893 



JOURNAL OF FORESTRY 



93 cubic feet. These computations were based on stands of second 

 growth near Nevada City between elevations of 2,000 and 4,500 feet 

 in the optimum region for Pinus ponderosa. 



The crown classes in the above bishop pine stand were divided 

 as follows : 



SEED EXTRACTION AND GERMINATION 



The bishop pine, being of the "closed cone" group of pines, retains 

 a large proportion of its seed for several years after maturity. The 

 following figures are the result of experiments on two lots of bishop 

 pine cones collected in the winter of 1916. The first lot came from 

 the large trees at Lufifenholz Creek, Humboldt County; the second 

 lot from a dense young stand 15 to 20 years old on an old burn in 

 the Del Monte Forest at Pacific Grove, Monterey County. As the 

 bishop pine frequently produces two and sometimes three whorls of 

 cones in a season, it is a difficult matter to determine the exact length 

 of time the cones have been held on the tree. With all of the Hum- 

 boldt cones ring counts were made on a section of the branch imme- 

 diately adjacent to each whorl of cones. While a few errors may 

 result from this method of procedure due to the presence of false 

 annual rings, it is believed that these have been reduced to a minimum. 

 Owing to lack of time it was not possible to use this method of age 

 determination with the cones from Pacific Grove so that these figures 

 cannot be considered so accurate, but are interesting for comparison. 



The oven used for extraction was of sheet iron set on a heavy iron 

 plate over a gas flame. In order to insure the necessary circulation 

 of air, the door was left slightly ajar which caused slight fluctuations 

 in the temperature. It was found that heating for long periods at 

 temperatures from 110 to 125° F. had very little effect and that 

 shorter periods, at temperatures of 160 to 170° F. produced more 

 satisfactory results. During at least one of the heating periods, the 

 temperature rose to slightly over 200° F. which, however, seemed 



