FOREST TREES. 35 
their ends during the summer; but any consider- 
able amount of pruning at that season retards the 
growth of the trees. The worst time to prune is the 
latter part of winter, and in spring just before or 
during the first flow of sap. Trees pruned at this 
time bleed more or less; the wounds do not heal 
readily, and the wood, saturated with sap, is apt to 
decay. Nevertheless, when trees are transplanted in 
spring they may be pruned, as they do not bleed 
when recently taken up. 
When the young trees become large enough to 
crowd, or materially check each other in growth, 
they must be thinned at one foot apart in the rows. 
Oaks and Hickories will grow to a proper size for 
hoop-poles before they will need thinning. When of 
‘this size they may be thinned so as to leave the remain- 
ing ones two feet apart. Care should be taken to 
leave the straightest and most vigorous trees. The 
thinning may be continued gradually as the trees 
grow larger, and those cut out, used for purposes to 
which their size and quality are adapted. The num- 
ber of trees which will grow to maturity upon an 
acre, is from three hundred to four hundred. Larches, 
Pines and Spruces can be more thickly grown than 
most deciduous trees. 
