Periodical Literature. 523 



fluence of light, in which the question of Hght and dull days, 

 artificial and natural light, color of light, intensity and duration 

 are subdivisions; 5. Influence of certain chemicals; 6. Time re- 

 quired and method of stating test results; 7. Amount of inevi- 

 table errors, which section is considerably elaborated on the mathe- 

 matical side. 



Four hundred different experiments with 160,000 grains have 

 given the basis of the following practical conclusions. 



1. A reliable test., always giving the same result, of pine and 

 spruce seed is possible in any season provided that always the 

 same conditions of moisture, temperature and light are given. 



2. The base for the test (filter paper best) must not be too 

 small, at least 50 sq. cm. for 100 grains. This size prevents danger 

 from infection of sound grains by infected ones and avoids the 

 need of changing the paper during the test. 



3. In lower temperatures germination begins considerably later 

 and proceeds much more slowly than in higher temperatures. 

 Otherwise, the same germination per cents, are obtained in either 

 temperature. It is, however, desirable to conduct the test under 

 or near optimum heat when the rapidity of germination is as- 

 sured and no danger from deterioration in high humid tempera- 

 ture is to be feared. This optimum is not the same with rapidly 

 and slowly germinating seeds, nor with germination in the dark 

 or under light. For pine and spruce, a constant temperature of 

 25 °C is most practical. 



If pine (not spruce) seed is exposed to changing high tempera- 

 tures a stimulus advancing germination is exercised; similar to 

 the stimulus of light, but not so vigorous. 



4. In pine seed tests under influence of daylight, the result is 

 sometimes stimulated by the intensity and by the duration of its 

 influence. This influence is not strong, but on short, dull days 

 it must be taken into account. The germination of pine seed 

 is favorably influenced by all rays of the spectrum, least, however, 

 by the short wavy, blue rays. Spruce seed reacts much less to 

 light, and the blue rays are indeed directly harmful. Hence red 

 lights should be used if artificial light is applied. Continuous 

 lighting is not necessary, 8 to 10 hours a day suffices. To be 



