1 6 Richard II. Boerkcr 



Practically all the accumulated foods in the endosperm must 

 be transformed by the action of enzymes, which in turn must 

 first be dissolved by water. Starch, which is insoluble in water, 

 is converted by means of the enzyme diastase into a soluble sugar. 

 Throughout germination the quantity of starch in the seed de- 

 creases ; the starch grains at first corrode and finally dissolve 

 completely. Many albuminoids (simple proteins) are likewise 

 insoluble in water and certain soluble albumens cannot diffuse 

 through membranes. A pepsin-like enzyme which develops dur- 

 ing germination acts upon the albuminoids, transforming them 

 into soluble and diffusible forms. Others are changed to crystal- 

 loids which after solution diffuse very readily. Fats and oils are 

 likewise insoluble. Certain enzymes during germination decom- 

 pose oil into its constituents, fatty acids and glycerin, the latter 

 easily soluble in water. It is well known that fatty acids when 

 set free assist the breaking up of oil in water into very fine drops 

 with the formation of an emulsion. 



Heat is important in the germination of the seed in that it may 

 accelerate, retard, or even entirely stagnate the processes begun 

 by the action of water. It might well be said that the rapidity of 

 germination depends to a large extent upon heat, since it has the 

 power to modify the action of enzymes. Temperature likewise 

 affects the diffusion of liquids. A considerable part of the heat 

 used in germination is generated by respiration. This process 

 sometimes raises the temperature of the seed as much as 40-50° 

 F. above the surrounding temperature. Certain seeds owe their 

 ability to germinate at very low temperatures (below freezing) 

 to the heat generated during respiration. Certain arctic and 

 alpine plants are able to blossom in the snow for this same reason. 



Seeds in water, seeds buried too deep, or seeds surrounded by 

 air deprived of oxygen do not germinate even if other conditions 

 are' favorable. In other words, water and heat are of little avail 

 without oxygen. Even before water and heat can act through 

 the agency of the enzymes, in many cases another factor must 

 come into play to release the enzymes. The latest investigations 

 show that the formation of diastase is intimately connected with 

 respiration. In a similar manner respiration supplies the energy 



