INTRODUCTORY REMARKS. 25 



these membranous tubes, arid of the spiral or annular 

 fibre which surrounds them. 



A knowledge of the fructification, if I may so express 

 myself, of that numerous and curious class of plants, the 

 Acrogens, could not be obtained without it; nor could 

 the existence of many of them, such as the Fungi, 

 Lichens, Algae, and some of the Musci, be proved. By 

 its powers even the ashes of vegetables may be seen to 

 contain the decisive characteristics of organic structure 5 

 and the long-debated question of the antiquarian, as to 

 whether the " fine linen of Egypt," in the times of the 

 Pharaohs, were of linen or cotton fibre, seeing the 

 latter is now indigenous to that country, is for ever set 

 at rest. 



In many of the larger portions of plants, such as the 

 cuticle of their leaves, the stomata, &c. which require 

 but a shallow magnifying power to display them, there 

 is as great a difference manifested when these are viewed 

 under an achromatic microscope, or under the old com- 

 pound, as is perceptible between the most highly-finished 

 miniature, where the most delicate features and even 

 the down on the skin are correctly depicted, and the 

 mere black and white profile, where we see but the rude 

 contour of the face. Surely, then, as works of art 

 merely, instruments which can effect so much as this 

 are justly entitled to a due share of consideration even 

 from the most refined and polished minds. 



In the foregoing remarks on the application of the 

 microscope to botanical purposes, I have given the 



