THE PINE -APPLE. 



653 



attention. It is certainly neither the most natu- 

 ral, efficient, or least dangerous, to have recourse 

 to the too common practice of pouring pailfuls 

 of cold water on the sur&ces of overheated 

 flues or hot-water pipes. Such a process is far 

 more likely to scald the foliage and bark of the 

 trees which are in direct proximity with the heat- 

 ed bodies, than to restore that necessary equili- 

 brium in the atmosphere of the house which has 

 been deranged by excessive evaporation. To this 

 process there are other objections besides scald- 

 ing. It is too transient in its effects, and this 

 the more so the hotter the heating bodies hap- 

 pen to be. Far more natural and effective 

 modes of supplying this diminished humidity 

 have been detailed (vol. i. pp. 350, 422); and 

 in addition to what we have there stated, we may 

 here add that, if sufficient care be taken to keep 

 the footpaths damp, and the borders in a proper 

 state of surface moisture, at temperatures from 

 60° to 65°, abundance of evaporation will arise 

 from them to replace that which is lost by con- 

 densation on the inner surface of the glass, and 

 the escape of moisture so produced through the 

 laps or fractures in the glass. In the case of 

 small houses and pits, where the roof can be con- 

 veniently covered, as also recommended vol. i. 

 p. 651, the loss of heat by radiation from the 

 exterior surface of the glass will be greatly 

 lessened, and consequently loss of moisture by 

 condensation on the interior will be in like 

 manner diminished. There are many plants 

 that experience little inconvenience from even 

 a considerable variation in the state of the hu- 

 midity. Others do so, and more especially 

 those that, like peaches and vines, are forced 

 into growth at an unnatural season ; and this 

 decidedly so during their period of flowering, 

 Betting their fruit, and also while it is ripening. 

 To regulate these matters with anything like 

 certainty, the hygrometer should be consulted, 

 and those of Daniel or of Simmons may be consi- 

 dered the most proper for the purpose. 



To those who do not use the hygrometer we 

 may say that, in trusting to appearances only, 

 they should bear in mind that there is a great 

 diSereuce in the quantity of artificial humidity 

 required between a house heated by smoke- 

 flues, or even hot- water pipes, and one heated 

 by fermentation ; evaporation and absorption 

 are rapidly going on in the former, while in 

 the latter the heat produced is supplied with 

 a considerable amount of moisture at the same 

 time. Notwithstanding what we have said in 

 favour of a humid atmosphere for the pine, 

 this must not be carried to excess, else the 

 most injurious effects would result. " No 

 more," Glendinning vrisely remarks, " should be 

 given in steaming or syringing at one time than 

 just enough to moisten the foliage, otherwise 

 the soil will become glutted, the plants will 

 remain stationary, and assume an unhealthy 

 appearance, indicated by the yellow sickly ap- 

 pearance of their foliage. Moisture, notwith- 

 standing, if properly and judiciously supplied, 

 is calculated to be of infinite advantage in 

 moderating the temperature and supplying a 

 material element in demand during an excess of 

 evaporation ; and which at the same time being a 

 VOL. II. 



primary article of food for the plants, is always 

 in requisition in proportion to the supply of 

 solar heat and light." The pine should never 

 be watered overhead while it is in blossom, and 

 at that period abundance of air should be given, 

 but not so as to reduce the temperature. This 

 is, indeed, the most critical period of its exist- 

 ence ; and if checked by being removed or re- 

 potted, or if water be allowed to fall into the 

 flowers, deformed and small imperfect fruit will 

 be the certain consequence. 



Bottom heat. — It seems to be an axiom in hor- 

 ticulture that all plants in a growing state should 

 have the temperature of the soil in which they 

 grow higher than that of the air by which their 

 leaves are surrounded. "Warmth," says Dr 

 Lindley (in"Theory of Horticulture"), "actsasa 

 stimulus to the vital forces, and its operation is 

 in proportion to its amount within certain limits. 

 If, then, the branches and leaves of a plant are 

 stimulated by warmth to a greater degree than 

 the roots, they will consume the sap of the stem 

 faster than the roots can renew it; and there- 

 fore nature takes care to provide against this, 

 by giving to the roots a medium permanently 

 more stimulating — that is, warmer — than to the 

 branches and leaves." 



The vine succeeds best in countries such as 

 Bordeaux and Madeira, the soil temperature in 

 the former being 76° and that of the latter 80°. 

 The pine-apple requires a still greater tempera- 

 ture during its period of growth. We believe 

 that the vine might be brought to great perfec- 

 tion in the south of England, if planted against 

 a southern wall, and in a vaulted border subter- 

 raneously heated, as has been exemplified at 

 Yester by the Marquis of Tweeddale, and the rip- 

 ening of the pine in the garden of Lady Rolle at 

 Bicton, near Weymouth, which, however, must be 

 regarded as an experiment, the success of which 

 depended upon the heat applied to its roots in the 

 bottom of the trench in which it was set. Some 

 experiments made by the late T. A. Knight have 

 been misrepresented or misunderstood, and for a 

 time led some to suppose that bottom heat to 

 the pine was injurious rather than the reverse. 

 That great horticulturist repeatedly disavowed 

 entertaining any such sentiments. He certainly 

 did express a belief "that the bark bed was 

 worse than useless;" and in this he was perfectly 

 correct, because its temperature is constantly 

 subject to excess and defect, and that more 

 especially as bark beds were in general managed 

 at the time he so wrote, and it must be con- 

 fessed are so with many even at this day. But 

 while Mr Knight was experimenting on the pine 

 and the melon, the temperature of his stoves 

 was kept up to from 70° to 85°; and he found, 

 by placing thermometers plunged in the soil in 

 the pots in which his plants grew, that the heat 

 at their roots was very nearly the same, being 

 surrounded by air at that high temperature, 

 which the soil acquired and retained, so that it 

 was found less subject to variation than had 

 they been plunged in a bed of fermenting mate- 

 rial. He further says, in " Horticultural Trans- 

 actions," vol. vii. p. 265, that the temperature of 

 the air was varied in his stove generally from 

 about 70° to 85°, and that the temperature of 



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