226 THE SOLID COMPONENTS OF PLANTS. 



ent species of plants, but most frequently green. In 

 this situation it is the seat of the color of the bark, in 

 the same manner as the rete mucosum, or reticulated 

 capillary membrane situated under the human cuticle, 

 is supposed to give the color to the skin. The cells 

 are filled with the same green juice in leaves, which 

 are composed of a layer of cellular substance placed 

 betwixt two layers of cuticle. The medulla or pith 

 of plants is, also, composed of these cells, filled in 

 young and succulent plants and branches with water, 

 or wat uy fluids ; but in older plants, and in the trunks 

 and branches of trees, not succulent, they are gener- 

 ally empty. In the latter the shape and structure of 

 the cells are most conspicuous, and easily observed. 

 Thus, if a transverse, or longitudinal section of a twig 

 of Spanish Broom, in the second year of the growth 

 of the twig, be placed under the microscope, or even 

 a common lens, the pith of it displays in the most 

 beautiful manner the hexagonal cells, the transparent 

 iridescent appearance of the membrane forming their 

 walls, and the situation of the communicating pores. 

 It is well seen also by the aid of the microscope in 

 the pith of many other plants. The petals of flowers 

 are almost entirely composed of cellular texture, the 

 cells of which are filled with juices fitted to refract and 

 reflect the rays of light, so as to produce the brilliant 

 and delicate tints with which the pencil of nature has 

 embellished these parts. In the same manner it en- 

 ters into the composition of the stamens, the stigma, 

 and even the pollen or fecundating farina of the flower. 

 The fleshy parts also of succulent roots, and of pulpy 

 fruits, are formed of this cellular texture filled with 

 different juices according to the nature of the roots 

 and the fruit. 



When the cellular texture is compressed, the cells 

 are found forming nearly parallelograms, as in the 



