91 PERIODIC OPHTHALMIA. 



flamed lungs, grease, and glanders, there we find most blindness; 

 and where these diseases are rarest, ophthalmia is least known. 

 We find farmers' horses going blind, because they are kept in foul, 

 badly ventilated stables ; and the same observation applies to 

 posting establishments, and to such of our country stables as are 

 ill-constructed and undrained. In some horses this poison of the 

 stables will affect one organ ; in other horses, some other organ ; 

 or it may affect the whole mass of blood, and afterwards shew 

 itself locally in some one or other of these organs. — As a proof 

 that this is not a local disease, we often find that the inflammation 

 at first is very trifling : we know nothing about it until we discover 

 it in the transparent cornea, and then even the inflammatory action 

 appears not one-tenth part so violent as what would proceed from a 

 blow ; and, yet, in the latter case it would in time subside without any 

 remedy at all being employed, while in the former all that we can 

 do proves of no avail. — The specific ophthalmia makes its appear- 

 ance, first, in an inflammation of the conjunctiva lining the eye- 

 lids ; then affects the membrane covering the opaque cornea, and 

 very soon afterwards we perceive vessels shooting into the trans- 

 parent cornea. — Horses labouring under this disease either perspire 

 profusely from exercise, or not at all. Seldom are they in a healthy 

 state. In perspiring so freely they evince debility ; in their skins 

 being dry, they shew themselves to be out of health. 



Coleman's Doctrine is shaken, Mr. Castley thought, by the 

 fact, that, in a regiment of cavalry, cases of ophthalmia, greatly more 

 in proportion, occur among troop horses than among the officers* 

 horses ; notwithstanding the stables in which the former are kept 

 are in accordance with regulations ventilated, and that the latter 

 stand in stables shut up as close as grooms choose to make them. I 

 cannot, however, myself, admit the force of this apparent objec- 

 tion. The officers' horses, generally speaking, are six years old and 

 UDwards; at least there are very few five-year-olds among them; 

 and none, most likely, of years four or three. Out of fifty cases of 

 ophthalmia occurring in my own regiment, I find eight three-year- 

 olds, thirteen four-year-olds, and five five-year-olds, making above 

 half of the whole number. And when we come to deduct — which 

 we have a right to do — such cases from the remaining twenty-four 



