212 EXPERIMENT STATION. [Jan. 



Accompanying the list is given the average monthly mean 

 temperatures for the growing season of 1907, March to Septem- 

 ber, inclusive, as compiled from the records of the United States 

 Weather Bureau and Canadian Meteorological Service. 



It appears from this that an average monthly mean tempera- 

 ture for the growing season of at least 60° is required for the 

 satisfactory development of the Ben Davis apple, and if grown 

 where a lower temj)erature prevails the product is likely to bo 

 inferior. 



That the poor quality of these northern-gi'own apples, as 

 shoA\m by their acidity, and dry, tasteless flesh, is due to lack of 

 sufficient heat to fully develop the fruit is indicated by the 

 results of certain work of the Bureau of Chemistry of the 

 United States Department of Agriculture on the development of 

 the Ben Davis,^ where is shown the constant increase of sugars 

 and decrease of acids with the development of the apples. It is 

 also shown that the tannin which is present in the partially 

 developed apples gradually disappears, and it is doubtless this 

 substance that gives the apples their astringent taste. 



Summary. 



1. Apples vary greatly in response to the widely varying 

 conditions of soil, and, more especially, climate, in the apple 

 regions of ISTorth America. The Ben Davis variety seems to be 

 especially variable. 



2. This variability may be accurately measured and studied 

 by means of statistical methods. 



3. The most striking variation is in the external form of 

 the apples, and this is accompanied by corresponding changes of 

 the internal structure. 



4. The cause of this variation is some factor or factors of 

 climate, which are closely related to latitude and the proximity 

 of large bodies of water. It is probable that humidity or tem- 

 perature, or both, may be the controlling factors. 



5. The differences in warmth of different growing seasons 

 definitely affect the size of the apples for that season. 



(), The most favorable temperature for development in size 



» Bureau of Chemistry, Bulletin 94, p. 44. 



