BRANCHING OF CALAMITES 33 



comparable to the spurs which bear the needles in 

 Pinus. 



The position of the branches with reference to the 

 nodes and leaf- traces was precisely the same in 

 Catamites as in the recent Equisetum. The pith of 

 the branch tapered towards the point of attachment, 

 so that its actual junction with the pith of the main 

 stem was effected by a slender neck of tissue. This fact 

 is shown quite clearly by sections of specimens passing 

 through the junction of stem and branch, and explains 

 one of the most characteristic forms of Calamitean casts, 

 which in a great many cases are tapered towards one end. 

 Figs. 2 and 3 each show the medullary cast of a branch 

 in connection with that of the stem, and confirm the 

 evidence, derived from sections, that the pith became 

 gradually smaller towards the point of attachment. 

 Some of the older observers thought that the tapered 

 end was the apex, thus turning the specimen wrong 

 way upwards. 1 The root-bearing base of the main stem 

 was also tapered. 



4. Other Types of Stem. — The type which I have 

 been describing so far is, as I have already said, the 

 Arthropitys of the French authors, and this is the 

 least complex of the Calamarian stems. We have 

 seen that the structure of the wood is, after all, very 

 simple. It consists essentially of the tracheae and the 

 medullary rays — including both primary and secondary 

 rays. The differentiation is about on a level with 



1 The proof that the pith tapers towards the base of the branch has 

 enabled us to determine with certainty the upper and lower ends of 

 specimens, a point otherwise by no means easy of decision. 



3 



