VASCULAR SYSTEMS OF FLORAL ORGANS. 157 
and it becomes a single cord of tracheæ when the ovules are 
reached. 
(4) An isolated cord of a peduncle with its wedge-like mass of 
tracheæ may increase in size like a fan, the outer portions con- 
tinually branching till they meet at the other end of a diameter, 
and so form a complete cylinder, which then constitutes the 
vascular cord of a pedicel. This occurs in Erodium cicutarium 
(xvi. 1-3; Pl. XXVI.) in forming the three pedicels of the umbel 
of that flower. 
(9) Another form of union oceurs when two adjacent members, 
say the cords of two sepals, throw off right and left portions 
which meet; they then may coalesce and run up the middle of 
the next membrane lying between them, of the following walls. 
This is what takes place in Campanula Medium, in order to supply 
the corolla with its five midribs, as illustrated by Ph. van 
Teighem. (See also Calendula, xxxvı. 10, 11; and Jasione, 
XXXIX. 4; Pl. XXIX.) 
(6) Another illustration is seen in the Umbelliferæ (xxx. 
Pl. XXVIIL). The two carpels stand face to face with the mar- 
gins in contact. The cords proper to the margins or placentas 
ought to be four in number; but as only one ovule is developed 
in each ovary-cell, they are reduced to two. These, which are 
slightly divergent at the base, soon coalesce, and form the one 
cord which runs up the middle of the common tissue between the 
ovary-cells. The cord becomes isolated in the ripe state of the 
fruit, and constitutes the so-called stylopod, which is therefore 
not axial, but carpellary. 
(7) Though marginal cords of carpels are usually quite distinct 
from the dorsal, except by being connected by lateral branches 
which anastomose with it, in Ranunculus Flammula (tr. 3: 
Pl. XXIII.) the two marginals run to the top of the ovary, then 
curling over it, pass down the opposite side, and finally join the 
dorsal cord. 
Other instances might be given; but the preceding illustra- 
tions will be sufficient to show how frequent and various are the 
methods of union and reunion between the cords. 
REARRANGEMENT OF THE ELEMENTS OF THE Corps. 
I have already said that as long as cords are axial ina peduncle 
or pedicel, the tracheæ are situated on the inner angle, and the 
