THE BLACK POPLAR. 453 
petual motion which it maintains in spring and 
summer, and until the time for the autumnal fall 
has arrived—it will be allowed that it gains, in this 
respect, what it loses in value as timber. The 
tremulousness of leaf in the Poplars is occasioned 
by a depression on each side of the footstalk just 
below the base of the leaf—giving increased 
flexibility to that part of the stalk, and by 
taking from the rigidity of the stem giving greater 
play to the motion of the breeze. Added to its 
rapidity of growth—the extreme ease with which 
it can be either raised from seed, from cuttings, by 
layers, and oftentimes by the numerous suckers 
that spring up around the trunks of some of the 
species—it has the further advantage that it will 
grow readily in and near towns. It is, therefore, 
a kind of Tree to be cultivated and loved by those 
who desire to make town life more cheerful than 
it is at present. Good, in the quality of richness, 
should be the nature of the soil in which Poplars 
are planted, and though they will grow almost 
anywhere, they prefer a moist soil, and, if pos- 
sible, the proximity of the stream-side. 
Populus nigra, the species which forms the 
