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, 

 Fier a-A email piece of an d structural characters of the plant 



the epidermis of the petal 



of a pansy ( viola tricolor), and all its parts. It is thus the Morplio- 



showing prolongations ol . 7 __ . , . 



the free (upper) sides of the logical Unit OI the plant. 



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



chartre. 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- 



FIG. 96. 



Fie. 9. 



Fitr. 9. A cross-section through the petiole of Nuphar advena ; s. s, star-shaped 

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

 Magnified. After Sachs. 



Fig. 9ft. Stellate cells from the pith of Juncus effusus, magnified. After Du- 

 chartre. 



ant of the physiological activities of its individual cells. 

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



