R. H. Compton. 
18 
Nigella damascena which Sterckx chiefly studied. The cotyledon 
bundle is regarded as consisting of three parts, a median centri¬ 
fugal and two laterals : into these parts it breaks up on entering 
the hypocotyl, and all three are inserted on a centripetal root- 
bundle. The cotyledonary trace dies away below, just as the 
root-bundle dies away above : there is a short region of mise eu 
rapport, characterised, according to Sterckx, by the presence of 
specially short connecting vessels. “ There is no continuation 
of the vessels of the root into the cotyledons, but there exist two 
sorts of wood elements; firstly those with centripetal development 
in the root and hypocotyl; secondly those with centrifugal develop¬ 
ment in the cotyledonary node, cotyledons, stem and leaf.” The 
analytical attitude of Sterckx is perhaps expressed most clearly by 
his criticism of the writers of whom Gerard is a type, who believe 
in the continuity of the vascular tissues of root, hypocotyl and 
cotyledons. “ If the interpretation of these botanists were 
correct ” says Sterckx “ it would be necessary to admit that the 
cotyledons, contrary to other appendicular organs, Jiave no 
insertion on the axis, that they have no bundles proper to them¬ 
selves, and that their bundles are only the continuation of those 
of the root and hypocotyl: in other words, there would be no 
cotyledonary trace.” 
The recognition of a median and two lateral bundles con¬ 
stituting the cotyledonary trace is a step in advance of the views 
of Gerard and Bonnier, and of the theory of the divergeant of 
Bertrand and Cornaille adopted by Chodat. But many criticisms 
may be levelled and the interpretation of the facts. The view of 
Sterckx entails a rigid system of morphological categories from 
which, in a patchwork fashion, the plant is supposed to be com¬ 
pounded. Such a conception is impossible when the matter is 
considered phylogenetically. Morphological differentiation implies 
primitive homogeneity. This is so, whether we adopt the view 
that the leaf is an emergence from a primitively simple axis, or the 
view that leaf, stem and root alike arose by specialisation of an 
originally undifferentiated dichotomously branching thallus. The 
very existence of such an organ as the hypocotyl, which up to the 
present has resisted all efforts at classification, is sufficient to shew 
that the strict analytical morphology is insufficient, and that 
broader ideas based on comparative study and phylogeny can alone 
be satisfactory. The patchwork view of the vascular system —a 
system developed for the physiological purpose of linking differen¬ 
tiated plant-members—fail a fortiori. 
