130 



LECTURE VIII. 



But this table does not only serve to shew that the quan- 

 tity of ash-constituents absorbed is in intimate relation with 

 the metabolic activity of the plant ; it also enables us to form 

 some idea as to the connexion of certain constituents with 

 certain phases of metabolic activity. This will be discussed 

 in the subsequent consideration of ash-constituents in detail. 

 It will suffice for the present to point out that, of the essential 

 ash-constituents, sulphur, phosphorus, and magnesium, are 

 the only elements which continued to increase in quantity in 

 the plant throughout the whole course of the experiment. 



Some valuable information is also to be obtained from a 

 consideration of the distribution of the ash in the plant. 

 Speaking generally we may say that the proportion of ash 

 increases from the root upwards to the leaves, a fact which 

 tends to prove that the leaves are the organs in which the 

 metabolism of the plant more especially takes place. The 

 following table of analyses may be given in illustration. 



Arendt has obtained the following results by a series of analyses of 

 different parts of the Oat-plant : the figures give the percentage of ash in 

 the dry solid of the plant. 



The constituents of the ash exist in the plant partly in 

 solution and partly in the form of insoluble compounds. 

 Hellriegel determined the following percentage in Clover : 



