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THE AMEBIC AN NATURALIST [Vol. XLVIII 



received from those who have helped in various ways in 

 the investigation. Thanks are due to the members of the 

 staff of the department of horticulture for suggestions 

 and encouragement, to the members of the library staff 

 who have rendered aid in the study of the literature of the 

 subject, to Mr. Geo. A. Olson, chemist of the experiment 

 station, who has analyzed the various samples of Grimes, 

 Jonathan, Yellow Bellflower, and Winesap, and finally 

 to the various fruit growers and others who have cooper- 

 ated in securing the fruit and have furnished notes on the 

 conditions of production. To all these the writer takes 

 pleasure in acknowledging his gratitude and indebted- 

 ness. 



Environmental Factors 

 Aside from small individual differences, better called 

 fluctuations than variations, and other more striking 

 modifications of comparatively infrequent occurrence 

 and obscure origin, which it is customary to explain as 

 bud variations, if, indeed, the application of a name to a 

 phenomenon can pass as an explanation, it is quite gener- 

 ally recognized that variation in any variety of fruit is 

 due to the operation of external influences. A knowledge 

 of the various factors which make up the environment 

 and their influence upon plant life is necessary to an in- 

 telligent study of variation. It should be noted, however, 

 that this influence is not necessarily the same with plants 

 propagated vegetatively as with those grown from seed. 

 In the latter case certain modifications of an adaptive 

 nature which enable the plant to fit in more perfectly with 

 its surroundings are apt to persist, while less favorable 

 modifications tend to disappear by the elimination of the 

 individuals possessing them. In the former case, on the 

 other hand, the modifications observed are the direct re- 

 sult of the conditions, unaffected by selection, and whether 

 desirable or not they persist as long as the environment is 

 unchanged and the vegetative propagation is continued, 

 unless, indeed, the environment is so unfavorable that the 



