Jan. io, 1914 
Drought-Resisting Adaptation in Maize 
299 
planting maize the soil is sandy, and in the absence of spring rains the 
surface layers are, of course, very dry. (See PI. XXXI, figs. 1 and 2.) 
The seed, to germinate at all, must be planted deep enough to be in con¬ 
tact with the moist soil. In Navajo fields near Tohatchi, N. Mex., plants 
were dug up, and the remains of seeds were found at depths ranging from 
13 to 18 cm. below the surface. Similar depths were found in a Zuni field 
near Black Rock, Ariz. (See PI. XXXI, fig. 1.) In a Hopi field at 
Polacca, Ariz., near the First Mesa, where the conditions are extreme, 
the seed had been planted at a depth of 25 cm. (See PI. XXX, fig. 1.) 
It thus appears that there is no fixed depth for planting, the custom being 
to plant deep enough to place the seed in moist soil. If the seed were 
planted at ordinary depths, germination might be delayed until the 
latter i part of June or the first of July, at which time the rains usually 
occur; or if the seeds germinated as a result of one of the occasional 
showers occurring in May, the plants would die from subsequent desic¬ 
cation. 
Like the long mesocotyl, the simple radicle of the Pueblo varieties of 
maize may be looked upon as an adaptation to the extreme conditions that 
exist where these types are grown. For six or eight weeks after planting, 
no rain can reasonably be expected, and during this time the moisture 
is constantly receding from the surface. By concentrating the energy 
of the seedling into a single root the latter is forced to greater depths and 
consequently kept in moister soil than would be the case were a number 
of seminal roots developed. 
Under ordinary conditions, where moisture is distributed through the 
entire seed bed, the seminal roots become of little importance as soon as 
the seedling is established and nodal roots have developed. If a half- 
grown or nearly mature com plant is carefully dug up, the seminal roots 
and traces of the seed can still be found, but they are usually dry and 
shrunken and are obviously of little use to the plant. This was also the 
condition found in Navajo and Zuni maize fields, though the seminal 
root was more strongly developed than in the eastern varieties. (See 
PI. XXIX, fig. 2.) But in the more extreme conditions existing in the 
fields near the Hopi villages, where the seeds were planted deeper, it was 
found that the seminal roots were relatively much larger and were still 
alive and fresh, making it apparent that they retain their function of 
supplying moisture and are able to play an important part during the 
entire life of the plant. 
In one Hopi field at the base of the First Mesa the hills of maize were 
planted about 20 feet apart, with from 10 to 20 plants in a hill. The 
soil was apparently pure sand washed down by the winter rains and 
entirely destitute of vegetation other than the planted maize. An 
average hill dug up in the field was found to contain 15 plants ranging 
from 60 to 90 cm. in height. (See PI. XXX, fig. 1.) The remains of the 
seeds were found at 25 cm. from the surface, and from each seed there 
