PROCEEDINGS OF THE CHEMICAL DEPARTMENT. 179 



The most remarkable changes which present themselves in 

 this stage are the diminution in the quantity of water contained in 

 the stalks, and the increased amount of albuminous compounds 

 in the leaves. The former is obviously due to the production of 

 woody fibre, as indicated by the increase in the percentage of 

 other organic matters, of which, in the stalks at least, that sub- 

 stance forms the preponderating ingredient, and is required to 

 give them the firmness necessary to support the increased weight 

 of the plant. The steady increase in the albuminous compounds 

 in the leaves is no doubt a store of these substances laid up for 

 the supply of the seed, which is now just beginning to form. 



In the mineral constituents the most striking change is 

 the great increase in the amount of lime in the stalks, and as 

 that substance is generally very abundant in the wood of large 

 trees, it is possible that it accompanies woody fibre, and assists 

 in strengthening the stems of plants generally in the same 

 manner as silica does those of the grasses and cereals. The ash 

 of the leaves does not materially differ from that of the former 

 stages. Most interesting, however, is that of the pods, which is 

 extremely rich in both potash and phosphoric acid, and in their 

 accumulation there we have evidence of a provision being made 

 for the supply of the seed with those elements which form so 

 large a proportion of the mineral matters of all seeds. From the 

 last table, giving the total amount of matters in the acre, this 

 effect becomes very apparent. In the third stage the entire 

 quantity of potash contained in kaves and stalks, &c, was 

 20 - 09 lbs. In the 4th stage it was 22*15 lbs., showing a very 

 small absolute increase. But now the pods contain 9-76 lbs., 

 or nearly half of the whole, and only 12*39 lbs. are left for leaves 

 and stalks together. A similar change has occurred in the dis- 

 tribution of phosphoric acid, there being in the third stage 33 - 09 

 lbs. in stalks and leaves 'ogather ; and in the fourth 40-06 lbs. 

 in all, of which 1 2*82 lbs. are in the ,pods, leaving only 27'24 lbs. 

 for the other parts. 



