Development in Equisetum. 71 
the centre of a bundle in the lower internode. Therefore it 
shows the carinal canal of the lower internode with the 
remains of the protoxylem ; the nodal portion of a bundle ; 
the bundle belonging to the leaf. For the same reason it 
does not show either of the two side-strands of xylem seen 
in transverse section of the mature internode (g, g\ Fig. 5); 
the bundle-strands contributed to the branches ; nor the 
bundles of the upper internode ; for the bifurcation has 
carried them out of the plane of section. With this is to be 
compared Fig. 2, a corresponding diagram from a transverse 
section passing through a node and cutting two bundles about 
their points of bifurcation. The branch-bundles (bb) and the 
leaf-bundles (lb) are seen passing out almost at the level of the 
bifurcation. 
The strong development of wood in the node, as seen in 
Figs. 1 and 2, at once attracts attention, so marked is its 
contrast with the feeble development in the internodes as seen 
in Figs. 1 and 5. The greater bulk of wood in the node is a 
well-known feature (see Duval-Jouve 1 and recently Stras- 
burger 2 ), but it appears that no attempt has hitherto been 
made to trace its development or to estimate its significance. 
Fig. 3 is from a transverse section through this mass of 
wood in a mature node of Equisetum maximum. The cells 
of the wood and of the bast, towards the middle of the bundle, 
are seen to be arranged in radial rows. Fig. 4 shows two 
such rows of cells more highly magnified. Now this regu- 
larity is not noticeable among the cells either of the wood 
nearer to the centre of the stem, or of the bast nearer to the 
periphery ; and the whole arrangement suggests that a plate 
of tissue has been intercalated between two older growths by 
the activity of a cambium-like meristem. 
Examination of radial (Fig. 9) and tangential (Fig. 8) 
sections, strengthens this opinion. We see there cells similar 
to those of an ordinary cambium ; and a cell-formation re- 
1 Duval-Jouve, Hist. nat. des Equisetum, PI. VIII, Fig. io. 
2 Strasburger, Ueber den Bau und die Verrichtungen der Leitungsbahnen, 
P- 433- 
