CATALOGUE. NATURAL aiSTORY, VEGETABLE PHYSIOLOGV. 



515 



Vastel on germination. Extr. B. 3of. Phil. 



n. 66. I'll. M. Vlir. 1S7. Gilb. XIV. 364. 

 Coulomb on the circulation of sap. M. Inst. 



11.246. Journ. Phys. XLIX. 392. Ph. M. 



VI. 310. Repert. XII. 356. 



Says, that it ascends, with some air, near the axis of the 

 tree. 



*Mirbel on vegetable anatomy. B. Soc. Phil. 



n. 60. Journ. Phys. LII. 336. . . With 



many figures. Ph. M. XIII. 36. 

 MiVie/ An atomic et physiologic vegetales. 2 v. 



8. B. B. 

 Darwin's phylologia. 4. Lond. 1800. R.I. 

 Th. de Saussure on the influence of the soil 



on vegetables. Journ. Phys. LI. 9. Gilb. 



VI. 459. 



Seems to think, that plants generate some calcariom 

 earth. 



Ik. de Saussure Recherches chimiques sur 

 la vegetation. 8. Par. 1804. R. I. 

 Ace. B. Soc. Phil. n. 86. 



Thinks, that all the solid contents are derived from the 

 soil. 



Miclielotti. Ph. M. IX. 240. 

 Velley on the food of plants. Repert. XII. 32. 

 Carradori on germination in oxygen. Journ. 



Phys. Llll. 253. 

 On the effect of light on germination. Journ. 



Phys. LIV. 3iy. 

 Solom^ on the temperature of vegetables. 



Ann. Ch. XL. 114. 

 Fairman engrafting. S. A. XX. 181. Nich. 



VI. 124. 

 Hunter on the nourishment of vegetables. 



Repert. ii. III. 349. 

 Jurine on the organization of leaves. Journ. 



Phys. LVI. 169. Ph. M. XVI. 3, 147. 



With figures. 



Edelcrantz's plaster for trees. B. Soc. Phil. 



n. 82. 

 B. Prevost on the tracheae of plants. Journ. 



Phys. LVII. 112. 



Account of Mr. Knight's Experiments on the descent of 

 the Sap in Trees. From the Journals of the Royal Jnsluy- 

 tution. I J. 71. 



The principal object of this paper is to point out the causey 

 of the descent of the sap from the leaves through the bark, 

 and of the consequent formation of wood. These causes Mr, 

 Knight supposes to be gravitation, agitation, and capillary 

 attraction, combined with some peculiar structure of the 

 vessels. 



From experiments on vine leaves, it appears that the per- 

 spiratory vessels of the leaf are confined to its under surface : 

 the upper part Mr. Knight considers as serving to receiv« 

 the influence of light, andas probably emitting oxygen gas; 

 and he quotes Boniiet'sexperiments, as showing that this sur- 

 face of the leaf, when detached from the plant, is capable 

 also of absorbing moisture. 



Mr. Knight removed a portion of the bark of the branch 

 of a vine which was in an inverted position, and he found that 

 new bark and wood were generated at the lip of the wound 

 which was actually uppermost ; and from a comparison of 

 this with his former experiments, he infers, that the force 

 of gravitatien is materially concerned in the circulation of 

 the sap. 



By means of bandages, Mr. Knight prevented the agita- 

 tion of some young apple trees in Some parts of their stems, 

 and in particular directions, while their motion was per- 

 mitted in other parts : and it was found that their growth 

 was the most considerable in the parts, which were freely 

 agitated, and that the diameter of the section was greater by 

 about one sixth in the direction of the motion. Hence we 

 may understand the greater thickness of the lower parts of 

 the trunk, and of single trees in exposed situations, while 

 the trees that form a wood, and shelter each otljer, are 

 higher and more slender. 



If a large tree has been deprived of motion, by cutting off 

 its foliage or otherwise, its growth is promoted by removing 

 the dry external layers of the bark, which appear to impede 

 the motion of the sap. 



Mr. Knight supposes that the expansion and contraction 

 of the alburnum, from changes of temperature, are partly 

 communicated to the bark, and assist in propelling its sap : 

 but that the principal cause of this motion is gravitation, 

 which operates more completely in the perpendicular parts 

 of the tree, than in the horizontal branches; hence these 

 branches are not liable to become top large for their strength, 

 in an unfavourable position. 



Leaves of the vine were succesfuUy grafted on the fruit- 

 stalk, the tendril, and the succulent shoot ; and a branch 

 was nourished by the leafstalk, the tendril, and the fruit- 



