652 Question on the Formation of the Alburnum. 



Art. V. A Question to the Author of "The Domestic Gardener's 

 Manual." By Mr. Main. 



Sir, 



In your Magazine, Vol. VIII. p. ] 42., there appears a com- 

 munication containing some very pertinent remarks, by the 

 talented author of The Domestic Gardener's Manual* C.M.H.S., 

 in which he very properly advises vegetable physiologists to 

 be cautious in forming general conclusions from imperfect 

 or partial appearances of either the motions of the fluids, 

 or the uses of the several organs of plants. This is good 

 advice; for it cannot be denied that there are certain points 

 in the science far from being explicit, especially to those who, 

 like myself, cannot dive deeply into the philosophy of it. 



In the communication alluded to, there is one of those 

 stumbling-blocks which is believed, and consequently tho- 

 roughly understood, by the author as well as Mr. Knight, 

 P.H.S., whom he quotes, and which, if he will condescend 

 to explain, would be, I can assure G. I. T., a very great 

 favour to us practical men. He is a lover of science, and, 

 I presume to think, would be gratified to enlighten those 

 that have not the advantages of either chemical knowledge 

 or extensive reading to assist their studies of vegetable 

 phenomena. 



The enigma I allude to is contained in the following sen- 

 tence: — " The nutriment absorbed becomes the true sap or 

 living blood of the plant by exposure to light in the leaf; 

 that it descends by the bark, by which the matter that forms 

 the layer of alburnum is deposited" The idea of the new layer 

 of alburnum being formed by, or out of, the true sap, is de- 

 clared again and again in Mr. Knight's writings, and reiter- 

 ated repeatedly in the Domestic Gardener's Manual ; but in 

 all cases, I beg leave to say, without sufficient proof. Now, as 

 it is high time that all obscurities should be, as far as possible, 

 cleared away from this interesting subject, and that no gratui- 

 tous concessions should be required of the student, I would 

 most respectfully beg leave to propose the following question : 

 — Is it possible that organic structure can be formed out of mere 

 fluids, 'whether simple or compound, as they are found in the 

 root, stem, leaves, formers, or fruit of plants ? If such a process 

 of accretion be possible, I would wish to be informed how it 

 takes place; and particularly, whether there be any similar pro- 

 cess or instance, in the whole range of animated nature, with 

 which it can be compared ? 



As a very superior chemist, and as a natural philosopher, 

 I beg of G. J. T. an answer to the above simple question : 



