and T'ripsacum serve such highly useful purposes and, at 
the same time, resemble so closely the now functionless 
maize cupule, that the latter appears to be a rudimentary 
homologue of the former. For example, the lateral wings 
of the rachis-segment, which correspond to the ‘‘rachis- 
flaps’’ of the maize cupule, serve to clasp the outer glume 
of an enclosed pistillate spikelet and, in this way, com- 
plete the structure of the fruit case. Below the lateral 
wings there are hairy notches which have an identical 
counterpart in maize and which, in teosinte and T'rvpsa- 
cum, serve as openings for the entrance of water prior to 
germination and for the protrusion of the primary root 
during germination. The dense hairs in the notch ex- 
clude small insects from the enclosure and the high de- 
gree of lignification of both rachis-segment and outer 
glume perfect this structure as a protective device. 
The homology between the cupulate rachis-segment 
of teosinte and T'vripsacum and the cupule of maize can 
not be doubted, although there are usually slight differ- 
ences in these structures. For example, the lining of the 
fruit-case cavity in teosinte and T’ripsacum is frequently 
more highly lignified and less pubescent than that of the 
maize cupule. Such extreme lignification and reduced 
pubescence as are found in teosinte may also occur in the 
cupules of teosinte-contaminated maize or in vestigial 
glume (Vg gene) maize. 
NATURE OF THE CUPULE IN THE AMERICAN Maydeae 
A consideration of the nature of the cupule in the 
American Maydeae will be centered on the cupule of 
maize, because it is more variable and amenable for ex- 
perimental studies than its homologue in teosinte and 
Tripsacum. 
Depressions in internodes. Compression of axillary 
buds against the adjacent young culm is known to be 
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