ILLUSTRATIONS. 



PLATES. 



Page. 



PLATE I. Typical western yellow pine turpentine area in Arizona.. Frontispiece. 

 II. Turpentined face on western yellow pine 8 



III. Fig. 1. Typical western yellow pine turpentine area in Califor- 



nia. Fig. 2. Typical western yellow pine turpentine area in 

 Colorado '. 16 



IV. Mature isolated pinon on turpentine area in Colorado 20 



TEXT FIGURES. 



FIG. 1. Location of experimental areas in Arizona 6 



2. Comparison of flow from north and south faces 14 



3. Relation between temperature and rate of flow of gum 15 



