7oi 
Seedling Structure of Gymnosperms. I. 
In the case of a seedling with four cotyledons (Series C) the accom- 
panying illustrations (Diag. 4) render a long description unnecessary. 
The first figure shows four cotyledons in transverse section ; of which two 
are considerably smaller than the others. 
Just above the region of insertion of the seed-leaves upon the axis 
the two smaller cotyledons fuse together (Diag. 4, Fig. 2). The four 
traces enter the axis as collateral structures, and during the inward passage 
a and b, the bundles of the smaller cotyledons, move towards one another 
while the phloems of c and d bifurcate (Diag. 4, Fig. 3). At a slightly 
lower level (Diag. 4, Fig. 4) a and b are orientated in such a manner 
that their protoxylems face one another, and c and d are seen to behave 
in a way already described above. The remaining figures, together with 
Fig. ii, Plate XXXV, show that the strands a and b act together in the 
Diagram 5. Cupressus torulosa. Transverse sections of the cotyledons at different levels of 
the proximal region. 
same way as does either c or d separately, and form one pole of the 
triarch root. 
The consideration of these facts leads to the inference that the two 
smaller seed-leaves may have been derived from a single pre-existing one ; 
in fact, that each represents a half-cotyledon. And this is confirmed by 
the one seedling of this same species which possessed five cotyledons 
(Series D). In this plant the seed-leaves were free at the tip, but towards 
the proximal end four of them joined together in the manner indicated 
by the first figure in Diag. 5 - Just above the cotyledonary node, the 
fifth one entered and completed the ring. The fused whorl has five 
bundles, corresponding to the seed-leaves, which are indicated alphabetically 
in the second figure. 
The transition, although very much slower, followed the course 
