MOISTURE IN SEEDS. 



265 



may be better said to be the potential energy inherent in 

 many chemical substances. The treasured energy in the 

 seed represents the sunlight of the summer in which the seed 

 ripened : it is a potential energy, which becomes actual 

 during germination. For its release, it requires moisture, 

 oxygen, and a definite temperature : when these conditions 

 conspire, changes take place in the chemical composition, 

 the microscopical characters, and the form of the embryo. 

 Moisture is absorbed, oxygen also is taken in, and carbon- 

 dioxide is evolved, the solid food is gradually changed into a 

 liquid form in which it can be used, new cells are constructed, 

 and new pai;ts are built up. The germ is so far extricated 

 that it can develop into a plantlet with green leaves, and, 

 when their activity is established so that the plant can trans- 

 form inorganic matters into organized substance, the period 

 of germination is iinished. The elementary facts just pre- 

 sented constitute an introduction to the recent researches 

 relative to seeds and their germination. 



1. The Absorption of Water hy Seeds. 



The amount absorbed before germination begins varies in 

 different seeds, as the following table shows. The first 

 column is by Hoffmann,^ the second is from Nobbe.^ 



The seeds of leguminous plants absorb a much larger 

 amount of water than do the cereals. F. Tschaplowitz ' 

 ascertained the amount of water absorbed by different seeds 

 (of pease, barley, wheat, and rye) before their germination 

 to be much greater in the case of the small than the large 



^ Hoffmann, Landwirths. Vers.-Stationen VII. 47. 



2 Sameukunde, 119. 



3 Wassergehalt und Quellimgswasser einiger Samen, — Landwirth. Ver- 

 suchs-Stat. 187(3, 412.- 



34 



