114 PROCESS OF NUTRITION. CHAP. III. 



central part of the root was, as in the foregoing 

 experiments, tinged the deepest ; but the wood of 

 a branch of the Apricot was tinged the deepest 

 towards the circumference, the pith and bark being 

 unaltered ; and in a case in which the branch was 

 stripped of a ring of bark, the wood was tinged as 

 before. On the surface of a transverse section of 

 a bud three black spots were distinguishable, indi- 

 cating the ascent of the coloured fluid ; and when 

 the experiment was made upon the stalk of French 

 Beans the tincture was found to have ascended only 

 by the bundles of woody fibre. 



DuHameJ. Du Hamel, in pursuit of the same object, mixed 

 a quantity of powdered Madder-root with the earth 

 in which a plant vegetated, hoping he might thus 

 succeed in detecting and tracing out the sap vessels, 

 in the same manner as he had succeeded in colour- 

 ing the bones of some animals by means of mixing 

 Madder-root with their food. But the experiment 

 failed. He then adopted the plan of Bonnet, 

 namely, that of steeping the extremity of a branch 

 or stem in a coloured fluid* The fluid he used was 

 ink ; and the subject of experiment branches of 

 the Fig, Elder, Honeysuckle, and Filbert. In ex- 

 amining some branches of the two former after 

 being steeped for several days, the part immersed 

 was found to be black throughout, but the upper 

 part was tinged only in the wood, which was co- 

 loured for the length of a foot, but more fairjtly 

 and oartially in proportion to the height. The pith 

 * 



