THE CELL AND PROTOPLASM. 



83 



the cells themselves are rather small, while the 



material deposited between them is abundant. 



This material be- 

 tween the cells is 

 really to be re- 

 garded as an ex- 

 cessively thick- 

 ened cell wall and 

 has been secreted 

 by the cell sub- 

 stance lying with- 

 in the cells, so 

 that a bit of car- 

 tilage is really a 

 mass of cells with 

 an exceptionally 

 thick cell wall. 

 At Fig. 16 is 

 shown a little 



blood. Here the cells are to be seen floating 



in a liquid. The liquid 



is colourless and it is the 



red colour in the blood 



cells which gives the 



blood its red colour. 



The liquid may here 



again be regarded as 



material produced by 



cells. At Fig. 17 is a 



bit of bone showing small 



irregular cells embedded 



within a large mass of 



material which has been FIG. IS.-A bit of cartilage. 



deposited by the cell. In this case the formed 



FIG. 14. Various shaped wood cells 

 from plant tissue. 



