374 Journal of Agricultural Research voi. xv, no. 7 



One of the most striking features of this material, normal as well as 

 blighted, is the high potassium content. While Wolff reports spinach 

 as containing 2.729 per cent of potash, calculated on the dry weight of 

 the material, the average percentage found in the normal tops here is 

 5.93 per cent and 4.08 per cent in the blighted tops. The roots seem to 

 contain less than the tops both in health and in disease, but there seems 

 to be more in the diseased than in the healthy roots. 



Sodium, which is present in less quantity than potassium, seems to be 

 more uniformly distributed throughout the plants. Like potassium, it 

 is usually more abundant in the tops than in the roots in both healthy 

 and diseased samples. Sodium is present in less quantity than potassium 

 in the tops, but in some cases this relation is reversed in the roots. 

 Wolff {4g) reports 5.816 per cent of sodium, a quantity, presumably in 

 the tops, about double that seen here in the normal tops. In any case, 

 spinach seems to absorb an unusual quantity of sodium, betraying 

 clearly its halophytic tendencies. 



The sulphate radical here, as in most plants, is rarely absorbed in large 

 quantity. According to Wolff (49), it reaches 1.113 per cent of the dry 

 weight of the plant material. Here the quantity found in the normal 

 tops is less than half of that amount, which in turn is about double that 

 found in the blighted tops. The roots are poorer than the corresponding 

 tops in each individual case. 



Phosphate absorption is not heavy in spinach at the stage in which the 

 disease appears, but seems to be influenced by the blight. In the tops 

 the average normal phosphate content is 1.31 per cent of the dry weight 

 of the plant, against 0.92 per cent in the blighted tops. This relation is 

 completely reversed in the roots, the normal samples coataining 0.98 

 per cent, against 1.32 per cent in the blighted roots. 



These results, which agree fairly well with Wolff's data, place spinach 

 with head lettuce and cauliflower hearts (Brassica oleracea hotrytis) near 

 the top of the list of leafy vegetables in the quantity of phosphates 

 absorbed. 



Aluminium, rarely absorbed in great quantity, is present in spinach in 

 small amounts. The normal and blighted tops contain alike nearly 0.7 

 per cent, calculated on dry weight, while the roots in samples of both 

 kinds agree in containing about 0.18 per cent each. According to Berthelot 

 and Andre (4), the roots of plants usually contain more aluminium than 

 the leaves. 



It is probable that the material here studied is unusually high in alu- 

 minium, since Czapek {12, p. 855) reports that, as a rule, a content of 

 more than 0.5 per cent of the total pure ash is not found. Here the 

 aluminium makes up about 3.3 per cent of the total ash in the normal 

 tops and nearly 4 per cent in the blighted tops. The proportion of 

 aluminium to total ash is less in the roots than in the tops in health and 

 in disease, one case excepted. 



