THE CAUSATION OF DISEASE. 83 



the offspring. We have distinct evidence that marriage of 

 brother and sister, uncle and niece, nephew and aunt — nay, 

 even of father and daughter, mother and son — has been 

 countenanced by law. # Nevertheless, although no ill effect 

 may be noticed during- the first few generations, long- continued 

 intermarriage has, there can be no doubt, an injurious effect 

 upon a race, and it may be positively asserted that it is a 

 " great law of Nature " that individuals- of distant relationship 

 should occasionally come into union. 



3 b and c. Abnormal blending of unlike hinds. — The two 

 abnormal characters may remain distinct, as when a man in- 

 herits gout from his father's side and phthisis from the maternal 

 line ; or possibly, in some rare cases, the two may blend into a 

 hybrid, when we should have a true " intermarriage of disease. "• 

 Rheumatoid arthritis, or " rheumatic gout,*' has been thought 

 to be a hybrid of gout and rheumatism, though, as Garrod has 

 shown, these two diseases are perfectly distinct. I can think of 

 no examples of such mongrel diseases worth mentioning, but 

 it seems to me quite certain that many disorders must be of 

 mongrel origin; for disease-tendencies are nothing else than 

 peculiar structural states, and if normal structural states are 

 capable of blending, the like must surely be true of abnormal 

 ones. When we reflect upon the mongrelization of dis- 

 eases which must be thus perpetually going on, we can under- 

 stand how intricately compounded many diseases must be. 

 This consideration alone should warn us against regarding all 

 diseases as specific and unchangeable. We shall, however, in 

 due course, meet with other evidence which will show the 

 absurdity of such a supposition. 



In treating of this subject of Mendings, I have somewhat 

 mechanically dissected the body into different elements or 

 systems, and have considered the bl endings of such individual 

 systems as though they were so many independent units ; but 

 we know, as a matter of fact, that each part of the body 

 works in harmony with all the others, and that the several parts 

 are capable of influencing one another in many mentally dis- 

 entangleable ways. Wherefore the blendings can only in rare 

 instances be localized in their effects. 



* Vide Huth on " Intermarriage of Near Kin." 



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