TREES THAT BUILD CITIES 13 



When the shades of night descend on a tree city, 

 what should be more natural than that artificial 

 light replace the bright rays of the sun? Trees 

 have eyes: that is, they have leaf-cells which not 

 only are sensitive to light but which can sometimes 

 concentrate and reflect light. Thus it would not 

 be surprising if trees occasionally found use for 

 their eyes at night. Yet it would seem that most 

 of the tree-citizens are temperate folk who go to 

 bed with the sun, for only occasionally do they use 

 lights and then most frequently in the quiet depths 

 of the tropic forests where they are most needed. 

 The chandeliers are certain damp and decaying 

 leaves either on the ground or on the trees. The 

 burners are yellow fungous growths appearing as 

 yellow spots on the leaves. The fuel is the leaves 

 themselves and the resultant illumination is a dull 

 and steady phosphorescent glow, varying in colour 

 with different leaves. Certain flowers, as the nas- 

 turtium, the tiger lily and the sunflower, also help 

 to illuminate the city with the same kind of flame. 



It must be admitted by even the most enthusiastic 

 naturalists that the development of such municipal 

 departments as those of police and fire is very much 

 in its infancy in a tree city. Yet there is often 

 indication of the beginnings of some splendid sys- 

 tems. Individual trees adopt many different kinds 



