GKNKRAI, MORPHOLOGY 



375 



of twelve coherent Jeaves, but thkteen have been counted : the sporangio- 



phores are usually six, that is, half the usual number of the leaves of the 



sterile whorls; but seven and eight have been seen in a single whorl of 



them, while no whorl of sixteen bracts has been seen. Hence it is clear 



that the sporangiophores bear no strict 



numerical relation to the sterile bracts. 



The position of the bracts in successive 



whorls of them alternates : the successive 



whorls of sporangiophores, on the other 



hand, do not alternate, " but are placed one 



above the other in vertical rows. Hence it 



is evident that their position can bear no 



constant relation to that of the bracts." 1 



This absence of a strict relation of the 

 sporangiophores to the bracts comes out 

 also in C. Ludwigi, described in detail by 

 Weiss.' 2 He remarks of this species that 

 the number of leaves in the sterile whorl is 

 evidently variable : he made several count- 

 ings, and concludes, " accordingly it may 

 be accepted that there were sixteen leaves 

 in the whorl, but that they might be re- 

 duced to twelve (or thirteen ? ) by abortion 

 of some of them." The leaves of the 

 neighbouring whorls certainly alternated. 

 Of the sporangiophores he says, the number 

 in each whorl is six, and the successive 

 whorls of sporangiophores stand vertically 

 above one another ; but he notes slight 

 deviations from this, perhaps due to torsion. 

 A still further step is depicted by Weiss, 3 

 in the case of Calamostachys germanica, 

 where apparently the narrow bracts are 

 approximately three times the number of 

 the sporangiophores ; but this is not speci- 

 fically stated to be the case in the text. 



On the other hand, it has been shown 

 clearly in the case Palaeostachya vera that 

 the number of bracts approximately corresponded directly to the number 

 of sporangiophores, though possibly in some cases they somewhat exceeded 



1 Williamson and Scott, " Further Observations on the Organisation of Fossil Plants, etc.,'' 

 part i., Phil. Trans., 1894, B, pp. 902-3. See also Scott, Studies, p. 47, etc. 

 ~ Abhandl. z. Geol. Spezialkarte, vol. ii., part i. , p. 38. 

 A L.c. , vol ii., part i., Taf. xvi., Fig. 3 K. 



FIG. 200. 



Palaeostachyapedunculata. Specimen 

 from the coal-shales, showing a fertile 

 shoot bearing about a dozen cones, and a 

 few leaves. >t = stem. About two-thirds 

 natural size. (After Williamson, Phil. 

 Trans. Will. Coll., 1060.) From Scott's 

 Sttuiics in Fossil Botany. 



