256 Dr. Tully on Datura. 
common, by the ice which was deposited in such immense 
quantities, by the freshet of 1818. 
In fact, I find the strongest reasons for concluding that 
there are as fixed and permanent specific distinctions be- 
tween what has been supposed in this country, to be 
tula, and what has been considered D. Stramonium, as are 
to be found in the science of Botany. I am well aware that 
the maxim, that for the distinction of species, regard is not 
to be had to color, size, taste, smell, or to the external sur- 
face, is, in general, correct; but as there is no one of those 
characters which are commonly the most permanent, that 
"is not occasionally variable, so too rigid an adherence to the 
above principle, may lead to error. Color, at least, when 
established by sufficient observation to be permanent, I think 
safely assumed as a specific character. 
Were I to define the term species, I should say it deno- 
ted all such individuals as are alike in every characteristic 
which is incapable of change by climate, soil, cultivation, time, 
or in short any accidental cause, and which is permanent an 
