PODOPHYLLUM. I 29 



parenchymatic cells down to the circle of fibro- vascular 

 biindles. The cells bordering on the epidermis are slightly 

 collenchymatic and average about 45 microns in diam- 

 eter. A great degree of polymorphism exists in these par- 

 enchymatic cells of the cortex. They vary greatly in size 

 and shape, yet in general conform to the oblong cylin- 

 drical type. The cells of the middle of this layer are on 

 the average larger than those on either side, measuring 

 about 100 microns on cross-section and 140 microns in 

 length. Most of them are filled with starch grains, and in 

 the regions of the nodes large rosette-shaped crystals are 

 frequent. The regions between the nodes are poorer in 

 such crystals in the fresh specimens. The circle of fibro- 

 vascular elements is quite irregular. The bundles vary 

 in completeness in a given cross-section, and also in differ- 

 ent parts of the rhizome. As a rule, they become larger 

 and more fully developed as the nodes are reached. 

 The bundles are distinctly separated and are typical. The 

 xylem consists of ducts, tracheids, woody parenchyma, 

 and a few wood fibres. The ducts vary from five to ten 

 in number, and are of the reticulated and pitted varieties. 

 A (ew spiral vessels are to be found in the inner angle of 

 the bundle. Tracheids are few and present no note- 

 worthy features. Woody parenchyma is not abundant, 

 and many of the bundles have no wood fibres, save in 

 the region of the nodes, where they become very marked 

 and characteristic. The cambium is irregular and deli- 

 cate, and is rarely found reaching across the interfascicu- 

 lar space to join the cambium of the adjoining bundle; 

 thus there is no well-marked cambium ring either in the 

 root or in the stem. The phloem contains sieve tubes, 

 accompanying cells, a few cambiform cells, and a few 

 bast-fibres. There is nothing peculiar in any of the 

 phloem elements, though many of the sieve tubes become 

 occluded to form keratenchyma. The sieve plates are 

 in many cases horizontal. The parenchyma of the 

 9 



