106 LINK ON THE FLUIDS OF PLANTS. 



termed beaded (en chapelet) are also as readily coloured as the true 

 vessels. 



It sometimes happens that the colour is not blue, but deep 

 green, although the solution of the sulphate of iron has been 

 exposed to the air for a sufficiently long time ; but this green colour 

 can be very well ascertained to be foreign to the vessels. I have 

 often seen the colour penetrate even the vessels of the leaves ; but 

 I have not hitherto seen it pass into the flowers. It often happens 

 also that the vessels of the stem have been tinged blue, while those 

 of the roots are not at all tinged, perhaps because the solution 

 of the cyanuret had all passed into the stem. M. De Candolle, 

 says, in his " Organagraphie," that there are no vessels (trache'es) 

 in the roots : I have found them in the roots of all vascular plants. 

 The preceding experiment furnishes an easy method of distinctly 

 indicating the vessels (vaisseaux) which conduct the sap in the 

 several parts of a plant. 



Some years ago I made experiments upon the resorption of plants, 

 which I published in a German journal. I took plants in garden 

 pots, and bent down branches of them so as to terminate in a- 

 glass filled with solution of arsenious acid, without separation from 

 the stem, or wounding them in any manner. The plants were 

 Linaria alpina, Cliffortia obcordata, Hemimeris coccinea, Mezem- 

 brianthemum glomeratum, and Xenopoma obovatum. After some 

 time, they all flagged, first the branches soaked in the solution, and 

 then the rest of the plant. I remarked that the plants which were 

 watered, resisted the effects of the poison longer than those which 

 were not watered j and that succulent plants, nourished by the juice 

 of their own leaves, could vegetate a long time without absorbing 

 poison sufficient to kill them. Absorption then goes on through the 

 leaves and branches, if the roots fail in affording the necessary supply 

 of water. If some leaves, or the point of the branch to be soaked, be 

 cut, the poison immediately enters the absorbing vessels (vaisseaux) 

 and the plant soon dies. 



I was anxious to ascertain whether this absorption is made by the 

 common vessels (Irache'es,) and not by other vessels (vaisseaux) ap- 

 propriated for this purpose. With this view, as in the preceding 

 experiments, I soaked brapches in a solution of the cyanuret of pot- 

 ass and iron; I then washed the branches with pure water, and 

 substituted for the cyanuret or solution of sulphate of iron. 

 These experiments were not uniformly successful, for it frequently 

 happened that the interior parts of the plants were not coloured; 



