408 RUSSELL— A CO^NIPARATIVE STUDY OF 



In the transverse section of the mature root (Fig. 4) of L. Douglasii, 

 there appears: Externally an epidermis essentially as in F. proser- 

 pinacoides. The cortex region beneath is deeper, but is of cells of the 

 same character. The endodermis and pericambium are as in F. proser- 

 pinacoides. The vascular strand is diarch, as before, but the xylem 

 plate is not uniseriate. The spiral tracheae are three in number, at the 

 outer edges of the xylem plate, much as in F. proserpinacoides. The 

 spiral vessels occupying the central part of the plate are arranged radially 

 about a central cell. There are about ten of these vessels in L. Douglasii. 



In a longitudinal section of the root tip region in Floerkea proser- 

 pinacoides the plerome cylinder is about 4 to 5 ceUs in width. Overhdng 

 the plerome is a regular periblem layer, which by its division gives rise 

 to the plerome and periblem. Over the periblem of the apex region of the 

 root is a crescentic group of cells which gives rise to both dermatogen and 

 root cap, and can therefore be called a cal}^trodermatogen layer. The 

 root cap arising from the division of this layer is conical, and about 

 five layers of cells thick in its deepest portion. 



The longitudinal section of the root tip in L. Douglasii shows the same 

 structure, differing only in having a wider plerome cyHnder than Floerkea. 



Stem 



The stem of Floerkea is weak and flaccid. It remains green, and 

 rarely branches in Floerkea. In Limnanthes Douglasii the stem is stouter 

 and is much branched, especially at its base. 



Sections of the stems of Floerkea proserpinacoides imbedded in paraffin 

 were cut, and stained in safranin and Delafield's haematoxyhn. In 

 such transverse sections, there is an external epidermal layer of small 

 rectangular cells, shghtly cuticularized (Fig. 5). Beneath the epi- 

 dermis is a layer of larger oblong cells, regular in shape, not thickened. 

 Within this is the cortical region, 6 to 7 cells in depth. The cortical cells 

 are large, round cells with thin walls. Throughout the cortical region are 

 definite circular inter-cellular spaces surrounded by a sheath of cortical 

 cells. The innermost cortical layer forms an indistinct endodermis. 

 Within the endodermis is the vascular strand. This consists of a num- 

 ber of collateral bundles, separated from each other by pith or paren- 

 chymatous tissue. There is no ring of wood formed. The bundles consist 

 of two or three spiral tracheae, and a varying number of spiral, or annu- 

 lar tracheids. The phloem is poorly developed, consisting of a few sieve 

 tubes and fewer phloem cells, forming a slightly darker stained patch 

 external to the xylem in the bundles. The two outermost layers of 



