180 
ORGANOGRAPHY. 
BOOK I. 
doubted though somewhat distorted stamen. Double Paeo- 
nies, Double Tulips, and many other monstrous flowers, 
particularly of an icosandrous or polyandrous structure, 
afford equally instructive specimens. It is for these reasons 
that it is stated in the Outlines of the first Principles of Bo- 
tanp, 307., that “ the anther is a modification of the lamina, 
and the filament of the petiole.” 
I ought, perhaps, to have put the explanation in a more 
extended form. A leaf consists of a midrib, on each side of 
which is a parenchymatous expansion, consisting of a double 
stratum of tissue, separated by vessels. In the anther the 
midrib assumes the form of the connective ; the double stra- 
tum on each side of the midrib is, at the centre, developed in 
the form of pollen, and hence the primitive quadrilocular 
structure of the anther, as above described. The line of de- 
hiscence in ordinary circumstances is the margin of the 
modified leaf. Schleiden makes this additional remark : — 
“ The normal leaf, as is well known, exhibits upon its upper 
surface cellular tissue, different in structure from that on the 
under ; to this we find that the pollen of the anterior and 
posterior cells of the anther corresponds. It may, perhaps, 
be possible, and certainly not uninteresting, to ascertain, by 
experiment, whether or not the pollen of one of these com- 
partments only possesses the external characters* of pollen, 
and likewise different functions in the process of impregna- 
tion, or whether in dioecious plants one kind would produce 
male, the other female embrvos.” 
Agardh considers a stamen to be composed of two leaves 
in a state of adhesion ; and that it is in fact a bud axillary to 
a sepal or petal. This is very nearly the opinion formerly 
entertained by Wolff. Eudlicher adopts this view to a cer- 
tain extent; and supposes the leaves to be rolled backwards, 
so that their under surface becomes the polliniferous part. 
But all this is mere hypothesis, unsupported by evidence, and 
in opposition to the direct observations of Mirbel and Schlei- 
den. The latter w^ell observes, that the stamens are evidently 
* It is so expressed in the translation in Taylor’s Magazine ; in the ori- 
ginal it is : “ oh vielleicht der pollen einer von beiden, niir der form nach 
pollen sei, und bei der befruchtung sich verschieden verhalte,” u. s. w. 
