CYCADEAE, MEDULLOSEAE. IO i 



be found in Cotta 1 first and next in Goppert 2 , and lastly and especially 

 in the new memoir on the group by Goppert and Stenzel 3 (Fig. 6). 

 In Medullosa stellata, Cotta, the oldest described species, we observe at 

 the first glance a double peripheral secondary growth interrupted here 

 and there by broad medullary rays, and almost always forming the outer 

 boundary of the specimens since the cortex is usually wanting. The 

 broad pith is traversed by so-called star-figures, annular woody bodies of 

 small diameter and radial structure. If their transverse section is circular, 



var. 0, major, G. and Stenz. 5 , from the same authors. 



they are termed by Goppert and Stenzel star-rings (Fig. 6, C ) ; if the section 

 passes through the ovoid into an elongated linear form, they are known 

 as plate-rings (Fig. 6, ). If we examine these rings more closely, we find 

 that each of them answers to a normal secondary growth, which has 

 developed its bast-layer on the outer, its woody layer on the inner side. 

 The plates of wood are narrow, the medullary rays which lie between them 

 increase greatly in breadth towards the outside, and the alternation of the 

 two causes the radial structure of the ring. The tissue in the centre of 

 the ring is unfortunately always destroyed, but in the case of the elongated 

 plate-rings there can be little doubt that, like the rest of the parenchyma 

 of the pith, it represents a partial pith in each ring. This may also have 

 been the case with the star-rings. On the other hand, the star-rings may 



1 Cotta (i)." 



und Stenzel (11). 



Goppert (3). 



Goppert und Stenzel (11). * Goppert (3). 



Goppert 



