OF THE PINE-APPLE. 



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covering cannot so well be adopted ; therefore the 

 most general method is to use light covers of 

 wood, or frames of wood, covered with painted 

 canvass. The covering the whole of the roof of a 

 hot-house in this manner is very troublesome, 

 and attended with great expense ; nor indeed is 

 it absolutely necessary, as I have observed above. 



When either of the above methods are practised, 

 it should be done with discretion. In many places, 

 the covers of the hot-houses are sometimes, in a 

 snowy, dark, severe, or rainy season, permitted to 

 remain on for many days together, which is very 

 detrimental to the plants, as they will in time draw 

 themselves weak by the continuance of such a 

 practice : for it is observable that plants grow 

 much faster in the dark than in the light; and 

 this is manifest from the progress of plants when 

 first they arise from seed, in the open ground, in the 

 spring of the year, when they do not grow half 

 so much in the day as in the night. But here it 

 must be observed, that the sun and light give ma- 

 turity to the nightly progress of plants ; and the 

 want of them soon causes the plants to grow lan- 

 guid, weak, and, in time, to die. 



It is also a bad practice to continue to cover 

 hot-houses late in the spring of the year, which is 

 injudiciously done in many places, even so late as 

 the middle of the month of May : for, as the 

 covers are seldom taken off till after six o'clock in 

 the morning, (the hour that labourers come to their 

 work at most places,) it makes the hot-house night 



