ON THE NATURE OF STIPULES 



211 



slit has appeared the commencement of the detachment 

 of the sheath. Still a little higher (fig. 325) the petiole 

 has detached itself from the sheath, but the two together 

 have a single cavity. The fibres D and E, before entering 

 the petiole, sent out several branches, D 1 , D 2 , D 3 , and E\ 

 E 2 and E 3 . Still higher we have the section shown in 

 fig. 326. A parenchymatous band, MN, now separates the 



Fig. 327. Fig. 328. 



Polygonum lapathifolium. 



cavity of the petiole P from that of the sheath T, which 

 encloses the stem. The sheath, therefore, is an append- 

 age inserted on the node, and receiving fibres derived 

 from the foliar fibres, before the latter have left the 

 branch. 



The sheath of the Castor Oil plant (Ricinus) is 

 constituted in the same manner, and, like that of the 

 Plane, all its fibres are derived from the foliar bundles. 



p2 



