LUTHER BURBANK 



chemical changes. Recent studies of the short 

 waves of light beyond the violet end of the 

 spectrum show that they have strong germicidal 

 power. 



It will be recalled that the celebrated Danish 

 physician Dr. Finsen developed a treatment of 

 local tubercular affections based on the principle 

 that ultra-violet light destroys the disease germs. 

 And most readers have heard of Dr. Woodward's 

 theory that very bright light is detrimental to all 

 living organisms. 



Possibly too much sunlight might have a dele- 

 terious ejffect on the seeds of such a plant as the 

 blackberry. Indeed, the fact that the berry quickly 

 develops pigments under ordinary conditions, and 

 develops them much earlier than the stage at 

 which it is desirable to have the fruit eaten by 

 birds, suggests that this pigment is protective to 

 the fruit itself in addition to its function of 

 making the fruit attractive to the bird. 



But be the explanation what it may, the fact 

 remains that very few fruits in a state of nature 

 are white; and no one needs to be told that fruits 

 of the many tribes of blackberries, with the single 

 exception of the one under present discussion, are 

 of a color fully to justify the name they bear. Yet 

 the experiment in breeding just recorded proves 

 that, at least under the conditions of artificial 



[52] 



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