IN-AND-IN BREEDING. 177 



Jews in Berlin, 27 in 10,000 are deaf-mutes, while the 

 proportion is only 6 in 10,000 among the Christian 

 population in that city; and apparently, therefore, 

 with great justice, he concludes that ' the hypothesis 

 of the pretended harmlessness of consanguineous mar- 

 riages is contradicted by the most evident and well- 

 authenticated facts.' " 1 



Statistics have been collected, apparently showing 

 that the cousins of persons who are deaf and dumb 

 are particularly subject to the same defect, and it has 

 been inferred that they furnish a satisfactory explana- 

 tion of the preceding statements. As we wish to pre- 

 sent as strong a case as possible in favor of the theory 

 that consanguineous marriages are likely to result in 

 defects in the offspring, the following statistics are 

 added : 



From "Wilde's " Eeport on the Deaf and Dumb of 

 Ireland" (as quoted by Sedgwick), it appears that 

 " in cases of single congenital mutism, where the re- 

 lations were also deaf and dumb, there were by the 

 father's side .... in one instance six cousins af- 

 fected ; in three cases there were four cousins, and in 

 nine cases two cousins all deaf-mutes. Where two of 

 the family were affected with congenital deaf-dumb- 



3, in two instances four cousins were in ' a similar 

 condition ; in two cases three cousins were deaf and 

 dumb, and in four instances two cousins were thus 

 affected. 



"Where three cases of congenital deaf -dumbness 

 occurred in the same family .... in five cases, two 

 cousins were in a similar condition. When the rela- 



1 British and Foreign Medico-Chirurgical Review, July, 1863, p. 179. 



