98 THE UNIVERSITY SCIENCE BULLETIN. 



One or several inner rows of cells, or almost all the inner half, 

 of the innermost anomalous xylem zone, on certain sides of stem 

 in some cross sections of region V (fig. 25, c'), and in all cross 

 sections of regions of stem below, is made up of thin-walled 

 cells, which resemble pith cells in cross section in shape and 

 relative size and have cellulose or slightly lignified walls (figs. 

 54 and 55). The rest of this zone is of the usual xylem struc- 

 ture (fig. 25, d'). 



Spiral tracheae are not pi-esent in the xylem of anomalous growth. 

 The tracheae are arranged in radial rows associated with other 

 tracheae scattered through each xylem zone (figs. 26 and 51), or 

 have a very irregular arrangement (figs. 50 and 53). The lumina 

 of the tracheae are usually circular in shape, but some are oval. 

 The lumina of the tracheae range from .010 to .080 mm. in diam- 

 eter, being relatively quite large, when compared with the lumina 

 of the tracheae in other members of the Chenopodieae. Solereder 

 ('08) states the usual diameter is .015 to .045 mm. in the Cheno- 

 podieae. 



The lumina of the tracheae are usually larger in the xylem zones 

 (fig. 53, 2?) external to the innermost xylem zone (fig. 51, p), but 

 the number of tracheae and the sizes of the lumina of the tracheae 

 are the same for relative areas of each of the xylem zones exterior 

 to the innermost xylem zone. 



In cross sections the wood fibers appear irregular in shape and 

 arrangement (fig. 53, o"), or may be rectangular or almost square 

 and arranged regularly in radial rows (fig. 57). 



The innermost anomalous phloem zone has been described 

 above. The other phloem zones resemble the innermost phloem 

 zone, but are somewhat broader, being composed of larger groups 

 of phloem (fig. 57, s), larger regions of secondary medullary ray 

 tissue (fig. 57, r), and two or more rows of pericycle cells located 

 exterior to the phloem groups and secondary medullary rays 

 (fig. 57, t). The anomalous phloem, although the cells are larger, 

 resembles the phloem of the primary vascular bundles (fig. 57, s). 

 The cell walls of most of the secondary medullary rays lignify to 

 some extent, but are thin (fig. 57, t). A few cells of a secondary 

 medullary ray, the walls of which are cellulose, are shown in 

 longitudinal section in fig. 59. The pericycle cells, in each phloem 

 zone, located exterior to the phloem groups and secondary medul- 

 lary rays (fig. 58, t) are similar to the cells of the secondary medul- 

 lary rays in size, shape and nature of cell walls. A longitudinal 

 view of these pericycle cells is shown in fig. 60. 



