Curtis's Botanical Magazine. 299 



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 leives; and 

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



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

 simple and efficient method of destroying the different species of insect that 

 infest the pine-apple plant, which I have practised during the last two j'ears 

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

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

 into them with a syringe. The mealybug 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 da^s, 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 Al'P/iail's Remem., and E)ic. of Gard., § 291 1.] 



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

 I endeavoured to ascertain the ellects 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 niuiibers very consitlerably, and, 

 after a third application, I could not discern an\'. Whether they had died, 

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

 fig trees into the ojjen air having arrived, I bad 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 Secretary. — 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." 



AuT. II. Catalogue of Works on Gardening, Agricidfjire, Botany, 

 Bural Architecture, Sfc, published since March last, xvith some 

 Account of those considered the most interesting. 



Britain. 



Curtis^s Botanical Magazine, or Flower-Garden disjilayed ; New Series. 

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



JVo. XXVII. for March, contains 

 2801 to 2897. i/ibiscus /iliiflorus. A mule, derived from //. /iliiflorus, 

 and H. i?6sa 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. Dntrochet, 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, th.e roots will always take the descending, and 

 the germs the ascending, line of that axis." 



