98 THE PRACTICE OF VETERINARY MEDICINE. 



quote the words of Professor Smith, ' Many of my country- 

 men are quite famib'ar with its effects.' The Duke of 

 Argyle, so the legend runs, out of the bountiful munifi- 

 cence of his heart and his purse, erected scratching-posts 

 throughout his dominion, so that the peasant or wayfarer 

 could stop and relieve his intolerable itching by having 

 a good scratch. Thus it was that the duke proved himself 

 to be a public benefactor, and thus it was that the ejaculation 

 of 'God bless the Duke of Argyle !' came into common use, 

 being heard occasionally even at the present day. The parasites 

 burrow into the flesh, and occur in the horse, man, sheep, 

 l^igs and cattle, and are also common to many other small 

 animals. Besides the sarcoptes there are ' dermatodectes,' 

 signifying 'the skin,' and 'to prick.' The dermatodectes 

 do not burrow beneath the skin, but simply hold on to and 

 l^rick the skin. They are common to the ox, horse and 

 sheep. Another variety is known as 'symbiotes.' They 

 neither burrow nor prick the skin, but nevertheless cause 

 considerable irritation, and are common to the horse and 

 ox. So three genera of ectozoa, or external parasites, as 

 mentioned above, aff'ect the horse and ox in common. 

 Certain conditions appear favourable to the attack and 

 propagation of the sarcoptes equi. A horse poorly cared 

 for, badly groomed, and in an unthrifty state generally is 

 in a favourable condition for the reception of the parasites. 

 The attack of the sarcoptes is at first slow, but having once 

 fairly secured a start, they spread with great rapidity, 

 irritating the skin and sometimes destroying the patient. 

 The sarcoptes will live the usual period on man, and then 

 die without propagating. 



The dermatodectes are less troublesome than the sarcoptes. 

 The symbiotes are often found affecting the legs of horses, 

 setting up irritation or itching, and causing the animal to 

 scratch the parts. The above-mentioned parasites are 



