with secondary bundles, the cxtra-fascieular cambium, and 

 the ccHular rind still covered with epidermis, immediately 

 beneatli which the cork is beginning to be developed from a 

 j)hellogen layer. In that figure he correctly represents the 

 libriform fibres of the rind as forming a nearly continuous 

 layer. In older stems, however, such as that 1 have figured, 

 these fibres become considerably separated from each other 

 by the general growth and expansion of the rind-paren- 

 chjma. Libriform fibres similar to those of Bougainvillca 

 have been described by Eegnault and Petersen in Fisonia. 

 It is to be noted that in the young stem there is very little 

 parenchyma to the inner side of the libriform fibres, while 

 in the older stem there is a considerable amount of what 

 may be called secondary rind-'parciichyma, internal to the 

 libriform fibres, developed out of the extra-fascicular cam- 

 bium, and consisting of cells disposed in radiating lines as 

 seen in transverse section (Plate III. (6), fig. 2, srp.). The 

 wood-cells are very irregularly disposed, and, from the way 

 in which they often pass gradually, so to speak, into the 

 adjacent parenchyma, seem to be little more than a prosen- 

 chymatous modification of the ground-tissue. With regard 

 to the occasional reticulated septa across the ducts, I may 

 mention that my pupil, Mr Robert Kidston, has discovered 

 in both stem and root of Tccovia radicans similar occasional 

 septa, which are almost indistinguishable in appearance from 

 those of Boufjainvillca. 



As to Testudinaria elephantipes, I cannot find any reference 

 to the remarkably beautiful septa across the large ducts, 

 although I scarcely think they can have escaped observa- 

 tion. The occurrence of several tracts of soft bast which I 

 have noted in the bundles in this plant, has already been 

 indicated as a characteristic peculiarity in Dioscorca and 

 Tamus by Guillaud.^ 



ALEXANDER DICKSON. 



December 1881. 



1 Guillaud, " Anatomie de la Tige des Monocotyledones," Ann. dc Sc. Nat., 

 VI. Ser. {Botaniquc), tome v. \). 167. 



