256 Dr. Tully on Datura, 



ance, when it could not be decidedly traced to some other 

 place, where it was previously known to grow. Thus, 

 there was none of the pea-green sort in New-Haven, till in- 

 troduced by Professor Ives, nor in Middletown, till brought 

 from the meadows of Wethersfield, where it has long been 

 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 D. Ta- 

 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 

 may b« 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 hy climate, soil, cultivation, time, 

 or in short any accidental cause, and which is permanent and 

 continued by propagation from seeds. If this is correct, a 

 species may be distinguished by any uniform and invariable 

 peculiarity which is thus perpetuated, and no two differing 

 individuals are to be considered as mere varieties, unless 

 their peculiarities are changeable and evidently occasioned 

 by soil, climate, cultivation, or other accidental causes, and 

 are by no means to be certainly perpetuated by seeds. 



If then the colour of the stalks of the two sorts of Datura 

 in question is once established by adequate observation, to 

 be permanent and invariable peculiarities, it is, in my view, 

 sufficient. The similarity of the plants in other respects, 

 falls far short of proving them to be only varieties, as it is 

 well known that distinct species often so nearly resemble 

 each other, as that their claim to distinction, can be estab- 

 lished only by long-continued, and close comparative exam- 

 ination ; and on the other hand, varieties are occasionally 

 so diverse, that equal pains is necessary to establish their 

 specific identity. The great similarity of the different spe- 



