ARE PLANTS INJURIOUS TO HEALTH ? 253 



work in the day-time, and that it is at night that the 

 carbonic acid is emitted. Here we meet them by the 

 information that in most cases the gardener in charge of 

 greenhouses often has to be up the greater part of the 

 night in winter, and the greenhouse from its warmth, 

 is universally taken as his sitting-room, and sometimes 

 as his bed-room ; such was my own experience for three 

 winters. I had charge of a large amount of glass, 

 situated nearly a mile from my boarding-house, too far 

 to go and come at midnight, with the thermometer 

 below zero. Our means of heating were entirely inade- 

 quate, so that the fires had to be looked to every three 

 or four hours. Disregarding all my kind-hearted em- 

 ployer's admonitions, I nightly slept on the floor of the 

 hot-house, which was rank with tropical growth. The 

 floor was just the place to inhale the gas, if there had 

 been much to inhale. It did not hurt me, however, and 

 has not yet, and that is now nearly forty years ago. 

 That plants are injurious to health in sleeping rooms is 

 one of the bugbear assertions that is willingly swallowed 

 by the gullible portion of the community, always ready to 

 assign effects to some tangible cause, and this, as the asser- 

 tion evinces some chemical lore, is very prevalent among 

 those disciples of Esculapius who are always willing to be 

 thought learned in the science so intimately connected 

 with their profession. 



