with hispid surfaces do not make their appearance until 
Stratum III. Thereafter, they increase progressively to 
Stratum V and fall off again in VI, a pattern quite simi- 
lar to that exhibited by bony cobs and probably for the 
same reason. A strong introgression of teosinte into 
maize, as in some segregates from maize-teosinte hy- 
brids, results in glabrous cupules. This is not surprising, 
since the inner surface of the bony shell of teosinte, the 
counterpart of the cupule in the rachis of maize, is al- 
ways glabrous. But a smaller amount of teosinte intro- 
gression may cause the hairs in the cupule merely to be 
shorter and stiffer. Thus the hispid condition encoun- 
tered in later strata of the Bat Cave material may well 
be a manifestation of teosinte (or Tripsacum) introgres- 
sion. 
Lower Glumes. The lower glumes of an ear of maize 
vary: (a) in texture which may be chaffy, fleshy, horny 
or bony; (b) in surface which may be glabrous, hispid 
or hairy; and (c) in venation which may be apparent to 
the eye or obscured by the thickness of the tissues. The 
data in Table I reveal that there are no truly chaffy or 
membranaceous glumes such as are found in modern pod 
corn. Neither are there bony glumes such as those found 
in teosinte until we reach Stratum III. Thereafter, the 
percentage of bony glumes increases progressively to 
Stratum V and falls off slightly in Stratum VI. The in- 
duration of the glumes is almost a certain sign of teosinte 
or Tripsacum introgression. Types with bony glumes 
similar to those found in the upper strata of this material 
are readily synthesized experimentally by substituting 
one or more chromosomes from teosinte for the corres- 
ponding maize chromosome. There is little doubt that 
the strong, bony glumes evident in much of the Bat Cave 
material is the product of introgression from teosinte or 
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