218 MYZODENDRON. [BOOK i. 



the disproportionate amount of scalariform tissue. The 

 structure of M. punctulatwn (another species) is however 

 far more abnormal, fibres of pleurenchyma being deposited 

 in the axis of the stem, thus replacing the pith and forming 

 very obsolete rays, and all future increment of the stem being 

 affected by an addition of layers of variously marked scalari- 

 form tissue alone, as far as I have been able to observe. 



" I shall next describe the course the vascular tissue pursues 

 in the newly formed buds and branches, and thus attempt to 

 explain the origin of the two series of woody plates which 

 this species and M. quadriflorum DC. possess. A transverse 

 section of the stem of a flower or leaf-bud made in the first 

 year of its formation, presents a mass of globular utricles, 

 covered with a delicate cuticle formed of one moniliform row 

 of cells, and traversed by one series of twenty or thirty 

 vascular bundles. These bundles descend from the base of 

 each leaf, traverse the branch and enter the stem. A trans- 

 verse section of the stem again, from which the bud or branch 

 is given off, and below the point of attachment of the latter, 

 presents two concentric series of vascular bundles, besides an 

 imperfect third consisting of a few scattered promiscuously 

 in the axis of the stem ; the outer series was formed in the 

 former, the inner is derived from the buds and branches of 

 the present year. 



" A longitudinal section through the axis of the stem, so 

 made as to pass also through the axis of the branch, clearly 

 shows that it is due to the position in which the buds are 

 developed, that a second series of wedges of wood is deposited. 

 The buds originate towards the axis of the stem, within the 

 vascular bundles of the previous year, and opposite the inser- 

 tion of the petiole. The whole of the vascular tissue 

 descending from a bud is consequently deposited within the 

 wood of the former year ; generally each bundle on entering 

 the stem from the branch divides, one portion joining the old 

 wood ; the other, remaining free, and descending the stem, 

 forms the second or inner plate of wood. The course of the 

 bundles is, however, very uncertain ; sometimes they do not 

 divide, but either join the old vascular tissue, or continue 

 free, and at others one portion crosses to the opposite side of 

 the stem. 



