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" We may regard the cell as a little independent organism, living 

 for itself alone. It imbibes fluid nutriment from the surrounding 

 parts, out of which, by chemical processes which are constantly in 

 action in the interior of the cell, it forms new substances which are 

 partly applied to the nutrition and growth of its walls, partly laid up 

 in store for future requirements ; partly again expelled as useless and 

 to make room for the entrance of new matters. In this constant play 

 of absorption and excretion, of chemical formation, transformation 

 and decomposition of substances, especially consists the life of the 

 cell, and, since the plant is nothing but a sum of many cells united 

 into a definite shape, also the life of the whole plant. 



" These cells in the course of their development become crowded 

 closely together, and thus form the whole mass of the plant, the cel- 

 lular tissue, which, however, may be divided into three principal 

 classes of tissue, according to the different forms of the cells, and 

 more especially according to their importance to the life of the plant." 

 —p. 45. 



One of the most curious things connected with the cell-structure of 

 plants is the power possessed by those minute bodies, which all owe 

 their origin to the same constituents, of forming the most varied 

 substances in their interior, which substances may be primarily di- 

 vided into such as are soluble in water and such as are insoluble. 

 To the former class belong albumen, gum, sugar, and the acids ; and 

 to the latter the fatty and aromatic oils. The most remarkable of 

 these substances is starch, whether regarded as playing a most im- 

 portant part in the nutrition of the animal kingdom, for which pur- 

 pose it is stored up in great quantity in various parts of the plant, 

 but more especially in the roots, tubers, seeds, fruits, and more rarely 

 the pith ; or as affording the only known mark of distinction between 

 the chemical composition of the elementary tissues of plants and 

 those of animals, since it occurs in the former in addition to the oxy- 

 gen, hydrogen, carbon and nitrogen common to the two kingdoms. 

 In the lecture upon " The Propagation of Plants," the author, after 

 referring to the almost infinite forms of animal life, all which, directly 

 or indirectly, derive their sustenance from the vegetable world, pro- 

 ceeds to develop his own views of the means provided for the repro- 

 duction and multiplication of organisms upon which depend the very 

 existence of so large a proportion of the inhabitants of our globe : 

 and says — 



" That this may not be effected by a simple, well defined form of 

 multiplication, as in the higher animals, is in itself evident, and be- 



