Chap. XII. INHERITANCE. 453 



of near objects, and frequently even of distant ones. This state 

 occurs congenitally, or at a very early age, often in several children 

 of the same family, where one of the parents has presented it. 1G 

 Secondly, myopia, or short-sight, in which the eye is egg-shaped and 

 too long from front to back ; the retina in this case lies behind the 

 focus, and is therefore fitted to see distinctly only very near objects. 

 This condition is not commonly congenital, but comes on in youth, 

 the liability to it being well known to be transmissible from parent 

 to child. The change from the spherical to the ovoidal shape seems 

 the immediate consequence of something like inflammation of the 

 coats, under which they yield, and there is ground for believing that 

 it may often originate in causes acting on the individual affected/ 7 

 and may thenceforward become transmissible. "When both parents 

 are myopic Mr. Bowman has observed the hereditary tendency in 

 this direction to be heightened, and some of the children to be 

 myopic at an earlier age or in a higher degree than their parents. 

 Thirdly, squinting is a familiar example of hereditary transmission : 

 it is frequently a result of such optical defects as have been above 

 mentioned; but the more primary and uncomplicated forms of it 

 are also sometimes in a marked degree transmitted in a family. 

 Fourthly, Cataract, or opacity of the crystalline lens, is commonly 

 observed in persons whose parents have been similarly affected, and 

 often at an earlier age in the children than in the parents. Occasion- 

 ally more than one child in a family is thus afflicted, one of whose 

 parents or other relations, presents the senile form of the complaint. 

 When cataract affects several members of a family in the same 

 generation, it is often seen to commence at about the same age in 

 each : e.g., in one family several infants or young persons may suffer 

 from it ; in another, several persons of middle age. Mr. Bowman 

 also informs me that he has occasionally seen, in several members of 

 the same family, various defects in either the right or left eye ; and 

 Mr. "White Cooper has often seen peculiarities of vision confined to 

 one eye reappearing in the same eye in the offspring. 18 



The following cases are taken from an able paper by Mr. W. 

 Sedgwick, and from Dr. Prosper Lucas. 19 Amaurosis, either con- 

 genital or coming on late in life, and causing total blindness, is often 

 inherited; it has been observed in three successive generations. 

 Congenital absence of the iris has likewise been transmitted for 



16 This affection, as I hear from sight is due to the habit of viewing 

 Mr. Bowman, has been ably described objects from a short distance, c'est 

 and spoken of as hereditary by Dr. le travail assidu, de pres. 



Donders of Utrecht, whose work was 18 Quoted by Mr. Herbert Spencer, 



published in English by the Sydenham ' Principles of Biology,' vol. i. p. 244. 



Society in 1864. 19 <■ British and Foreign Medico- 



17 M. Giraud-Teulon has recently Chirurg. Review,' April, 1861, pp. 

 collected abundant statistical evidence, 482-6; ' L'Hered. Nat.,' torn. i. pp 

 ' Revue des Cours Scientifiques,' Sept., 391-408. 



1870, p. 625, showing that short 



