500 Tansley and Lulham . — A Study of the 
TABLE SHOWING THE DIFFERENT STAGES OF PROGRESSIVE COMPLICATION 
IN THE RHIZOME AND LEAF-TRACE {continued). 
( 2 ) Starved intermediate plants. 
Stage. 
Plants 
in which 
it occurs. 
Rhizome. 
Leaf -trace. 
Internode. 
Node. 
VIII. 
G. 
As in VII : but 
internal phloem 
of second cylin- 
der constant. 
As in VII. 
Horseshoe-shaped in section, 
with incurved abaxially di- 
rected xylem-hooks. 
IX. 
H. 
Second cylinder 
solenostelic. 
Second cylinder filling gap 
made in first and entirely 
supplying the lateral loops 
of the trace. 
Horseshoe-shaped in section, 
with incurved abaxially (back- 
wardly) directed limbs form- 
ing the lateral loops. 
( 3 ) ‘ Adult' plants. 
X. 
As in IX. 
As in IX. 
Adult type ; i. e. horseshoe- 
shaped section with incurved 
abaxially (backwardly) direct- 
ed limbs continued by again 
incurved adaxially (forwardly) 
directed ones, so that the lateral 
loops are spirally twisted on the 
sides of the primitive arch. 
Adaxially directed limbs not 
continued down to actual in- 
sertion of trace. 
XI. 
As in X, with 
sometimes a 
third protostelic 
cylinder (dia- 
gram). 
Supply of lateral loops of 
trace (arising from second 
cylinder) branches on each 
side into two ; an inner 
division which supplies the 
abaxially directed limb, 
and an outer division 
which supplies the ad- 
axially directed limb of 
the lateral loop. 
Adult type ; adaxially directed 
limbs continued down to the 
insertion of the trace. 
XII. 
Three concentric 
cylinders of 
which the third 
(innermost) is 
either proto- 
stelic (with 
solid xylem), of 
Lindsaya - type 
(with internal 
phloem), or so- 
lenostelic (dia- 
gram). 
The nodal connexion of the 
second cylinder with the 
first takes place far for- 
ward in the node (often 
in front of the area of in- 
sertion of the trace), by 
the gradual raising of the 
roof of the second cylin- 
der till it comes in con- 
tact with lateral loops of 
the trace or their continua- 
tions forward (diagram). 
The third cylinder joins 
the second in front of the 
node and closes the gap 
formed in the roof of the 
second. 
Adult type ; the ultimate ad- 
axially directed limbs of the 
lateral loops continued down- 
wards and forwards as flanges 
attached to the edges of the 
gap in the second cylinder. 
