108 Principles of Plant Culture. 
food in the stem gradually moves in the direction of the 
terminal buds. 
178. Cuttings (358) of Woody Plants are Prefer= 
ably Made io Autumn, in climates of severe winters, and 
buried in the ground below the limit of hard freezing, in 
order that callusing (73) and the transfer of food may make 
some progress before the final planting. 
179. The «Turn of the Year.’’ Toward the close 
of the dormant season, vegetation, as if benefited by-the 
rest, is prepared to start with renewed vigor, even at moder- 
ate temperatures. Buds, that remained dormant during the 
latter part of the previous summer, push into growth with 
the first warm days of spring, and many seeds, that could 
not be induced to germinate the preceding autumn, start 
with vigor as soon as the soil is sufficiently warm. 
The cause for this vigorous resumption of plant growth, 
after the rest period, is not well understood, but the 
exposure to cold, in the case of temperate plants, and to 
prolonged dryness in that of tropical ones, doubtless 
explains it in part, for it is well known that potato tubers 
may be induced to start their buds soon after maturity by 
exposing them to the sun a few days, or by placing them 
for a like time in a refrigerator containing ice. By these 
means, farmers of Tennessee grow a second crop of potatoes 
in the latter part of summer and during autumn. 
Plants under glass usually thrive better after midwinter 
than before, and the most favorable time to plant secds of 
greenhouse plants is toward the close of the natural rest 
period. 
180. The Round of Plant Life we have now traced, 
from the first swelling of the planted seed, through the 
