60 Princrples of Plant Culture. 
branch. This cuts off the downward current of assimilated 
food, and so starves the protoplasm of the roots. If the 
notch is made after the leaves have expanded in spring, 
and extends only through the bark, the leaves may remain 
fresh for several weeks, since the transpiration current, 
which passes through the sap-wood (78), may continue. 
The roots, however, since they receive no nourishment, will 
soon cease to grow and will die from starvation before the 
following spring. If the notch is cut deep enough to reach 
through the sap-wood, cutting off both the ascending and 
descending currents, death of the tree speedily ensues. 
82. Root Starvation may occur Without Girdling. 
In seasons of extreme drought, when the leaves are poorly 
supplied with crude food materials from the soil, the amount 
of assimilated material may be so meagre that the food cur- 
rent will be exhausted before it reaches the roots. In such 
cases the roots perish, and the tree is found dead the follow- 
ing spring. This most frequently occurs with trees on poor 
soil, that have suffered from insect attacks, as well as from 
a dearth of water. It often occurs also in recently trans- 
planted trees that fail to make satisfactory growth the first 
season. 
83. To Destroy the most Persistent Weeds we 
Starve the Roots by preventing all leaf growth (339). 
84. Restriction of the Growth Current Promotes 
Fruitfulness by causing an accumulation of assimilated 
food in the stem and branches (135 B). 
85. The Storage of Reserve Food. In healthy plants, 
food is assimilated faster than it is consumed by growth. 
The surplus is used in the production of flowers and seeds 
(135 A), and in repairing damages, as the healing of wounds 
