500 EXPLANATION OF THE PLATES. 



Figs. 9, 10. Griffithsia corallina Ag. 



9. Terminal cell of a stem, -080 of a line long, *040 

 broad. The cavity is filled with transparent, colourless 

 fluid. The wall is coated by a layer of dull brownish-red 

 contents, except at the apex, where a slightly coloured, 

 finely granular mucilage lies upon the membrane. 



1 0. The terminal cell has divided into two secondary cells 

 by parietal cell -formation. The lower one contains trans- 

 parent, colourless fluid, and is coated with a layer of dull 

 brownish-red contents. The upper, smaller cell, has 

 upon its walls a distinct layer of slightly coloured, finely 

 granular mucilage, and is filled internally with a dull-red 

 granular mass. (If the cell becomes larger, the almost 

 colourless, mucilaginous layer diminishes on the lower 

 and lateral walls, so that it can no longer be clearly 

 distinguished, it only remains distinctly evident at the 

 growing point. The remaining dark red, granular con- 

 tents divide with the growth of the cell in the interior, 

 and remain lying upon the wall.) 



UTRICULAR STRUCTURES. 

 PLATE II. 



Figs. 10, 11 . Chlorophyll-utricles from the pro-embryo of 



Pteris nemoralis Willd. 



10, a, 6, c. In normal conditions : they possess a dis- 

 tinct membrane, homogeneous green contents, and starch- 

 granules, which have become coloured blue by the com- 

 mencement of the action of an aqueous solution of iodine 

 upon them. a. A round chlorophyll-utricle with two 

 starch-granules. Diam. of the utricle ='003 of aline. 



b. A longish chlorophyll-utricle with one starch-granule. 



c. A chlorophyll-utricle which has divided into two 

 secondary utricles by means of a septum. 



