38 THE PLANT. 



various stages of growth, we observe the greatest dis- 

 parities. In the second stage, a quantity of potash, 

 amounting in the. aggregate to 49 -29 pounds, was ab- 

 sorbed in 35 days ; and of this, the roots were found to 

 contain 8 '02 pounds, equal to one-sixth the leaves 

 41*27 pounds, equal to five-sixths. The same propor- 

 tion namely, about five to one was found to exist 

 between the weight of the leaves produced, and that of 

 the roots. 



In the third stage, the weight of the roots produced 

 exceeded that of tire leaves ; and of the 80 pounds of 

 potash absorbed by the plants, 34 pounds, or more than 

 one-third, remained in the roots. The same was found 

 to be the case with phosphoric acid, and the other 

 mineral constituents ; that is to say, they were found 

 distributed in varying proportions, corresponding to the 

 growth and increase of the mass of the overground and 

 underground organs of the turnip plants, which, in the 

 various stages, are likewise not uniform. 



If we regard the mere increase of the leaves and 

 roots in mineral substances, without reference to the 

 total amount of them absorbed by the entire plant, it 

 appears to be most irregular, and to proceed by ' fits 

 and starts.' The plant receives every day nearly the 

 same quantity of phosphoric acid, nitrogen, salt, and 

 sulphuric acid, which are distributed in the several 

 parts of the plant, leaves, or roots, where they are re- 

 quired for use. The chief difference observable is in 

 the increase of potash, which in the third stage is out 

 of all proportion greater than that of the other mineral 

 constituents. 



It is highly probable that from the raw material 

 i. e. the carbonic acid, water, ammonia, phosphoric acid, 

 sulphuric acid, with the cooperation of the alkalis, 

 earths, &c. the chemical process engenders in. the 

 plant simply a nitrogenous and sulphureous substance, 

 belonging to the albumen group, and only one non- 

 nitrogenous substance, belonging to the group of hydro- 

 carbons. The former retains its character during 

 the period of vegetation; while the non-nitrogenous 



