OF THE WOODY ZONE IN CALAMITE. 165 



prosenchymatous cells. This is shown in figs. 6 and 15, 

 in both of which a thin layer of cells is seen, both above 

 and at each side of each radius (/). But the case is alto- 

 gether altered in the plane above the radii corresponding 

 with the centre of the node. 



At this point the radiating vascular laminse forming the 

 wedges c in fig. 13 become detached from each other by 

 the intrusion of cellular masses, as seen in fig. 16. Some- 

 times these cells are in a single row {16 g), when they are 

 undistinguishable from the ordinary medullary rays; at 

 others, as at 16 A, h! , we have unmistakable proof that they 

 are identical with the fusiform cells of the prosenchymatous 

 cellular tracts (fig. 6 c?). It appears that at each node the 

 fusiform cells and the muriform ones of the medullary rays 

 become blended and undistinguishable from each other, 

 a connexion being thus established between these tissues 

 at each articulation, such as does not exist in the inter- 

 nodes. 



It is almost impossible to describe or delineate the 

 wonderful meanderings of the vessels as they ascend across 

 the node. One object of their windings is their redistri- 

 bution to the two nearest vascular tracts immediately 

 above the node. Fig. 15 attempts a representation of this 

 singular rearrangement, the same thing being partially 

 shown in the upper part of the similar tangential section 

 (fig. 6). The vessels of the vascular tract (15 c) diverge as 

 they pass between the two medullary radii (/,/), to be re- 

 distributed to the vascular tracts [c , c'), part going to the 

 one and part to the other, whilst many are deflected 

 hither and thither, as if unable to decide which course to 

 take. Throughout all these serpent-like contortions we 

 have abundantly displayed the arrangement represented in 

 fig. 16. But the most remarkable feature connected with 

 this redistribution is seen above the vascular tract (15 c), 

 at the portion of the node immediately below the pros- 



