BOTANY. 



organism ; it absorbs nourishment, assimilates, grows, and 

 reproduces its kind. In the higher plants, although this 

 independence is not so evident, it still 

 exists in a considerable degree. Here 

 each cell is an individual in a commu- 

 nity ; but it still has a life-history of its 

 own, a formation (genesis), growth, ma- 

 turity, and death. It is the unit in the 

 plant. Upon its changes in size, form, 

 and structure depend the volume, shape, 

 etai and structural characters of the plant 



thefree"(upper) sides of the logical Unit of the plant. 



cells. Mag. After Du- A , , , , . , 



ehartre. 22. As the whole structure of the 



plant is an aggregation of cells, so the functions of the 

 whole, or of any part of a plant are but the sum or result- 



Pie. 9. 



Fit;. 0. A cross-section through the petiole of Nuphar advena ; s, , star-shaped 

 cells projecting into the intercellular spaces i, i ; g. a reduced fibro-vascular bundle. 

 Magnified. After Sachs. 



Fig. 96. Stellate cells from the pith of Jiincun e/uKus, magnified. After Du- 

 chartre. 



ant of the physiological activities of its individual cells. 

 The cell is thus also the Physiological Unit of the plant. 



