7o 6 
Hill and de Fraine. — On the 
a similar state of affairs in the first whorl of foliage leaves. In this, and 
in the other plants dealt with, the general rule is that the number of 
the leaves in the first foliar whorl is equal to the number of cotyledons, 
and that the number of those in the second foliar whorl of the plumule 
is double the number of seed-leaves. This particular seedling of C. robusta 
had the usual number of leaves at the first plumular node, but one of them 
was very distinctly and unequally bifid at the apex ; further, the leaf, 
instead of having the normal single vascular bundle, had two, perfectly 
distinct throughout, so that a transverse section had the appearance usually 
presented by a similar section of the double leaves of Sciadopitys. 
It may, of course, be argued that this is an example of the fusion 
of two leaves, but on the whole we are of the opinion that it is an instance 
of the bifurcation of a single leaf. 
Callitris rhomboidea , R. Br., resembles Actinostr obits as regards the 
splitting of the metaxylem and rotation of the protoxylem of the cotyledon- 
traces, during the journey towards the centre of the hypocotyl. The 
rotation of the protoxylem is, however, not quite of so definite a character 
as in Actinostr obus. 
Widdringtonia Mahoni , Mast., shows a slight advance to what obtains 
in C. robusta . A bifurcation of the phloem and metaxylem in each of 
the bundles of the two cotyledons takes place within the seed-leaves, 
and is accompanied by a rotation of the protoxylem, which varies in 
amount in different individuals, and also in the cotyledons of the same 
plant. This rotation is completed during the inward passage of the 
seed-leaf-traces to the centre of the hypocotyl, so that a diarch root 
quickly results. 
Widdringtonia Whytei , Rendle, is practically identical, as regards the 
features under consideration, with W. Mahoni. The rotation of the 
protoxylem is, if anything, more strongly marked in W. Whytei , and 
takes place at a somewhat higher level in each of the cotyledons. 
One plant of this species deserves more special mention, inasmuch 
as it exhibited a fusion of the two cotyledons, strongly recalling the 
appearance of the foliage leaves of Sciadopitys . The seed-leaves were 
quite free at the tips, but at a slightly lower level they fused together 
by their edges in the manner indicated in the accompanying diagram (7). 
The transition took place in the manner already described, and illustrated 
in Diag. 7. 
ABIETINEAE. 
Taxodiinae. 
Sequoia sempervirens , Endl. The number of cotyledons, as far as 
has been seen, is two ; and structurally they do not differ in any marked 
degree from those of the foregoing plants, excepting in the fact that, in 
