Taster I. Six isogenic stocks, differing in alleles at the 7'u locus, com- 
pared in various characteristics. 
Genotypes 
Characteristics TuTu, Tutul| Tutu \tubtu’ | tubtu | tutu 
Total weight inflorescences, gms. 28.9 | 39.9 | 72.2 | 98.9 | 133.3 | 180.1 
Weight of tassels 28.9 | 18.3 | 12.7 9.2 6.7 4.9 
Weight of ears 0.0 | 21.6 | 59.5 | 89.7 | 126.6 | 125.2 
Percentage of total in ears 0.0 54.1 | 82.4 | 90.7 | 95.0] 96.2 
Percent pistillate spikelets in tassels 79.9 0.9 0.0 0.0 0.0 0.0 
Average length staminate glumes, cms.| 2.7 1.9 1.7 1.4 1.2 1.0 
Total weight of cobs, gms. 0.0 6.4 | 20.6 | 24.5 | 24.0] 22.7 
Weight of pistillate glumes 0.0 5.3 | 16.5 | 17.7 | 14.2 8.7 
Weight of rachises 0.0 1.1 4.1 6.8 | 10.5 | 10.9 
Percentage of total in rachises _ 17.2 | 19.9 | 27.8 | 42.5) 55.6 
glumes, which are not needed in cultivated maize, has 
been accompanied by an increase in the size and weight 
of the rachis, which is both the grain-bearing structure 
and the container of the system of supply. In short, a 
substantial part of corn’s evolution under domestication 
can be explained by a change in the hereditary material 
at this single locus. No such profound and significant 
changes in the direction away from a wild plant toward 
a highly useful, domesticated one can be demonstrated 
for teopod or corn grass or any other character in corn. 
Perhaps it should be stated that we do not regard the 
monstrous pod corn represented by the genotype 7'u Tu 
in this particular series as a model of the ancestral form. 
It probably does have some of the essential characteris- 
tics of wild corn—tassel seeds, long glumes, slender ra- 
chises—but in highly exaggerated forms. Consequently 
a comparison of the six genotypes on this particular ge- 
netic background provides a kind of biologically magni- 
fied view of some of the changes which have occurred in 
evolution under domestication. 
[ 842 | 
