20 BOTANICAL GAZETTE [JANUARY 
The accuracy of text fig. 1 may be confirmed by reference to 
figs. 7-14. It follows from simple geometrical considerations that 
as the stem becomes more slender in its upper portion, the radially 
subtending part of the foliar ray in the thicker region 1 of the stem 
automatically disappears from view. 
The cambial conditions in dicotyledonous herbs are illustrated 
by text fig. 2, in which a represents the stouter lower region of the 
aerial axis of an herbaceous Potentilla. There are 5 outstanding 
segments of the stem, alternating with 5 depressed. The pro- 
jecting portions of the wood cylinder dine the presence of a cam- 
bium, indicated by a heavy line separating the xylem and phloem. 
In the depressed segments the wood has become largely parenchy- 
matous storage tissue, subtended inwardly by the vascular foliar . 
