194 
E. Drabble. 
empty cottage with a big room, on the end of the marsh. This was 
turned into a temporary laboratory, where the necessary weighings, 
titrations, and dryings were carried on. Most of the apparatus 
employed has been left at this cottage, which will be available for 
future work. 
Section III. completed and extended the general map made 
last year, and levelled the whole area. 
Of minor pieces of work, outside the sectional organisation the 
following may be mentioned. Countings of the numbers of seed¬ 
lings on given selected areas at different periods between April 
and September were made, so as to trace the course of competition 
etc., on the annuals during the growing season. Last year’s “ grid- 
system ” was re-surveyed and the changes noted. A good zonation 
in the jf uncus -association was discovered and mapped. 
The organisation of the expedition worked exceedingly well 
and smoothly. As a part of the training of advanced students it is 
felt that these expeditions are of very high value. As a scientific 
investigation the particular piece of work grows in magnitude and 
complexity as attempts are made to face the various fundamental 
problems involved ; while it certainly does not diminish in interest 
and attractiveness. A. G. T. 
A NOTE ON VASCULAR TISSUE. 
By E. Drabble. 
O many leading anatomists have endeavoured to exalt the 
central cylinder of vascular plants into a tissue system of a 
nature quite distinct from the ground-tissue (or according to most 
authors the cortex) that it might almost be concluded that this view 
had been established. Nevertheless there is a point of view from 
which the structures in question assume a totally different aspect. 
As indicating certain difficulties in accepting some of the views 
that now to a large extent hold the field, rather than as an attempt 
to advocate any alternative scheme, the following notes have been 
put together. 
Only two theories will be considered at any length. In the first 
place we have the conclusions drawn by Mr. L. A. Boodle as the 
result of his extensive work on the anatomy of various groups of 
ferns (1,2,3), and according to him the most primitive existing 
form of cylinder is the so-called protostelc —a central strand of xylem 
surrounded by phloem with a ring of endodermis enclosing the whole. 
By the non-development of tracheidal tissue in the centre of the 
