STOCKING AND MANAGING WARDIAN CASES. 245 



The principal care necessary is to see that the case 

 does not suffer from want of water. The moment the 

 door is opened, or the glass raised, the moisture, which 

 was suspended in the air, or condensed on the sides 

 of the case, flies off, and an equalization of temperature 

 begins between the air in the case and that in the room. 

 That in the case soon parts with its moisture, and becomes 

 dry and unfit to sustain the plants in health and beauty, 

 unless the earth in the case is again watered. When too 

 much water has been given (which is readily seen by the 

 glass always remaining clouded), opening the door and 

 admitting external air is necessary to the health of the 

 plants. In this matter, experience will be the best teacher. 

 Few cases are perfectly air tight, and usually enough air 

 will be admitted through cracks and ill-fitting shades, for 

 the health of ferns and lycopodia. The advantage of such 

 cases is, that they are sufficiently close to exclude dust and 

 noxious gases, yet admit of ventilation at times favorable 

 for the operation. 



For cases made on the ordinary principle, that is, as close 



as ordinary workmanship will make them, the best plants are 



ferns and lycopodia, because these naturally love a close, 



moist atmosphere, and whatever facilities the case may 



21 * 



