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MORPHOLOGY. 



the nutrition of its membrane, and the latter upon the presence of a 

 nutrient fluid, that second cause of form will almost always be a conse- 

 quence of the first, so soon as the cells are removed from an immediate 

 contact with the nutrient fluid. A linear arrangement of the cells may, 

 therefore, easily produce a greater expansion lengthwise, &c. By way of 

 illustration of the regular arrangement of newly developed cells, I will 

 .only cite the case of two cells of the stomate. Here two young cells arise 

 in a parent-eel), formed, without exception, exactly in such a manner that 

 they lie in a plane with the epidermis, and never so as to lie one upon 

 another, as seen from the exterior of this membrane. 



75. Regular mathematical forms never occur in plants, with 

 the exception of the spherical form of individual cells. We term 

 those forms in plants regular which admit of being divided into 

 .two equal parts by many sections passing through an imaginary 



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axis (); and symmetrical, ,those that can only be divided by one 

 single section into two equal parts, standing in the relation of right 

 and left to each other 



As each separate cell is a wholly independent individual, and as only a 

 few simple individuals of the second order are formed by the mere col- 

 lection of cells, while most plants acquire their whole form from the 

 combination of these latter; and since each individual of the first and 

 second order may be considered per se, owing to the independence of 

 external influences possessed by its existence, without, at the same time, 

 its being on that account exempt from a connection with the whole, it will 

 easily be understood how very indefinite the form of most plants must be. 

 We consequently meet with regularity, or even symmetry, in the sense 

 above applied to the terms, in but a very small number of entire plants, 

 as, for instance, in Protococcus, Phascum, Equisetum, Wolffia, Melo- 

 cactus. We more frequently meet with both in the individual parts of 

 plants, especially in the reproductive apparatus of the higher plants 

 which have the closest morphological and physiological connection ; for 

 instance, in the capsule of mosses, in blossoms and fruits ; we also often 

 find .only symmetry, at least in the leaves, and in whole individuals of the 



