COMPOSITION OF CELLULAR MATTER. 105 



It is exceedingly difficult in any case to separate the cellular from the 

 incrusting matter of wood, so as to obtain the means of determining by 

 analysis the exact difference in their elementary constitution. Under 

 the impression that in very light and porous substances he sliould ob- 

 tain the cellular matter in a purer form, Payen analysed the fibre of 

 cotton — the pith of the elder, the cellular substance of the cucumber, of 

 the mushroom, and of other fungi, the spongy matter which forms the 

 extremities of the roots of plants, and various other similar substances, 

 and in all these varieties he found the hydrogen and oxygen to exist in 

 the proportions to form water. The mean of his analyses was very 

 nearly as follows — which for the purpose of comparison I shall contrast 

 with that of Dr. Prout : 



100 100* 



In both these analyses the hydrogen is very nearly 8 times that of 

 the oxygen. All these substances, therefore, may be represented by 

 carbon and water, though the woody fibre of Dr. Prout contains 5 per 

 cent, more carbon than the cellular matter of Payen. 



If we calculate the number of equivalents of each element contained 

 in these two varietiesf of vegetable fibre composed as above exhibited, 

 we find in the one 12 of carbon, 8 of hydrogen, and 8 of oxygen ; in 

 the other, 12 of carbon, 10 of hydrogen, and 10 of oxygen. They may 

 therefore, be conveniently represented by the following formulae : 



WooDT Fibre by Cj2 Hg Cj 



Cellular Fibre. . . . by C12 H,o C^q 

 It is not unlikely that both of these forms of matter may exist, as 

 well in the perfect wood of trees as in the less consolidated pith of the 

 elder, or in the fibres of cotton — and that they may occur intermingled 

 also in varying proportions with other substances, containing hydrogen 

 in excess.J 



m its natural state, is a fact to which it will be important to advert when we consider here- 

 after the chemical changes which the food undergoes in the interior of the plant. 



• Meyen's JaJiresbericht, 1839, p. 10. 



t This is done very simply by dividing the carbon by 6, and the oxygen by 8 (see page 

 36), thus- 

 Carbon ... 50 -h 6 = 8-33 C which numbers ) 12 

 Hydrogen • • 555 = 5-55 } are to each / 8 

 Oxygen - • . 4445 -^ 8 = 555 ( other as ) 8 



X The existence of a variety of cellular fibre identical in constitution with common starch, 

 as this of Payen is, (see subsequent section, p. 106,) was previously rendered probable by 

 the observations of Dr. Schleiden, that the embryo of the Scholia latifolia, consisting of 

 pores and vessels, the sides of which exhibit listinct concentric layers, is entirely soluble 

 in water, with the exception of the outer rind ; and that its solution becomes blue on the 

 addition of iodine. It would appear as if the cellular substance were in this case wholly 

 composed of Starch. iPoggeTidorfs AnncUen, xliii., p. 398.) It may, however, be in such a 

 state of tenuity in the embryo of this plant, as to be easily changed into starch by the action 

 of hot water; and it is still by no means certain that the cellular fibre analyzed by Payen 

 may not also have undergone a change by the treatment to which it was previously subject- 

 ed. I am unable, however, to speak decidedly on this subject, as I have not seen the de- 

 tails of M. Pay en's several papers. (See subsequent section, on the mutual transformationa 

 of tcoody fibre, star ch, gum, and sugar, p. 112.) 



