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THE AMERICAN NATURALIST [Vol. XLYIII 



production of red pigment is quite narrow in most varie- 

 ties and poor color may result from either deficiency or 

 excess. Latitude and altitude affect the color only as 

 they modify the factors upon which color depends, caus- 

 ing them to approach or recede from the optimum. The 

 influence of elements in the soil is not well understood. 

 It is probable that soils containing sufficient iron for the 

 proper development of chlorophyll contain an abundance 

 for the production of red pigment in apples. 



Aside from such differences as depend upon the hand- 

 ling of the fruit, variations in keeping quality appear to 

 follow the law of the optimum in the same manner as the 

 other characters of the fruit. Conditions which favor the 

 best all-round development result, as a rule, in good keep- 

 ing quality. Apples grown under irrigation are said to 

 keep poorly probably because of their unbalanced adapta- 

 tion to the environment. Certain factors which favor de- 

 velopment and maturity are present in excess, resulting 

 in overgrown or overripe fruit. 



Varieties differ in specific gravity according to the 

 extent of intercellular spaces in the flesh and the open- 

 ness of the core. Overgrown specimens are low in speci- 

 fic gravity. As a rule, those lots which kept best in any 

 variety had the highest specific gravity. ' 



Chemical composition is associated somewhat with 

 quality. High sucrose content results in richness of 

 flavor. Fruit of high quality has the sugars and acids 

 well balanced and the flavoring constituents well devel- 

 oped. A heavy juice is usually associated with a high 

 content of soluble solids. Fruit grown under irrigation 

 is ordinarily rather low in soluble solids. There seems 

 to be no constant relation between the amount of sunlight 

 and the production of sugars, and flavors appear to de- 

 velop best in a relatively cool climate. 



