found only occasionally in Mexico and in the southwest- 
ern United States, where at least two varieties are cul- 
tivated by the Hopi. Runner bean use by the Hopi is 
almost certainly an historic introduction in view of their 
absence from archaeological sites thought to be associated 
with Hopi prehistory. 
In July 1957, Kaplan briefly visited Ciudad Ocampo, 
below the Sierras in which the caves are situated, taking 
with him pods of the excavated Phaseolus coccineus and 
seeds of purple variegated and self-colored, white, modern 
runner beans. During the Sunday market, residents of 
Ocampo and others from villages higher up in the Sierras 
were shown the samples and asked to identify them. No 
one recognized the seeds or pods as belonging to either 
wild or cultivated plants with which they were familiar. 
It is safe to conclude that P. coccineus is not now utilized 
in the area in which the excavations were made. 
The archaeological runner bean pods, notwithstanding 
their morphological similarities to modern types, differ 
from them in certain microscopic features. Some of these 
differences are quantitative and are related to cell-wall 
thickness and fiber-cell size. Furthermore, the archaeo- 
logical pods are more tightly twisted than are those of 
modern cultivated varieties. Most striking is the abun- 
dance of sclerids or stone cells in the archaeological ma- 
terial as contrasted with their absence in modern runner 
bean pods. Although the reduction of sclerids in the 
domestication of fleshy fruits is of obvious adaptive value, 
it would not constitute a selective factor in the domesti- 
‘ation of beans. Even if the pods were used in the green 
state, it is doubtful that the appearance of more edible 
varieties with fewer stone cells ever occurred as the re- 
sult of human intervention. Since these stone cells affect 
qualities of pods which would be used in the immature 
state, any selection for their reduction would have re- 
[ 48 | 
