1911.] PUBLIC DOCUMENT — No. 31. 179 



advice ;uk1 criticism, and to Prof. F. A. Waugh as well, who 

 has givcu inauj helpful suggestions. The chemical work has 

 been under the direction of Dr. Charles Wellington, and assist- 

 ance in the analytical work has been rendered by Mr. E. L. 

 Winn and Mr. B, Ostrolenk of the senior class in the college. 

 Many experiment station horticulturists and fruit growers in 

 many sections of the country have aided by giving information 

 and by furnishing samples of apples. It is impossible to name 

 them all here, but their many favors are here acknowledged and 

 hearty appreciation extended. 



II. THE CAUSES OP VARIETAL VARIATION. 



The causes of the great differences in apple varieties may be 

 gr()U]:ed under three heads: those arising from (1) cultural 

 conditions, (i^) differences in soil types, (3) differences in 

 climate. 



CuLTUKAL Variations. 



The methods pursued in the growing and in the care of the 

 trees have great influence on the character of the fruit. It is 

 affected in every way, in size, form, color, keeping (piality, ship- 

 jnng quality and dessert quality. These variations have been 

 given only incidental investigation of such ])hases as relate 

 directly to the climatic differences that have been the special 

 object of study. A few of these may, however, be given pass- 

 ing attention at this [xiint. 



Every orchardist growing any number of trees is aware that 

 there are great differences in the individuality of the trees, even 

 when grown in the same orchard and under apparently identical 

 conditions of climate and soil. One tree may be very produc- 

 tive and its neighbor only moderately so. The apples may differ 

 in many of their characters. Further along in this j^aper some 

 data are presented bearing on this question (see page 194). 

 These individual differences have been ascribed to various 

 causes, the principal ones of which are. perhaps, those of bud 

 variations or varietal " strains," and that of the influence of 

 the stock. 



The method of handling the soil has great influence on the 

 fruit, especially Avhether the orchard is in sod or is cultivated. 



