Nov. i, 1920 Composition of Normal and Mottled Citrus Leaves 1 67 



Throughout this work we have determined the aluminum. Quali- 

 tative tests usually indicated this element to be present, but the quantity- 

 was never more than a few tenths of 1 per cent of the ash. Frequently 

 the amount was undeterminable. The manganese was also determined in 

 several samples. The amount was found to vary from 0.1 per cent to 

 0.2 per cent of the ash. 



The size of the leaves as gauged by their average weights was recorded, 

 but there appears to be no consistent difference in composition referable 

 to the size of the leaf. As is well known, the size of apparently normal 

 orange leaves may vary widely. Even on a given tree, the fully mature 

 leaves of certain cycles of growth may be at least twice as large as others. 



From the analysis of many other samples in this laboratory it may be 

 said that the composition of mature orange leaves when grown in Cali- 

 fornia is remarkably uniform, provided, however, that the leaves be 

 borne on vigorous trees. On the other hand, the composition of the leaves 

 of improperly nourished and diseased trees may vary widely. If the 

 supply of available nitrate be deficient, the content of nitrogen in the 

 leaves may be considerably below that reported above, but there seems 

 to be some doubt whether the reverse is true. 



COMPOSITION OF LEMON AND GRAPEFRUIT LEAVES 



The analysis of mature Eureka lemon and Marsh seedless grapefruit 

 leaves is submitted in Tables TTI and IV. 



Two of the samples of lemon leaves were collected in midwinter and 

 the other on August 29. They were grown on widely different types 

 of soil. The Riverside sample grew on sandy loam, the Whittier sample 

 on heavy adobe, and the Tustin sample on highly calcareous sandy loam 

 soil. The grapefruit leaves were grown on sandy loam. 



The composition of the different samples of lemon leaves is fairly 

 uniform, the average being similar to the average composition of Valencia 

 orange leaves. On the other hand, the composition of the grapefruit 

 leaves closely resembles that of Navel orange leaves. 



The composition of the leaves of the different varieties and species of 

 citrus has been found to be remarkably uniform from the standpoint of 

 both the ash and the dry matter. A more detailed discussion of the 

 composition will be given below. 



