140 Our Field and Forest Trees 



days. In autumn or winter, the cells which are 

 in the pith-rays may contain sugar or oil, and they 

 are almost certain to contain countless tiny starch 



grains saved here to be 

 made over into nourish- 

 ing food for growing 

 shoots next spring. 



When wood is cut 

 down in winter, many of 

 its cells are found to be 

 so filled with starch 

 grains that water cannot 



Fig. 33. Cross section of a young paSS thrOUgh it. So 



" winter-hewn lumber," 

 as it is called, is greatly preferred for the staves 

 of barrels which are to hold liquids. " Summer- 

 wood " is much more porous, and the contents of 

 the barrel are liable to evaporate through these 

 pores. 



In April, May, and June the trees are building 

 new substance. Around every trunk, between the 

 wood and the inner bark, there is at this season 

 a sheathing of young cells full of life and ready 

 to make new wood and new bark. These building 

 cells are called cambium. They get to work early 

 in the spring, and after their yearly task is well 

 under way trees can be easily peeled. As old 

 farmers say " the bark will run." 



When we peel a bough we break many cells 

 of the Innermost bark. In winter these cells are 



