. INTRODUCTORY REMARKS. 2? 



branches of the fir tribe. It will tell you whether the 

 wood might be easily cleft asunder, like deal; or would 

 sooner break, like beech ; whether it was elastic, like the 

 pine so admirably suited for the masts of ships; or, like 

 the stubborn oak, would rather snap than yield to the 

 wind. These are some of the ordinary properties deve- 

 loped by the microscope. 



Again, in taking a more minute physiological survey, 

 our information will be by no means less complete. For 

 these same specimens will disclose to us, under the 

 microscope, the form and arrangement of their woody 

 fibres, the disposition of their barks, the beautiful struc- 

 ture of the tubular receptacles, by which their secretions 

 have been carried on and their growth promoted. In 

 short, so much will be revealed by them in this manner, 

 that the actual distinction between a wild and a culti- 

 vated tree may be, in some cases, clearly traced. " Thus, 

 in the cultivated cherry, the plates of the medullary rays 

 are very thin, the adhesions of them to the bark are very 

 slight, and hence a section of the wood of that plant ex- 

 hibits a pale, smooth, homogeneous appearance; but, 

 in the wild cherry, the medullary plates are much thicker, 

 they adhere to the bark by deep broad spaces, and are 

 arranged with great irregularity, so that a section of the 

 wood of that variety has a deeper colour, and a twisted, 

 knotty, very uneven appearance*." 



Should they be specimens of endogenous woods (ver- 

 * Lipdley's Botany, page 241. 



