INFLUENCE OF HEAT IN NATURE. 53 



and lets a thousand cold-imprisoned plants go 

 free ; this clothes the forest with its leafy 

 honours, ripens the green untempting burden 

 of the orchard, and makes all creation to re- 

 joice. All the day long the sun pours down 

 upon the earth unfailing streams of this life- 

 giving principle, which then become diffused 

 into the surrounding air; so making the breeze 

 soft and warm, or penetrate a little distance 

 into the soil, whence they again in part disperse 

 into the air at night, when the sun has left us. 

 Every object we behold is influenced to a 

 greater or less degree by this principle. This 

 nettle and that blade of grass; the one all 

 covered with hairs, the other polished and 

 glistening, are both affected by the warm sum- 

 mer rays, but not both alike. The nettle, 

 being rough, is a good radiator, and therefore 

 loses heat faster than the grass which is smooth 

 and a bad radiator ; but then the nettle is also 

 a good absorber of heat, whereas the grass 

 absorbs it slowly. Undoubtedly this difference 

 of properties as respects heat was not appointed 

 in vain. We do not know why, but it is cer- 

 tainly necessary for the well-being of both 

 plants, that they should be as they are. Per- 

 haps the nettle may require to absorb much 

 heat, and very quickly, in order to perfect some 

 of the chemical phenomena of its growth ; 



