654 W or s dell. — A Shtdy of the Vascular System in 
Ferns ; on the other hand, it is quite possible that they have descended 
from a Fern-like ancestor. 
In order to determine the nature of the phylogenetic history, we are 
accustomed to study that of the ontogeny under the right and proper 
belief that the latter, as a rule, is a condensed recapitulation of the former. 
But to apply this method right and left, quite regardless of the nature 
of the prevailing circumstances, as has been done by some botanists, 
is surely unwise. I am quite unable to follow the argument used by 
Professor Jeffrey — that because the stem of the seedling Monocotyledon 
possesses a cylindrical and not a scattered arrangement of the bundles, 
that therefore the scattered system, as found in the mature stem, 
has been derived phylogenetically from a cylindrical system. For, sup- 
posing, for the sake of argument, that the scattered system of bundles 
is phylogenetically the primitive one, this character could not possibly 
be found in the seedling plant, for the cotyledons and earliest foliage-leaves, 
and, therefore, a fortiori , the stem, are far too rudimentary and limited in 
spatial tissue-development to be able to exhibit anything of the nature of 
a ranked or scattered grouping of the vascular bundles ; there simply is no 
room for it ; hence the cylindrical arrangement must necessarily and 
inevitably prevail ; but in proportion as the successively-formed leaves and 
the stem increase in size does the scattered arrangement gradually begin to 
appear upon the scene. This is an excellent instance of a case where the 
ontogenetic history proceeds in a direction the precise reverse of that of the 
phylogenetic history. It is, therefore, to the adidt plant that we must turn 
in order to unravel the phylogenetic history of the vascular system. 
Assuming that the grandifoliate was the primitive condition of the 
Angiosperm, and that the vascular structure of the stem was derived 
directly from that of the leaf — and knowing, as we do, that foliar organs 
tend to retain a primitive structure for a much longer period than is the 
case with the stem, owing to the greater modification which the latter, 
as the common carrier of all organs of the plant, must necessarily undergo — 
we should expect that in a good many cases, viz. in those in which the 
leaves have not as yet followed the stem in the process of modification, 
a key to the primitive structure of the stem would be found in the present 
structure of the leaves ; and this I believe to be in many instances indeed 
the case. In these cases, e.g. many Umbelliferae, the stem possesses 
an almost what I may call typical parvifoliate structure, i. e. with bundles 
arranged in a ring ; while that of the leaf is typically grandifoliate, i. e. with 
scattered bundles. Only in rare cases do we find the converse to be true 
(e.g. Anemone rivularis). In a great many cases both organs are equally 
and similarly modified. 
Now, if we assume, for the sake of argument, the case of a plant under- 
going reduction from a parvifoliate to a grandifoliate habit, it is quite 
