Are they beneficial or not ? 53 



it. During the day however dead leaves and diseased 

 parts of plants and also the flowers give out a small 

 portion of carhon, but it has no efiect on the air if the 

 plants are kept free of dead leaves and decaying parts ; 

 the great amount of leafage on a plant will absorb far 

 more carbon than the blossoms can give out. Thus 

 you see plants in a room during daylight are really a 

 benefit instead of being otherwise, since they purify 

 the air by absorbing and removing carbon which is 

 injurious to our health, giving out at the same time 

 oxygen which is a necessity of our life. So much 

 cannot be said for them after daylight departs ; then 

 the order of things is reversed, for during the hours of 

 darkness the plants absorb and retain oxygen and 

 release and give out carbon to the air ; this of necessity 

 would be injurious to our health if there were no 

 remedy or counteracting influence to nullify the bad 

 effects. You can receive no harm from the carbon if 

 you leave your bedroom window a little open during 

 the night to cause a circulation of fresh air ; the least 

 bit will do. You should do this in any case during 

 summer, for it is very beneficial to the health of the 

 sleepers. Or if you place the plants on the floor the 

 evil will be remedied to a great extent, for the carbon 

 which is half as heavy as common air, will fall to the 

 floor. But when we know that " we breathe out but 

 a small quantity of carbon during the hours of sleep 

 as compared with the quantity exhaled during the 

 day," and that " the quantity of carbon given out by 

 the plants at the same time is not large," the presence 

 of plants in your bedroom at night can scarcely have 



