EXPLANATION OF THE PLATES. «>4J 



CUTICULAR PORES. 



Fig. 6. — Foliar apertures or pores, on the upper disk of tlir 

 leaves of T'iola adorata illustrative of the double ring with 

 which they arc sometimes, apparently, surrounded. 



Fig. 7. — The cuticular pore in Marchantia, situated in the centre 

 of a slight elevation. 



Fig. 8. — The cuticular pores on the hack of the leaves of Com- 

 mon Oleander (JYerium Oleander), which are oval and guard- 

 ed by connivent hairs (a.b.) They are comparatively much 

 larger than any of the other kinds of pores. 



Fig. 9. — A transverse section of the curious pore (d.) of the 

 Oleander, above, magnified, and showing its penetration into 

 the substance of the parenchyma (c.) and lined internally as 

 well as externally with hairs ; its lining membrane, which is a 

 production of the epidermis (a.) is not visibly porous through 

 glasses of the highest powers. The section of tins leaf, also, 

 displays an example of a cutis consisting of 4 layers of 

 cells. \b.) 



Fig. 10. — The quadrilateral pore surrounded by an elevated mar- 

 gin, found on both surfaces of the leaves of the American 

 Aloe (Agave Americana), and of all the other species of the 

 succulent tribe to which it belongs. In the real Aloes the 

 pores are always circular. 



Fig. 11. — An example of the space between the pore, or the 

 shield and the enclosing ring, divided into distinct portions, 

 as seen on the lower disk of the leaves of Lilac. 



Fig. 12. — A circular pore in the centre of a circular shield, as 

 beautifully displayed, on both surfaces of Cactus Opuntia or 

 the Prickly Pear. 



Fig. 13. — A portion of the cuticle of the leaf of the Indian Corn 

 (Zea mays), magnified, a. a. The cuticular or pneumatic, 

 pores, b. b. The supposed lymphatic vessels. 



Fig. 14. — A more enlarged view of the structure of the cuticular 

 pore in the leaf of the Zea mays. 



Fig. 15. — The respiratory pores of the cuticle of the culm of 

 wheat (Triticum (Estivum). 



Fig. 16. — The cuticular pores, and the course of the lymphatics 

 on the superior disk of the leaf of Hoya carnosa which are 

 nearly regular hexagons. 



