HOTHOUSES. 



160 



HOTA. 



I G5° or 70°, even during bright sun- 



! sliine ; but if, during the night, it 



j falls as low as 45"' or 50°, no bad 



; consequences will ensue. In severe 



j vreather, the sashes may be pro- 



: tected at night with mats, boards, 



! canvas, or hurdles, covered with 



! thatch or reeds. Hotbeds should 



j always be placed in a sheltered situa- 



I tion, open to the south, and, if pos- 



j sible, on dry soil. When the heat of 



j the dung begins to fall low, it may 



j be renewed by exterior linings, which 



j are narrow masses of fermenting 



j dung placed round the main bed of 



j dung ; but for raising flower-seeds 



I tills is seldom necessary. 



I Hothouses differ from green- 



j houses in being kept at a higher 



i temperature, so as to suit tropical 



I plants ; and in having a flat bed 



I for the principal part of the plants 



I to stand on, instead of a sloping 



i stage of shelves. This bed is com- 



i nionly surrounded by a narrow brick 



j wall, two or three feet high, and filled 



I with tan, in which the plants are 



i plunged ; but in some cases, instead 



i of tan, or any other fermenting 



; material, there is a cavity beneath 



i the bed, in which flues or pipes of 



; hot water are placed ; and the sur- 



j face of the bed is either covered 



I with sand, or some other material 



calculated to retain an equality of 



moisture, in which the pots are 



plunged in the same manner as in 



the tan. Some cultivators do not 



use any materials in which to plunge 



the f)ots, but merely set them on the 



' surface of the bed, trusting to the 



general heat of the air of the house, 



! or the heat emitted through the 



: bottom of the pit from the pipes or 



flues below, taking care to keep the 



surface of the bed on which the pots 



: stand moist, by pouring water over 



it at least once a day. The heat of 



hothouses for ordinary tropical i)lants 



j should at no period of the day or 



year be lower than 65° ; but in 

 summer, during bright sunshine, 

 it may be as high as 70°, 80°, or 

 90°. During winter it should never 

 be lower than 60° in the daytime. 

 In hothouses devoted to the growth 

 of orchideous plants, a higher tem- 

 perature is requisite than for the 

 ordinary plants of the tropics, and 

 also a proportionately greater de- 

 gree of moisture ; and in order to 

 attain the latter object, the floor of 

 the house, or the hot water pipes, 

 should be frequently sprinkled with 

 water. 



HoTTO^KiA, — PrimidacecB. — The 

 Feather Foil, or Water Yiolet. — An 

 aquatic British plant, which pro- 

 duces a pretty effect, from its pink 

 flowers, on the borders of ponds and 

 ditches where the soil is gravelly. 



Hound's Tongue. — See Cyno- 



GLO'SSUM. 



Houseleek.— See Sempervi'ttjm. 

 Ho'VEA. — Leguminosce. — Beau- 

 tiful dwarf shrubs, natives of Aus- 

 tralia, which require a greenhouse 

 in Great Britain. They should be 

 grown in a mixture of sandy loam 

 and peat ; and they may be propa- 

 gated by cuttings, which are rather 

 difficult to strike ; and which should, 

 therefore, be put under a bell-glass, 

 in pure sand, and plunged into a 



I hotbed. 



Hot'a. — A sclepiaddcece. — The 

 most common species, If. carnosa, 

 has curious wax-like flowers, from 



1 which drops a sweet, honey-like 



i juice. It is a hothouse climber, 

 which requires a light rich soil, and 

 is propagated by cuttings, which, 

 however, will not strike without 



\ the help of bottom-heat. It is 

 sometimes grown in greenhouses, if 

 in a warm situation, exposed to the 

 sun. In this case, it should be 

 trained close to the glass, and a 

 mat, or some other covering, thrown 

 over the roof of the house in severe 



