72 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
these substances are gradually formed as the processes of con- 
version into mould proceed. 
As regards the mineral constituents of leaves and forest litter 
generally, it will be seen from the following table that the leaf is 
very rich in manurial constituents :— 
Average Composition of Forest Litter in parts per 1000 of 
Dry Matter. 
sy 
Senet a oD = & <= 5 
Leaves of 2 = E 3 et ge 2 cee J 
= S S) = oS Og, | SF] so = 
Ay & R a = | re) at jas al 
| Beech, .. .. | 56| 3:0] '-6 | 25-0] 3°6 | 1°5.| 3-0 | 1°0 | gum 
| Oak, L . | 49] 16 | 3 | 24-01 2:0] -3 | 4:0 | 2°2 | 15 
Tarchays, ‘ 40 1°8 5 8739/27 Sa) On|) des 6 || 23 
| Scots Fir, : 15 15 6 6:0 | 1°5 5 (a 5 | 2 
Red Spruce, . AD | 156°) °6 12020) }>223") 1-00) 21 °7 |G) 
| White Spruce, . 38 | 2°6 5 | 24°0 | 25 | 10 | 2:8] 10) 28 
| Mosses, . NBL TV a B68) ee ee 
| Ferns, . . | 67 | 24:0|2:7| 8314-7] 111 5-5 | 2°3 | 14 
| Heather, . Se | | eS Bee | 1-0) 125. 1-0 ees 
| Wheat Straw,. | 54] 70] -7| 3°:0|11°3! ‘3 |] 2°6 | 1°3 | 36 
| Barley ,, . | 48| 11:0] 2°0| 4°0|1:2| -3 | 2-1 | 1°8 | 25 
| Oat aca Ps | 47 |10°4]1°4] 4:012°0| -7| 2°01] 1°5 | 28 
Along with the leaves, there is given in the table the composi- 
tion of mosses, ferns, and heather, which form a large proportion 
of forest litter; and there is also given, for the sake of comparison, 
the composition of the straw commonly used as farm litter. 
Jt will be seen that the litter produced by the leaves of forest 
trees is distinguished by the large amount of lime, and the com- 
paratively small amount of potash it contains, thus differing from 
the straw of cereals, which is rich in potash and poor in lime. 
Poorest of all in ash constituents is the leaf of the Scots fir. 
The leaves of the oak and the beech are relatively rich in manurial 
constituents, and it is to the large amount of phosphoric acid and 
nitrogen that the former owes its reputation as a source of good 
leaf-mould. 
It is evident from the above analysis that the removal of forest 
litter, for the purpose of making leaf-mould, which is now a con- 
siderable industry here as well as on the Continent, must result 
