112 



ON THE PLANT-CELL. 



Respecting the process by which the reservoirs of proper juices are 

 filled with the matters contained in them, the preparation of this matter 

 by the neighbouring cells, and the power through which these materials 

 are secreted within the reservoirs, we as yet know nothing. All these 

 particulars being left out of consideration, the only differences pre- 

 sented by the intercellular spaces, which are filled with a solid substance, 

 arise from the nature of the secreted substance. These spaces present 

 two varieties of form. In the wood of dicotyledons, and in other instances, 

 the narrow intercellular passages are frequently occupied by a substance 

 homogeneous in appearance, its colour and tenacity differing in some 

 degree from those of the cell-wall. 



On the other hand, the constitution of the intercellular substance be- 

 tween the cells of the external cortical layer in the Chenopodiacce, Ama- 

 ranthacece, Umbelliferce, Malvaceae, &c., is more remarkable. 



If we examine these cells in a 

 transverse section of Abutilen 

 graveolens (fig. 99.), we observe 

 large intercellular spaces formed 

 by from three to six cells (b). From 

 each of the cell-walls, forming 

 the boundaries of the space, there 

 projects into it a semi-solid, semi- 

 gelatinous mass (a); the aggre- l^J^1/~Xi/ V V/ JLt 

 gate, however, of these masses 

 is not sufficient to fill up the 

 whole intercellular space. 



In Amaranthus viridis (fig. 100.), three cells on a transverse section 

 present a stellate form (b\ and in this way constitute very spacious, 



100 



rounded, intercellular passages, which also are partially filled with a 

 secreted substance (a), exhibiting concentric laminse, which run parallel 



99 Transverse section from the outer cortical layer of Abutilon graveolens. a, The 

 intercellular substance secreted by the cell-walls. 6, Cells. 



100 Transverse section of the outer cortical layer of Amaranthus viridis. a, The inter- 

 cellular substance secreted in lamina? by the cells. 



