Igor} DISTRIBUTION OF RED COLOR 333 
place, but little retarded by the loss of light. Stahl? (1896) 
agreed with Kerner and Pick in the belief that the red color is a 
device for promoting the change and passing of food stuffs, not 
however in its use asa light screen, but by raising the tempera- 
ture of plant tissues through its property of converting light into 
heat; cold delays these processes. This warming up of the 
plant also favors transpiration, an ecological factor as impor- 
tant in Stahl’s view as the one mentioned. Overton® (1899) 
presented the theory that the red color is a glucoside compound, 
produced as a result of sugar concentration in the cell, under 
the influence of intense light and cool temperature. He assigned 
no distinct ecological significance to red color and in reality 
gave us a theory which is a modification of Von Mohl’s. Mac- 
Dougal (1896) has given a good popular account of the theories 
concerning red color. 
Little attention has been given to the study of red color in 
the eastern United States. Stahl and Overton cite this region 
with the Alps as offering the best conditions by far for a great 
display of color. No attempt, so far as I can find, has been 
made anywhere to study comprehensively the red color in sum- 
mer foliage, or, in fact, to work up the subject at all in a statis- 
tical way, and therefore with a view to seeing how far statistical 
observations made in New England may agree with the principal 
theories this study is offered. Thanks are due to Mr. M.L. 
Fernald, of the Gray Herbarium, for naming many plants, 
and to Dr. W. F. Ganong, of Smith College, with whose kind 
assistance and direction the working out of the data was done. 
The plants examined were gathered at random in North- 
hampton and vicinity, Springfield, Warren and Woods Hole, 
Mass., and in Squirrel island, Maine. The proportion of situa- 
tions, dry and wet, shady and sunny, from which the specimens 
were taken was about the same. At first only those plants were 
7 Ueber bunte Laubblatter. Ann. Jard. bot. Buit. 13 : 137. 
8 Beobachtungen und Versuche iiber das Eintreten von rothen Zellsaft bei Pflanzen. 
Prings. Jahrb. 33:171 
9 Physiology of color in plants. Pop. Sci. Monthly 4g: 1. 
