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THE AMERICAN NATURALIST [Vot, XLVIII 



time provinces of Canada, and the Pacific coast. Shaw's 

 papers dealing with this subject have already been noted. 

 Upon studying the climate in these localities, it was found 

 that the temperature for two or three weeks after the 

 blooming season was notably lower than in the sections 

 where the Ben Davis assumes its normal shape. Since 

 this appeared to be the only factor constant for the 

 several localities, it is suggested as the explanation of 

 this variation. It has been shown, however, that temper- 

 ature is incapable of influencing form except by its action 

 through the functions of the plant in modifying the effect 

 of some other factor. It is the writer's opinion that the 

 elongation is due to the relative moisture supply of the 

 different parts of the apple at this period of develop- 

 ment as influenced by the temperature ; that it is primar- 

 ily a modification due to the moisture relation rather 

 than to the direct effect of temperature, the latter being 

 a secondary cause. The rapidity of circulation of the sap 

 and therefore the supply of moisture to the organs of the 

 plant is greatly influenced by the temperature. It is a 

 well-known fact of plant physiology that much less moist- 

 ure passes through the plant in the cool davs of spring 

 than during the warmer weather of midsummer. A re- 

 duction of the temperature at this time results in a still 

 more sluggish movement of the sap. In the period im- 

 mediately after blooming the energy of the plant, so far 

 as the development of the fruit is concerned, is directed 

 primarily to the proper nourishment of the growing seeds 

 and the adjacent parts. If at this time the circulation 

 of the sap is retarded by a temperature unwontedly low 

 for the variety, the moisture supply of the fruit is 

 lessened and a relatively larger amount goes to the seeds 

 and adjacent parts, while the pulpy portion of the fruit 

 receives a more scant supply. As a result, the axillary 

 development is proportionately greater than the swelling 

 of the fruit due to the accumulation of moisture in the 

 superficial tissues. After some two or three weeks the 

 form of the fruit becomes fixed and is not noticably in- 

 fluenced by the moisture supply thereafter. 



