JULY. 



WASHING THE TREES. 



y u ly 5. One scarcely realizes how much the trees 

 in and round great cities suffer from soot until one 

 sees them go up several shades in colour after heavy 

 rain in summer. The lime trees particularly had 

 been getting blacker and blacker with each day of 

 the prolonged fine weather, because they are specially 

 favoured by the green " blight " insects that produce 

 the honey dew, which, covering the leaves of the 

 lower branches, prepares a sticky surface to catch 

 every particle of descending soot. Seeing that trees 

 breathe through a multitude of tiny mouths upon 

 their leaves mouths which open and shut, and under 

 the microscope show two lips almost human in out- 

 line, so constant is Nature to the types of mechanism 

 by which she achieves her ends one would think 

 that the limes must have gone perilously near to 

 suffocation when their leaves were coated with a 

 sticky layer of sugar and soot. But Nature was not 

 born yesterday, and impurities of the atmosphere 

 have existed in all ages ; so she has by experience 

 learned to put most of the mouths of plants on the 

 under sides of the leaves. Thus even the sootiest of 

 limes has some millions of unchoked mouths to get 

 along with during drought. 



