cores. ‘The larger grains, 88 in number, from these upper 
levels (above 6.0 meters) presumably represent the pol- 
len of cultivated maize, and indeed many grains are well 
within the upper range of several modern varieties. Three 
grains of intermediate size and pore-ratio in the upper 
levels (8.3 and 8.6 meters) possibly represent the pollen 
of teosinte, a common weed in and around the maize 
fields in the Valley of Mexico 
today. Three grains contorm- 
ing to Tripsacum were secured 
from the upper levels of the 
Belles Artes core and, interest- 
ingly enough, one Tripsacum 
grain from the 45 meter level 
of the same core. No pollen 
— 120 p grains Clearly assignable to teo- 
Text Fic. 2. Diagram show-  sinte were found below the 3.6 
ing the pore-axisrelationship. and 3.3 meter levels respec- 
Note that the outer borders of an te “t] ek 
: 7 » Y > >»; . %f> » 4 Oo, 
the annulus (shaded portion Ively in either core (hex Ig 
. oe — 
surrounding the pore) are in- a? This May indicate that teo- 
cluded in the pore measure-  ginte did not become. estab- 
mt. (The: ratio ie deter- ; : : ; ; 
meet CI 1¢ ratio is deter- Ji hed in the Valley of Mexico 
mined by dividing the numer- . . a ; 
ies) value, in antexeng, of the. UNUL Some time alter iname- 
long axis by the numerical cultivation had begun. How- 
value,in microns,of the pore. ) ever, the total number of grains 
involved is small and the differences in levels may repre- 
sent the product of sampling. 
By far the most significant discovery is that of large 
pollen grains, closely resembling modern maize, in the 
69 and 70 meter levels in the Belles Artes core. A total 
of 19 large grains were secured, 14 of which were sufh- 
ciently preserved to permit a pore-axis measurement. Of 
the 19, 8 are well outside the extreme size-range for teo- 
sinte, as determined in this study, and of the remaining 
11, four are outside the extreme range of the pore-axis 
i aaa 
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