48 THE PLANT. 



power to transform inorganic nutritive substances into 

 organic formative materials. 



It is quite clear that the enlargement of the first leaves 

 and roots and the production of new ones, must have 

 required azotised and unazotised substances in the same 

 proportion as in the seed, which makes it probable that 

 the organic operations of the plant under the dominion of 

 sunhght uniformly produce in all periods of growth the 

 same materials, i. e. the constituent elements of the seed, 

 wliich serve to build up the plant, being formed into 

 leaves, stems, and root-fibres, or finally into seed. The 

 soluble constituents of a bud, a tuber, or the root of a 

 perennial plant, are identical mth the seed constitu- 

 ents. The cereal plant produces azotised and unazotised 

 substances in the same proportion as in the albumen 

 (farinaceous body). The potato plant produces the con- 

 stituents of the tuber, which are formed into leaves and 

 branches or roots ; or, if the external conditions are no 

 longer favourable to the formation of leaves and roots, 

 accumulate again in the underground stem, to form new 

 tubers.* 



While the growth of the plant continues, the first as 

 well as the last leaves and roots, will, with a proper 

 supply of food, maintain their existence, since they repro- 

 duce out of the nutriment supphed to them the identical 

 constituents from which they themselves arose. The 



* Boussiugault lias observed that even seeds weighing two or three 

 milligi-ammes, sown in an absolutely sterile soil, will produce plants 

 in which all the organs are developed, but their weight, after months, 

 does not amount to much more than that of the original seed, even if 

 they vegetate in the open air ; and the result is more marked if they grow 

 in a confined atmosphere. The plants remain delicate, and appear 

 reduced in all dimensions ; they may, however, grow, flower, and even 

 bear seed, which only requires a fertile soil to produce again a plant of 

 the natural size. {' Compt. rend.' t. xliv. p. 940.) 



