ORGANIZATION OF THE FOSSIL PLANTS Of THE COAL-MEASURES. 757 
seen in transverse section of the stem, the root passing out through the cortex i ip an 
approximately horizontal direction.* 
There can be no question that these appendages were really roots. In both cases 
the organ possesses a cortex of its own, distinct from that of the stem on which it 
grows. The organs in question must, therefore, have been endogenous in origin. 
We have figured part of a remarkably fine longitudinal section from one of the 
Dulesgate specimens, showing the bases of three adventitious roots, placed one above 
the other in a vertical row (Plate 27, fig. 28). This specimen has the central cylinder, 
including the pericycle, preserved in great perfection; the cortex, however, is almost 
destroyed, so that at first there seemed to be some doubt whether the main axis 
was a root ora stem. That the latter is the case is proved by the persistent cortical 
sclerotic masses (sc.), which are quite characteristic of the stem, and also by the fact 
that another part of the section shows a leaf-trace bundle, passing through the 
pericycle. 
One of the three adventitious roots is seen in exactly median section. The con- 
nection of its tracheze with those of the primary wood of the stem is quite clear; 
the root lies exactly opposite one of the protoxylem strands of the stem. The base 
of the root has formed some secondary wood, which is continuous with that of the 
parent stem. The phloém is not shown in this root, but can be recognized in the 
next, which, as well as the third one, is cut somewhat tangentially. In all the roots 
the limits of their cortex can be traced. The stem has formed a much larger amount 
of secondary wood near the bases of the roots than elsewhere. This wood is chiefly 
developed above the insertion of the roots, @.¢., in the direction towards the apex of 
the stem, as determined by the course of the leaf-trace bundles. The pericycle has also 
undergone an enormous thickening, with tangential cell-divisions, around the bases of 
the roots. Between their bases secondary tissue, partly consisting of wood, has been 
formed in the pericycle in a very anomalous manner; much of this tissue is seen in 
transverse section, so the direction of the tracheides must have been tangential with 
reference to the stem. There seems, in fact, to have been a special “réseau 
radicifére,” as it is called by VAN TigcHeM,t in connection with the bases of these 
roots. 
In fig. 29 we have shown a curious structure which we think may probably repre- 
sent a very young root enclosed within the cortex of the stem. The section is a 
nearly complete transverse one of a good-sized stem with a considerable amount of 
secondary wood. ‘The root-like organ is embedded in the cortex,’ immediately 
beneath the outer sclerenchymatous layer, and is seen in approximately transverse 
section. 
A central cylinder can be distinguished, but we could detect no lignified elements. 
* Wiiuamson, “ Organization,” Part I1V., Plate 30, fig. 36; Part XVIL., Plate 14, fig. 14. 
+ “Traité-de Botanique,” p. 787. The same structure is beautifully shown in transverse section in 
C.N. 1915 A. 
