i 38 Jeffry. — Infranodal Organs in 
Since there was, apparently, good reason for inverting the 
figures of the surface of Calamitean stems, the question arose 
whether a similar procedure should not be adopted in the 
case of those representing the course of the branches and 
leaf-traces through the secondary wood. In Equisetum the 
leaf-traces pass very quickly above the branches on their 
upward course in the cortex. Assuming that the disposition 
of the leaf-traces in Equisetum represents the course of the 
leaf-traces in the young Calamite, the writer was led to the 
conclusion that the leaf-traces should lie above the branches 
in the secondary wood of Calamites, since in modern plants, 
even where the leaves persist for several years, the course of 
their traces is practically that which is present in the young 
stem. Compare Photographs i and 9, Pis. VIII and IX. This 
view of the matter seemed to be supported by figures of 
Williamson reproduced in my memoir already mentioned. 
In these figures certain structures, imbedded for the most 
part in the so-called nodal wood, above the infranodal strands, 
are interpreted by Williamson as the beginnings of branches. 
Williamson and Scott subsequently announced that these 
were not branches, but leaf-traces. In Equisetum foliar traces 
are never found imbedded in the nodal wood, and branches 
do not occur Over infranodal strands. By inverting these 
figures it became possible to regard these indications as 
belonging to branches. An examination of the fossils, how- 
ever, has shown that the structures in question are really 
leaf-traces and not branches. Dr. Scott 1 has recently pub- 
lished an admirable figure of a tangential section of the wood 
of a Calamite, in which the indications are clearly recognizable 
as leaf-traces, which is not the case in all the earlier figures. 
This occurrence of the leaf-traces apparently imbedded in the 
so-called nodal wood, even in sections quite close to the 
medulla, is probably to be explained by the reduction of 
the metaxylem, since a similar reduction has been shown 
by Dr. Scott to be present in the internodal strands. It 
follows, of course, if the structures figured by Williamson in 
1 Studies in Fossil Botany, p. 25. 
