390 



Journal of Agricultural Research 



Vol. XV. No. 7 



When the two parts of the table are compared, it is readily seen that 

 the healthy spinach samples, without exception, show a higher moisture 

 content than the corresponding diseased samples. This is true not only 

 of the entire plant, but of the leaves and roots as well. In other words, 

 the spinach disease, physiologically characterized by a pronounced 

 retardation of growth, is characterized chemically by a lower moisture 

 content of its tissues. These data stand in full agreement with 

 observations on certain animal tissues in disease and health. The water 

 percentage of mouse carcinomata has been found by Cramer {ii) to 

 correspond with their rate of growth, the more rapidly growing tissues 

 of the cancer showing a higher water content than the normal tissue, and 

 vice versa. Evidently the rapidly growing plant cells like those of the 

 cancer build up tissues with a comparatively high water content. 



SPINACH NITROGEN 



Since the main object was to ascertain the difference in quality and 

 quantity of the nitrogenous compounds occurring in healthy spinach, on 

 the one hand, and in diseased spinach, on the other, a number of nitrogen 

 estimations were made according to the Gunning modification of 

 Kjeldahl's method. As the moisture content of the spinach materials 

 was not uniformly maintained it was necessary, in addition to nitrogen, 

 also to run moisture estimations. The data which are recorded in Table 

 III represent as a rule the average of two or more individual analyses. 



Table III. — Nitrogen content of healthy and diseased spinach 



HEALTHY SPINACH 



DISEASED SPINACH 



Dec. I, 1915, 

 and Jan. 21, 

 1916. 

 do 



May 6,1916 



do 



Entire 

 plant. 



Feb. 14-1S, 

 3-59- 



Feb. 14-15, 



4-21. 

 May 13-15, 

 I 3-07. 

 Roots May 15, 2.74 



Leaves 

 ..do... 



Feb. 17,3.66 

 Feb. 19,4-13 



Mar. IS, 3.57 Mar. 16, 3.57 Mar. 17, 3.53 



I I 



Mar. 16, 4.31 Mar. 17,4.31 Mar. 29,4.22 



The examination of Table III (first part) reveals the fact that in the 

 healthy plant the leaves have the highest and the roots the lowest nitro- 

 gen content, the figures for the entire plant lying between these two 

 values. Likewise, by referring to Table III (second section) it may be 



