80 Forest Club Annual 



to perform an absolute test or when the latter is unnecessary for 

 the result sought. A provisional test is of value when selecting; 

 areas for seed collecting in order to ascertain whether the seed 

 on the area under consideration is of a high enough fertility to 

 warrant the operation. Among the commoner provisional tests 

 may be mentioned the knife test, the heat test and the water test. 



The knife test consists in merely cutting open a number of 

 seeds (one hundred at the very least) and judging from the 

 condition of the kernel whether the seed is fertile or not. A 

 plump kernel usually means a fertile seed, while a shriveled 

 kernel means a worthless one. After the operator has had con- 

 siderable experience in this line, much skill is attained in judging 

 the seeds. The final germination per cent obtained by this test is 

 usually higher than that resulting from an absolute germina- 

 tion test with the same seed. 



For the heat test a sample of seed is placed in a pan which 

 is then heated to a rather high temperature, care being taken 

 not to char or burn the seed coats. Those seeds which break 

 open are judged to be fertile, those remaining closed, worthless. 

 The principle is that of popping corn. This method is best 

 with fresh seed. As to its accuracy and reliability, the writer 

 is unable to give information. 



In the third method mentioned, the water test, the sample of 

 seeds is placed in a bucket or other receptacle containing enough 

 cold water to entirely cover the seeds if they should all sink. 

 They are then thoroughly stirred up in order to completely \vet 

 the seed coats and free them from air bubbles. The seeds that 

 sink are counted as fertile and those that float, worthless. It is 

 impossible to use this method at all with the lighter coniferous 

 seeds, since all will float, and it is altogether unreliable for the 

 heavier seeds. 



Of these three provisional tests, the knife test is the most 

 satisfactory, since it comes closest to the absolute germination 

 test and can be made with the minimum of preparation. 



Absolute germination tests may be subdivided into two 

 classes, paper or cloth tests and soil tests. In the former, the 

 seeds are placed upon moist paper, such as filter paper or blot- 

 ting paper, usually in a moist chamber, Petri dish or some other 

 form of receptacle which permits ready access of light. In the 

 latter, the seeds are sown directly in soil which is moistened by 

 means of surface watering. 



The paper or cloth test is principally used in testing agri- 

 cultural seeds and is also widely used abroad for testing tree 

 seeds. The advantages of this method over the soil test are that 



