CELLULAR TISSUE. 17 



the tissue — as, for example, in the fleshy Cotyledons, and 

 farinaceous albumen of seeds, the parenchyma of tuber- 

 cles, &c. 



2d. There are also found in the cellules of the folia- 

 ceous parenchyma other little globules, more frequently 

 applied to the walls, which are generally coloured green 

 by the action of the light : they are capable of assuming 

 different colours ; but remain colourless, and scarcely, 

 if at all, visible in the parts not exposed to the light. 

 These globules are of a resinous nature, and constitute 

 the green matter of leaves, or that which some chemists 

 call Chlorophylle. The coloured globules of the cellules 

 of flowers may be compared with this class of bodies, 

 for several reasons. It results from several very cu- 

 rious experiments, performed by Macaire, that this 

 same matter is coloured red or yellow in the autumn, 

 and that this is the same matter wliich, difierently co- 

 loured, is again found in the calyx, and even in the 

 corolla and the other parts of fructification ; conse- 

 quently the name of Chlorophylle is very improper: 

 we may, by analogy with the word fecula, term it 

 Chromule. 



3d. Finally, the cellules of wood, of alburnum, and 

 of the layers of the bark, contain, according to the 

 observations of Dutrochet, granules of woody matter, 

 wliich are applied to their walls, encrusting them, and 

 rendering them opaque, constituting the difierences so 

 remarkable among the difierent woods. 



If we remove these three classes of matter, the tissue 

 of the cellules, viewed under very powerful microscopes, 

 appears perfectly transparent, and represents neither 

 regular folds, nor dots adhering to it, nor visible pores, 

 Mirbel has vigorously supported the contrary opinion, 

 and has even represented the romid cellules marked with 

 pores, encircled by a raised border, or with transverse 



Vol. I. c 



