40 



the sunny side of wooded roads are apt to be colored various 

 hues as red, purple brown, or jet black, while similar plants 

 on the opposite and shaded side retain the normal green 

 color. 



If a leaf of Lonicera chances to be turned so that the 

 inner side is outermost and faces the sun, it will assume a 

 deep blue color, much different from the usual purple-brown 

 of the other side, this being on account of the different 

 character of that surface. If it happens that one leaf par- 

 tially shades the one below or even at some distance in the 

 rear, the shaded portion will simply change in the usual 

 manner, commonly to yellow, while the projecting part, 

 whether tip, side, or entire border, receiving a more intense 

 heat will, in the case of a -maple, be likely to become scarlet, 

 or in Lonicera a purple brown, and in Ilex an inky black ; 

 the contour of the upper leaf, whether rounded or angular, 

 will be photographed as before stated upon the lower one, 

 and when from intense cold the sides of Lonicera become so 

 strongly reflexed as to become tubular, the sun paints only 

 a longitudinal streak along the prominent rounded part. 

 All of these evergreens are subjected to substantially the 

 same degree of cold, but cold alone, at least as a rule, is 

 incompetent to change the green color; it is the freezing 

 and rapid thawing in the sun of the leaves, causing evapo- 

 ration faster than absorption, which causes disruption of the 

 chlorophyll. 



Other evergreens which [)artially change color from these 

 causes are Mahonia, Forsythia, Rumex, Sphagnum, Black- 

 berry, Cranberry, Pyxadanthera, Pipsissewa, Sheep Laurel, 

 Privet, Strawberry, Pyrola. 



According to Kraus, the chlorophyll of certain evergreens 

 is not disintegrated by sun and frost, but a reddish or 

 yellowish substance develops, supposed to be tannin, which 

 conceals the unchanged green granules during the cold 

 season. This may refer to the class of evergreens includ- 



