THE CELL AND PROTOPLASM. 



85 



seems sometimes to be composed mostly of 

 what we have called formed 

 material. 



It must not be imagined, 

 however, that a very rigid 

 line can be drawn between the 

 cell itself and the material it 

 forms. The formed material 

 is in many cases simply a 

 thickened cell wall, and this 

 we commonly regard as part 

 of the cell. In 

 many cases the 

 formed material is 



tissue are shown at 

 c, and the fibres or 

 formed matter at/. 



, 



CCll Walls 



which the 

 living substance 



has been withdrawn (Fig 14). In 

 other cases the cell substance acquires 

 peculiar functions, so that what seems 

 to be the formed material is really a 

 modified cell body and is still active 

 and alive. Such is the case in the 

 muscle. In other cases the formed 

 material appears to be manufactured 

 within the cell and secreted, as in the 

 case of bone. No sharp lines can be 

 drawn, however, between the various 

 types. But the distinction between A 

 formed material and cell body is nerve fibre - 



-, 11 i showing the 



a convenient one and may well be ceii with its 

 retained in the discussion of cells. nucl eusat. 

 In our discussion of the fundamental vital pro- 



of 



