172 



DADDS VETERINARY MEDICINE AND SURGERY. 



at length, these muscles appear to act involuntarily on the slightest 

 touch of any body whatever. 



THE (ESTRUS EQtJI. 



1. The female fly. about to deposit an egg. 



2. The male fly. 



3. The egg ; its natural size. 



4. The egg magnified. 



5. The newly-hatched bot. 



6. The bot full-grown. 



7. The head of a bot magnified. 

 «. The chrysalis. 



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 days, they become ripe, after which time the slightest 

 application of warmth and moisture is sufficient to bring forth, in 

 an instant, the latent larva?. At this time, if the tongue of the 

 horse touches the egg, its operculium is thrown open, and a small 

 active worm is produced, which readily adheres to the moist surface 

 of the tongue, and is thence conveyed with the food to the stom- 



