142 Professor Alexander Dickson on the 



punctum xegeiationis is not at the apex of the organ, 

 between the two small projecting points ; and if it be at the 

 apex then the organ must be regarded as a cladode. I am 

 quite prepared to recognise in the aforesaid projecting 

 points two rudimentary leaves ; but it seems to me that 

 M. Carriere's monstrosity proves the puncium vegetationis to 

 be at the apex, and not at the base of the organ, where 

 according to the views of Von Mohl and Strasburger it 

 ought to be. 



In attempting to controvert the opinion that the squama 

 fnictifera is cladodial, Eichler makes a statement which 

 would, indeed, furnish a strong argument against that 

 opinion, and tell similarly against my view of the 

 Sciadopitys "needle," if only it were of universal applica- 

 bilit}'. "No cladodium," says he, "not even the most 

 leaf-like, has the vascular bundles in a plane, and all with 

 their xytem on the same side ; but in all Cladodia (I 

 examined Pmscus, Xi/lojjJiylla, Carmichaelia, Phyllocladus^ 

 MilTdoibechia, and others) the vascular bundles (either 

 all of them, or at least those in the middle of the organ) 

 are arranged around a common centre, with their -xylem 

 internal, as in an ordinary stem."* I would not dispute 

 the accuracy of Professor Eichler's observations as 

 regards the cladodes of Xylopthylla, Carmicliuelia, Pliyl- 

 locladus, and Muhlenheckia ; but with regard to Buscus his 

 statement must be received with due limitations. The only 

 species of Buscus where such an arrangement can be seen in 

 the cladodial expansion are those in which an inflorescence 

 springs from the middle of the organ ; and I would sur- 

 mise that the cladodes examined by him were only of the 

 commoner species, R. aculeatus or B. Hypoglossum, in which 

 there is this complication of a mesial inflorescence either 

 in esse or rn posse. In the cladodes of B. androgyjim, B. 

 ro.ceinosus, and Myrsip)hyllum asparagoides, however, the 

 case is very different. In these, where there is the highest 

 and most leaf-like specialisation of the cladodial structure, 

 we have no such complication. In these, there is no mid- 



* Von Mohl (loc. cif., p. 19), inaking use of the same argument in support of 

 his contention that in the needle of Scixtdopitys, we have to do with a 

 foliar structure and not with a cladode, refers to the absence of " any indica- 

 tion of the circular arrangement of the vascular bundles around a central pith, 

 such as is found in the cladode of Phyllocladtis. " 



