198 Reserve Material of Plants. 



several years past, been endeavoring to determine the possible 

 existence of similar conditions in plants growing tinder ordinary 

 influences, and their relation to specific diseases. The results of 

 our examinations show most conclusively, that in certain diseases, 

 e.g., peach yellows, we have to deal with essentially the same 

 histological characteristics as were artificially produced by Nobbe 

 and Schroeder in the case of buckwheat, and not only that, 

 but that the disease can be produced and cured at will. 



In order to understand this, it will be necessary to deal with 

 the experiments in both their chemical and botanical aspects. 



In dealing with the chemical changes involved, it was deemed 

 essential, first of all, to determine what mineral constituents 

 normally enter into the composition of both fruit and wood in 

 its healthy condition, and to compare these quantitatively with 

 the constituents found in the ash of corresponding structures in 

 a state of disease. The analyses obtained were as follows : — 



Fruit of Crawford's Early. Healthy. Diseased. 



Ferric oxide 0-58 0.46 



Calcium oxide 2.64 4-68 



Magnesium oxide 6*29 5-49 



Phospheric acid 16*02 18-07 



Potassium oxide 74-46 71-30 



100-00 100-00 



These results at once made it clear that in the diseased, as 

 compared with the healthy, the ash contains more phospheric 

 acid and lime, and less potash. Previous examinations and ex- 

 periments with strawberries and grapes had already demonstrated 

 the superior importance of potash in improving the qualities of 

 these fruits, and the inferior value of lime, and it seemed possible 

 that similar results might be obtained here in the case of the 

 peach. Analyses were, therefore, made of the diseased wood, and 

 acting upon the theory that potash and chlorine were probably the 

 two elements most needed, a number of diseased trees were treated 

 with muriate of potash. After the lapse of a few years, they 

 lost all appearance of disease, and were restored to such a con- 

 dition of health that, up to the present time, they have been 

 most profitable in their production of fruit. An analysis of the 



