342 BOTANICAL GAZETTE [November 



forest of Pinus Miirrayana and Pseudotsuga mucronata at an approxi- 

 mate altitude of 2550"^, with a northwest exposure. At this station 

 three sets of observations were taken on July 13, 25, and August 29. 

 The other station, at which but one set of observations was made on 

 August 29, was in a grove of young pines on a northwest exposure at 

 an approximate altitude of 2520"^. The first of these I shall call 

 Station A, the second Station B. 



Temperatures 



Station A (Observations July 13, 10:50 A. M.; 25, 3:20 p. M.; August 29, 6:45 A. m.) 

 Station B (Observation August 29, 1 140 p. M.) 



Minima 9?6 11° i2?5 i4°5 iS''* 



Maxima 13° i4?5 2&^ 2^.2$ 20^25 



♦Two observations. 



Relative humidity 



Station A (Observations July 25, 3:20 p. M.; August 29, 6:45 p. m.) 

 Station B (Observation August 29, 1:40 p. M.) 



Minima 43 per cent. 45 per cent. 



Maxima 67 per cent. 64 per cent. 



Water content 



Observations 11,25^"* 22.5— ii- 25*=°^ 



Station A July 25 9.8 per cent. 6.9 per cent^ 



August 29 6.7 per cent. 9 • 5 P^r c^^^^. 



Station B August 29 5.3 per cent. 4.2 per cent^ 



(5) THE APINUS FLEXILIS FORMATION 



mountain slopes from 



m 



up to timber-line. In the lower part of its range it is represented by 

 only a few scattering individuals, but above 3000^ it is the dominant 

 pine formation. Here it extensively overlaps the Picea-Abies forma- 

 tion, but I have thought best not to classify it with the latter as 

 Apinus-Picea-Abies formation, because it occupies as a rule higher, 

 drier ground than the firs and spruces, which are found in the canon 

 bottoms as well as on the higher slopes. 



Even in the virgin forest, the trees are separated by comparatively 

 wide intervals, but their spreading tops meeting overhead produce a 

 sufficiently dense shade to exclude all but a few straggling invaders 



mosses 



and Vaccinium microphylhim^ which form 



of the forest floor. This last species forms a loose strasfdinii layer 



!gh mountams 



