LUTHER BURBANK 



ample, is much less well adapted to propagate its 

 kind than a single one. Yet from the standpoint 

 of the plant developer the double condition is de- 

 sirable, as it enhances the beauty of the flower. 



In the case of the human subject, however, 

 the traits are adjudged by another standard, and 

 are considered desirable only if they conduce to 

 the welfare of the individual and the race. So we 

 are usually concerned with the exclusion of un- 

 desirable qualities, and it is these that have 

 hitherto been chiefly studied by students of hered- 

 ity. But the fact that some at least of these 

 qualities are transmitted along Mendelian lines 

 gives clews that are invaluable. 



The analogy with plant experiments shows how 

 a defective trait that acts as a recessive factor in 

 inheritance any mental deficiency or suscepti- 

 bility to tuberculosis may be ingrained in a fam- 

 ily and result disastrously. But, contrariwise, 

 this same knowledge points the way to the elimi- 

 nation of such a defective strain. 



Just as Mr. Burbank could not fix the abnor- 

 mal quality of his wild geranium leaf without in- 

 breeding, so the defective quality in the human 

 subject is not likely to be fixed unless a person 

 having the defect mates with another having a 

 similar defect. 



And this gives us a clew to a full understand- 

 ing of the question of cousin marriage, regarding 

 which there has been a good deal of difference 

 of opinion among students of heredity in the past. 

 In the light of the new knowledge it would appear 



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