28 MONOGRAPHY OF THE GENUS CAMELLIA. 



a fire in the furnace, to temper the fresh admitted air. If this mode is im- 

 practicable, in consequence of the intensity of the cold, it must be attempted 

 to remove the moisture, where it is collected on the glass, by the use of 

 cloths, fastened to a staff. When it is necessary to keep up the fire for a 

 long time, on account of the cold, it must not be forgotten to water the 

 Camellias, which are near the furnace and funnel, and even all the others, 

 if it is requisite j for if the earth becomes too dry, it causes, as we have ex- 

 perienced, irreparable disasters. 



Section 6. — The ventilation and temperature of green-houses. 



The air being one of the most indispensable elements, to the prosperous 

 condition of plants, it is requisite that it be temperate and circulate freely in 

 the green-house. An active, dry and cold air is injurious to the Camellia j 

 while a humid and warm air is favorable to its vegetation, A thermometer, 

 therefore, should be placed in the green-house to regulate its temperature j 

 and although the Camellia may be exposed to some degrees of cold, without 

 suffering j still to render its florescence certain and perfect, it is necessary 

 that it should enjoy a temperature, of from 45 to 50 degrees of Fahrenheit's 

 thermometer. 



As long as the exterior atmosphere, is near those degrees, — which should 

 be indicated by a good thermometer exposed to the north in the garden, the 

 doors and sashes of the green-house may be left openj but they should be 

 carefully watched and shut as soon as the external temperature descends to 

 only ten or twelve degrees above the point of congelation. 



It is useful to give air to the Camellias every morning, even when the 

 weather is a little cold, if the sun is bright above the horizon. As the leaves 

 of the Camellia, present quite a large, shining, porous and slightly humid 

 surface, they attract the dust, which is continually circulating in the green- 

 house, and soon become covered with it. These foreign bodies prevent the 

 exercise of their absorbent functions, or rather, obstruct the pores, which are 

 destined to inspire the surrounding nutritious gases, as well as to expire those 

 which are disengaged from the plant. It is therefore necessary, that from 

 time to time, during the winter, this dust should be removed from the plants. 

 The following are the modes of doing it. 



Some persons wash the leaves with a piece of sponge j but while the 



