36 THE STORY OF PLANT LIFE 



of the cotyledons and the plumule, the elongation of 

 the hypocotyl or the epicotyl as the seedling gradually 

 merges into a green plant independent of the reserves 

 stored up in the seed, all these constitute phases in 

 the plant's life-history. 



Unfortunately the study of the plant in this stage 

 has been somewhat restricted to the physiological 

 side of germination. There are, however, in addition 

 to this aspect, which must not be omitted, of course, 

 others. It is only possible to indicate in a summary 

 some of these, and this applies to all the other parts 

 of the introduction. 



The writer merely wishes to indicate the main 

 points or processes involved, without describing 

 them at this stage in detail. It has been his aim 

 rather to indicate the place of each process, etc., in 

 the whole study of botany, and the relative import- 

 ance of each or their bearing upon the others. 



In regard to seeds and germination, then, apart 

 from the actual process, there are questions of 

 interest, such as the necessary conditions for 

 germination, the soil-characters, water content, 

 density, etc. When a seed is dispersed to a distance 

 it is trying an experiment, as it were, in germinating 

 in its particular station. Some conditions might 

 suit it better than others. The length of time 

 required in germination, the period of germination, 

 the character of the cotyledons, their length of per- 

 sistence and characters are points worthy of study 

 in this connection. The amount of heat required 



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