EFFECTS OP LIGHT. 267 



dried rootlets, which are of course brittle, and hence 

 easily detached from the grain. After this, the 

 malt is once more spread out and exposed to the air, 

 in order that it may mellow and become soft and 

 mealy. 



696. There are several chemical means by which 

 germination may be accelerated, but in general very 

 little benefit is derived from such processes. Thus, 

 for example, substances which have a strong affinity 

 for hydrogen assist germination, because they tend 

 to decompose water, and set free oxygen. For this 

 reason, solutions containing free chlorine are found 

 to cause seeds to germinate more rapidly than they 

 would otherwise do. 



697; When seeds are sown in the earth, they are 

 placed in a situation where they are protected from 

 the action of light, and exposed to the influence of 

 air and moisture ; and provided they are not too 

 cold, that is, above the freezing point of water, they 

 will germinate and produce plants. Below that tem- 

 perature seeds cannot germinate, because, as has 

 been already said, the action of water is in the first 

 instance to soften the seed, and this it cannot effect 

 when so cold as to assume the solid form itself. If 

 buried too deep in the soil, the free access of air to 

 the seeds will be retarded, or even perhaps wholly 

 prevented, and under these circumstances of course 

 they cannot grow. 



698. The faature of the soil, too, is of considerable 

 importance: very clayey soils allow a less perfect 



