INTRODUCTION, 



ANATOMY OF PLANTS. 



VEGETABLE TISSUES. 



On a microscopical examination of the organs, or parts of plants, they will 

 be found to consist of vesicles, tubes, and fibres, constituting what is termed 

 cellular, vascular, and woody tissues. 



Cellular Tissue is of universal occurrence, no part being destitute of it, in 

 some form, and many wholly composed of it. It consists of membranous 

 vesicles or cells, cohering together. They are of various forms, depending 

 on the circumstances under which they are placed. When first formed they 

 are nearly globular or ovate, but when pressed together from any cause, they 

 assume other shapes, and their sides 

 become flattened ; when the pressure Fi &- l - 



is uniform, they become twelve-sided, 

 or else cubical; when the pressure 

 is lateral they assume a prismatical 

 or cylindrical form. In general, this 

 elongation takes place in the direc- 

 tion of the growth, but in the stems 

 of many trees, there is a peculiar 

 set of cells extending from the cen- 

 tre to the circumference, which are 



longest horizontally ; the cells being of an oblong, flattened shape, and ar- 

 ranged like bricks in a wall. The cells contain fluid, and often solid matter. 

 This tissue or parenchyma constitutes the pulpy and succulent parts of plants, 

 the pith, the leaves, with the exception of the veins, a part of the bark, &c. 

 It sometimes is so compressed as to be very hard, as in the stone of a peach. 



Woody Tissue has received the name of fibre from its always existing in 

 an elongated thread-like form. It consists of vesicles of cellular tissue drawn 

 out into tubes of great tenuity and toughness, each end tapering to a fine 

 point. These tubes are closely applied to each other by their sides, so as to 

 form cords or bundles of fibres. Woody fibre is designed to convey fluid 

 in the direction of its length, and is readily permeated by it. This tissue is 



2 



Cellular tissue, a Separate vesicles, b Section of 

 cubical vesicles of pith, c Section of flattened 

 vesicles. 



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