188 Reply to Mr. Main*s Qiiestion 



extent of the bark, as was deposited by a similar extent of 

 bark which retained its natural place and state. 



Now, if the matter of the alburnum was not deposited by 

 the bark upon the folds of the paper, will Mr. Main be so 

 obliging as to explain by the agency of what body it was de- 

 posited, and from whence the substance of it was derived? 



Perhaps that degree of reflection which is certainly due to 

 a fact so interesting as the one I have just presented in the 

 form of a question to Mr. Main, will assist him in the removal 

 of some of those " stumbling-blocks" which he alludes to; 

 and 1 now hasten to reply to those enquiries which are more 

 immediately directed to myself. I am asked whether " it is 

 possible that organic structure can be formed out of mere 

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

 root, stem, leaves, flowers, or fruits of plants?" 



Is it to be believed that Mr. Main was serious and in ear- 

 nest when he penned this enquiry ? Could he have reflected 

 for one moment upon a multiplicity of facts connected with 

 the nutriment of plants, that must have come under his 

 observation ? Without trespassing further. Sir, upon your 

 pages, I think I might content myself by referring my querist 

 to the paper upon i^alsamina hortensis (Vol. VIII. p. 403. to 

 407.) for an ample and sufiicient answer to his question ; but, 

 perhaps, courtesy requires that I should adduce some other 

 facts that will apply directly to it. Before I proceed to do 

 so, I must, however, request him to oblige me by re-perusing 

 that paper on the balsam : and now, presuming that he has 

 so done, I would ask, how, if Mr. Main believes it to be a 

 philosophical truth that the roots of plants are incapable of 

 imbibing an atom of the most impalpable powders, that they 

 cannot absorb particles of matter so inconceivably fine as 

 those afforded to water by the solution of a colouring mate- 

 rial ; how, if he believes these things, he can imagine that any 

 substance more solid, or of greater density, than pure water 

 can enter into, or be conveyed through, the conducting ves- 

 sels of a vegetable body, be they cellular or tubular? 



But, perhaps, it may be argued that colouring matters have 

 unquestionably been observed to pass into the vegetable 

 structure. In fact, I myself have proved that they can be 

 taken up by a variety of vegetable subjects ; but these have 

 always been mutilations, not perfect plants in a healthy and 

 growing state. However, without dwelling further upon that 

 which I noticed particularly in another place, I proceed to 

 solicit Mr. Main's attention to a striking fact, that bears upon 

 the subject of his enquiry. Any plant growing in a pot 

 might serve my present purpose; but I select the vine, because 



