Seedling Structure of Gymnosperms. II. 213 
pairs. A more careful examination shows that the members of each pair 
fuse together immediately above the cotyledonary node, thus having the 
appearance of a two-pronged fork with a short handle, which suggests that 
each pair has been derived by the longitudinal fission of a single structure. 
Fig. 4 b , Plate XV, represents an abnormal seedling with seemingly three 
cotyledons ; really, one with two slender prongs and one single member. 
Structure . The epidermis is covered with a thick cuticle, and so also 
is the outer surface of the guard-cells of the stomates, which are sunken well 
below the general level of the epidermis ; secretory cells are abundant and 
each prong of a cotyledon has three resin ducts in the upper region, situated 
one at each end and the third just beneath the hypodermis in the middle 
line of the ventral side (Diagram 9. Fig. 1). In the lower regions the resin 
ducts become more numerous, some being situated in the mesophyll. The 
vascular bundles are endarch and collateral throughout the whole length of 
the cotyledon and, at the extreme tip, consist only of tracheae. Transfusion 
elements are fairly common, more especially in the apical region. 
