70 



TALKS AFIELD. 



A Peep at the Inside. 

 The ordinary visible plants are made up 

 of great numbers of microscopic cells of an 

 infinite variety of size and shape. When 

 these cells begin to grow they are usually 

 spherical, but they soon become curiously 

 compressed or contorted by the pressure of 

 one upon another. In portions of the plant 

 where the pressure is the same upon all sides, 

 the cells become symmetrically twelve-sided, 

 as in the magnified portion of pith in Fig. 58. 

 It is not often, how- 

 ever, that such cells 

 occur. Some cells 

 become much elon- 

 . «. -mrM, n gated ; and when 

 / \tMm mi *^^y have woody 

 \ r% I l/yvi walls, they are 

 known as the wood 

 Fig. 58. cells. (Fig. 59.) 



Other elongated cells are those 

 which are commonly known as ves- 

 sels. They are tubes which run through the 

 stems of plants, often liaving upon their 

 walls peculiar markings, as dots, disks, spi- 

 rals, and rings. Portions of vessels with 

 these annular and spiral markings are shown 



