422 Chronicles of Science. [July, 



4. BOTANY— VEGETABLE PHYSIOLOGY AND MOE- 

 PHOLOGY; AND RECENT LITEEATUEE. 



Aster salignus. — We some time since noted the discovery of this 

 plant by Mr. Hiern, of St. John's College, near Cambridge. Two 

 ladies — Miss Bever and Miss Edmonds — announce its occuiTence 

 on the shores of Derwentwater. Besides in Cambridge, this plant 

 also occurs in several places on the banks of the Tay, between 

 Dalguise and Seggieden. In one locahty below Perth, Dr. White 

 remarks that it is associated with several introduced plants, 

 such as Linaria reopens, Petasites alba, Sanguisorlia Canadensis, 

 Mimulus luteus, Crocus vermis, and Narcissus pseudo -narcissus, 

 which are all common, more or less, and established along the 

 banks of the river. In France, Aster novi Belgii seems to hold 

 the same place as A. salignus does in Britain — that of an exotic 

 plant, well established on the banks of several rivers, as near Stras- 

 bourg, Langres, and Lyons. 



A Method of Bleaching Wood Pulp. — M. Ouvh, a French 

 chemist, states that chloride of lime is open to this objection in the 

 process of pulp-bleaching for the purposes of paper manufactories, 

 viz. that if at all in excess, it gives a yellow colour to the pulp. 

 Powerful acids also, without exception, tend to give a reddish tinge 

 to the paper when exposed for a long time to the action of sun 

 or moisture (whence the colour of many foreign papers in books), 

 and the least trace of iron is sufficient in a very short time to 

 blacken the pulp. M. Ouvli says he has succeeded in avoiding all 

 these inconveniences by the use of the following mixture. For a 

 hundred- weight of wood-pulp, 400 grammes (iths of a pound) of 

 oxalic acid are taken; this has the double advantage of bleaching 

 the colouring matter already oxidized, and of neutralizing the 

 alkaline principles which favom' such oxidation. To the oxalic 

 acid one pound or a little more of sulphate of alumina is added, 

 entirely deprived of iron. The principal agent in this mode of 

 bleaching is the oxalic acid, the power of which over vegetable 

 colouring matters is well known. The alum has no bleaching 

 power of its own, but forms with the coloiu-ing matter of the 

 wood an almost colourless " lake," which has the effect of in- 

 creasing the brilliancy of the pulp. 



Curvature in Plants. — M. Ed. Prillieux has studied this subject 

 in a very detailed manner — experiments both on ]ilants and on imi- 

 tative models having been extensively made. He arrives at the 

 conclusion that a purely mechanical cause must be attributed to 

 the curvature produced by shocks and vibrations on buds, contrary 

 to general opinion, which had considered these plu^nomena as of 

 a very different character and peculiar to living beings (whereas 



