THEORY OF THE STRUCTURE OF PLANTS. 339 
well as several of the others, has two of its parts suppressed, and are 
perfectly consistent with the theory previously explained. 
4. Many Cruciferee become tetrandrous by pelorization; ethers are 
normally so, In either case the four stamens are thus equal. This, I 
answer, is at least as easily explaimed in onr theory as on that of the 
separation of stamens into two. 
5. Finally, certain Cruciferz instead of returning to the quaternary 
type recede from it. The single stamens undergo a change analogous 
or very similar to that of the double pair. One of us has observed, 
flowers of Matthiola incana, im which the single stamens were cleft 
throughout their entire length, each portion being provided with half 
an anther and half a filament. M. Lestiboudois speaks of a 
Cheiranthus Cheiri in which these stamens were completely geminated, 
not laterally as the longer pair, but from without inwards. M. 
Lermye met with a flower of the same species, which had the lower 
stamens doubled exactly as the upper. Now let these cases be fairly 
considered : the first appears to show that a stamen may be occasionally 
slit vertically, but it is acknowledged that there is no increase in the 
real number of parts, each portion it is expressly stated consisting of 
half an anther (a single cell,) andhalf a filament. This may render 
more probable Dr. Lindley’s explanation of Fumaviacese, destroying 
an analogy on which Dr. Gray greatly relies, but it supplies no 
argument in favour of a single primitive organ haying become two 
perfect ones with all their parts. The case observed by Lestiboudois 
is apparently not one of Chorisis, but of development under the 
stimulus of cultivation of the gland, which is often noticed wethin the 
short stamens; that of M. Lermye requires to be more accurately 
described, but it must not be hastily assumed to have consisted in a 
division of the single stamen into two perfeet ones, it may have been 
a ease like that seen by one of the authors themselves, a mere fissure 
of the stamen into two parts; or it is perhaps just possible that the 
single stamen may have been suppressed, and the two glands which 
often appear at each side of it, developed into a pair of stamens, It 
is certainly not sufficient without more exact information, to support 
or overthrow a theory. Dr. Gray relies so completely on the arga- 
ments of Messrs. Moquin Tandon and Webb, that £ need only farther 
observe that even if Chorisis furnishes the true explanation of the 
symmetry of Fumariacie, which I hold to be very doubtful, there is 
no such relation between that order and Brassicaceze as would oblige 
