INTRODUCTION. 



XXI 



comes more and more hollow, till its final diffolution. In defcribing 

 the plants, in this work, I have carefully noted thefe changes : but all 

 flems of this kind are to be confidered as folid, when that circumftance is 

 made ufe of, by way of fpecific character ; and where it is faid, that a 

 ftem is folid, it is meant, when the plant is in a ftate of growth and 

 vigour; when it is faid, that a ftem is fjlular, it is to be underftood from 

 its firft appearance above ground. 



I have endeavoured in all the figures, to give proper attention to the 

 Roots of the Agarics ; a part of them which feems to have been greatly 

 neglected, though moft of the fpecies are furnifhed either with a proper, 

 01 a common root. It generally confifts of a tuberous piece, of a propor- 

 tionable iize, and a tough hard fubftance ; which is, as it were, incorpo- 

 rated into the bafe of the ftem, and emits fibres into the ground or other 

 matter, for the fupport of the plant. It is often, however, overlooked, 

 for if the plant is not taken up with care, the bafe of the ftem breaks, 

 and the root, with its fibres, remains in the ground, and efcapes our 

 notice. 



Figure, in the Pileus of Agarics, which has by many been confidered 

 as a character of fpecific distinction, has been a fource of much per- 

 plexity ; the truth of this aflertion will be obvious, when we confider, 

 that in many fpecies the feveral Terms, globular, oval, convex, umbeli- 

 cated, and funnel-fhaped, may, with equal propriety, be applied to the 

 fame individual fpecimen, in the various ftages of its growth. Thefe 

 mutations of figure are carefully noted throughout the work, both on the. 

 plates and in the defcriptions ; and where the figure of the pileus is 

 brought in, as aiding to the fpecific character, it is meant, to denote its 

 figure when in a ftate of perfect growth, or between the laft excefs of its 

 increafe, and the firft approaches of its decay. Laceration or rents in the 

 pileus, which are always a certain fign of its approaching decay, are the 

 effect of contraction in its fubftance, and depend in fome meafure on the 

 dtynefs or moifture of the air; for in rainy feafons, when the plant can 



imbibe 



