SCIENCE IN THE PLANT WORLD 
of the air which man and animals contaminate. 
Besides this general use of gases common 
to nearly all plants, a few of the members of 
the vegetable world specialize in the production 
of protective and poisonous vapours of various 
composition. One of the most interesting of 
these is the Gas Plant of the South American 
jungles. This beautiful white-flowered in- 
habitant of the tropics is entirely protected from 
leaf-destroying insects and birds by the poi- 
sonous vapours it constantly pours forth. 
The plants are expert chemists, and the reac- 
tions in which they engage are, on the whole, 
much simpler than those which go on in the 
bodies of animals. Vegetable tissue is largely 
carbon, hydrogen, oxygen and nitrogen. It is 
a curious fact that instead of using the abundant 
carbon compounds present in decomposed ani- 
mal and vegetable matter of the soil the plants 
get most of their carbon from the carbon dioxide 
of the air. Inversely, they largely disregard the 
seventy-eight per cent nitrogen of the air, and 
extract that element from the complicated com- 
pounds found in the soil, or take it from the 
air only by aid of certain Bacteria. 
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