Where the Tree Is Alive 



This section of the trunk of a small tree is pictured in 



such a way as to expose the Cambium layer, just beneath the 



outer bark. In this layer are located all the protoplasmic cells, aside 



from those in the leaves, that are really alive. A portion of the 



woody tissue just beneath the Cambium conveys the watery solution 



upward from the roots; but the return flow of sugary sap takes place 



solely in the Cambium layer, where also the protoplasmic or life 



activities go on, through which the tree grows; growth itself 



being due to the deposit of what is virtually waste 



material from the cell. The central wood 



fibers of the trunk are totally dead. 



