TREES PURIFY THE AIR. 145 



hundreds of thousands of years ago, various kinds of hickory 

 on what became the Jura Mountains, for in the quarries of 

 those mountains the leaves and fruit of the tree had been 

 found, but since the historical period had begun, the hickory 

 had not been found in Europe. Here we have four species, 

 perfectly well characterized, and all of them very beautiful 

 trees. I showed him all of them, and pointed out the difl'er- 

 ences. He recognized with deli":ht the characters of all. 



I could easily enlarge upon this subject, but there are other 

 things about which I wish to speak. I say that by planting 

 your own fields with trees, you not only make your homes 

 more pleasant, but you make them healthier, and you make 

 your own domain more valuable. Here, gentlemen, is a flxct 

 which every individual ought to know. It is a most important 

 fact in the relations of the vegetable world to mankind. 

 Every tree is a purifier of the atmosphere. There are on 

 the leaves of every tree literally millions of little openings, 

 large enough for the particles of air to enter, and into which 

 the}' do enter. When a breeze passes over a forest, or over a 

 single tree, the particles of air enter these little openings in 

 the leaves, and there the leaves part with their carbonic acid, 

 which is so unwholesome to breathe ; they part with their 

 nitrogen, and with everything else, really, M^hich is not per- 

 fectly wholesome, and they pour into the air pure oxygen. The 

 forest thus completely purifies the air that blows through it ; it 

 takes from it everything that is poisonous or even injurious 

 to man, and throws out to us pure oxygen, or that mixture 

 of oxygen which is best for us to hreathe. I say, gentlemen, 

 that this fact ought to be generally known, because it is a 

 fact of vast importance. It has not been long known ; and I 

 have visited places where the recent knowledge of that fact 

 has done a great deal of good. There are regions in Italy 

 which anciently were very wholesome and pleasant places to 

 live in, but which, for the last one or two hundred years, 

 have been grooving more and more unhealthy, until, a few 

 years ago, the}'^ were considered pestiferous and unsafe for 

 anybody to live in, and those who dwelt there took care to go 

 away at certain seasons of the year. This was in a part of 

 Italy nearest the sea, which is thence called Maremma. 

 Within a few years, trees have been planted in various places 



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