LECT. in RAISING PLANTS, CROPS, AND TREES 43 



all the finest pods of beans and peas, and save only 

 the thin and weak for sowing. By saving the seeds in 

 an unusually fine pod of peas and beans, sowing them, 

 and selecting the best from these again, improved 

 varieties of great value have been established. This 

 is called improvement by selection, and is within the 

 power of any man to elf ect. It is not improvement 

 by fertilisation, which is a more delicate process, but 

 attainable by steady hands guided by thoughtful heads. 



Germination is the first growth of seeds, and is 

 worthy of careful study, because when the process is 

 well understood, and the necessary conditions are 

 comprehended and provided, failures are not likely to 

 occur. The seeds, we have said, must be good. Some 

 are in the best condition the first year, such as peas, 

 beans, carrots, onions, and parsnips, and though older 

 seed may grow, it is not to be trusted. New seeds 

 are not absolutely essential of the cabbage family, 

 including turnips, as fine well-harvested samples re- 

 main good for half a dozen years or more. 



The chief requisites for seed germination are soil- 

 warmth and moisture, with oxygen gas from the air. 

 In the absence of any of these essentials there can be no 

 growth. Some seeds if buried too deeply may have 

 sufficient moisture, but that is of no service if they 

 are sealed from the air ; others may have air in 

 abundance, but if they are too near the surface, or on 

 it, may lack moisture, and therefore remain inert. 

 The amount of heat required varies for different 

 kinds, but some warmth is essential for all. 



Seeds germinate best in the dark, and if small seeds 

 are sown on, not in the soil, and this is constantly 

 moist, and no light reaches them, they grow freely; 

 but they would not do half so well in full light, even 

 if they had warmth and moisture. 



Heat is evolved in the process of germination, as 



