22 



very rich iu potassium salts will absorb almost uo soda. The amount 

 of potassa annually required per hectare of pine forest is about 7.5 

 kilos, of wheat iield 37.5 kilos, of clover field 102 kilos, and of potato 

 field 125 kilos. Other things being equal, an increase of potassa will 

 increase to a certain degree the i)ercentage of carbohydrates, and 

 further, potassa is reported to be present in larger proportions iu those 

 l^arts in which the carbohydrates are transported, as in the parenchyma 

 of the bark and pith. 



Secondary potassium phosphate possibly forms loose combinations 

 with proteins more easily than does sodium phosphate, since an increase 

 of potassium phosphate is generally accompanied by an increase of 

 proteins, as in the seeds. Pollen .grains also seem to be rich in this salt; 

 at least Eamann found that of the ash in the pine pollen 50.74 per cent 

 was i)otassa and 30.08 per cent phosphoric acid. Seeds always contain 

 much more potassium phosphate than sodium phosphate, while on the 

 other hand the proportion of soda to potassa in form of other salts 

 than j)hosphates is often found to be larger in the leaves and roots.^ 



The following table shows the composition of seeds of Gramineae and 

 Leguminosfe, the latter containing, as is known, relatively more protein 

 than the former : 



Analysis of the seeds of Graminece and Leguminosce.* 



* These figures Vere taken from E. Wolff's Aschen Analysen, Vol. I. 



Calculating from the above data the amount of soda and potassa for 

 1,000 parts of dry organic matter, the seeds of Graminete contain 0.48 

 part soda and 5.67 parts potassa, while those of Leguminosjc contain 

 0.70 part soda and 12.66 parts potassa. It is seen, therefore, that there 



' In some cases the amount of soda found in the leaves exceeds even that of potassa. 

 Wolff's tables give for the leaf of Daucus carota a total ash content of 13.53 per cent 

 for the dry matter, and for 100 parts of this ash 19.83 parts soda, but only 11.26 parts 

 of potassa. The occasionally rather large soda content in tlie leaves is due to the 

 current of transpiration, containing .sodium salts among other things. 



