6o v 



Richard H. Bocrker 



so as to make it an ideal soil for germination. Hence we might 

 expect to find the longest germination periods in the sand. The 

 average figures show that this is the case in each group of species. 

 The shortest periods in every case are either in the loam or the 

 gravel because loam is unfavorable from one standpoint and 

 gravel from another. 



In comparing the check cultures of the three groups of species 

 it will be seen that xerophilous species germinate first, xero- 

 mesophilous next, and mesophilous last. In other words the 

 drier the habitat the sooner germination starts, granting that the 

 conditions are favorable. 



TABLE XII 



The Effect of Light and Soil Texture on the Germination of Mesophi- 

 lous Species 



Species 



Light 



Check 

 Culture 



a >> 



ho 



- 



T3 c/l 



.2 > 



P4 M 



Medium 

 Shade 





'V c/j 

 2 >> 



Dense 



Shade 



he rt 



a," 



Soil Texture 



Check 

 Culture 



a >* 



he a 



o >, 



Sand 



C r, 



a! >i 



T3 t. 



Gravel 



C Ui 



he rt 





Pimis taeda 



Catalpa speciosa (Ind.).. . . 



Quercus rubra 



Betula papyrifera 



Pinus lambertiana 



Abies magnified 



Sequoia washingloniana . . . 



Tsuga heterophylla 



Picea sitkensis 



Pseudotsuga taxifolia 

 (Wash.) 



Averages 2 



34 

 18 

 40 



34 

 70 



44 

 16 

 66 



22 



6 



I 

 28 



I 

 36 

 52 

 18 



I 

 6o 



22 28 



35-9 28.6 



34 

 o 

 30 

 34 

 76 

 24 

 16 

 o 

 18 



22 



6 



o 



18 



I 



20 



54 

 6 

 o 



64 



54 



32 

 16 

 26 



34 

 70 

 36 



14 

 o 



14 

 14 



8 



1 

 42 



1 

 24 

 54 

 14 



o 

 36 



62 



3i.7 



27.930.0 



30.1 



34 

 18 

 40 



34 



70 



44 

 16 

 66 

 22 



6 



1 

 28 



1 

 36 

 52 

 18 



1 

 60 



22 28 



28 

 

 38 

 34 

 52 

 96 

 16 



44 

 18 



38 



12 



o 



46 



1 



16 



2 



24 

 42 

 64 



44 



40 

 o 



1 

 



30 54 



34 1 



80 18 



50 48 



22 1 



56 8 



18 64 



36 48 



38.7 



25.5 40.427.940.7 27.0- 



Tables similar to X, XI, and XII were constructed showing the 

 effect of these habitat factors upon the germination per cent, of 

 the species. This table is not given but the most significant facts 

 which it shows are given here and in a later table. It is interesting 

 to note that of the 37 species used in the experiments the highest 



2 Catalpa speciosa and Tsuga heterophylla not included in averages of 

 light cultures. Catalpa speciosa not included in soil-texture averages. 



