124 OUR FAEM CROPS. 



seed, and which is so valuable as an alimentary substance 

 to man, is in itself perfectly insoluble in water, and there- 

 fore would not be in that state available to the plant, 

 as it could not accompany the sap when it begins to cir- 

 culate in the nascent germ. But it is necessary that, 

 immediately vitality commences, a supply of materials 

 should be provided in order to support it : the " diastase/' 

 therefore, is found close to the base of the seed, where 

 the vessels terminate in the farinaceous matter. This 

 acting on the starch, converts it finally into sugar, which 

 in itself is readily soluble in water, and in that state 

 is conditioned at once to circulate through the fine capil- 

 lary vessels of the young plant, and be carried to its 

 extreme points of growth. When this service is per- 

 formed all the starch converted into sugar, and all the 

 sugar assimilated by the plant the functions of this agent 

 (the diastase} cease; and it undergoes itself a change, 

 furnishing to the young plant that supply of nitrogenized 

 food which forms a necessary portion of its structure. By 

 this time the plant, if the produce of a fully developed, 

 healthy parent (seed), has reared its head above the 

 ground, has thrown up a stem with true leaves to collect 

 its organic food from the atmosphere, and is provided with 

 roots sufficient to supply from the soil its future mineral 

 or inorganic wants. 



Now, had the starch originally existed in the state of 

 sugar, this seed would not have been adapted for the 

 purposes for which seeds are intended, the sugar would 

 speedily have entered into fermentation, and the chemical 

 action thus set up would at once have destroyed its vi- 

 tality. With starch although in itself so analogous with, 

 and so readily convertible into, sugar we find a different 

 condition of stability. This remains unchanged for any 

 period of time, and is always in a state ready for the 

 changes which its functions in the germinating seed re- 



