The cupule lining in relation to the pulvinus. Evidence 
that the wings of the cupule consist of more than just a 
flap of the rind comes from the experimental in-folding 
of these structures. When these wings are bent over into 
the cavity, as can be seen in the diagram of the teosinte 
derivative (Plate IV, fig. 2), the reconstituted axis re- 
sembles more closely the structure of the pulvinus and 
associated axis (fig. 1) than it does that of the culm (fig. 
3). The resemblance of this wing-filled cupule to the 
structure of the pulvinus is revealed by close similarities 
in size, position and numbers of cells in the areas con- 
cerned of a sweet-corn inbred (Purdue 39). Although the 
total number of cells extending from the large (common) 
bundles outward through the center of the cupule com- 
bined with those through a folded-in wing exceeds by 
about thirty cells the growth which occurs between the 
large bundles and the epidermis of the barren rachis be- 
tween the cupules (Plate III, fig. 1), it nonetheless cor- 
responds almost exactly in number and size of cells with 
those which occupy the corresponding position through 
the pulvinus (Plate V). 
Evidence of a relationship between the pulvinus and 
cupule lining may also be shown by a hypothetical 
manipulation of the pulvinus into acupule. Starting with 
the pulvinus (Plate IV, fig. 1), if one visualizes a central 
split perpendicular to the epidermis extending inward to 
a point just beyond the small bundles and then diverging 
in both directions along a line parallel to the epidermis 
for the width of the pulvinus, then the flaps therein dis- 
sected will resemble in-folded wings of a cupule. By 
folding these wings out laterally and away from the 
cavity, one may produce the structure of a cupule (such 
as in fig. 2)in which all of the small bundles are removed 
to lateral wings and in which there is a layer of small 
cells (represented by cross-hatching) exposed over the 
[11 ] 
