76 Various Tints of Autumnal Foliage. [January, 



comparatively unaltered for weeks, those of the other trees 

 just named often turn from light yellow to brown in the 

 course of a day or two. The correspondence between the 

 artificial and natural colours in these various cases is ex- 

 tremely close ; and though the tint of many leaves is very 

 much modified by the presence of other colours, yet I trust 

 that the examples I have described will sufficiently well 

 illustrate the fact that the most characteristic brown or 

 orange shades are mainly due to the various kinds of 

 phaiophyil, derived from the oxidisation of previously 

 existing soluble compounds more or less characteristic of 

 particular species or varieties of trees. The two principal 

 kinds are those seen to advantage in the beech and in the 

 Spanish chesnut or elm, but it seems as if they very commonly 

 occurred mixed in very variable proportion, not only in 

 different sorts of trees but in different leaves of the same, so 

 as to give rise to every shade of redder or yellower brown, 

 made more or less dull by the presence of more or less of 

 the dark humus. Another very important modification of 

 the tints is that dependent on the continued presence of 

 chlorophyll, after the chrysophyll has been completely 

 altered. This entirely prevents the development of any 

 brilliant tints, since it makes what would otherwise be a 

 fine orange-brown merely a dull brown-green, like that 

 commonly met with in the faded leaves of the alder. In 

 such cases, the chlorophyll is sometimes found to have been 

 completely changed into the dull green modification produced 

 by the action of acids on the brighter green kind. I need 

 scarcely say that many leaves are variably and sometimes 

 very curiously mottled, on account of the changes I have 

 described having occurred partially and in patches. There 

 seems to be a connection between some of these facts and the 

 conditions under which the trees grow, and we cannot there- 

 fore be surprised that differences in climate, and variations 

 in the weather of particular years, very materially modify 

 the character of the prevailing tints. On this account, 

 perhaps, some of the illustrations I have chosen may not be 

 appropriate in all cases, being chiefly derived from the 

 district with which I am most familiar. 



The following table will serve to show the general relation 

 of the various groups of colouring matters, their prevailing 

 tint when alone, and the varying shades which result from 

 the mixture of varying quantities of any of the two con- 

 nected by brackets. I have also inserted on the left hand 

 side the condition of the leaves of which, on the whole, the 

 colours may be considered characteristic, commencing with 



