INDIRECT INJURIES CAUSED BY INSECTS. 161 



they have a second which produces bots under their 

 skin ; not improbably the same species that in a similar 

 way attacks the latter, as I have stated above. We have 

 heard that the vaccine disease is derived from the cow 

 and the horse, and the small-pox is said to have origi- 

 nated in the heels of the camel: but neither the ingeni- 

 ous Dr. Jenner nor any other writer on this subject has 

 informed us that the rein-deer is subject to the distemper 

 last named ; yet Linne quotes the learned work of a 

 Swedish physician on Sj/philh, who gravely gives this as 

 a fact * ! ! The inoculator, in truth, is the gad-flv, the 

 tumours it causes are the pustules, and its larvae are the 

 pus. — It is astonishing how dreadfully these poor ani- 

 mals in hot weather are terrified and injured by them: 

 ten of these flies will put a herd of five hundred into the 

 greatest agitation. They cannot stand still a minute, 

 no not a moment, without changing their posture, puff- 

 ing and blowing, sneezing and snorting, stamping and 

 tossing continually; every individual trembling and 

 pushing its neighbour about. The ovipositor of this fly 

 is similar to that of the ox-breese, consisting of several 

 tubular joints which slip into each other; and therefore 

 Linne was probably mistaken in supposing that it lays 

 its eggs npoTi the skin of the animal, and that the bot, 

 when it appears, eats its way through it ^ : there can be 

 little doubt (or else what is the use of such an appa- 

 ratus ?) that it bores a hole in the skin and there deposits 

 the eggs. About the beginning of July the rein-deer 



3. he strangely observes under the former species, " Habitat in equo- 

 rum fauce, per nares intrans ! " confounding probably G^. veterinus 

 of Mr. Clark with the true CE. nasalis. 



" Ijach, Lapp. i. 280. ^ Flor. Lapp. 79. 



VOL. I. M 



