28 
NATURE NOTES 
roots come out of the branches, and when they reach the 
ground, penetrate it, and then they assist the main trunk by 
absorbing water and so act as additional stems. 
Root Contraction. — In order to bring subterranean stems 
below the surface of the soil to their proper depths, the roots 
often have an important duty to do by contracting their length. 
The process begins in the oldest part of the root and continues 
downwards towards the apex. Transverse folds or wrinkles are 
well seen in many tap-roots. They are produced by a change of 
form in the cortical cells, which shorten in a longitudinal direc- 
tion together with a transverse extension, and absorb water at 
the same time. The central cylinder of the root, in which are 
the vessels, becomes forcibly compressed. The outer surface 
then gradually dies and thus becomes folded into ridges. The 
amount of actual shortening varies from 5 to lo per cent, of the 
total length of the contracting part, or even to 30 or 40 per 
cent. The effect is a gradual pulling down of the whole plant 
into the soil. This may be seen in the way the tips of long 
bramble shoots, when rooting in the soil, are dragged below it. 
Many plants possess no contractile roots, as the colchicum, 
tulip, &c., others have some contractile and others not so. Not 
infrequently contractile roots are fleshy, and as this feature is 
due to the cortex it is especially such roots which are contrac- 
tile. If a bulb has reached its normal depth by the aid of 
successively produced contractile roots, and these are no longer 
produced, and it be again placed near but below the surface, 
contractile roots will again be produced in order to carry it once 
more down to its proper level. 
George Henslow. 
AN EAST ANGLIAN “HANGER.” 
JHE grass-bordered path at the foot of the Hanger is 
covered with a ruddy carpet of fallen beech leaves, 
amid which the nutty mast lies hidden, its presence 
' only revealed by its pebbly hardness beneath the feet. 
Much of the mast, however, still hangs on the trees, and will 
remain there all through the winter, long after the last of the 
acorns have been scattered by the boisterous winds. There was 
such a wind last night, and signs of its havoc are to be seen on 
every side. Bristly bunches of sweet chestnut burrs are strewn 
all about the slope of the Hanger ; many of the elms and ashes 
are almost leafless ; and even the hardy oaks have been partially 
stripped of their scarcely withered leaves. One stormy night 
has wrought more change than a fortnight of quiet autumn days. 
Yet to-day one can hardly realise that the “ little summer of 
St. Luke ” is past, so warmly shines the sun and so pleasantly 
