SPORE-PRODUCING MEMBERS 



407 



Comparing this with Fig. 225, Which is from the axis of Calamostachys 

 Binneyana, .there is a similarity in outline of the primary stele ; but as 

 this is not constant in the species it cannot bear weight in the comparison. 

 The points of importance are, the similar canals, of like position to those 

 of 6". insigne, and like them showing the position of the protoxylem ; the 

 continuous medullary rays, and the similarity of the tracheides. These 



Fit;. 223. 



Chcirostrobns Pettycurensis. Diagram. The upper part in transverse, the lower in 

 radial section ; the position of the organs corresponds in the two sections, i. Transverse 

 section. Six complete sporophylls, each with three segments, are shown ; Sp. a = section 

 passing through sterile segments; S^.6 ditto through fertile segments, or sporangio- 

 phores ; j/=lamina of sterile segment ; ^j = downward outgrowths of sterile laminae cut 

 transversely ; $/ = their apices, transverse ; _/== peltate sporangiophores ; ^. in sporangia. 

 Note that in Sp.a each peltate lamina,/", is seen in two distinct lobes, with the sterile lamina 

 between ; v.b\, -v.ba vascular bundles of two whorls. 2. Radial section. The sporophylls 

 are separated from one airbther for clearness' sake, in nature they are in close contact. 

 ,*/.r = axis of cone; fj^its stele; ^/* = base of sporophyll. Other lettering as in trans- 

 verse section. The diagram is true to nature as regards proportions of parts, as well as 

 their relative position. X about 2. (From Scott's Studies in Fossil Botany.) 



features appear to indicate a real structural resemblance, and it is important 

 to note that the nearest approach is between the oldest of the Sphenophylls 

 and the strobilar structure of a Calamite : for according to the views here 

 advanced, it is in the strobilus that the more primitive structure might be 

 anticipated. 



A special interest in relation to the strobiloid theory attaches to 

 Sphenophyllum majus, with its ill-defined cone. It is important to note 

 that this state, so prominent in Lycopodium, is found in that species 



