GEOWTH 



313 



by permanent change of form. It is the process of passing 

 from the embryonic to the adult condition. We must not 

 assume that every increase of bulk is necessarily growth ; 

 for, as we shall see, in growing cells and members there is 

 a constant stretching of the cell or tissue by hydrostatic 



FIG. 135. PORTION OF SECTION OF STEM OF RUSH, SHOWING STELLATE 

 TISSUE OF THE PITH, WITH LARGE INTERCELLULAR SPACES. 



pressure or turgidity, which can be distinguished from 

 growth by the fact that it can be removed, the result being 

 a certain diminution of the size of the part under consideration. 

 Growth in the lowliest plants may be co-extensive with 

 the plant-body. In all plants of any considerable size, 

 however, it is localised in particular regions, and in them 



