DICOTYLEDONOUS EMBRYO. 845 
The cotyledons are usually thick and fleshy, as those of the 
Bean and Almond (jig. 768), in which case they are termed 
fleshy ; at other times they are thin and leaf-like, as in the Lime 
(fig. 764, c, c), when they are said to be foliaceows. The folia- 
ceous cotyledons are frequently provided with veins, and stomata 
may be also sometimes observed on their epidermis ; but these 
structures are rarely to be found in fleshy cotyledons. Fleshy 
cotyledons serve a similar purpose to the albumen, by acting as 
reservoirs of nutritious matters for the use of the young plant 
during germination ; hence, when the albumen is absent, the 
cotyledons are generally proportionately increased in size. 
The cotyledons are commonly sessile, and their margins are 
usually entire, but exceptions occur to both these characters ; 
thus, in Geraniwm molle (fig. 773, p), they are petiolate ; while 
in the Lime (fig. 774, ¢, c) they are distinctly lobed ; and in the 
Geranium (fig. 773, c), they are also somewhat divided or lobed 
at their ends. 
The cotyledons also vary in their relative positions to each 
other. Generally they are placed parallel, or face to face, as in 
the Almond (fig. 768), Pea (jig. 16), and Bean ; but they fre- 
quently depart widely from such a relation, and assume others 
analogous to those already described in speaking of the verna- 
tion of leaves and the estivation of the floral envelopes. Thus 
each of the cotyledons may be either reclinate, conduplicate, con- 
volute, or circinate. These are the commoner conditions, and 
in such instances both cotyledons are either folded or rolled in 
the same direction, so that they appear to form but one body ; 
or in rare cases they are folded in opposite directions, and be- 
come equitant or obvolute; or other still more complicated 
arrangements may occur. 
Bren 74. iGo imos BiG F162 
Fig. 774. Vertical section of the seed of the Pansy or Heartsease. 4. Hilum. 
pl. Embryo with its radicle, 7, and cotyledons, co. ch. Chalaza. ad. 
Albumen. 7a. Raphe. The embryo is erect or homotropouns. Fig. 775. 
Vertical section of the seed of the Poppy, with the embryo slightly 
curved in the axis of albumen. Fig.776. Vertical section of the seed of 
Bunias, showing its spiral embryo. 
The position of the radicle in relation to the cotyledons is 
also liable to much variation. Thus the radicle may follow 
the same direction as the cotyledons, or a different one. In the 
former case, if the embryo be straight, the radicle will be more 
