i54 INHERITANCE. Chap. XIL 



three generations, a cleft-iris for four generations, being limited in 

 this latter case to the males of the family. Opacity of the cornea 

 and congenital smallness of the eyes have been inherited. Portal 

 records a curious case, in which a father and two sons were rendered 

 blind, whenever the head was bent downwards, apparently owing to 

 the crystalline lens, with its capsule, slipping through an unusually 

 large pupil into the anterior chamber of the eye. Day-blindness, or im- 

 perfect vision under a bright light, is inherited, as is night-blindness, 

 or an incapacity to see except under a strong light : a case has been 

 recorded, by M. Cunier, of this latter defect having affected eighty- 

 five members of the same family during six generations. The 

 singular incapacity of distinguishing colours, which has been called 

 Daltonism, is notoriously hereditary, and has been traced through 

 five generations, in which it was confined to the female sex. 



With respect to the colour of the iris : deficiency of colouring 

 matter is well known to be hereditary in albinoes. The iris of one 

 eye being of different colour from that of the other, and the iris 

 being spotted, are cases which have been inherited. Mr. Sedgwick 

 gives, in addition, on the authority of Dr. Osborne, 20 the following 

 curious instance of strong inheritance : a family of sixteen sons and 

 five daughters all had eyes " resembling in miniature the markings 

 on the back of a tortoiseshell cat." The mother of this large family 

 had three sisters and a brother all similarly marked, and they 

 derived this peculiarity from their mother, who belonged to a 

 family notorious for transmitting it to their posterity. 



Finally, Dr. Lucas emphatically remarks that there is not one 

 single faculty of the eye which is not subject to anomalies ; and not 

 one which is not subjected to the principle of inheritance. Mr. 

 Bowman agrees with the general truth of this proposition ; which of 

 course does not imply that all malformations are necessarily 

 inherited ; this would not even follow if both parents were affected 

 by an anomaly which in most cases was transmissible. 



Even if no single fact had been known with respect to the 

 inheritance of disease and malformations by man, the evidence 

 would have been ample in the case of the horse. And this 

 might have been expected, as horses breed much quicker than 

 man, are matched with care, and are highly valued. I have 

 consulted many works, and the unanimity of the belief by 

 veterinaries of all nations in the transmission of various 

 morbid tendencies is surprising. Authors who have had wide 

 experience give in detail many singular cases, and assert that 

 contracted feet, with the numerous contingent evils, of ring- 

 bones, curbs, splints, spavin, founder and weakness of the front 



20 Dr. Osborne, Pres. of Royal this case in the ' Dublin Medical 

 College of Phys. in Ireland, published Journal,' for 1835. 



