EXPLANATION OF THE ILLUSTRATIONS 
Prare XXIII. The largest cobs, about two thirds 
natural size, found in each of the six successive 
strata in the Bat Cave material. Although there 
has been a progressive increase in maximum size 
from stratum to stratum, the type found in the first 
stratum has persisted throughout the series. 
Pirate XXIV. A. Variations in kernel size in the 
six successive strata of the Bat Cave material, nat- 
ural size. The kernels, like the cobs, have increased 
in mean size from stratum to stratum, but the small- 
est size has persisted throughout the series. B. An 
artist’s reconstruction, natural size, of the primi- 
tive pod-pop corn found in the lowest stratum of 
the Bat Cave refuse heap. This primitive maize 
shows no evidence of having been derived from 
teosinte. C. The cob from Stratum I, natural size, 
upon which the reconstruction in B is based. 
Pirate XXV. A. A cob, natural size, with promi- 
nent horny glumes produced experimentally from 
a maize-teosinte hybrid. The cob has been soaked 
in sulphuric acid to simulate aging. B, C, D, E 
and F are cobs from the upper strata of the Bat 
Cave showing teosinte introgression, natural size. 
Pirate XXVI. Bat Cave cobs, natural size, show- 
ing individual teosinte characteristics. A, B, C. 
Distichous spikes from Strata IV, V and VI, re- 
spectively. D, E. Cobs bearing some single spike- 
lets, from Strata IV and V, respectively. F, G, H. 
Three cobs which are similar in their Jw alleles, 
but which differ in the degree of teosinte intro- 
gression. 
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