' Queries and Answers. 255 



that this material abounds chiefly in the innermost layers of the wood ; and 

 Biot has shown that its flow is chiefly in an upward or downward direction, 

 according to the state of the atmosphere. I would suggest, that, as the cen- 

 tral portions of trees are deprived of vitality, they cannot be otherwise consi- 

 dered than as porous channels, through which the water imbibed by the 

 roots (and probably by the leaves, also, in rainy weather) is conveyed : when 

 lodged there, it serves as a reservoir, from which those portions of the tree 

 (as the leaves and outer layers) in which vitality resides are constantly fur- 

 nished with the materials necessary to the elaboration of the proper juices 

 upon which their nutrition depends. 



2. With respect to the developement of roots from the uppermost rim, and 

 branches from the lowermost, round the ringed spaces on the trunks of trees, 

 when kept moist in the way desci'ibed, I conceive these combined results 

 are strictly identical with what takes place in two separate and ordinary ope- 

 rations : I mean in the developement of roots at the base of a cutting, and the 

 developement of leaf-buds round the surface of the stool of a felled tree. 

 Suppose the trees in the present case had been cut completely through, their 

 stumps left in the ground, and the upper portions planted; the compound 

 results obtained by Mr. Niven would then be referred to the two separate ones 

 here alluded to. The multiplication and variation in the modes of obtaining 

 these results are always interesting and useful ; but I conceive no new fact has 

 been elicited in these experiments, by which any additional light is thrown upon 

 the mode in which wood is developed. Whilst connecting this developement 

 of branches in Mr. Niven's experiments with the ordinary developement of 

 buds from stools, I may, perhaps, mention an analogous result, which my 

 brother showed me lately. He had sown a number of orange seeds in a pot ; 

 and, as they came up thickly crowded, he cut down most of them close to 

 the ground, expecting that this would cause them to die, and leave space for 

 the two or three he wished to keep. He was surprised to find the surface of 

 the wound heal over, and in all cases buds develope themselves within the 

 margin. 



I suspect Mr. Niven will find that none of the trees which he has ringed 

 deeper than the liber will live more than three or four years. — J. S. Henslow. 

 ■Cambridge, Aprils. \%iiS. 



Art. III. Queries and Anstvers. 



Do decaying Leaves absorb, and assist in evaporating, the Sap of the Plant ? 

 (p. 206.) — A correspondent of yours, J. M. C. N., in the April Number of 

 this Magazine, p. 207., in referring to a remark on " withered leaves," in 

 Maund's Botanic Garden, has connected my name with that publication, con- 

 founding it, as I presume, with the Botanist, which is the only work of Mr, 

 Maund's in which I have consented to render him any assistance. I conceive 

 Mr. Maund must be correct in recommending the speedy removal of leaves 

 which have either rotted or are evidently dying from some injury ; but I can 

 hardly suppose that he intended to generalise to the extent which your cor- 

 respondent imagines, or would recommend the removal of withered leaves 

 from trees where Nature teaches they should remain as a winter clothing 

 to protect the young buds. I should suppose that the withering of leaves 

 must generally be taken as a clear indication that they are no longer, or only 

 very slightly, performing their natural functions, both of exhalation and absorp- 

 tion of the sap. — J. S. Henslow. Cambridge, April 3. 1838. 

 _ An Ai'ticle on the forcing of Flowers in Winter, such as roses, lilacs, the de- 

 ciduous azaleas, hyacinths, &c., as practised in the London nurseries, would 

 be very useful to many country readers of this Magazine. A list of the best 

 varieties for forcing would increase the value of the paper; and the routine 

 treatment of the plants throughout the year might also be included. — 



j.B.w. y ^ 



