OF THE FOSSIL PLANTS OF THE COAL-MEASUEES. 
491 
represents the section viewed as an opaque object, in which the white crystallized car- 
bonate of lime with which the fistular pith is filled, and which has also occupied these 
canals, causes them to stand out with remarkable clearness. In the example of Gala- 
mopitus described in my previous memoir, I figured some sections of the vascular bundles 
going off to the branches where the vascular tissues were so conspicuous and had so 
remarkable an arrangement as conclusively to demonstrate their true character ; and 
though in the specimen under consideration the similar structures (fig. 25, m) are not 
so highly developed, there is no question that in both examples their nature is the same. 
These facts do away with the possibility of the canals in question having any direct 
relationship with the branches. 
At the Meeting of the British Association at Liverpool, Mr. Carruthers suggested 
that these organs were points from which roots had been given off. Such, however, 
cannot have been the case, since in the specimens in which they occur they exist 
throughout the entire length of the stem from its base to its summit. Moreover they 
are located in the centre of the cellular tissue of the upper part of each primary medul- 
lary ray, whilst, as I shall immediately demonstrate, there is abundant evidence proving 
that the roots were given off from the lower part of each internode. The position 
of these canals in relation to each internode of the stem — their isolation, internally amid 
the cellular tissue of the medulla, and externally in that of the primary medullary ray 
— the obvious mode of their formation, 1st, by the rupture, and, 2nd, by the absorption 
of those cellular tissues — the entire absence from every example yet examined of all 
trace of vascular tissue, either in the medulla from which they spring, or in that accom- 
panying them in their outward course — and finally, the circumstance that they are 
always filled with the same inorganic material as that which occupies the fistular cavi- 
ties of the pith, are facts pointing irresistibly to a common conclusion, viz. that these 
organs were narrow canals, arranged in a verticil immediately below the transverse medul- 
lary septum of each node, and that they formed channels of communication through the 
woody zone, between the uppermost part of each internodal fistular cavity and the inner 
surface of the bark'*. Being fully convinced that such is their true nature, I propose to> 
recognize them by the name of “ infranodal canals ” instead of “ verticillate medullary 
radii,” which I formerly applied to them. 
In the tangential section now figured, these canals exhibit an ohlong contour ; in all 
those described in my preceding memoir on the subject they were round . It will he 
seen that these differences correspond with what we find in the more ordinary, structure- 
less Calamites of this class occurring so frequently in beds of shale and sandstone. 
Having described the more important varieties of structure seen in our specimens, I 
will now endeavour to correlate these with the common forms so frequently seen in 
cabinets. 
* I have represented one of these canals at l in the restored fig. 1, hut ha.ving no conception what effect they 
had upon the hark, I have represented the latter as extended across their open extremities. This arrangement 
of the bark is purely hypothetical ; the canals may have penetrated it as well as the ligneous zone. 
