30 
PRELIMINARY TREATISE. 
that can be most depended upon in each order as indicating 
a diversity of kind. My own thoughts have been earnestly 
directed to that inquiry, but I feel my decision obstructed 
not only by the want of perfect knowledge of the natural 
order which I have attempted to arrange, but of the diversi- 
ties of the whole vegetable kingdom. I am inclined to 
believe that every true generic character is manifested by, 
and therefore should be founded on, some difference of struc- 
ture in the male or female constituents of the plant, the male 
being the perianth and stamens, the female the germen, 
ovary, style, and stigma, and of course the mature fruit. 
The difficulty is to ascertain which are substantial differences 
and which are only modifications of structure, and how far 
the points of structure which are invariable in the indivi- 
duals of one race may be variable in another. Concerning 
this, which is the basis of botany, the opinion of its pro- 
fessors is fluctuating and undecided. Of late years their 
attention has been directed with great propriety to the fruit, 
but it has not been yet established in what an absolute diversity 
of the seed consists. The bent of my own opinion is, that 
the nearer to the base of either the male or female consti- 
tuent any diversity manifests itself, the greater is its impor- 
tance ; and with great diffidence in making any suggestion 
on the subject, which I feel that I have not sufficient infor- 
mation to substantiate, and which, if it should prove to be 
upon the whole correct, will be assuredly subject to modifi- 
cations or exceptions, I am nevertheless desirous of drawing 
the attention of botanists to its consideration. I look upon 
the perianth as superadded to the stamens, and therefore 
further from the base than the anthers. Under this view it 
would be apparent that the absolute disseverment of the base 
of the segments of the perianth (a point so entirely overlooked 
in botanical characters, that we cannot ascertain from the 
terms used whether the perianth is quite cleft or deeply 
cleft) is of more importance in framing a generic character 
than any difference in the form or position of its upper part ; 
that the absence or presence of a tube is of more importance 
than the form of the limb, the stamen being of greater con- 
sequence than the perianth, to which the stamen is the inte- 
rior and proper base. Under this view it would be apparent 
that the stigma is the least important part of the female con- 
stituent. The point concerning which I feel the greatest 
difficulty is the degree of weight which is to be assigned to a 
