HICK : CALAMOSTACHYS BINNEYANA. 
281 
On the accompanying plate he gives a figure (fig. 3) which is 
referred to as illustrating this structure, but the section it represents 
is an oblique one, and the figure is not conclusive as to the central 
position of the vascular tissue. 
Binney in his account of the axis is somewhat lacking in precision."' 
Without quoting his exact words it will suffice to say that from his 
description and figures there can be little doubt that he regarded 
the central part of the axis as being composed of vascular tissue of 
the scalariform type. His figures which were admirably drawn by 
Fitch, represent two transverse and four longitudinal sections. In 
the former, the elements in the center of the axis remind us much 
more of parenchyma than of vascular tissue, while the latter not 
being exactly radial, are certainly not decisive of the vascular 
nature of the central part of the axis. 
Williamson has dealt with the minute structure of the axis in 
several of his memoirs on carboniferous plants. In Part L.f without 
entering into details, he insists that the axis differs widely from the 
stem of Calamitps, stating that " the vascular tissues are all found 
in the central part." In Part V.,J the strobilus is subjected to a 
detailed description, as a result of which the center of the axis is said 
to be " composed of a cluster of barred vessels," and an enlarged 
figure of part of a transverse section of the axis is given to illustrate 
this feature. In Parts IX. | and X.§ the same view is maintained, and 
in the latter we have additional figures, both longitudinal and trans- 
verse, in the former of which the central tissue is drawn as consisting 
of elongated vascular elements with scalariform markings. In Part 
XV.H however a change is made in the mode of description, and the 
central part of the axis is spoken of as containing a " quasi-medullary 
cellular parenchyma." Finally, in the first part of an index to the 
Memoirs,*" a foot-note is inserted stating that " there has been much 
difficulty in defining the structure of this axis which varies much in 
different specimens." At the same time it is added that the center 
* Loc. cit., pp. 23-27. t Op. cit., Part I., 1871, p 501. 
t Op. cit., Pb. v., 1874, p. 61. || Ibid., Pt. ix., 1878, p. 334. 
§ Ibid., Pt. x., 1880, p. 503. r Ibid., Pt. xv., 1889, p. 160. 
** Proceedings of the Manchester Literaiy and Philosophical Society, 1890-91. 
Reprint, p. 14. 
