56 



HOW CEOPS GROW. 



Fig. 10 representa an extremely thin slice from the stem of a cabbage, 

 magnifled 330 diameters. The iiuited w;ills of two cells are seen in sec- 

 tion at a, while at 6 an empty space is noticed. 



Fig. 10. 



The outer coating, or wall, of the cell is cellulose. This 

 substance is accordingly the skeleton or framework of the 

 plant, and the material that gives tough- 

 ness and solidity to its parts. Next to 

 water it is the most abundant body in 

 the vegetable world. 



All plants and all parts of all plants 

 contain cellulose, but it is relatively m.ost 

 abundant in their stems and leaves. In 

 seeds it forms a large portion of the husk, 

 shell, or other outer coating, but in the 

 interior of the seed it exists in small 

 quantity. 



The fibers of cotton, (Fig. 11, a,) hemp, 

 and flax, (Fig. 11, b,) and white cloth and 

 unsized paper made from these materials, 

 are nearly pure cellulose. 



The fibers of cotton, hemp, and flax, are simply 



_.^ long and tbiclc-walled cells, the appearance of 



°' ' which, when highly magnified, is shown in fig. 



11, where a represents the thinner, more soft, and collapsed cotton fiber, 



and 6 the thicker and more durable fiber of linen. 



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