; 



IN-AND-IN BREEDING. 181 



the number of Jews in Paris is estimated at twenty 

 five thousand, only four of them are deaf-mutes. 

 Again, with respect to the greater frequency of deaf- 

 mutism in other races among the offspring of those 

 who are allied, compared with those who are aliens 

 by blood, although the facts adduced by M. Boudin 

 and other writers are undoubtedly correct, yet the in- 

 ference that has been drawn from them is in like man- 

 ner probably erroneousj for all, or nearly all, the illus- 

 trations of deaf -mutism in these cases of consanguinity, 

 have occurred in circumscribed localities, where deaf- 

 mutism, independent of consanguinity, is more com- 

 mon than elsewhere. Mr. W. K. Scott, of the Deaf 

 and Dimib Institution at Exeter, has lately called at- 

 tention to the fact that deaf-mutism occurs in much 

 larger proportion in secluded and rural populations 

 than in urban and manufacturing districts; in the 

 union of Crediton, in Devonshire, one in 1,143 of the 

 population is a deaf-mute, and in the Scilly Islands 

 this is still more remarkably shown by the fact that 

 there are no less than six deaf-mutes in a population 



f 2,677, or one in 446. But perhaps the strongest 

 argument against the unqualified admission in these 

 cases of consanguinity as the fons et origo mali, is 

 e fact that deaf-mutism cannot as a rule be directly 

 transmitted to the offspring even in those 'cases in 

 which both the parents are deaf-mutes ; for it is chiefly 



y means of breeding-in that peculiarities of structure 

 among the lower animals are perpetuated ; and their 

 hereditary transmission is effected with so much cer- 

 tainty and facility that it would be difficult, in the 

 present day, to say what amount of abnormal develop- 



