184 AUTUMNAL LEAVES. 



or breathing pores, take in the carbon of the 

 atmosphere to form their solid parts. How beauti- 

 fully adapted are these processes to the require- 

 ments of the animal world we have shown, with 

 some elaboration, in ' OUR WOODLAND TREES.' Here 

 let it suffice to say that the carbonic acid gas, un- 

 wholesome to man and rejected by all breathing 

 animals, is absorbed by leaves for their benefit 

 and for the benefit of the animal kingdom, whilst 

 the leaves give off, as their contribution to the 

 vitality of the world, the life-giving oxygen which 

 man and the animals around him require, perform- 

 ing thus a function by which a compound gas is 

 made to serve the plant-use and the needs of 

 the animal world. But there are, of necessity, 

 times and seasons for the performance of this 

 useful and beautiful function and these again 

 are admirably adapted to the requirements and 

 for the happiness of mankind. It is mostly during 

 the daytime that man is occupied out of doors, and 

 then it is that the plant world, under the influence 

 of the sun, is giving off its oxygen for his benefit. 

 At night when man is asleep, oxygen is largely 

 absorbed by the green parts of leaves. When 



