THE RUBBER TRADE 517 
of power everywhere manifested in nature. In the 
north the Sugar Maple secretes a sugary sap so 
abundantly that many gallons can be annually 
drawn away from a single tree without diminishing 
its production in future years or perceptibly 
shortening its life. In the tropics, other trees 
produce so different a substance as caoutchouc 
(or india-rubber) which can be indefinitely extracted 
in the same manner. It is impossible to believe 
that these, and a hundred other diverse kinds of 
sap, were not primarily developed to further the 
growth and vigour of the plant itself and to aid it 
in its struggle for existence with other plants. 
Yet whenever man draws off this precious fluid 
for his own purposes, nature seems always ready 
to make up the deficiency, so that the plant shall 
not suffer injury. It may perhaps be the case 
that this wonderful recuperative power has been 
developed for the purpose of guarding against the 
chance injuries inflicted by boring insects, wood- 
pecking birds, or scratching, biting, and goring 
mammals, whose combined attacks might otherwise 
destroy the vigour of the species and thus endanger 
its existence. Perhaps even we may trace the 
gummy or milky nature of so many saps, and their 
coagulation on exposure to the air, to the need for 
checking the loss that might occur if wounds, which 
may be made by hundreds on the smaller branches, 
twigs, and buds, were not rapidly self-healing. 
To this simple need of vegetative life we may owe 
that wonderful diversity in the products of the plant 
world which renders it an inexhaustible storehouse 
to supply the ever-growing needs of civilised man, 
whether for purely sensuous enjoyments as in fruits 
