z& The VEGETABLE SYSTEM. 
trace in thefe extreme inftances, the outlines of a proportional ad- 
vance in growth, as in climate. The Jerufalem Artichoak is 70 degrees 
more South ; and it is feventy times as tall. The Hollyhock of Borneo, has 
the Erne heighth of twelve feet ; and Moufe-Ear its original three 
inches at the fame diftance North in Afia, as America. 
These are the Extreams, fo far as I have found ; he that would 
fill up the intermediate degrees, muft find the Plants on which the cli- 
mate adts with lead interruption ; and he muft meafure thefe in places 
where they have their genuine ftature. Nightfhade upon the Downs, 
is three inches in height ; upon a Dunghill, it is a yard or more ; but 
neither of thefe is the true, that is, the natural height of the Plant. 
There will be an opportunity, in the courfe of this work, to exa- 
mine thefe differences of the fame Plant, and their caufes : the princi- 
ples of that enquiry are laid down in a preceding volume ; only let the 
general idea of them have fo much weight here, as to fhew that a 
rule may be juft, though liable to a million of exceptions. 
That difference in the ftature of a Plant, which we fee can arife in 
the fame place, from any one of many accidents, we muft not be afto- 
nifhed to find take place in very remote countries ; nor muft we bring 
this different height, when there is no other, as a reafon to fuppofe 
two Plants not the fame, which are the produdt of countries, fuppofcd 
not to have any in common. The Xanthium, which is our pre- 
fent immediate fubjedt, is one of Nature’s univerfal Plants ; more fo 
indeed, than any of thofe which take their little circles round the Pole. 
Befide being found throughout Europe and Afia, Africa affords it j and 
what is more to our immediate purpofe here, America. 
Nor is it limited to any one part of the new world any more than 
of the old ; I have received it from Quebec t from Carolina , from St. 
Chrijlophers , and from Jamaica j nor does the Plant in any of thefe 
places differ from the wild Englifh kind, any other way than in fta- 
ture and luxuriance of growth. With us the Plant is eighteen inches 
high j in Canada it grows to fix feet : there is in the general afpedt, an 
appearance of difference, but, when examined, it vanifhes. 
This 
