55^ British Association for the Advancement of Science. 



one above the other, from below ; the former having the appearance 

 of roots, the latter were brunches with leaves. 



3. The bark and two layers of alburnum were cut away. The tree 

 was at the time unhealthy ; it however put forth its leaves on that 

 and the ensuing spring, but shortly after died. No sap was observed 

 above or below the wounded part. Roots were developed from the 

 upper, and branches from the lower part of the section. 



4. The bark and six layers of alburnum were taken off. The tree 

 became much less vigorous, but did not die, and otherwise presented 

 the same appearance as the last. 



5. The bark and twelve layers of alburnum were stripped. The 

 consequences were again similar to the last two ; the alburnum above 

 and below the cut being dry, but an accidental cut that penetrated 

 into the heart-wood exuded sap. 



6. This was a repetition of the experiment of Palisot de Beauvais, 

 by cutting away a circular ring of bark around a single branch. The 

 branch continued to grow, and roots sprouted from the under surface 

 of the isolated bark and branch. 



7. In this the whole of the wood of the tree was cut away, except 

 four pillars, composed of bark and sap-wood. In this case, the sap 

 first appeared from above, descending by the pith, and then from the 

 heart-wood, the alburnum being dry. In this case the sap must have 

 passed up the alburnum, and horizontally through to the heart- wood. 



Mr. Nevin inferred from these experiments — 1. That the life of 

 the tree does not depend on the liber or cambium. 2. A descent of 

 sap takes place before the developement of leaves. 3. That new mat- 

 ter arises from below j which had not previously been allowed. He 

 thought there were two distinct principles in the tree, — one, the as- 

 cending, or leaf principle ; the other, the descending or root principle. 

 Mr. Nevin had also performed some experiments on the conversion of 

 roots into branches, and came to the conclusion, that buds or branches 

 might be developed from any part of the root above its extreme end, 

 from which point it was impossible for buds to be developed. 



Professor Lindley remarked that these experiments confirmed en- 

 tirely the theory of the structure of wood adopted by Du Petit Thouars. 

 He did not think that the existence of any new principle could be in- 

 ferred from the experiments. In the seventh experiment the hori- 

 zontal circulation of the sap was proved, and confirmed the accuracy 

 of Hall's experiment of cutting a tree nearly through on alternate 

 sides, when the sap still ascended. 



Section of Chemistry and Mineralogy , Sept. 1 2. — Mr. Hartley read a 

 paper, 'On the Corroding of Iron by salt water.' The object of the 

 paper was to show that brass protects both bar and cast-iron in a very 

 perfect manner. The brass did not appear to have undergone any ac- 

 tion, which, as stated by the President, (Mr. Faraday,) is rather op- 

 posed to received notions of electro-chemical action. 



Dr. Andrews next read a paper, • On some singular modifications 

 of the ordinary action of nitric acid on certain Metals.' Bismuth in 

 nitric acid of specific gravity 1*4, was rapidly acted upon, but this ac- 

 tion immediately ceased when the bar was touched by platinum. On 



