12 VEGETABLE PHYSIOLOGY 



direction of the divisions we get filaments (fig. 13), plates 

 (fig. 14), or masses of cells, the latter undergoing much 

 subsequent differentiation according to their ultimate 

 dimensions and the nature of their habitat or environment. 



FIG. 13. FILAMENTS OF Nottoc. 

 (After Luerssen.) 



FIG. 14. Fed aslrum, CONSIST- 

 ING OF A PLATE OF CELLS. 



The protoplasm being the living substance of the plant 

 is possessed of certain properties which are not shared by 

 the framework on which it rests. It is, indeed, the centre 

 of all the activities which the plant manifests. It assimi- 

 lates the food which the plant requires and carries out all 



FIG. 15. VEGETABLE CELLS. 



A, very young ; B, a little older, showing commencing formation of vacuole. 

 p, protoplasm ; n, nucleus ; v, a vacuole. 



the chemical processes necessary for life. It constructs 

 the framework of the plant by which it is itself supported. 

 It receives impressions from without, and regulates the 

 responses which the plant as a whole makes to those im- 

 pressions, both by internal and external movements or 

 changes of position, and by modification of its metabolism. 



