260 de Fr nine. — The Morphology and Anatomy of the 
Pflanzenstoff, der moglicherweise in der Zelle in glykosidischer Bindung 
auftritt and which he states occurs ‘ im Zellinhalte in alien parenchy- 
matischen Zellen (auch Markstrahlen, Phloemparenchyma) der Wurzel- 
rinde ’. 
Examination of the root for the presence of tannin indicates that 
a substance of this nature occurs in practically all the parenchyma cells 
of the cortex, medullary rays, and phloem, as 
well as in the cork : hence it is concluded that 
this substance is probably identical with the 
plumbagin of Tunmann, more especially since 
‘ at one time it was thought that tannins were 
substances of a glucosidic nature and occurred in 
the plant in combination with a carbohydrate 
complex such as glucose ; . . . . this is undoubtedly 
so in some cases \ l 
The cork cambium gives rise internally to a 
zone of secondary cortex. This cortex is com- 
posed of thin walled parenchyma, the majority 
of the cells of which contain plumbagin ; immedi- 
ately beyond the phloem lies a broad almost con- 
tinuous band of sclerenchyma fibres (s.f.) , while 
groups of sclerenchymatous cells or sclereidcs of 
varying sizes (w<r.) are scattered throughout the 
cortex, as is shown in Text-fig. n. 
It is evident that the structure of such a root ' 
as has been described is admirably adapted to 
the conditions under which the plant grows in 
the shingle of a lateral bank. The compara- 
tively few vessels and the narrow zone of phloem 
are in relation to the small translocation which is 
required in the very slow growing plant. The out- 
Of paToZarootofTE standing characters are the great tensile strength 
bank plant of A. binervosa. given by the predominance of fibres in the xylem, 
xyiem; 4 /f°secondary pi"lSm[ and the incompressibility provided by the sclereides 
s.f. sclerenchyma fibres; s.c. in the cortex : the combination of these two char- 
sclereides; s.co. secondary cor- . 
tex; /. periderm. acters produces even in the very slender roots a 
structure resembling a steel wire. 
An examination of the structure of the root of a plant grown from seed 
in ordinary soil reveals the effect of the habitat on the structure of the root 
in a very striking way. In Text-fig. 12 , A represents a section through the 
two-year-old root of a Main bank plant, while B is the root of a plant 
of similar age grown from seed in garden soil. The proportion of stele 
1 H aas and Hill: loc. cit., p. 205. 
