Anatomy of the Vine. 1 9 



drawing fig. 3., at bed e) will be seen precipitating into the 

 latter solution sundry beautiful distinct blue specks. This 

 precipitate or blue colour arises from the union of the prussiate 

 of potash, which had ascended from the cup by those vessels, 

 and now discharges itself into the sulphate of iron. You may 

 easily see the difference of the two precipitates : that of the 

 liber will be black, from the causes already mentioned, whilst 

 that on the vessels of the alburnum will be a deep blue. 

 Again, with a sharp clean knife, cut a collet in a longitudinal 

 direction ; then apply the sulphate of iron, and immediately 

 will be seen the blue precipitate in the same sort of vessels, but 

 of considerable length; and by carefully cutting the alburnum 

 lengthwise, they may be seen an inch long, or upwards. 



The continuation of these ascending vessels might be dis- 

 covered in the stalk, and also in the leaf of the vine, by the 

 blue precipitate, were it not for the gallic acid of the liber, 

 from its black precipitate blending immediately with the Prus- 

 sian blue, so that the two sets of vessels cannot be distinguished 

 from each other. However, recourse may be had to others ; 

 either the shoot of an apple tree, which contains no gallic acid, 

 or to some of the cabbage tribe, which I prefer, from their 

 leaves being smooth and broad. Therefore, place some large 

 cabbage or broccoli leaves, or even a cabbage plant run to 

 seed cut off a little above the ground, in a cup, with the solu- 

 tion of the prussiate of potash, for 36 hours. On cutting their 

 stalks across, or any part of their leaves, in any direction, and 

 applying the sulphate of iron, the ascending sap-vessels, by the 

 blue precipitate, will be immediately seen in them. After- 

 wards, it may be a satisfaction to apply the sulphate of iron to 

 some leaves that have not been prepared with the solution of 

 the prussiate of potash ; but no precipitate will be discovered, 

 thus showing the absence of gallic acid. If some of the cab- 

 bages, &c, be left three or four days in the solution, the vessels 

 of the cellular texture will be seen most beantifully, when cut 

 through, by applying to them the sulphate of iron. If one 

 experiment be more gratifying than another, it is seeing the 

 ramification of those minute vessels, not only conspicuously in 

 the stem, the stalk, and the leaf, but more so in the medulla. 



I think it is very evident (reasoning by analogy) that, had it 

 not been for the precipitate formed by the gallic acid, the 

 ascent of the prussiate of potash would have been traced in the 

 ascending vessels of the stalks, and also in the leaves, of the 

 vine. The ascending vessels may be clearly seen, by the above 

 process, in the flower of the white lily, and also in the fruits 

 of the peach, pear, and apple, provided they are left on the 

 branches ; but not so well in the currant, raspberry, or straw- 



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