Primulaceae. 173 



apex of the rhizome which are always distinctly collateral. 

 These bundles („steles", v.Tieghem) are surrounded by sheaths 

 having Gasparian spots on the radial walls, and vary in shape 

 from circular to oblong-arched. The walls of the parenchyma 

 show pores, and its cells contained some starch (at end of 

 July). In the proximity of the vascular bundles, the ele- 

 ments of the parenchyma are often arranged in fairly regular 

 radial rows. 



The Peduncle is provided with a 4— 6-layered scleren- 

 chyma-ring, which however is reduced to 3 — 4 layers opposite 

 each of the vascular bundles ; these latter are arranged in a 

 regular circle. In a longitudinal section this sclerenchyma- 

 ring appears to consist of elongated, cylindrical parenchyma- 

 tous cells, densely and finely pored and with lignified walls. 

 On the inner side of the ring, the sclerenchy matous tissue 

 closely surrounds the leptome of the vascular bundles, thus 

 affording some degree of protection. In the stereom, as well 

 as in the medulla, near the vascular bundles, there are cells 

 containing a brown substance, the nature of which, however, 

 could not be further determined. Outside the sclerenchyma- 

 ring the peduncle show^s 4 — 6 layers of parenchymatous cells, 

 lengthened axially and with large intercellular spaces com- 

 municating with the atmosphere through numerous stomates 

 in the epidermis. Numerous chlorophyll granules are present 

 in this parenchyma. 



The pedicels attain a thickness of about 0.75 mm, and 

 have on the whole the same anatomical structure as the 

 peduncle. 



The Leaf. The epidermal cells on the upper surface 

 are larger and have thicker walls than those on the lower 

 surface (fig. 4). The lateral walls are undulating, more so 

 on the lower surface of the leaf. The outer walls show fine 

 cuticular striations, especially near the margin of the leaf and 

 above the midrib. The stomates are level with the surface 



