CONSANGUINEOUS MARRIAGES 243 
In the light of what is known of the effects of inbreeding and 
cross breeding in plants and animals it is obvious that we are not 
in a position to draw conclusions a priori in regard to inbreeding 
and cross breeding in man. In the absence of direct observations 
on the effect of crossing of any two races of human beings, we 
might expect as a probable result that, in regard to general vigor, 
(1) the progeny would be superior to both parents, (2) that they 
would be inferior to both, (3) that they would be superior to the 
one and inferior to the other, or (4) that they would be on the 
same general level as either one. We might predict with some 
assurance what would be the probable outcome as to the inheri- 
tance of eye color, hair color and some other characters whose 
mode of transmission has been studied in other cases. But con- 
cerning most of the qualities that render one race superior to 
another we should be justified in making only very guarded 
suppositions. 
The results of inbreeding and cross breeding in man present a 
general similarity to those observed in plants and animals. They 
may reasonably be interpreted according to the Mendelian 
scheme, although this circumstance might not enable us to say 
whether, in general, they are desirable or the reverse. In regard 
to the effect of consanguineous marriages especially, there has 
accumulated a large number of observations. It is an undoubted 
fact that such matings have frequently been followed by the 
appearance of undesirable characteristics in the offspring. But in 
weighing the evidence on this point one has to guard against being 
unduly impressed by facts which have been especially selected to 
support a particular thesis. Numerous cases have been reported 
in which various defects have been associated with consanguin- 
eous matings. It would be possible, however, to amass many 
instances of this kind even if consanguinity had nothing to do 
with the production of defect. With this caveat in mind let us 
consider this possible influence of consanguinity in bringing to 
light certain hereditary traits. 
The réle of consanguinity in bringing forth feeble-minded off- 
spring has been discussed by many authors who have reported 
