Reserve Material of Plants. 199 



wood was now made for comparison with that of the diseased 

 wood. The results follow : — 



Wood of Crawford's Early. Restored. Diseased. 



Ferric oxide 0-52 1*45 



Calcium oxide 54-52 64-23 



Magnesium oxide 7*58 10-28 



Phosph eric acid 11-37 8-37 



Potassium oxide 26-01 15-67 



100.00 100.00 



This comparison shows the same deficiency of potash and 

 excess of lime in the diseased, as previously noted, and what is 

 of great significance, that the excess of lime in the one and 

 deficiency of potash in the other, or the decrease of lime in the 

 healthy and the corresponding increase of potash, stand about in 

 the relation of equivalent value. Other analyses fully confirmed 

 these results, and the final conclusions reached were, that, since 

 in the diseased condition there was always an excess of lime and 

 deficiency of potash, and as the relations of these could be changed 

 by conditions of treatment causing increase of potash and de- 

 crease of lime, together with the promotion of a healthy organism, 

 that, so far as chemical data could determine, the disease was 

 caused by, or at least associated with, imperfect nutrition. 



At this stage, it became most important to determine the re- 

 lation of the reserve material to these various changes, and in 

 order to arrive at a clear understanding of this, we must discuss 

 the various external and internal indications of disease. 



Among the external features which characterize the disease 

 in peaches, we must take into consideration the formation of the 

 fruit, the formation of the wood, the color of the bark and the 

 color and size of the foliage. 



The color of the bark is one of the first symptoms to develop. 

 Instead of retaining the natural, reddish hue which all healthy 

 trees possess until well advanced in years, the bark turns dark 

 and has the external appearance of drying up. As the tree be- 

 comes more involved in disease, the foliage begins to show indica- 

 tions of the fact. The normal size of the leaf is from 15 to 18 

 cm. in length. The color is a rich leaf green. The outline is 

 somewhat wavy, but the surface is uniform and not depressed by 

 irregular curlings. As the disease advances, however, the leaves 



