Illustrations 



FIGURE PAGE 



i8 The result of recurring fires 60 



19 A " fire line " in the Uncompahgre National 



Forest, Colorado 60 



20 Section of a tree trunk to show how the 



dates of fires are ascertained from the re- 

 maining surviving trees 64 



21 Arapahoe National Forest, Colorado, forest 



officers ready to leave a tool box to go to 



a fire 68 



22 National forests and drainage of the United 



States 72 



23 " Muskeg " fringing Mitishto river ... 86 



24 Packing across Muskeg Brule 86 



25 An average prairie homestead just after set- 



tlement, near Pense, Saskatchewan ... 90 



26 The same place two years after planting . . 90 



27 Yellow pine cones spread to dry on canvas 



sheets, Uncompahgre National Forest . . 100 



28 Extracting yellow pine seed from the cones . 100 



29 A seedling maple of the natural size, show- 



ing the root hairs ; a bit of the root mag- 

 nified 116 



30 The tip of a root much magnified, showing 



the root hairs and the root cap . . . . 117 



31 A sweet birch, which, when it was a seed, 



fell on stony ground 120 



32 Wood of a spruce showing its cellular 



structure 123 



33 Cross section of a young oak 140 



34 Top of a stump showing the growth rings . 142 



35 The " stock " and " scion " prepared for 



" approach grafting " ; " approach graft- 

 ing " completed 143 



36 Neighbor beeches grafted together by the 



wind 144 



37 Branches of alder and of poplar-leaved birch 



showing lenticels 151 



