\2 VEGETABLE ORGANOGRAPHY. 



is not, under the same magnifying power, more than 

 one millimetre ; so that there are 5,100 cellules under 

 a millimetre square of the natural size. 



Section II. 

 Of the different Forms of the Cellules. 



The Cellules of cellular tissue, considered only as to 

 their general form, present themselves under four prin- 

 cipal forms: viz. 1st, round; 2d, spindle-shaped, or 

 tapering towards the two extremities ; 3d, tubular, or 

 prism-shaped, that is to say, not narrowed at the ex - 

 tremities ; 4th, elongated transversely. 



The ROUND (PL 1, fig. 1) seems to be the original 

 form of the cellules ; and it may be said in this sense, 

 that all the other appearances which they present, result 

 from the unequal pressure which they exercise on one 

 another during their growth; that they thus become 

 hexahedral, or nearly so (PI. 1, fig. 2,4, 5, and 6), when 

 they are equally pressed on all sides ; that they take an 

 elongated form, either in a horizontal direction or in a 

 transverse one, when the pressure is exercised on one or 

 the other side : but in all these cases it is necessary to 

 be careful to remember, that the forms of the cellules 

 will not be as regular as the figures which have been 

 published would lead us to think. It is evident that, in 

 representing them with the exaggerated regularity which 

 the majority of plates exhibit, one would wish either 

 to point out that state which one would suppose normal, 

 rather than to represent exactly the appearance of these 

 organs from simple observation ; or to disentangle the 



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