PERIODIC ophthal^iia. 91 



look upon the hereditary influence as predisponent only — not ex- 

 citant; not sufficient of itself to produce ophthalmia. 



Is THIS Predisposition Constitutional or Local] In 

 other words, is it something in the blood — some idiosyncrasy 

 which predisposes? — or, is the predisposition inherent in the form- 

 ation or excitability of the eye] These are most interesting ques- 

 tions, of which various facts and observations current among us 

 may be brought forward by way of elucidation. " According to 

 my own experience," says Mr. Castley, in The Veterinarian 

 for 1831, " ophthalmia is much more frequent towards the north 

 than in the southern parts of Europe. In Spain and Portugal it is 

 a complaint of rare occurrence, whereas in France and England 

 it prevails to a considerable extent ; but certainly, most of all, in 

 Ireland. I feel no hesitation in saying, that there are far more 

 blind and half-blind horses in Ireland than are to be found in any 

 other country, proportionably to its size, in Europe ; and I think 

 this is to be accounted for on the score of hereditary predisposi- 

 tion" — owing, in fact, to the little or no attention paid to the stock 

 bred from. " A Yorkshire breeder considers it of great consequence 

 to have a sire free from defects and blemishes : but in Ireland, for 

 a stallion to be blind or half-blind, appears to be no detriment to 

 him ; and as for the dam, supposing she be blind, the Irish make a 

 point of breeding from her, because (continues Mr. C.) she is fit for 

 nothing else." — Farrier Major Kemp, who had served with the 10th 

 Hussars in Ireland, informed me that he had observed that grey 

 horses appeared most subject to the disease. It is commonly ob- 

 served among ourselves in England, that what are called ''pig-eyed" 

 horses, with large coarse heads, are more liable than others ; such 

 horses having at the same time thick skins and fleshy legs, and 

 being soft or mongrel bred — bred, perhaps, in low or fenny and poor 

 pastures ; of which stamp are many French and Flemish horses. 



Professor Coleman denied all hereditary influence. " I re- 

 collect," says Mr. Castley — in The Veterinarian for 1830-31 — 

 " when at the Veterinary College, observing to our worthy Pro- 

 fessor, Mr Coleman, that the practical breeders of horses in York- 

 shire considered this complaint in a great measure hereditary ; 

 and for that reason they almost always had great objection to 



