SEPTEMBER. 259 



the tropics the temperature of the soil varies from 1 to 5 or more degrees 

 higher than the air throughout the year. Of course there are many 

 causes in operation which will affect particular localities and cause a 

 difference of a few degrees ; but for our purpose we shall be safe in 

 assuming that where tropical and other plants attain their greatest 

 vigour and productiveness, the soil in which they grow is warmer than 

 the air which surrounds them. 



To be sure we have some intelligent men amongst us, who, fully 

 alive to the important point in cultivation we are advocating, have 

 adopted this in their practice ; and amongst others we may mention 

 Mr. Ivison, of Syon House, and Mr, Scott, of Leigh Park, both culti- 

 vators of exotic fruits ; and we have no doubt that the success which 

 has attended their efforts in fruiting the Mangosteen and other rare 

 exotics is mainly owing to the adoption of a good bottom heat and free 

 ventilation. Indeed, we have the fact recorded by I\Ir. Ivison that in 

 the case of the Mangosteen at Syon, the magnificent fruit which 

 rewarded his care was obtained by such means. 



That the cultivation of many other plants, natives of tropical climates, 

 %vould be far more successful than is now the case we firmly believe, if 

 the roots were placed in bottom heat, and at the same time air (in the 

 summer season) supplied much more freely than is at present the 

 practice ; and further, we have no doubt that many plants hitherto 

 considered tender and difficult to grow, would flourish if plunged or 

 planted in bottom heat, and gradually inured to a full exposure to the 

 weather in summer. We are convinced this would be the case from an 

 experiment we made a few years back with some stove plants in pots, 

 which we plunged in a common pit heated by linings, and which was 

 kept up through the summer ; about June we removed the sashes 

 entirely having previously prepared the plants for this change by having air 

 on by night. The plants, which consisted of Clerodendrons, Allamandas, 

 Echites, and similar things, grew with a luxuriance httle expected, and 

 the health and vigour of their leaves, and glowing beauty of their 

 flowers, convinced us at the time that by a nearly similar arrangement 

 — substituting hot- water pipes for the dung — a display of tropical 

 plants might be obtained out of doors from the middle of July to the 

 end of September, or perhaps even later, which would far exceed the 

 best managed under glass. 



There are some exotic fruits which we have no doubt might be made 

 to succeed by similar means ; and among others a crop of autumn 

 Pine-apples might be obtained without the intervention of glass. That 

 this can be done we are sure ; but whether it would pay or not as a 

 commercial speculation we are not so sure. We have an opinion, how- 

 ever, that in districts where iron and coals are cheap, Pines might be 

 grown in large quantities, on this plan, cheap enough to compete with 

 the West Indians, now so numerous everywhere ; but on this we may 

 be wrong. We therefore pass from this subject, for the purpose of 

 pointing out the great advantage there will be in the application of 

 bottom heat to many plants now cultivated. 



{To he continued.) 



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