i 36 Jeffrey* — Infranodal Organs in 
in which it is ordinarily employed in the literature referring 
to the Equisetales, viz. as equivalent to the so-called nodal 
wood 1 . In the memoir of Williamson and Scott 2 on Cala- 
mites, the term node is used in the ordinary botanical sense, 
viz. as marked by the exit of the leaf-traces. This different 
use of the term is the less apparent because these authors 
continue to employ the expression, ‘nodal wood/ for the 
peculiar tracheary zone just above the insertion of the leaf- 
traces (i. e. node in their sense). It would seem to be pre- 
ferable to abandon this term altogether and to designate 
the tracheary zone the supranodal wood, especially since 
the branches which they describe as originating ‘ above the 
node ’ are directly attached to the peculiar zone in question. 
It will be apparent from the above statement that, in regard 
to the mode of origin of branches in Equiseta and Calamites, 
there is no real difference of opinion between the writer and 
the authors cited above. 
In the sixth paragraph of the conclusions the statement 
is made that ‘ the more conspicuous series of nodules on the 
medullary casts of Calamites are impressions not of William- 
son’s infranodal canals, but, on the contrary, of the short, 
cylindrical medullary cavities of modified rhizophorous 
branches, homologous with those of living Equiseta.’ This 
statement rested on a number of data. 
In the first place, the writer has called attention to the 
fact that in Equisetum the leaf-traces lie above the woody 
cylinder of the branches in the cortex of the main axis 3 , 
although they are originally below them 4 . In nearly all the 
figures which represent the stems of Calamites with the 
surface preserved ( Calamitina of Weiss), the leaf-scars are 
placed below the branches. The writer argued, since ‘the 
Calamite, so far as anatomy goes, is simply an Equisetum 
with secondary thickening 5 ,’ it was extremely improbable 
1 Cf. Seward, Fossil Plants, 1898, p. 251, and especially description of figure 
on p. 252. 
a Phil. Trans. Roy. Soc., vol. clxxxv (1894), B. 3 Op. cit., Plate 29, Fig. 2. 
4 Op. cit., Plate 26, Fig. 16. 
3 Scott, Studies in Fossil Botany, 1900, p. 23. 
