320 Mr. Clark'j' Observations on the Genus Oejlrus. 



aware other reafons may be alfo affigned for it), that thofe horfes 

 which are not expofed to the hots, more frequently are infected 

 with the glanders, farcy, &c. as thofe of the army, poft-coaches, 

 port-waggons, and dray-horfes, thefe being rarely fpared, from the 

 nature of their work, to graze on the commons, and thus be ex- 

 pofed to receive them. 



If, after a more minute refearch into their effects on the fyitem, 

 the utility of thefe native jl'imuli of animals fhould be eftablimed, 

 and, like the leech, or the cantharides, they fhould be called in to 

 the aid of veterinary medicine, it would not be impracticable to 

 adminifter them artificially by means of their ova. 



If the flimulus is confidered as of too gentle a nature, it is in 

 fome meafure atoned for by its permanency, and the unlimited 

 power of increafing their numbers j at l^aft, by the ad m in ift ration 

 •of them in this way, we might accurately afcertain their real 

 effects, and whether they are fo fatal as has been imagined. 



Linnaeus has alfo obferved of the pediculus, u rodendo caput 

 " exciat achores, apud puerulos voraces incarceratos, indeque ftru- 

 u mofos, ficque prarfervat a coryza, tuffi, csecitate, epilepfia," &c. 



In the fame way the worms in children, I am induced to believe, 

 are wholefome to them in a certain quantity, by conftantly irri- 

 tating the membranes of the interlines, and preventing the accefs 

 of worfe diforders. But however ufeful a few of thefe natural 

 fihiudi of animals may be, the increafe of their numbers, by pro- 

 ducing bad confequences, ihould at all times be prevented. 



The fheep are particularly fubject to diforders attended with ver- 

 tigo, probably arifmg from an affection of the brain; and the larvte of 

 the CE. Ovis are certainly very favourably fituated on the neighbour- 

 ing membranes of the maxillary finufes, and may perhaps tend to 

 divert the attack of this diforder, or render it lefs fatal. 



Remarks 



