December.'] rooms — camellias. 



305 



and give out oxygen by their under ones, thereby tending to 

 purify the air^ in as far as animal life is concerned, because 

 carbonic acid gas is pernicious to animals, and oxygen is 

 what that life requires. It is in the light, however, that 

 these operations are carried on, for in the dark plants give 

 out carbonic. It does not appear that any of the scentless 

 products given out by plants are injurious to human beings, 

 because those who live among accumulated plants are not 

 less healthy than others, but rather enjoy more uninterrupted 

 health, which, of itself, is a sufficient recommendation for 

 all to spend their leisure moments in so healthful and rational 

 an employment. 



26* 



