THE INHERITANCE OF DISEASE 113 



from it and described it) ; the other is haemophilia, or the 

 "bleeder disease." The latter condition is due to a 

 strange anomalous perviousness of the bloodvessels, which 

 makes individuals suffering from it liable to severe, often 

 uncontrollable bleeding on the slightest provocation, be 

 it a small cut or the drawing of a tooth. Both affections 

 show a curious manner of inheritance. Only male members 

 of the affected family inherit the disease. But though the 

 females are free from the disease, they transmit it to their 



M F 



Fig. 45. — Pedigree of Bleeders. 



{From J. A. Thomson, "Heredity.") 



The black letters indicate the " bleeders." 



male progeny. The above is a pedigree of such a 

 " bleeder " family, given in Thomson's Heredity, the thick 

 letters indicating the affected subjects or " bleeders." 



(c) Alcoholism. 



We deal separately with alcoholism for a twofold reason. 

 Firstly, the subject is of such vast practical importance 

 that too much emphasis cannot be laid upon it. Secondly, 

 there is a good deal of ignorance and misconception with 

 regard to this question, which is not at all conducive to a 

 proper understanding of the " drink problem." 



Drunkenness is generally looked upon as if it were an 

 entity. Some would call it a trait of character, others a 

 disease. It is neither. The habit a person may have of 



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