Curtis's Botanical Magazine. 299 



-^t) 



for the leaves of this plant, like the stems of potato plants, are subject to 

 the conflicting influence of gravitation* and of light, the one labouring to 

 give a perpendicular, the other a horizontal direction to the leaves; and 

 the comparative power of one agent increasing as that of the other decreases. 



" I shall conclude the present communication wirh an account of a very 

 simple and efficient method of destroying the difFerentspecies of insect that 

 infest the pine-apple plant, which I have practised during the last two years 

 with perfect success. Pine-apple plants are not at all injured by having 

 water at the temperature of 150° of Fahrenheit's scale thrown upon and 

 into them with a syringe. The mealy bug does not appear to be injured by 

 a single washing, or immersion for a short time, in water of the above men- 

 tioned temperature; but if the application be repeated three or four times, 

 on as many successive days, it wholly disappears. My gardener has, I have 

 reason to believe, used water of a higher temperature than 150°, without 

 any injury to the plants ; but as hot water, when applied in the way above 

 mentioned, will operate according to the compound ratio of its quantity 

 and temperature, I would recommend the gardener, when he first uses it, 

 to apply it to a worthless plant, and not to use water of quite so high a 

 temperature as 150°. [See M'PhaU's Remevi., and Enc. of Gard., § 291 1.] 



" Having some red spiders upon the leaves of a fig tree in the stove, 

 I endeavoured to ascertain the effects of hot v/ater upon these. The first 

 application of it appeared only to render them more alert and active ; a 

 second appeared to have diminished their numbers very considerably, and, 

 after a third application, I could not discern any. Whether they had died, 

 or marched off" only, I am ignorant ; and the period at which I remove my 

 fig trees into the open air having arrived, I had no further opportunity of 

 trying the experiment. I applied the water to the mature and somewhat 

 old leaves only of the fig trees. 



" Note by the Seci'etary. — March 30. 1829. During the last season, 

 several specimens of the fruit of the pine-apple, managed as above described, 

 were sent to the Society by Mr. Knight. They were all, without exception, 

 of the very best quality in point of flavour; they were universally destitute 

 of fibre, and, in every respect, as perfectly grown as any I ever saw of the 

 same size." 



Art. II. Catalogue of Works on Gardening, Agriculture, Botany, 

 Rural Architecture, &;c., published since March last, ivith some 

 Account of those considered the most interesting. 



Britain. 



Curtis' s Botanical Magazine, or Flower-Garden displayed; New Series. 

 Edited by Dr. Hooker. In 8vo Numbers, monthly. Ss, 6d. col. ; 3s. plain. 



No. XXVII. for March, contains 

 2891 to 2897. i/ibiscus /iliiflorus. A mule, derived from i7. /iliiflorus, 

 and H. Rosa, sinensis ; a charming plant, sent from the Mauritius to Mr. 



" * The influence of gravitation upon the forms of plants is still greater 

 than I have inferred in my paper in the Philosophical Transactions upon 

 that subject. M. Dutrochet, having used very superior machinery to that 

 employed by me, discovered that if a seed be made to revolve upon its 

 own axis, and its axis of rotation made to dip only a degree and a half 

 below the horizontal line, the roots will always take the descending, and 

 the germs the ascending, line of that axis." 



