TrsoucHiNA Moricanbiana, BAILL. 249 
tip. The decision upon this point must, however, be held over 
for determination hereafter, as also must be the meaning of 
certain curious thick-walled cells that are visible in the cortex. 
My thanks are due to Professor Bayley Balfour, under 
whose direction this investigation has been carried out ; also to 
Dr. A. W. Borthwick for many valuable suggestions. 
EXPLANATION OF THE FIGURES IN PLATE 
XLVII. 
Illustrating Miss Chandler’ s Paper on ‘‘ oo Roots in Tibouchina 
Moricandiana, Bai 
Aerial roots, r, on growing plant. 
itto. f 
Aerial root swollen at the end and with shee of branch rootlets. 
. Aerial root swollen at the end and with two unequal lobes. 
Aerial root swollen at the end and with one normal branch behind the 
extremity. 
Aerial root ending in two lobes formed by fusion. 
Aerial root like that in Fig. 
Aerial root spread out in a esduted manner and ending in three lobes. 
Aerial root, undivided, showing transverse wrinkling. 
o. Diagrams illustrating arrest and fusion of the aerial root. 
>| 
— 
2S 2 2S 
GPO pm 
a 
s? ee 
A. The primary aerial root, P, with pith and vascular system, has 
been arrested in growth and its es has died off, whilst the 
portion behind the tip has grown out as two diverging lobes, S, 
Ss, each with a pith and surrounding vascular system. The 
cavity formed by the dying out of the root tip and tissue adjacent 
to it is bounded by an inner cambium (shaded in the figure), from 
which is formed a portion of the vascular system, V,, V,, of each 
of the divergent lobes, the other portion of their vascular systems, 
V, V,, being the direct continuation in each case of half of the 
vascular system of the primary root 
B, Illustrates the same general features as A, but here the end of 
the primary aerial root dilates to form a wider cavity, and from the 
edges of this trumpet-like expansion branch rootlets, 7, arises. 
Fic, 11. Aerial root in transverse section, showing normal structure. 
Fic. 12. The same at the older stage. 
Fic. 13. Aerial root in transverse section, level of A in Fig. 10A, showing beginning 
of Ee out of central tissue of roots after death of the tip. Inner 
cam ¢, beginning to form. 
Fic. 14. The same o hess 1 E in Fig. top. The inner cambium, zc, well formed. 
Cuticularised and collapsing cells formed from inner cambium lining the 
cavity in root. 7, possible initials of branch rootlets. 
