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ON THE THEOUT OF DEDOTJBLEMENT OR DEDUPLICATION. 
ON THE THEORY OF DEDOUBLEMENT, OK DEDUPLICATION* 
OTIHE term dedouhlement originated, we believe, with two Montpellier botanists, of well-deserved 
H reputation, wbo have paid much attention to theoretical morphology — Professor Duval, and his 
pupil, Professor Moquin Tandon ; and was fii-st apphed to the case of floral envelopes which appear to 
have a tendency to separate into two layers, an inner one and an outer one, and thus to unline, as it 
were ; which may be given as the literal meaning of the word dedoiihler. But it has been gradually 
extended to all cases where any number of floral organs occupy the place normally taken by a single 
one. Tliis phenomenon, which has only recently been generally comprehended, is of great importance 
in explaining the morphology of the flower ; but wc think that the mode in wliich it takes place, is far 
from being satisfactorily explained by the statement that it is always by dedupHcation. 
In a normal regular flower, it is muversally admitted that each sepal, petal, stamen, and cai-pel, is an 
axile appendage of the same morphological natm'e as the stem-leaf, and to which we, therefore, mor- 
phologically extend the term leaf. Therefore, in investigating the various anomalous developments 
which we observe in any one set of axile appendages, we must carefully compare them with analogous 
anomalies of the leaf in every one of its forms, fi-om the stem-leaf to the carpel. 
Ordinary stem-leaves show a very strong development of the vascular system, in the shape of 
petiole, ribs, and veins, and, in many instances, a great readiness to produce from it convex or scutelli- 
form glands, t 
These occur most frequently at the top of the petiole, or near the base of the Umb, one or more on 
each side, or on the sm-face of the petiole or principal veins near the base of the limb. They are also 
found occasionally at the end of the midi'ib or lateral veins, or will break out irregularly at any part 
of the petiole, ribs, or veins. The general sm'face of the leaf will only produce haii-s, aculei, or other 
appendages of the cellular tissue, except in cases of disease or monstrosity, where an extraordinary 
flow of sap will induce the formation of foliaceous ajipendages or regular buds on the margin or any 
part of the surface. But as these cases are as frequently further departm'cs fi-om what may be termed 
the normal state, as approaches to it, great care should always be taken in adducing them in support 
of morphological theories. 
As we approach the flower a gradual change takes place in the leaf, and, more especially in its 
size ; but still we have even an increased preponderance of the vascular system and its glands, in some 
cases the bracts being reduced to a mere stalk, with one or two large glands. But when we come to 
the floral envelope, a sudden change takes place, not only in their position on the axis, but in their 
textm-e ; the vascular system, especially in theii- jietals, is reduced to extreme tenuity, and the cellular 
tissue is proportionately more developed. Glands, in then' ordinary form, become rare, or are 
variously deformed, assuming, frequently, very ii-regular shapes, and a petaloid consistence. In the 
leaves forming the andrwcium, a partial retm-n to the system of stem-leaves takes place, inasmuch as 
the filament is entii-ely reduced to the vascular system, its glands are converted into anthers, and the 
cellular parenchyma is only occasionally represented in an expanded connecti\Tim or shght mem- 
braneous expansion of the filament. The carpellary leaves have, again, a more or less developed 
cellular parenchyma, as well as a strong vascular system, the glands becoming sometimes prominent 
glanduliform stigmata, or sometimes papillose stigmatic surfaces of extreme tenuity. 
Such being the close morphological analogy between the stamen and the stem-leaf, we would next 
observe that multiplication takes place in the latter almost universally in one place (either horizontal 
or, from various causes, more or less vertical), by the ramification or the separation from the base, of its 
libs, each branch being more or less connected with the remainder of the leaf, or assuming the form 
of a distinct leaflet. Wherever a tuft of leaves occupies on the stem the place of an ordinary leaf, it is 
not by ramification of the leaf, but by the partial development of the axillary bud, of which the axis 
is not elongated. 
Proceeding now, upon these grounds, to compare the modifications of the stamens to those of the 
stem-leaves, taking the ordinary stamen to represent the petiole (the filament), with a gland on each 
side of its apex (the two cells of the anther), we see these glands sometimes runted into one (the one- 
celled anther by confluence), or reduced to one by abortion (the dimidiate anther), or sometimes really 
single and terminal, or increased to fom- or more in pans, or two or more superposed or irregularly 
arranged, as in the stem-leaf glands so in the staminal anthers. J A split stamen, bearing one cell of 
* From llQ6ker''s Journal of Botany, December, 18-19. 
t We advert to the true glands, ■which always appear to be in close connexion "with the vaseulai" sj^stem— not to those vesicles of 
essential oil scattered through the cellular tissue, ■which are also designated by the name of glands. 
t The cori'espondenec of the anthers to the glands of leaves would receive still further confirmation, if it be true that in 
Coelobogyne fertilization is effected by a viscid fluid exuded from the glands of the bractea?. 
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