694 JOURNAL OF FORESTRY 



Table 2. — Per Cent per Day of Most Rapid Germination 



Tests in Jacob- Tests in Basis for com- 



Species. ggjj germinator. sand. parison, days. 



Larix occidentalis 91 3-i 2 



Pseudotsuga taxifolia 7-9 ^-7 2 



Pinus ponderosa 3-9 3-5 2 



Pinus monticola 2.0 1.2 2 



Pinus strobus 2.0 0.8 2 



Pinus contorta 18.0 I4-0 3 



Thuja plicata.... 15-8 7-0 3 



Picea engelmanni 170 11. 6 3 



Tsuga heterophylla 5-3 6.5 3 



Average 9-0 5-7 



Table 3. — Days Required for Complete Germination 



Tests in Jacob- Tests in 



Species. ggjj grerminator. sand. 



Larix occidentalis 25 40+ 



Pseudotsuga taxifolia 25 40+ 



Pinus ponderosa 30 60 



Pinus monticola (a) 200 



Pinus strobus (a) 200 



Pinus contorta 20 20 



Thuja pHcata 15 25 



Picea engelmanni 15 25 



Tsuga heterophylla 25 25 



(a) Not completed. 



A comparison of the results by the two methods was made on the 

 basis of (i) the total germination per cents attained when the tests in 

 the germinator were practically complete ; (2) the highest rates attained 

 during the periods of the most rapid germination, and (3) the time 

 germination began. (The terms "germinating force" and "germinating 

 energy" are avoided because their meaning is not always clear.) Briefly 

 stated, all of the nine species tested gave a much higher germination 

 per cent by the Jacobsen method, and all except tsuga showed a greater 

 maximum rate and earlier beginning. This difference is most strikingly 

 brought out in the case of larix, picea, and pinus ponderosa, which 

 more than doubled their counts in the germinator. 



The results prove that the Jacobsen germinator is more suitable than 

 sand for scientific work and for ordinary seed testing. More uniform 

 results are secured and the method can readily be duplicated and stand- 

 ardized. The light, heat, and moisture conditions may more readily be 

 controlled and measured than is possible wath sand tests, and the condi- 

 tion of the seed may readily be observed at any time and seed may be 

 removed at will for the purpose of physiological study. This method 

 possesses great economic advantages which are worthy of consideration 



