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1901] ‘DISTRIBUTION OF RED COLOR 341 
In stems, petioles, veins, and leaf-blades the largest percent- 
ages are for an even distribution of red color upon the surfaces 
of these parts. This would seem to show either that the shoot 
was evenly lighted or that some factor other than sunlight was 
the determining one in causing red color. However, the upper 
surfaces of the leaves, veins, and petioles show more color than 
under surfaces, and this accords with observations of others. 
Kerner’s theory of protection from too great light, and Stahl’s of 
increasing transpiration through the aid of red, apply here, 
although it is hard to see, as said before, why there is need of 
greater photosynthesis than is brought about by naturally favor- 
able conditions. Overton’s view is not applicable, for cool tem- 
perature is certainly not a factor in the conditions. The disap- 
pearance of red color in leaves when greater shade is present, 
and the great number of cases where red is located in the epi- 
dermis, are favorable to Kerner’s theory of protection. 
Another fact agreeing with the latter theory is in the case of 
upright stems, where one side, the side always toward the sun, 
Shows often the more color. This was noticed continually in 
Ambrosia. 
The red color is intensified at the joints of stems and peti- 
oles. This deepening of color, as well as that upon the upper 
surface of parts, is greatest in proportion in plants growing in 
wet shady situations. The theory of Stahl applies here, for the 
passing of food materials may be checked somewhat at the joint, 
where tubes pass into the stem; but Overton’s theory applies 
just as well, since conduction is delayed here and sugar must be 
concentrated in the cells of this region. Cool temperature does 
not appear here however. Any theory of protection from light 
is not applicable, since the joints are as much shielded as the 
other parts of the shoot. 
A large number of cases were found where the stem was 
very red near the ground. None of the theories seem to fit this 
fact. 
Cases where color is absent just at the joints and present 
upon the rest of the stem, where petioles are red near the blade 
