GBEMIKATION. 363 



in the free state. Free nitrogen appears in considerable 

 amount (Schulz, Jour, fur Prakt. Ghem., 87, p. 163), 

 while very minute quantities of Hydrogen and of Nitro- 

 gen combine to gaseous ammonia (NHj). 



Heat developed in Germination. — These chemical 

 changes, like all processes of oxidation, are accompanied 

 with the production of heat. The elevation of temper- ' 

 ature may be imperceptible in the germination of a sin- 

 gle seed, but the heaps of sprouting grain seen in the 

 malt-house, warm so rapidly and to such an extent that 

 much care is requisite to regulate the process ; otherwise 

 the malt is damaged by over-heating. 



3. The Transfer of the Nutriment of the Seed- 

 ling from the cotyledons or endosperm where it has un- 

 dergone solution, takes place through the medium of the 

 water which the seed absorbs so largely at first. This 

 water fills the cells of the seed, and, dissolving their con- 

 tents, carries them into the young plant as rapidly as 

 they are required. The path of their transfer lies through 

 the point where the embryo is attached to the cotyle- 

 dons ; thence they are distributed at first chiefly down- 

 wards into the extending radicles, after a little while 

 both downwards and upwards toward the extremities of 

 the seedling. 



Sachs has observed that the carbhydrates (sugar and 

 dextrin) occupy the cellular tissue of tlie rind and pith, 

 which are penetrated by nuiaerons air-passages ; while 

 at first the albuminoids chiefly diffuse themselves through 

 the intermediate cambial tissue, which is destitute of 

 air-passages, and are present in largest relative quantity 

 at the extreme ends of the rootlets and of the plumule. 



In another chapter we shall notice at length the phe- 

 nomena and physical laws which govern the diffusion of 

 liquids into each other and through membranes similar 

 to those which constitute the walls of the cells of plants, 

 and there shall be able to gather some idea of the causes 



