47 



in time, as indicated by some of the results of the past year. There 

 is some evidence, however, that certain of these negatives really in- 

 dicate a toxic action that is manifested only under certain condi- 

 tions, but we have not yet carried this far enough for definite state- 

 ments. 



The important advantage shown by manure, especially in Table 

 VI, is doubtless largely due to the very full crops on the manure 

 plots of those experiments during the past year, which was rather 

 of an off year for the similar plots receiving complete fertilizer. 

 The better moisture-conservation under the manure and the larger 

 amounts of plant food carried in it also probably account for a part 

 of the superiority. In general, however, we do not find any im- 

 portant superiority in manure over a proper commercial fertilizer, 

 neither in actual nor net increases. Alanure is undoubtedly a safe 

 and valuable material to apply in orchards, when it can be satis- 

 factorily obtained in sufficient amounts. But with very few ex- 

 ceptions, thus far in our experiments as a whole, wherever manure 

 has given important increases, these increases have been approached 

 or surpassed by a proper commercial fertilizer. 



Correlation Between Yield and Grov^th. 



In regard to growth, it will be observed that, in general, the 

 improvements in it have accompanied those in yield. The same 

 materials that have improved the one have generally improved the 

 other. In other words, as a rule, our best growing plots have been 

 our best fruiting plots. Contrary to a prevalent notion, therefore, 

 we may say that growth and fruiting are not necessarily antagonis- 

 tic, but rather are associated, unless either should occur in abnormal 

 amount. 



Data and Deductions on Color. 



In regard to color, it will be observed in Tables V and VI that 

 none of the applications have given any important increases, and 

 most of them have given decreases. Similar results have also been 

 uniformly obtained elsewhere, so far as we have received the re- 

 ports. The same is essentially true of applications of iron salts. 

 From these and other considerations, therefore, we believe that color 

 in apples cannot be materially improved by soil applications, and 

 that it is primariily dependent on maturity and sunlight. 



This refers only to the red colors in apples. The yellow colors 

 can probably not be affected by any external agency. Physiologi- 

 cally, the yellow color is connected with certain bodies located in 

 rhe superficial layers of cells in the apple skin. It develops inde- 

 pendent of light, and its intensity depends merely upon the degree 

 of maturity or ripeness. The red color, on the other hand, is a 

 constituent of the cell sap; it is capable of being influenced by a 

 number of agencies; and its intensity is dependent primarily upon 

 the amount of light received during the latter stages of maturity. 

 In other words, we get back to its dependence upon maturity and 

 sunlight. Conditions increasing one or both of these factors, such 



