76 Forest Club Annual 



abscissa and the clays as the ordinate. In time it may be possible 

 to establish empirical tables for natural regions based on the 

 number of days required for seeds of a certain practical germina- 

 tion and final germination to reach the culmination point in the 

 daily germination curve, that is, the day on which the greatest 

 number of seeds germinate. Then all seeds tested could be re- 

 ferred directly to these tables to determine whether the seed 

 was above or below average quality and in this way the value of 

 any seed could be determined accurately and readily. 



FACTORS INFLUENCING GERMINATION. 



A certain amount of light is required to secure the best 

 germination of coniferous seeds. Haack* found that for pine 



*Haack: Keimung und Bewertung des Kiefernsamens. Zeitschrift fur 

 Forst und Jagdwesen, 38:449. 



seeds the final germination as well as the practical germination 

 was lower in darkness than in light. The same investigator also 

 found** for pine and spruce seeds that it sufficed to germinate 



**Haack: Die Priifung des Kiefernsamens. (Zeitschrift fur Forst und 

 Jagdwesen 44:193-222, 273-307). Abstract in Experiment Station Record 

 27:243. 



the seed in light for a period of from 8 to 10 hours daily and that 

 the best intensity of light was one which would allow comfortable 

 reading. There was little difference in the results whether the 

 experiment was carried on in daylight or in artificial light. He 

 states that the seeds should not be exposed to the direct rays of 

 the sun. The tests were carried on in a filter paper apparatus. 



For soil tests the ordinary light in a greenhouse is entirely 

 satisfactory during the winter months, but when the sun's rays 

 become more intense in the spring and summer the greenhouse 

 glass should be whitewashed. 



It has been well proved that variation of temperature within 

 each twenty-four hour period materially aids germination. This 

 variation, of course, must not exceed certain limits, since either 

 too high or too low a temperature will absolutely preclude 

 germination. Haack***, using a filter paper apparatus, found that 



***Haack: Keimung und Bewertung des KiefVrnsamens. Zeitscliri ft I'iir 

 Forst und .Jagdwesen, 38:458. 



germination of pine seeds was retarded if the temperature fell 

 below 20 degrees C. (68 degrees F.) and that the germinating 



