THE FLUIDS OF PLANTS. 159 



the rays and medullary sheath, serve to nourish and develope the cam- 

 bium into a ligneous and cortical zone. 



This gum, dissolved in water in its descent by the bark, is able to 

 assist on one side the secretions which are forming there, and on the 

 other to supply nutriment to the cambium, or the partially- organised 

 juice which contains the rudiment of the new zones. The gummy 

 matter, which also descends through the alburnum, serves likewise to 

 nourish the cambium, or the new woody zone ; this is the gum which 

 as it descends by the bark is stopped in its course by an annular sec- 

 tion, whereby it is compelled to undergo the action of the cellules for 

 its conversion into ligneous matter for the purpose of nourishing the 

 bark and developing in it a protuberance formed on the trunks of 

 woody vegetables (bourrelet). 



Throughout the whole of its course the gummy matter can be ab- 

 sorbed by the cellules which are not filled and which retain their vital 

 action ; thus all the cellules of the alburnum and of the liber — like so 

 many hygroscopic bladders — absorb the gummy water which surrounds 

 them ; each of them elaborates it by its own peculiar action, and can 

 thus, according to its nature, transform the gummy matter into fecula, 

 sugar, orlignine with so much the greater facility, as the whole four sub- 

 stances scarcely differ ; and we often in our laboratories have a proof 

 that they can be converted into one another. This is especially the 

 case in the experiments on the conversion of lignine and starch into 

 hydrated sugar by the action of sulphuric acid. The gum and the 

 sugar appears to be, in this series of decompositions, the two transitory 

 conditions, and their extreme solubility in water exposes them con- 

 stantly to be drawn away towards the most energetic organs. 



The fecula and the lignine are of a more permanent nature ; the 

 fecula settles itself as though it were stored in the organs which must 

 ultimately be developed ; it retains the soluble matter, which is pro- 

 tected from the water by the iusoluble covering that surrounds it. 



In short, the lignine is deposited in those particular organs which 

 have reached the complete stage of their development, or in the tissues 

 themselves of the vegetable membranes, nor does it appear to be of a 

 nature fitted to be transferred again to the other parts. 



[It would be presumptuous in me to assert that the above is erro- 

 neous; but I owe it to my readers to state, that however high De 

 Candolle ranks in genuine science, he has also, with a fatuity not un- 

 common in men of distinguished genius, strongly advocated all the 

 absurd fancies of vegetable metamorphoses, and even piques himself 

 upon being in a great measure the author of these fancies. — Editor.] 



