422 The Rev. J. B. Reade on the Chemical Composition 



three elements, oxygen, hydrogen, and carbon, the exact pro- 

 portion in which these are united being uncertain ; and that 

 therefore it remains to be ascertained whether the two organic 

 elements of vegetable structure are identical in chemical com- 

 position, and whether the membrane and fibre which com- 

 pose the cells and tubes in different parts of plants are always 

 of the same kind. It is further observed by the same author 

 that an inquiry into this subject would be one of extreme dif- 

 ficulty, if not qf absolute impossibility with the present resources 

 of' chemistry. 



It gives me great pleasure to be able to lay before the 

 members of the British Association a few well ascertained 

 facts on a subject, of which the difficulty has hitherto pre- 

 vented it from being placed even among the debatable ques- 

 tions in the philosophy of botany. Having, on many occa- 

 sions, had the good fortune to witness the admirable tact with 

 which Mr. Robert Rigg, of Walworth, effects the chemical 

 analysis of vegetable products, I felt convinced, when I saw 

 Professor Henslow's remarks, that the difficulty, which has 

 appeared to be almost insurmountable, would be readily over- 

 come in my friend's laboratory*. I therefore separated the 

 spiral vessels which form the central column of the roots of 

 the hyacinth from their surrounding cellular tissue, and the 

 membrane and fibre thus obtained furnished upon analysis 

 the following results. 



Spiral Vessels. Cellular Tissue. 



Carbon 41*8 Carbon 39*2 



Hydrogen 1-1 Oxygen 7*4 



Nitrogen 4*3 Nitrogen 3*9 



Water 51*8 Water 48*5 



Residual matter TO Residual matter TO 



100- 100- 



Experiments made upon the gross material, and without 

 separating the fibre from its investing membrane, give hydro- 

 gen and oxygen in the proportion to form water. This fact, 

 which has been long known to Mr. Rigg, admirably confirms 

 the separate experiments which were made at my suggestion, 

 and from which it appears that the excess of hydrogen in the 

 fibre, and excess of oxygen in the membrane, are also so nearly 

 in the proportion to form water. It is also found that the 

 petals of the hyacinth contain an excess of oxygen, while the 

 pistils and pollen are marked by an excess of hydrogen. This 



[* Notices of papers by Mr. Rigg on Fermentation and the Chemical 

 Changes of Germination will be found in Lond. and Edinb. Phil. iMag., 

 vol. ix. p. 535.— Edit.] 



