342 BOTANICAL GAZETTE [NOVEMBER 
only, where old tendrils are very red, where color is present in 
the hairs of leaves and not in the leaf surfaces, are unexplained 
by any theory ; also the appearance of red under the same con- 
ditions which usually favor the disappearance of color. 
Stahl has given a plausible explanation of color in plants of 
the moist tropics, where color is located in the cells of tissues 
near the surface. Overton explains autumnal and spring color- 
ation, but finds, although he can produce colorin internal tissues 
of the plant, he is seldom able to do so in epidermal layers. 
None of the explanations given apply to all the cases here 
recorded. 
In conclusion it is seen that the statistical observations pre- 
sented fit no one theory in all particulars. Some facts agree 
with no theory at all so far as known. The suggestion may be 
made that with further experimental study red color may be 
found subserving a number of purposes or having a number of 
different meanings; or, on the other hand, it may be due to an 
entirely unknown cause which may fit all cases. 
BOTANICAL LABORATORY, SMITH COLLEGE, 
Northampton, Mass. 
