S2 JOURNAL OF THE [July. 



lary rays, and show a slight tendency to border pits when adjoin- 

 ing elements so marked. At I another very common form is 

 ■shown. These latter cells would correspond to Sanio's interme- 

 diate tissue, in that they are libriform, contain food, and have all 

 the characteristics of parenchyma; but in no case could oblique, 

 slit-like markings be found. The libriform tissue, L, affords ex- 

 cellent examples of sclerenchyma. The cells appear stratified, 

 showing a Hgnified outer wall, a thicker middle layer, and a homo- 

 geneous gelatinous inner layer (Fig. 1 1). The fibres often appear 

 filled with the granular residue of the cell contents. In no case 

 examined did they show striation or pitting. In the first year 

 their growth appears very regular, but thereafter the ends extend 

 themselves at sharp angles radially and tangentially. Thus the 

 wood offers much resistance to splitting along any plane and 

 gives great toughness to the vine. 



The medullary rays extend in uni- or multi-seriate radial rows 

 through the wood, the wider bands extending to the pith, while 

 narrow ones appear between, formed each succeeding year as the 

 dilatation of the stem continues. In tangential sectron their 

 mode of origin from the cambium cell is evident. Considering 

 now the phloem, it will be seen to be composed of bundles of 

 sclerenchyma alternating with rows of parenchyma and sieve 

 tubes. The regularity of this arrangement is often interrupted 

 by the unequal growth of the parenchyma and the dilatation of 

 the medullary ray. The sclerenchyma, B, resemb'es closely the 

 fibres of the xylem. They exceed it, however, in length, but not 

 in thickness (Fig. 13). The outer layer is less Hgnified than 

 that of the wood, while the cartilaginous layer is greatly devel- 

 oped, often filling irregularly the entire lumen. Apparently 

 there is no middle lamina (Fig. 14). Scattered through the 

 sclerenchyma are fibres containing crystals. These septate cells 

 were not without occurrence in the wood, especially in the older 

 zone. In the bast they appear the first year and become at once 

 its most pronounced feature. These crystal-bearing fibres seem 

 to arise directly from the cambium, and have the general form of 

 the bast. After the formation of the crystals each is separated 

 by transverse divisions of the fibre. From twenty to thirty of 

 these crystals appear in a fibre, each chamber being nicely pro- 

 portioned to the size of the crystal. The fibres are not lignified, 



