78 PLANT LIFE ON THE FARM. 



accumulated for future use. The food is neither made nor 

 elaborated in them, but simply stored, having been formed 

 in the leaves and conveyed to the storehouse. At one 

 time, therefore, the leaver and stem may be full of starch, 

 at another they may be destitute of it, owing to its having 

 been transferred to the seed or the bulb. 



While the origin of the starch is now well known and 

 the processes connected with its formation and transport 

 fairly understood, it is not so with the nitrogenous 

 matters. The nitrogen, as we have seen, enters the plant 

 by the root, and is therefore not directly dependent on 

 light or chlorophyll action. Nitrogenous compounds are 

 not formed in the seed, but conveyed to them just as the 

 starch is. 



The carbonaceous reserve-materials that is, the starch, 

 the sugar, the oil, the colouring matters are all the 

 direct result of the action of the green matter acted on by 

 light; the starch and the sugar are essential requisites 

 for the building up of the cell-membrane, the albuminoid 

 or nitrogen-containing substances being, in their turn, 

 essential to the formation of the protoplasm and of the 

 chlorophyll. 



Germination. The conditions under which germination 

 takes place need not be alluded to at any length, as they 

 are the same as those requisite for growth, and practically 

 every cultivator knows that air (oxygen), moisture, and 

 heat, varying in amount according to the plant and accord- 

 ing to circumstances, are required, and that his success 

 depends in great measure upon the proper tillage of the 

 soil which secures these requisites. When the seed, or 

 rather the embryo plant within it, begins to grow, water is 



