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of their ftipes with the pofition of their gills, 
which, being the part wherein the fructifica- 
tions are contained, is of the greateft import- 
ance. They vary much in almoft every 
circumftance belonging to them, except in 
colour, which in all other plants is the moll 
variable of all their characters ; the colour of 
the gills, on this account, is the mark, which 
has lately been adopted for the diftindlion of 
the fpecies : their colour is fuppofed to be 
principally, if not wholly, caufed by that of 
the fructification or feeds, and is faid to have 
been found fufficient, with their ftrufture, to 
afford permanent fpecific diftinctions. Thefe 
colours change, when the plant begins to 
decay; and of thofe agarics, which diffolve 
away in an ink-like liquor, the gills in their 
young Hate are white ; fo that, to judge of 
their colour, the plant mud be gathered in it's 
firfl ftate of expanlion, when they will be 
found to be gray. It is the colour of the flat 
fide of the gills which muft be attended to in 
the fyftem I am explaining to you, becaufe 
the colour at the edge in fome plants is dif- 
ferent through all the ftages of growth ; and 
in others, it changes fooner than that of the 
fides, evidently from the . discharge of the 
feeds., 
