

72 



INHERITANCE. 



Chap. XIV. 



any way directly connected with the organs of reproduction 



conspicuously pi 

 these 



With 



domesticated 



secondary characters are often found to diffi 

 greatly from the state in which they exist in the 

 species. And ^the principle of inheritance as limited by 



' 1 """" 2ters mi g bt ^ve been first acquired and 



parent 



subsequently modified 



Dr. P. Lucas, who has collected many facts on this subject shows 26 

 that when a peculiarity, in no manner connected with the reproductive 

 organs, appears in either parent, it is often transmitted exclusively to the 

 offspring of the same sex, or to a much greater number of them than of 

 the opposite sex. Thus, in the family of Lambert, the horn-like projection, 

 on the skm were transmitted from the father to his sons and grandsons 



f.T ; *?** lia f b6en With ° ther Cases of ichth yosis, with supernumerary 

 digits, with a deficiency of digits and phalanges, and in a lesser degree 



with various diseases, especially with colour-blindness, and a hemorrhagic 

 diathesis, that is, an extreme liability to profuse and uncontrollable 

 bleeding from trifling wounds. On the other hand, mothers have trans- 

 mitted, during several generations, to their daughters alone, supernumerary 

 and deficient digits, colour-blindness, and other peculiarities. So that we 

 see that the very same peculiarity may become attached to either sex, 

 and be long inherited by that sex alone ; but the attachment in certain 

 cases is much more frequent to one than the other sex. The same peculi- 

 arities also may be promiscuously transmitted to either sex. Dr. Lucas gives 

 other cases, showing that the male occasionally transmits his peculiarities 

 to his daughters alone, and the mother to her sons alone ; but even in this 



we see that inheritance is to a certain extent, though inversely, 

 regulated by sex. Dr. Lucas, after weighing the whole evidence, comes 

 to the conclusion that every peculiarity, according to the sex in which 



it first appears, tends to be transmitted in a greater or lesser degree to 

 that sex. 



A few details from the many cases collected by Mr. Sedgwick, 26 may be 

 here given. Colour-blindness, from some unknown cause, shows itself 

 much oftener in males than in females ; in upwards of two hundred cases 

 collected by Mr. Sedgwick, nine-tenths related to men ; but it is eminently 

 liable to be transmitted through women. In the case given by Dr. Earle, 

 members of eight related families were affected during five generations : 

 these families consisted of sixty-one individuals, namely, of thirty-two males, 

 of whom nine-sixteenths were incapable of distinguishing colour, and of 

 twenty-nine females, of whom only one-fifteenth were thus affected. Al- 



case 



25 



' L'Hered. Nat.,' torn. ii. pp. 137- tary Diseases, ' Brit, and For. Mer!.- 



165. See, also, Mr. Sedgwick's four 



memoirs, immediately to be referred to. 



26 On Sexual Limitation in Heredi- 



Chirurg. Eeview/ April, 1861, p. 477; 

 July, p. 198 ; April, 1863, p. 445 ; and 

 July, p. 159. 











