EXPLANATION OF THE PLATES. 



PLATE I. 



ALL THE FIGURES ARE GREATLY MAGNIFIED. 



FIG. 1. Two cells from the Snow-berry. In each is perceived a 

 nucleus a, and, proceeding from or towards this, numerous currents 

 of a yellowish mucilaginous substance. In some of them the direc- 

 tion of the currents is indicated by an arrow. 



FIG. 2. Two cells from the leaf of the Pink. In these may be 

 distinguished the colourless cell-wall, a delicate, yellowish, mucila- 

 ginous coating, and some large granules coloured by chlorophyll. 



FIG. 3. A cell from the same plant, which has been moistened 

 with a drop of nitric acid and some tincture of iodine. The green 

 granules have become brown, the mucilaginous coat is coagulated 

 and thus has become retracted from the wall of the cell, and forms a 

 sac lying loosely within it. 



FIG. 4. A reticulated fibrous cell from the leaf of the broad- 

 leaved Gesneria (Gesneria latifolia). 



F IG . 5 . A spiral fibrous cell from the leaf of a tropical Orchi- 

 daceous plant (Maxillaria atropurpurea) . 



FIG. 7. An annular fibrous cell from the stem of the Italian 

 reed (Arundo Donax). 



FIG. 8. A very short bass fibre (elongated cell) from the stem 

 of the Flax. 



FIG. 9. A little piece of a cotton fibre. 



FIG. 10. A piece of a filament of raw silk from a cocoon. 



FIG. 11. A small portion of a fibre of sheep's wool. 



FIG. 12. A small piece of the epidermis stripped from a leaf of 

 the Tulip. It is composed of longish, somewhat six-sided cells, and 

 this piece exhibits four sto mates or breathing pores, a. 



FIG. 13. A delicate section from the stem of the Italian reed, so 

 cut that it only contains one of the vascular bundles (the tough fibres 



