Seedling Structure of Gymnosperms . II. 197 
Series D. Nine cotyledons. The changes resulting in root-structure 
were the same as described for the previous individual, the vascular ring 
was, however, so close as to render the absolute identification of the 
separate bundles almost impossible. A triarch root resulted ; and of the 
cotyledons, three may be considered subsidiary and the rest, half-cotyledons. 
The transition took place in a manner identical to that followed by Abies 
pectinata (see Diagram 2, Figs. 1, 4, 5, and 6). 
Picea nigra , Link. The number of seed-leaves is six or seven, and the 
rearrangement of their vascular tissues takes place as in P. ajanensis and 
requires no further detailed description. Attention, however, may be drawn 
to one seedling (Series C). It has been seen that one seedling of Abies 
sibirica provided an example of a tetrarch root-structure becoming triarch in 
a very short space ; this particular seedling of P. nigra illustrates the same 
change in a more marked degree. The plant had seven seed-leaves, the 
bundles of which behaved in a normal fashion ; two gave rise to one pole 
of the root, and two, together with a subsidiary strand, gave rise to another, 
the remaining two commenced to rotate so that it was naturally expected 
that a triarch root would result. This, however, did not occur ; the last 
pair of bundles mentioned, which commenced redistribution of their vascular 
elements, stopped the rearrangement so that a diarch root resulted. 
These changes recall the similar ones which occur in some species of 
Mirabitis. 
Picea morinda , Link. The seed-leaves vary from eight to ten, and 
the transition-phenomena are the same as in P. ajanensis , a triarch root 
being formed. 
Picea alba , Ait, is described by Dangeard 1 . The number of seed- 
leaves varies from five to seven, the mesophyll is homogeneous and resin 
ducts are absent. In the case of a seedling with six cotyledons, the 
transition resembles in all essentials that described above for P. ajanensis. 
Cedrus. 
The cotyledons are numerous, varying in number from nine to eleven, 
which is in agreement with the number found by Masters 2 . Their structure 
calls for but little comment; each has a single vascular bundle which is 
endarch throughout the whole length of the member. Transfusion tra- 
cheides in our material were absent ; older cotyledons might exhibit them, 
for a certain number of immature elements occurred in places where they 
might be supposed to be formed. Fibrous elements occur on the dorsal 
side of the soft bast, and secretory cells also are abundant. Resin ducts 
are present in the seed-leaves of C. Deodara ; but are absent in the cotyle- 
dons of C. atlantica. When present, there are two resin-canals in each leaf, 
one being situated in each of the dorsal corners. 
1 Dangeard : Le Botanist e, iii. 1892. 
2 loc. cit. 
