110 THE LIFE OF A TREE. 
Coquimbo. Iwas at Copiapo at the time, and 
there the people, with equal envy, talked of the 
abundant rain in another spot. In ten days a 
single shower of rain covered a previous desert 
place with pasture: and it was very curious to 
notice that just so far as the shower extended 
this green pasture existed; all beyond was as 
barren as before.”’* Some calculations have been 
made as to the quantity of water consumed by 
plants, which are interesting. Thus a sunflower 
has been found to consume daily twenty-two 
ounces of water; and upon calculation, during 
one summer, an acre of land planted with sun- 
flowers, at a moderate distance apart, would con- 
sume nearly two millions of pounds of water. 
An acre of cabbages would consume more than 
five millions of pounds in one summer, and an 
acre of hop-plants as much as six or seven 
millions of pounds. 
The water is taken up chiefly by the roots 
of the tree, is then converted into sap, and as it is 
* In another place Mr. Darwin speaks of the effects of a great 
drought. “During this time so little rain fell, that the vegetation 
even to the thistles failed, the nooks were dried up, and the whole 
country assumed the appearance of a dusty high road.” 
