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DR JOHN M‘LEAN THOMPSON ON NEW STELAR FACTS, 
cortical tissue. But whatever view is entertained of the origin of pith and other 
stelar tissues during descent, the ontogeny holds a permanent structural record 
of the stelar changes which have occurred in each individual organism. These 
changes are fully revealed only by exhaustive ontogenetic study, but even when they 
are known it is doubtful how far they recapitulate the stelar changes of the ancestry. 
On this point light may be shed by the study of related organisms. At the present 
moment the sum of available ontogenetic evidence is small, and includes fragmentary 
records. But though supplemented by a large body of fact from adult structure, 
it is still an inadequate basis for the superstructure of theory which it must bear. 
The evidences in favour of the view of intrastelar origin of pith are only in a few 
cases sufficient, while confluence of pockets, on which the theory of cortical origin 
of pith is founded, has not been demonstrated. 
In the following pages new ontogenetic facts are given for a number of Ferns. 
In some instances these are complete, in others incomplete ; but with the structural 
facts already known they may form a broader basis than has hitherto been available 
on which to found a stelar theory for the Ferns. It is held that they in no way 
support a theory of cortical origin of pith, but in each case medullation, and in 
some cases solenostely arise in the ontogeny entirely by intrastelar readjustment in 
which a change of procambial destination, as indicated above, is mainly operative. 
The facts recorded are dealt with in a rough ascending scale, but are not to be 
interpreted as constituting a strict phylogeny. 
Schizaeacese. 
Stelar Anatomy of the Sporeling of Schizsea malaccana, Bk. # 
Figs. 1-6 represent successive transverse sections of the stele of the stem, and are 
drawn to a uniform magnification. Fig. 1 is from the incomplete base of the stem. 
In the sclerotic cortex is a leaf-trace (L) which has departed from the lower portion 
of the stele. It is improbable that this is the first leaf-trace formed for this plant, 
but for convenience of description it may be referred to as such. The stelar xylem is 
parenchymatous, and is surrounded by unbroken bands of phloem (Ph.), pericycle (Pr.), 
and endodermis (En.). At A the tracheides and wood-parenchyma are segregated, 
the latter forming a definite mass to the inside of an arc of phloem and xylem (X), 
which at a higher level supplies the second leaf-trace. In fig. 2 the second leaf-trace 
(L) is almost free from the stele. It has departed in the protostelic manner, causing 
no marked disruption of the stelar xylem, but the stelar phloem is interrupted. 
An irregular bridge of endodermal cells (B) partially spans the isthmus between 
the leaf-trace and the stele. This bridge is completed in sections immediately 
following the one now figured, and the liberation of the leaf-trace leaves no gap in 
the endodermis of either leaf-trace or stele. Local segregations of wood-parenchyma 
* The sections on which the following statements are founded are Nos. 1603-1605 in Prof. Gw ynne- Vaughan’s 
collection of preparations in the Botanical Department, Glasgow University. ■ * 
