470 Fr. J. Mathiesen. 



intervening parenchyma-rays. Secondary growth in thick- 

 ness takes place, and in connection with this a similar cleft- 

 formation in the phloem as in that of the root. The pith is 

 wide, and does not die away. 



The Leaf. The epidermal cells of both the upper and 

 lower surface have thin, finely poröse and almost straight 

 to slightly wavy lateral walls (Fig. 39, С and D). Stomata 

 occur only on the lower surface; they are surrounded by 

 4 — 6 cells. The transverse section shows 1 — 2 layers of well- 

 developed palisades and a spongy tissue consisting in part 

 of rather copiously branching cells (Fig. 39, A). Non-glan- 

 dular hairs of the type shown in Fig. 39, В occur both on 

 the stem and leaf; they are found in particularly great num- 

 bers on the basal portions of the foliage-leaves of the portion 

 of the stem with elongated internodes, and on the leaves 

 subtending the flowers, but more sparingly on the basal 

 portion of the rosette-leaves proper, and only singly on the 

 leaf-lobes, and then always on the upper surface. On the 

 epidermis of the lower surface, under the branches of the 

 veins of higher order, glandular hairs of the usual type are 

 found; the epidermal cells upon which the glandular hairs 

 are seated, have straighter, thicker and more highly poröse 

 lateral walls, than have those which surround them. 



Chlorophyll was present in abundance in the whole of 

 the mesophyll and was also found in the epidermis of the 

 lower surface. 



No difference could be observed as regards the anatomical 

 structure of the leaves of the rosette and of those on the 

 portion of the stem with elongated internodes. 



