THE CELL AND PROTOPLASM. 



6 7 



tissue would readily show itself to be made of 



similar cells. 



In animal tissues the cellular structure is not 



so easily seen, largely because the products made 



by the cells, the formed products, become relatively 



more abundant 

 and the cells 

 themselves not 

 so prominent. 

 But the cellular 



structureisnone 

 the less demon- 



FlG. 12. Plant cells with thick walls, from c traK1^ Tn TTirr 

 a fern. .iraplC. J rig. 



15, for instance, 



will be seen a bit of cartilage where the cells them- 

 selves are rather small, while the material depos- 

 ited between them is abundant. This material 

 between the cells is really to be regarded as 

 an excessively thickened cell wall and has been 

 secreted by 

 the cell sub- 

 stance lying 

 within the 

 cells, so that 

 a bit of car- 

 tilage is really 

 amass of cells 

 with an excep- 

 tionally thick 

 cell wall. At 



"Pip- j(C jc FIG. 13. Section of a potato showing different 



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 



shaped cells, the inner and larger ones being 

 filled with grains of starch. 



