254 PLANT-BREEBINJ 



the inner qualities or characters of the plant, but others are 

 the product of reactions to external stimuli. 



The difference observed in these cases may be considered 

 from a broader point of view. Some cases of correlation 

 are caused by characters which may become active in more 

 than one organ of the plant. The faculty of producing the 

 anthocyanin dye may display itself in flowers, fruits, and 

 seeds, in stems and stalks, in leaves and scales, in one word, 

 in almost all the organs of the plant. It is evidently every- 

 where the same character, even where it sweetens the taste, 

 by lessening the amount of tannin. So it is with the lacinia- 

 tion, which may affect leaves and petals. In all these cases 

 the idea of unit-characters is pressed upon us. It is the 

 assumption that the same unit becomes active in the dif- 

 ferent parts of the same organism. 



In the other cases different qualities may depend in the 

 same manner upon the changes of the environmental con- 

 ditions of life. If these are favorable all will increase, but 

 under adverse influences they will decrease together. In 

 this way different unit-characters may be correlated but 

 the relation is more in the nature of accidental coincidence 

 than of actual identity. 



All in all, the study of these correlations is of the highest 

 interest, as well for science as for practice. By means of 

 them we may predict one quality or one function from the 

 study of others. Insignificant characters or organs may 

 show us the way and guide us in our selection. The more 

 we familiarize ourselves with such seemingly subordinate 

 marks, and with their relation to the qualities, which deter- 

 mine the commercial worth of the plant or of the harvest, 

 the better we shall be prepared for the work of selection. 

 To judge quinces from their seedlings, as Burbank did, 

 may seem incredible to those who are not initiated into 

 the mystery of this principle, but it can be learned, either 



