182 SUBURBAN GARDENS 
hungry little mouth, and the greatest tree is 
as dependent upon these as the humblest little 
annual, its massive woody roots being fre- 
quently no more than anchors. 
Contact with the food is the first mechanical 
essential to feeding, in either the vegetable or 
animal kingdom. The food of plants is taken 
in solution from the earth, in other words it 
is a liquid diet strictly, and it is absorbed 
through the delicate walls of these tiny, soft, 
tender little feeding rootlets, passes up along 
the canal which runs through even the tiniest, 
into the larger rootlets whence these spring, 
and so on, up and up until the main “ trunk 
line” is reached; and then still up into branch 
and twig and leaf, every part receiving due pro- 
portion of its particular requirement as the 
transit is made, until finally, through the leaves, 
the water, strained of its organic and mineral 
content, is transpired and returns to the atmos- 
phere ; in the course of a single summer day an 
ordinary tree will yield fifty gallons of water 
— perhaps much more — under the insistent 
heat of the sun. Vegetation generally is cal- 
culated as transpiring from forty to one hun- 
dred gallons of water to every pound of dry 
growth. 
All plants as they grow, establish the equili- 
