Anatomy of the Vine. 137 



ence in number at every joint : sometimes an increase, at 

 others a diminution; but, upon the whole, the number of 

 divisions at the top corresponded nearly with those at the lower 

 end, although the shoot was of considerable length. 



I flatter myself that many will repeat these experiments. 

 Should any one have the patience to examine and dissect the 

 whole of the bundles of a summer shoot of a vine, I should 

 esteem the communication of it, either to Mr. Loudon or 

 myself, with a drawing, a particular favour ; but, I can assure 

 him, it is a labyrinth only to be discovered by one of great 

 patience and perseverance. I have many times attempted the 

 task without success : as far as I went, I could clearly perceive 

 the system was extremely regular, and that every bundle had 

 its particular place of destination. The middle of July is the 

 best time to make the experiment, when the bundles of vas- 

 cular texture are firmly attached ; but, a month later, they 

 lose a little of their vital action. 



The use of the vessels of the vascular texture of the bark is 

 to convey part of the descending sap, or secreted juice, down- 

 wards, during the summer. My endeavours have not been so 

 successful as I could have wished, in filling these vessels with 

 a black precipitate, similar to my experiments in p. 24., by 

 the sulphate of iron. It is fortunately, however, of little con- 

 sequence, as these vessels in some other plants are filled with 

 a milky fluid, which arises in the leaf, and descends by similar 

 vessels. It requires some little management to retain this fluid 

 in the branch, when it is detached from the parent tree, dur- 

 ing the time of removing the cuticle and cellular texture while 

 you lay bare these bundles of the vascular texture. The 

 plant I should recommend for that purpose is commonly called 

 the caper shrub (.Euphorbza iathyris) : it is found in most 

 gardens ; the seeds of it are about the size of caper buds, the 

 stem is of a tolerably hard substance, and these vessels in it 

 are firm, and readily discovered. Choose for the experiment, in 

 the autumn, the lower part of a summer shoot of a two years old 

 plant : tie a collet tightly round, with some thick cotton thread ; 

 then cut it off below the bandage, when you will find very little 

 discharge from the upper separated parts, owing to the ligature 

 upon them ; but the lower remaining stem will bleed profusely. 

 These vessels, by the above precaution, will be tolerably well 

 under your control while you try any experiment upon them. 

 The moment that one is punctured, it discharges immediately 

 its milky fluid : they must be separately cut, to empty them, 

 which shows they have no communication with each other. 

 These vessels of the vine commence at the lower end of the 

 summer shoot, and continue to the point of the leaves, carry- 



