Jan. 6,1919 ^^h Absorption by Spinach 19 



In order to bring out more clearly the relationships involved in Table 

 I, graphs have been prepared in which quantities are indicated on a 

 uniform scale. In figure i appear the values found for the tops, and in 

 figure 2 similar values for the roots. Each unit on the perpendicular 

 axis represents o.i per cent of dry weight in every case. 



TOTAL ASH 



A casual inspection of these results reveals the fact that the total 

 ash content of the tops calculated as percentage of dry weight, while 

 showing considerable variation, is always greatly in excess of that of 

 the roots, in obedience to the general rule.^ As regards the influence 

 of specific substances on the total ash absorption certain coincidences 

 may be noted. The total ash reached its minimum in both roots and 

 stems in the plot treated with potash. It is depressed in the tops nearly 

 as much in the presence of the basic mixture, to a less degree in the 

 roots. In general, the quantity of ash constituents is kss for the roots 

 in the plots treated with sodium salts and in the untreated control than 

 in the other plots. 



Of the single salts calcium carbonate alone goes with a total ash in 

 the roots, approaching that seen in the mixtures of several salts. This 

 depressing action of the sodium salts is not seen in the ash content of 

 the tops. Acid phosphate goes with the highest total ash seen in any 

 sample of roots; sodium chlorid and manure, with the highest totals 

 seen in the tops. 



INDIVIDUAL ASH COXSTITUENTS 



In examining the quantities of the different ash constituents seen in 

 Table I it will be noted that in some cases there is a great variation 

 among the different plots ; in others little difference is to be seen. Those 

 showing great variation are silica, potash, and soda; those showing 

 little change with the change in outside conditions are lime, magnesia, 

 phosphorus pentoxid, sulphur trioxid, manganous oxid, alumina, and 

 ferric oxid. It seems as though all plants were able to absorb these 

 from the soil to a point of steady equilibrium without much regard to 

 the substances offered. It appears that even when an excess of any of 

 the ions present in this latter group of compounds is present no con- 

 siderable increase in the absorption of these ions takes place. 



The quantity of ions absorbed from the group of variable salts seems 

 much more subject to influence from the added salts. In some cases 

 the ions present in excess are themselves absorbed in greater quantity. 

 This seems to be the case with sodium-nitrate and sodium-chlorid plots, 

 in which considerably greater quantities of soda appear in the ash of 

 the tops than in any other plots. Sodium sulphat e, however, gives no 



1 PAiLADiN, W. PFLANZENPHYSiOLOGiE. Bearb. atifgrund der 6. russischen aufl. p. 88. BerUn, ig"- 



