produced, which readily adheres to the moist surfiw: 
of the tongue, an’ is thence conveyed with the food to the sta * 
