THROUGH CUMULATIVE SEGREGATION. 
211 
races, one with good powers of hearing and the other with an 
increasing liability to deafness. To secure such divergence it is 
necessary that segregative influences should be introduced, such 
as have been most amply furnished by the modern system of 
education for the deaf. Under these influences those endowed 
with hearing and those without hearing have been separated into 
two communities, the members of each having but little oppor- 
tunity for acquaintance beyond the limits of that community ; 
each community having separate schools, separate newspapers, 
and to some extent a separate language. As the result of this 
segregation marriages between the two classes have been greatly 
diminished ; and little by little two races are arising, the hearing 
race and the deaf race.* 
Seasons oe a General Character eor considering Selection 
without Independent Generation an Unsatiseactory 
Explanation oe Divergent Evolution. 
1. The divergence is often confined to characters which seem 
to have no possible relations of adaptation either to the environ- 
ment or to other members of the species, and, therefore, to be 
independent of both Natural and Reflexive Selection. 
2. Divergence relating to adaptive characters successfully 
propagated involves different kinds rather than different degrees 
of adaptation and advantage ; and, as Adaptational Selection de- 
pends on the difference of degrees of advantage, it cannot account 
for the divergence of forms possessing equal degrees of ad- 
vantage. 
3. In the very nature of its action, we see that Adaptational 
Selection unaccompanied by Independent Generation must pro- 
duce essentially mouotypic transformation. 
4. In artificial breeding, Independent Generation is found to be 
an essential condition for the production of divergent races ; and 
there is no reason to doubt that the same law holds good in the 
divergence of natural forms. 
5. The general fact that species possessing high powers and 
large opportunities for migration occupy large areas, while those 
* See paper by Alexander Graham Bell, read before the National Academy 
of Sciences, November 13, 1883, upon the “ Formation of a Deaf Variety of the 
Human Race ; ” also a review of the same in ‘ The Popular Science Monthly,’ 
vol. xxvii. p. 15, entitled “ Can Man be Modified by Selection?” 
