Periodical Literature. 183 



Tolerance and intolerance, then, graded from species to species, 

 and reduced volume production with decrease of light, the light — 

 needing reacting more than tolerant to withdrawal of light, are 

 well-established facts. 



To establish more precisely the relation between soil moisture 

 and light requirements a few investigations were made. In a 

 stand of Douglas Fir, 21 years old, three plats of about 7 square 

 feet were planted with 8 or 9 yearlings each of five species be- 

 sides acorns and beech nuts. On two plats, the soil of the plats 

 was isolated by cutting through all roots of the Douglas Fir and 

 placing boards 16 inches deep as sidewalls. After planting and 

 sowing in the spring, all three plats were thoroughly watered, 

 and again one of them only whenever three days without rain 

 occurred, keeping it well watered through the season. 



During July and August of the same year all the plants on all 

 three plats died, the two kinds of pine first, then the spruce and 

 finally the Douglas and Nordmann Firs. 



At the same time two plats, leaving out the watered one, were 

 located and planted similarly in a 21 year old pine stand of 

 normal density, (one-seventh of total daylight) on fresh soil. 

 At the end of June the condition of the plants on both plats was 

 satisfactory, especially of the firs. At the end of September both 

 firs, Scotch Pine and oak were in excellent condition, of spruces 

 4 on each plat had died, of Austrian Pine on the isolated plat all 

 8 were green ; on the non-isolated plat, one had died, that is to 

 say, no difference in the two plats was noticeable. 



In the following spring by the middle of May the firs and the 

 oaks showed excellent condition and remained so through the 

 season. Three spruces were alive on the isolated, 4 on the non- 

 isolated plat, the living plants on both plats showing no difference 

 while the two species of pines looked hopeless, and by the end 

 of September on the isolated plat they were all dead ; in the non- 

 isolated 3 and 4 were still hanging on, but died the next year. 

 Yet the water contents at 8 to 10 inches, after it had not rained 

 for 11 days, was found on the isolated plat as 23.2, on the non- 

 isolated as 16.8 per cent, showing the pumping capacity of the 

 roots. 



The pines then, which are less demanding as regards water 

 supply perished because not receiving enough light, while the 



