620 FARM ' SEEDS ' : GENERAL 



3. Germijiatioa Capacity. — Purity by itself is not sufficient 

 guarantee of the value of a sample, as the seeds may be all 

 dead or very much weakened. After determining the purity, 

 it is therefore necessary to proceed further with the examina- 

 tion in order to ascertain how many of the seeds are capable 

 of growth. 



Certain external conditions are necessary before the embryo 

 in the seed will begin to manifest signs of active Ufe. These 

 are an adequate supply of water, presence of air, and a suitable 

 temperature. The embryo or young plant inside the seed 

 however must be alive, or growth cannot take place, and it is 

 very necessary to test seeds from this point of view. No amount 

 of experience in the examination of the external characters can 

 decide if seeds are living or dead. As will be pointed out later, 

 the colour, brightness, and similar features of seeds are in certain 

 instances indicative of germinating power, but the only satis- 

 factory method of ascertaining their capability of growth is to 

 actually test the samples by placing them under conditions 

 suitable for germination. 



Before we explain how to carry out this kind of test, it may be 

 useful to mention that poor germination capacity may be due to 

 various causes. When normally produced by the parent, the 

 embryo or young plant in a completely ripened seed is a living 

 structure. It may remain dormant inside the seed for a consider 

 able period and yet be capable of developing into active life 

 when suitable conditions are fulfilled. Nevertheless, embryos 

 gradually die, and the time taken to lose life completely, although 

 a point still in dispute, is, so far as practical purposes are con- 

 cerned, comparatively short Samples of wheat, for instance, are 

 usually found to be completely dead in considerably less than 

 ten years, the number of seeds capable of germination when 

 kept even three years, is very small compared with the first 

 season after harvesting the crop. Age, therefore, is productive 

 of weak germination capacity, and old seed should always be 



