508 MacDouGaL: SoME CORRELATIONS OF LEAVES 
The enlarged stipules exhibited a thickness four or five times 
as great as the normal, chiefly due to increase in tissues and dif- 
ferentiations toward the structure of a typical lamina. A median 
layer of loosely arranged parenchymatous tissue contained much 
chlorophyl which was almost wholly lacking from the normal 
organ. This mesophyllary tissue also exhibited numerous inter- 
cellular spaces, and was altogether well adapted to carrying on 
photosynthetic and transpiratory functions. 
The entire stipule, which is usually closely appressed to the 
petiole, was held at a more widely divergent angle than the normal. 
These adaptations have greater significance when it is understood 
that the total amount of stipular surface presented by a delami- 
nated branch would amount to about fifteen or sixteen times as 
much as the normal. This comparatively normal increase, how- 
ever, does not result in developing a foliar surface of more than 
one or two per cent. of that of the normal leafy branch. 
Sections of the sixth internode from the base of the twigs 
formed in 1903 were examined in order to ascertain the effect of 
deprivation of the laminar structures and their partial replacement 
by the stipules. It has already been pointed out that the branches 
which had been delaminated had developed more internodes, the 
total lengths of which were less than of twigs normally grown, and 
had the appearance of being slightly thicker, but no measurements 
were made which might form the basis of an exact comparison. 
- The epidermal tissues of the treated branch had greater radial 
and tangential diameters, and the underlying collenchymatous 
layers were but slightly thickened. The medio-cortex contained 
much more chlorophyl than the normal. The bast fibers were 
not so heavily thickened as in the normal, and the walls of all the 
internal tissues exhibited a slight yellowish tinge. The cambium 
showed a greater number of layers than the normal. The xylem 
was irregularly developed and seemed to have attained a less 
advanced stage of differentiation in its various elements than in 
the normal. The tangential development was notably deficient 
and the separate bundles were separated by wide rays of pith. 
On June 15 the delaminated branches had assumed the appeat- 
ance of a resting stage. The formation of leaves had ceased, and 
nearly all of the stipules had fallen off. The buds in the axils of 
