Nebraska Experiment Station Research Bulletin 19 
56 
per unit of cross section, 100 and 115; (5) number of stomata 
per unit area of epidermis, 100 and 106; (6) length of stomata, 
100 and 95; (T) length of stomatal aperture, 100 and 88; (8) 
length of epidermal cell, 100 and 98; and (9) width of epidermal 
cell, 100 and 93. 
The immediate result of growing corn under more adverse 
climatic conditions, namely, shortage of heat units and mois- 
ture, is to reduce the vegetative development in all its phases. 
Stalks become shorter, and bear the ear closer to the ground; 
leaf development and the production of plant substances are 
markedly reduced. The general effect is to reduce the oppor- 
tunity for transpiration and photosynthesis. Associated with 
this reduction in vegetative growth is found a reduction in the 
size of the vegetative unit — the cell. Accordingly, under the 
more adverse conditions the leaves are thinner, as are also the 
epidermis and the cuticle. The stomata are more numerous in 
a given area of leaf surface. The stomata as well as the stomatal 
apertures are somewhat reduced in size. Furthermore, the cells 
being smaller, more vascular bundles occur in a unit of cross- 
section. 
The fallacy of viewing such changes as being teleological 
or purposive is seen in the existence of both favorable ancl un- 
favorable reactions to adverse climatic conditions, moisture short- 
age being one of these conditions. A reduction in the plant size 
and leaf area and stomatal aperture indicates favorable reactions 
for reduced water requirements. On the other hand, a thinner 
epidermis and cuticle and a relative increase in number of sto- 
mata and water carrying vascular bundles suggest greater water 
dissipating capacity, and, therefore, must be considered as an 
adverse development inconsistent with the idea of purposive- 
ness. Probably the true explanation of these reactions is that 
the reduced turgor and reduced rapidity of cell division caused 
bv limited moisture and heat results in a materially smaller 
physical development. 
When a comparison is made of native adapted corn types 
grown in their respective home localities, a combination of two 
entirely distinct factors is involved in the relative plant develop- 
ment. namely heredity and environment. Differences due to 
hereditary adaptation cannot be definitely determined by such 
comparisons, since the effect of the difference in environment is 
not eliminated. 
Such comparisons of native home-grown corn types dis- 
close that corn from the more adverse conditions, moisture 
shortage being one of the conditions, is smaller in practically 
rll of its vegetative growth characters. The stalk and ear 
height, leaf area and plant substance are markedly lower. The 
