56 



THE TISSUES OF PLANTS 



tion of cells already existing, which causes growth or the 

 extension of the parts of plants. In this respect precisely, 

 the same laws operate in plants composed of a single row 

 of cells, as when nature works on a more enlarged scale. 

 The most important physiological truths may therefore be 

 learned from vegetation apparently insignificant. " Natura 

 wnwiis 



Fig. 13. 



Branching summit of a fresh water plant, Conferva glomerata, magnified, 

 showing at upper a, the partitions forming by the infolding process, and at 

 lower a, the partitions complete. 



* Linnaeus. 



