346 
branches copiously when entering the lamina. This branching 
occurs in B. lanuginosum at a lower level in the petiole. Nume- 
rous cells with brown contents occur in the parenchyma of the 
leaf; they fail, however, to stain with iron chloride or vesuvin. 
Fig. 11. Fig. 12. Fies f3: 
The Root. 
The vascular system of the root shows exactly the same 
condition as described by Campbell (9) for B. virginianum: 
a tetrarch or pentarch bundle, with alternating phloem and 
exarch xylem. The endodermis is developed partly as a pro- 
tective Caspary layer, partly as a starch layer of irregular shape. 
We will consider first the lower, unwrinkled part of a root 
(Fig. 19) and study the departure of the secondary traces. 
In the case investigated (Fig. 19), two secondary roots left 
the primary root at exactly the same place. Two of the five 
root-xylems are engaged in supplying these two roots, while 
the enclosed phloem branches to form the two new phloems. 
