No. 574] VARIATION IN THE APPLE 



623 



would be premature. Dry air and sunshine are favorable 

 to the production of clear, smooth skin. 



Color. — There seems to be no doubt that the coloration 

 of apples depends upon the influence of several factors of 

 which light is usually the most important, The impor- 

 tance of light is easily demonstrated by covering the fruit 

 during development either wholly or in part. The in- 

 tensity of illumination is also, evidently, quite narrow in 

 its limits, so that a point is soon reached at which the 

 color begins to pale owing to excess of illumination. It 

 has been frequently noted that apples grown near the 

 southern limit of the range of a variety are paler than 

 those grown farther to the north. This effect appears to 

 be the result of an excess of the two factors, heat and 

 light. It has been mentioned in the discussion of the 

 characters of several varieties that, contrary to the gen- 

 eral impression, those grown in Washington east of the 

 Cascades where insolation is intense were less highly 

 colored than those from western Washington or the east- 

 ern states. The most marked example of this kind which 

 the writer has observed is the Northern Spy. Again, 

 contrary to the general impression, most of the samples 

 from elevated locations were poorly colored, a fact which 

 may be attributed partly to the strong insolation and 

 partly to the poor development due to the low summer 

 temperature. It appears, therefore, that either too 

 strong or too weak illumination may result in poorly 

 colored fruit and that the best color is developed under a 

 condition of optimum intensity of the light. 



It is suggested above that temperature may influ- 

 ence color. This is most commonly observed in the 

 case of apples grown under conditions of too 

 high summer temperature, though a deterioration 

 in color also results if the temperature is much 

 below the optimum for the variety. It is often 

 stated that apples become more highly colored the farther 

 north they are grown. This is only true in part. Those 

 varieties which are adapted to the most northerly por- 

 tions of the apple belt are able to develop their highest 



