FUNCTION OF AZOTISED MATTER IN PERENNIALS. 47 



substance derived from tlie seed, should so long be able 

 to perform its assigned functions, apparently without suf- 

 fering any alteration ; so that in the body of the living 

 plant, made to produce and collect it, it would seem to 

 possess a kind of indestructibility. 



K we consider, that, in the cited experiment with the 

 French bean, a great part of the additional unazotised 

 substances which were produced fell away in the dying 

 leaves from the body of the plant, it will be seen that the 

 supply of mineral substances was of no use to the bean- 

 plant in the absence of nitrogenous food. 



Lastly, it is quite intelligible that the amount of azo- 

 tised matter contained in a bean might perhaps suffice to 

 sustain for years the vegetation of one of the conifers 

 with persistent leaves, and to produce many liundred — 

 perhaps many thousand — times its own weight of woody 

 substance ; and that such a plant upon a barren soil alto- 

 gether unsuited for other plants, might thrive with a very 

 sparing supply of nitrogenous food, if the soil contained a 

 proper store of those mineral substances which are indis- 

 pensable for the generation of unazotised matter. 



The growth of a plant essentially consists in the en- 

 largement and multiplication of the organs of nutrition, 

 i.e. the leaves and roots. The enlargement of the first, 

 or the production of a second leaf or root fibre, requires 

 the same conditions as the production of the first. The 

 analysis of the seeds teaches us with tolerable certainty 

 what these conditions are. In the normal conditions of 

 nutrition, the fii'st roots and leaves, whose elements were 

 suppHed by the seed, produce from certain mineral sub- 

 stances organic compounds, which become parts and 

 constituents of themselves, or constituents of fresh leaves 

 and roots, consisting of the same elements and having tlie 

 identical properties of the first, i. e. they possess the same 



