Notes on the Conducting Tissue-System 
in Bryophyta. 
BY 
A. G. TANSLEY, M.A., 
Assistant Professor of Botany , 
AND 
EDITH CHICK, B.Sc., 
Quain Student in Botany , University College, London. 
With Plates I and II. 
Introductory. 
I T was in 1813 that A. P. de Candolle separated the groups 
we now call Pteridophyta and Phanerogarnia under the 
common name of Vasculares from the Cellulares (Bryophyta 
and Thallophyta). Although the term ‘vascular plant’ 
(Gefasspflanze) has lost in the light of modern anatomical 
knowledge its literal significance as applied to plants con- 
taining vessels formed by the fusion of cells, it is still 
commonly and usefully applied to the Pteridophytes and 
Phanerogams as possessing a double conducting or ‘ vascular 5 
system of well-differentiated type. In this, two definite tissue- 
elements — the tracheid and the sieve-tube— are the respective 
essential components of the two conducting tissues— the 
[Annals of Botany, Vol. XV. No. LVII. March, 1901.] 
B 
