54) Royal Society. 



by the abstraction of a certain amount of water in the course of the 

 circulation, (first between the blood corpuscles and the plasma in 

 which they swim, and then between the liquor sanguinis and the 

 containing channels,) must have on the capillary circulation, which 

 he conceives it is calculated to facilitate. 



2. " Further Observations on the descending fluids of Plants, and 

 more especially the Cambium." By George Rainey, Esq. Commu- 

 nicated by P. M. Roget, M.D., Sec. R.S. 



The author relates an experiment in proof of the sap descending 

 from the upper to the lower part of an exogenous tree, through vessels 

 which are continuous from the leaves to the roots ; the course of 

 these vessels being shown by the addition of a solution of iodide of 

 potassium after they had taken up by absorption a quantity of a 

 solution of acetate of lead. The fluids in these vessels are, he con- 

 ceives, separated from the sap, which is ascending from the roots, 

 only by the membrane of which they are composed. When the 

 leaf-buds of a tree are vegetating, large separations are observable 

 between the cells of the bark, and also between the bark and the 

 wood ; while no such separations are apparent when the leaf-buds 

 are entirely inactive. These separations are various in size, and 

 irregular in form ; their parietes consist of rows of cells, piled up 

 one above another, like the bricks of a wall : and their cavities all 

 communicate with one another. From these and other anatomical 

 facts, which are given in detail by the author, he concludes that the 

 propulsion of the sap along the vessels, resulting from the opera- 

 tion of endosmose, will explain the descent of the cambium, which, 

 being the nutritious portion of the vegetable fluids, corresponds in 

 its nature to the chyle in animals. 



March 23. — A paper was read, entitled, " Notice of an Extraor- 

 dinary Luminous Appearance seen in the Heavens on the 17th of 

 March, 1843," in a Letter to S. H. Christie, Esq., Sec. R.S., by Sir 

 John F. W. Herschel, Bart., F.R.S. 



Collingwood, March 17, 1843. 



My Dear Sir, — This evening, at half-past seven o'clock, I received 

 notice from one of my servants of a luminous appearance in the 

 sky, visible towards the S.W., which I immediately ran out to ob- 

 serve, and which, as it differed in some remarkable particulars from 

 any phenomenon of the kind I have ever before observed or seen 

 described, I think it not unlikely to prove interesting to the Royal 

 Society. 



The evening was one of uncommon serenity and beauty: the 

 moon, only thirty-eight hours after the full, having considerable south 

 declination, was not yet risen. In consequence, the sun being already 

 far enough below the horizon to leave only a faint glow of twilight 

 in the west, the stars shone with unsubdued brilliancy, no cloud 

 being visible in any quarter. Orion in particular was seen in all 

 its splendour ; and commencing below that constellation, and stretch- 

 ing obliquely westward and downwards, nearly, but not quite to 

 the horizon, was seen the luminous appearance in question. Its 

 general aspect was that of a perfectly straight, narrow band of con- 



