36 



Richard H. Boerker 



degree of light, namely, the number of days which elapsed before 

 germination began, the number of days in the germination period, 

 and lastly the final germination per cent. 



The number of seeds used of each species in each culture made 

 was as follows : ioo seeds each of Catalpa speciosa, Acer rubrum, 

 Gleditschia triacanthos, Pinus taeda, Pinus ponderosa (Idaho), 

 Abies grandis, Abies lasiocarpa, Pinus ponderosa (Mon.), Pinus 

 ponderosa (Harney), Pinus ponderosa (Calif.), Pinus jeffreyi, 

 Pinus lambertiana, Pinus coulteri, Abies magnified, and Pseu- 

 dotsugd tdxifolid (Wash.) ; 25 seeds of Quercus rubra, 400 of 

 Betuld papyrifera, and 200 seeds of all other species. 



When a number of check cultures were combined as was noted 

 previously it became necessary to average the results obtained in 

 several cultures under the same set of conditions. Thus the check 

 cultures used in each series show the same data in every case. 

 Three cultures of each of the following species were averaged 

 together: Catalpa speciosa (Ind.), Pinus strobus, Quercus rubra, 

 Pinus divaricata, Robinia pseudacacia, Betuld pdpyrifera, Pinus 

 ponderosd (S. D.), Pseudotsuga taxifolia (N. M.), Pinus pon- 

 derosa (N. M.), and Pinus ponderosa (Calif.). Two cultures of 

 each of the following species were averaged together: Pinus 

 palustris, Pinus resinosa, Pinus jeffreyi, Pinus lambertiana. and 

 Pinus coulteri. All other species in the check cultures were 

 planted but once. 



In Table I 10 species out of a total of 14 germinated in the 

 dense shade before they did in the open light culture. Only 

 one species, Pinus palustris, germinated first in the open light, 

 one species, Gleditschia triacanthos, did not germinate in the open 

 light at all, and two species germinated simultaneously in all three 

 cultures. Pinus strobus germinated 8 days earlier in the dense 

 shade than in the open light, Pinus divdriedtd 2 to 4 days, Pinus 

 resinosa 10 days, Pinus tdedd 2 days, Cdtalpd speciosd 2 days, 

 Quercus rubra 14 days, Robinid pseuddedcid 2 days, and Acer 

 rubrum 4 days. 



In 9 cases the germination period is longer in the dense shade 

 than in the open light and, considering the shade cultures together, 



