Bui. 1167, U. S. Dept. of Agriculture. 
Plate VI, 
H£ 
CO ? o 
< = - 
w = = 
UJ — c 
O - r, 
< ll 
_l 3 . 
13 s 
CO o 
~ o .- 
ill 
M o S 
c = -= 
l_ a -^ 
< i§ w . 
< h~>. 
UJ o 
