346 On the Action of delacked Leaves of Plants. 



united by two longitudinal sections through the b;iik, which ex- 

 tended from the extremities of the upper tranvcr&c sections to 

 the extremities of the lower; by which means, pieces of bark, 

 about half an inch broad, and nearly an inch long, were hcpa- 

 rated from the adjoining bark. These were then detached from 

 the alburnum, and surrounded by two folds ofpajjer coated with 

 wax on each side; by which all connexion and cominuuication 

 v.ith the tree, except through the divided leaf-stalks, were cut 

 off. The insulated pieces of bark, nevertheless, contimird to 

 grow, and extended downwards, and laterally, and in thickness; 

 and thin la\ ers of alburnum were deposited. 



Leaves of th.e potatoe, without anv portion of bark being at-^ 

 tached to them, were taken from the plants, just at the period 

 when the tuberous roots began to be formed ; and I conceived 

 that these leaves, consistently with my former experiments and 

 conclusions, nnist contain portions of the living organizable 

 matter, which would subsequently have been found in their tu- 

 berous roots. The leaves were, therefore, planted in potjs, and 

 placed under glass, where, being regularlv and properly supplied 

 with water, they continued to live till winter, though without 

 emitting tihrous roots; and I then expected to find some small 

 tubers at their bases. In this expectation I was disappointed; 

 but the result of the experiment was not less satisfactory, the 

 bases of t!ie leaf-stalks themselves having sv,-ollen into conie 

 bodies of more than two inches in circumference, and being 

 found to consist of matter apparent!)' similar to that which coni-r 

 poses the tuberous roots of the plant. The enlarged parts of 

 the leaf-stalks remained alive in the following spring; but whether 

 they are capable of generating buds or not, I have not been able 

 to ascertain. 



Leaves of mint were planted in the same manner as those 

 above mentioned; which grew, and continued alive through the 

 uinter, and were still living in the end of the last month, having 

 assumed the character of the thick fleshy leaves of ceigreeii 

 trees. Upon examining the mould in the pots, I found it to 

 contain very numerous roots, which must have derived their uic- 

 duliary, and their cortical, and alburnous substances from mat- 

 ter which had emanated and descended from the leaves. 



I had fre.'juer.tly observed, in former experiments, that the 

 destruction of the mature leaves of young plants not only sus- 

 pended the growth of the roots, but also the growth of the im- 

 mature le;tves ; whence I inferred, in a, former conununication, 

 that the organizable matter, which composes the yoimg leaves, 

 has always imdcrgonc a previous preparation in other leaves of 

 the plant, either of the same, or preceding bcason ; and I was 

 thence led to expect that, uiidei- favourable circunibtauce;., the 



mature 



