252 PRACTICAL FLORICULTURE. 



Geraniums, Blue Lobelias, Lysimachia, or Golden Money- 

 wort, may be used with excellent effect. By the use of 

 hydraulic cement instead of lime, the rock-work can bo 

 made of a pleasing drab color. A rockery so formed and 

 planted, without having any pretensions to being " nat- 

 ural," is always an interesting and attractive object on a 

 well-kept lawii. 



CHAPTER XLVII. 

 ARE PLANTS INJURIOUS TO HEALTH? 



Even yet, with all the light of experience on the sub- 

 ject, if physicians are asked if plants kept in rooms are in- 

 jurious to health, three out of six will reply that they are. 



They will generally follow up the reply by a learned 

 disquisition on horticultural chemistry ; will tell you that 

 at night plants give out carbonic acid, which is poisonous 

 to animal life, and consequently if we sleep in a room 

 where plants are kept, we of necessity inhale this gas, 

 and sickness will follow. These worthies generally suc- 

 ceed in their specious reasoning, and the poor plants, 

 that have bloomed gaily all summer, are often consigned 

 to the coal cellar for their winter's quarters, if given 

 quarters at all. No theory can be more destitute of 

 truth ; that plants give out carbonic acid may be, but 

 that it is given out in quantities sufficient to affect our 

 health in the slightest degree is utter nonsense. 



No healthier class of men can be found than green- 

 house operators, which makes me sometimes think that 

 plants have a health-giving effect rather than otherwise. 

 But doctors may tell us that our workmen are only at 



