SECT. I. ORGANOGRAPHY AND GLOSSOLOGY. 



25 



which result from different combinations of these ele- 

 mentary organs. These may be considered as of two 

 kinds. The first includes such as are found on the 

 surface of the several external organs, of which in fact 

 they are only subordinate parts, just as the skin, hair, 

 feathers, &c. clothe the body and particular members of 

 animals. We may call these superficial organs, the 

 " Investing organs." The other kind may be styled 

 the " Complex organs," and will include all those 

 which we have already classed under the ascending and 

 descending series, alluded to in art. 10., and of which the 

 investing organs form only subordinate parts. 



(29.) Epidermis. The surface of all parts of plants 

 (except the spongioles and some stigmata to be described 

 hereafter) is covered, at least when young, with a thin 

 skin, which may easily be detached, especially from the 

 leaves, and most readily after these organs have been 

 allowed to macerate for a few days in water. This 

 skin is termed the " epidermis," or " cuticle," and 

 when placed under the microscope, it exhibits a 

 delicate network (fig. 16.), whose meshes are either 



either quadrangular, hexagonal, or of other polygonal 

 forms; or else they are irregularly bordered by waved and 

 sinuous lines, extending over the whole surface. Very 

 frequently also, a set of pores may be observed, hav- 

 ing a sort of glandular border (a), which are scat- 

 tered over the epidermis at intervals. These pores 

 are termed " stomata." It was not until very lately 

 that the real structure of the epidermis was well under- 

 stood ; but M. A. Brongniart has shown, in the 



