STIGMA IN NYMPHAA, 67 
Practically, the stigma is the peculiar tissue which forms 
the external communication of the conducting tissue. 
Theoretically, it is a production of the placenta along 
the margins of the carpellary leaf. 
It was necessary to examine central placentation.] 
If the stigma be the denuded apex of the midrib, its 
most simple form will be that of a punctum; from that point 
it may be assumed to be decurrent, thus including those 
stigmata which have an inferior or anterior sinus, but not 
those with a superior sinus; for, however liable organs of the 
same nature are to coalesce, I do not know any instance in 
which an organ becomes divided along its mesial line. 
This theory is also objectionable as deriving the origin of 
the softest vegetable tissue, from the hardest portion of a leaf. 
The true apex of the midrib is, I think, pointed out by the 
end of the vascular bundle. 
Or, if cases exist in which the stigmatic surfaces occupy 
both faces of the style below the end of the vessels, it is 
necessary to allow that they may occupy the back as well as 
. the front of the iplo Examine gramineous stigmata and 
Composite. 
The stigmata of N deh are apathulate, furrowed in the 
centre, and spread over rays of a similar form, but prolonged 
beyond in some other species into a long incurved process. 
The centre of the whole is rather depressed, occupied by a 
conical fleshy cellular mass of small size. 
Each of these corresponds to a cell of the ovaria, so that 
this is composed of many carpellary leaves, though condupli- 
cated; the sides of each being ovuliferous, the channel of 
communication is the furrow. 
The septa are evidently double; each side is lined by 
placental tissue, which is even thickened towards the axis, 
where however it has no ovula; these placente unite the 
carpella at the summit, and produce a structure like that of 
Hydnora, except that in Hydnora the carpels look convo- 
luted. Even the ovula are inclined to encroach upon the 
dorsum, but they never rise from the centre. 
The septa. are reticulately venose, and are distinct above. 
