306 COMPOSITE ORGANS. CHAP. II, 



areas they occupy, which communicate with one 

 another by means of certain ducts or vessels ori- 

 ginating in their circumference, and forming part 

 of the general net-work, which is composed of two 

 distinct but adherent laminae. Finally, they are re- 

 garded as being organs of perspiration ; and their 

 peculiar areas, which consist also of two distinct 

 but not adherent laminae, are regarded as forming 

 receptacles for perspirable matter. The number of 

 them discoverable in the extent of a square line 

 amounts to about 577-* 



Compa- Comparetti, Professor of Botany at Padua, de- 

 scribes the epidermis as consisting of a net-work 

 of fibres ascending in an oblique direction, and 

 forming hexagonal meshes of various sizes and po- 

 sitions, but of which the vertical sides are the 

 longest ; the area of the meshes being occupied by 

 opaque or transparent points, of an oval or roundish 

 figure, that seem to be somewhat inflated, as if 

 filled up with air or water. Upon a more minute 

 inspection the points seemed to be composed of 

 three small fibres, two of which were lateral, and 

 one central. If the bubble contained within them 

 escaped or was dispersed, the area became depressed 

 at the circumference, but transparent at the centre, 

 which was still however occupied by a small black 

 point. His observations were made chiefly on the 

 epidermis of succulent plants, such as the Lily, 

 Poppy, Spurge, and plants with compound flowers, 

 * Tracts relative to Botany, London, 1805. 



