88 BOTANY. 



toadstools, muslirooms, and other large fungi, noting tlie absence of 

 chlorophyll. 



(o) Carefully remove a dodder (Cuscuta) from the plant upon 

 which it is parasitic, and observe the suckers which penetrate the 

 tissues of the host. 



GEOWTH. 



156. Growth of the Cell. — A young cell consists of a 

 nucleus and a solid (continuous) mass of cytoplasm closely 

 invested by a wall. During the nutritive processes de- 

 scribed above the substance of the cytoplasm is increased, 

 and this requires an increase in the area of the wall ; these 

 two increments constitute the simple growth of the cell. 

 Later, the absorption of water and the formation of a large 

 vacuole, with or without an increase in the mass of the 

 protoplasm, may require the increase in the area of the 

 wall; this also is growth of the cell. In its increase in 

 area the wall is first distended by the internal pressure 

 and new matter (cellulose) is secreted upon or in it, thus 

 permanently increasing its area. 



157. Growth of the Plant-body. — In simple plants 

 every cell may grow, producing an aggregate growth of 

 the whole plant-body. As each cell reaches a certain size 

 it divides into two, which then grow, and divide again, 

 and so on. Continued growth thus involves the growth of 

 the cells and their fission, and where the plant-body or the 

 growing member is made up of similar cells growth takes 

 place in all its parts. Where, however, the plant-body is 

 made up of dissimilar cells, involving and implying dis- 

 similarity of function, growth is sooner or later confined 

 to particular masses of cells, occupying definite portions of 

 the plant-body or its organs. In such cases growth is gen- 

 erally confined to the younger cell-masses, but it must be 

 remembered also that some cell-masses have a short 



