Part IV.] Caccia: Selection method of treatment in India. 347 
number of years which it takes a second class tree to pass into the 
first class. Again, if the whole forest be divided into “ x” equal 
annual coupes, the number of Class II trees annually becoming 
exploitable in each anniial coupe will be — 
All Class II trees 
— Number of years it takes a Class II tree to become Clas.s I 
X 
If “.c” be made equal to the period of the felling rotation, that is, 
equal to the number of years it takes a Class 11 tree to become 
Class I, the number of trees annually becoming exploitable in each 
coupe will be — 
All Class II trees 
_(No. of years in felling rotation) 
No. of years in felling rotation 
It follows, therefore, theoretically that if each coupe be worked 
over in regular order year by year, the number of trees of the second 
class, which will have passed over into the first class, to be found 
in each coupe as it is worked over will be at the end of the growing 
season — 
All Class II trees 
j Felling roiation 
Felling rotatTon^trees in the coupe worked over in the 1st year. 
2 X do. do. do. 2nd „ 
3x do. do. do. Srd ,, 
All Class II trees 
Felling rotation X iMling rotation 
Fellino' rotatioir trees in the coupe worked over m the 
last year of felling rotation. 
This formula is generally applied to the forest as a whole, by 
fixing the maximum possibility, in all cases where the forest is 
worked over once in the period of the felling rotation, as all Class I 
trees j)lns ^ Class II trees (calculating for the middle of the grow- 
ing sea.son). 
As a purely theoretical application of these principles, however, 
the method of calculating the possibility for the sal forests of the 
