362 THE TREND OF THE RACE 
tend, when isolated so that they do not interbreed or interbreed 
only at rare intervals, to diverge in character. 
Membership in a religious organization acts as a barrier to 
check free intercrossing. Catholics usually marry Catholics, 
Jews generally marry Jews for reasons of religion as well as of 
race, and Protestants not only generally marry Protestants, but 
they commonly marry within their own particular sect. “In 
Prussia,” according to Mayo-Smith, “‘during the period 1875-90, 
94.77 per cent of the Protestant men, 88.20 per cent of the Catho- 
lic and 94.79 per cent of the Jewish, married women of the same 
religious confession.” 
Formerly the tendency to marry within the fold was much 
stronger than now. The Quakers expelled members who married 
into other denominations. And in denominations in which 
outside marriages were not forbidden, the general sentiment 
deterred most of the members from marrying persons of different 
religious views. The customs of limiting marriage to members of 
a group tends eventually to produce a uniform type with char- 
acteristics somewhat different from those of other inbred groups. 
A multiplicity of sects each discouraging marriage outside its own 
organization tends to break up a people into a multiplicity of 
types, each of which tends to become more and more uniform in 
character as time goes on. Where sects are small in numbers this 
may well produce noticable results in a few generations. 
When we compare the present influence of religion with the 
influence which it is feasible for it to exert we cannot fail to 
become conscious of a painful discrepancy. Protestant Chris- 
tianity has practically failed to affect the practice of its adherents 
in regard to one of the most fundamental of duties. And the 
Catholic church which has attained a measure of success in 
checking the restriction of births, gives indiscriminate encourage- 
ment to the fecundity of all classes whether their heredity is good 
or bad. The Right Rev. Monsignor W. F. Brown in setting forth 
the attitude of the Church before the National Birth Rate Com- 
mission declared that the State cannot lawfully forbid the mar- 
riage of the physically defective or even the feeble-minded. If 
