38 A. G. Tansley. 
leaf-trace. (Gwynne-Vaughan ’01 ; see also 
Van Tieghem, Traite de Botanique, 2e ed., 
Tome 2., p. 1372, 1891). 
Solenostele (as used in these lectures). A stele in which the 
vascular tissue is arranged in a hollow cylinder 
of xylem, lined within and without by phloem, 
pericycle and endodermis, the continuity of 
which is interrupted by leaf-gaps which do not 
overlap. 
Perforated Solenostele. A solenostele in which gaps other 
than leaf-gaps occur. (These lectures). 
Dictyostele. A stele in which the hollow cylinder of the soleno- 
stelic type is interrupted by leaf-gaps which 
overlap. (Brebner ’02). 
Perforated Dictyostele. A dictyostele in which gaps, other 
than leaf-gaps occur. (These lectures). 
Dissected Dictyostele. A perforated dictyostele in which the 
strands of the stelar network are reduced 
to thin threads. (These lectures). 
Meristele. The individual vascular strand of a perforated soleno¬ 
stele or of a dictyostele. (Brebner ’02, not Van 
Tieghem). 
Monocycly. The condition of a stem which possesses a single 
stem cylinder, whether haplostelic, solenostelic 
or dictyostelic. (These lectures). 
Polycycly. The condition of a stem which possesses accessory 
vascular strands or cylinders in addition to the 
principal cylinder. (These lectures). 
Di-, Tri-cycly. The condition of a stem which possesses two or 
three concentric vascular cylinders. (These 
lectures). 
Note.—T he use of the terms polystely, gamostely, dialystely should 
be discontinued altogether, so far at least as the ferns are 
concerned. No phenomena are known in the Filicinean 
series corresponding with these concepts. 
BIBLIOGRAPHY. 
In the following List of Titles no attempt has been made at completeness, 
but all the works on the morphological anatomy of the vascular system of 
ferns which have been directly referred to in the text have been cited. 
1. Arber, E. A. Newell. “ On the Past History of the Ferns.” Ann. of 
Bot., Vol. 20, London, 1906. 
