82 



THE STORY OF LIFE'S MECHANISM. 



of different shape which, having become dead, 

 have lost their contents and simply remain 

 as dead cell walls. Each was in its earlier 

 history filled with cell substance and contained 



a nucleus. In 

 a similar 

 way any bit 

 of vegetable 

 tissue would 

 readily show 

 itself to be 

 made of simi- 

 lar 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 



FIG. 12 Plant cells with thick walls, 

 from a fern. 



. 13. Section of a potato showing different shaped cells, the 

 inner and larger ones being filled with grains of starch. 



more abundant and the cells themselves not 

 so prominent. But the cellular structure is 

 none the less demonstrable. In Fig. 15, for 

 instance, will be seen a bit of cartilage where 



