60 THE CAUSATION OF DISEASE. 



offspring which would tend to inherit his peculiarities. In 

 this way, by accumulation from generation to generation, the 

 antlers of the stag have attained their present dimensions. 

 And the same is true of countless other sexual peculiarities, 

 which enable the male to secure the female. 



Darwin has further shown that characters acquired by one sex 

 at an early period of life — before the time of sexual activity — 

 tend to be transmitted to either sex alike ; but that characters 

 appearing in one sex during the period of sexual activity tend to 

 be inherited by that sex alone. He further points out that new 

 characters tend to attach themselves by preference to the male 

 sex.* These facts have an undoubted application to pathology, 

 for we find that diseases attack the two sexes with much greater 

 impartiality during childhood than in the period of sexual life ; 

 and perhaps the same is true, though in a far less degree, of the 

 period of post-sexual life. This tendency of special structural 

 characteristics to be transmitted along either sex, may be 

 termed the principle of " sexual heredity." But such sexual 

 heredity is not confined to sexual differences. It holds good 

 universally — that is to say, any character whatever, when 

 acquired by one sex, be it physiological or pathological, tends 

 in the offspring to appear in the same sex. Many diseases 

 illustrate this truth. Thus, gout is acquired by the male at a 

 particular period of life, and tends to appear in the male 

 descendants at the same age. 



Mr. Sedgewick has published some interesting papers on 

 " The Influence of Sex in Limiting Hereditary Transmission," t 

 and amongst other cases he records several of congenital 

 abnormities — such as an abnormal number of fingers or 

 phalanges — descending along the one sexual line. 



Concerning this tendency for structural peculiarities to 

 appear in one sex only, of successive generations, be it care- 

 fully noted that the peculiarity may pass potentially throvgh the 

 opposite sex. Thus A suffers from gout : his sons will be apt 

 to inherit the complaint, and his sons' sons ; the daughters, on 

 the other hand, will tend to escape, but their sons will be liable 



* " Descent of Man," second edition, p. 32. 



f Medico- Chirurgical Review, April and July 1863. 



