THE ORGANIC ELEMENTS. 9 



not make it a simple substance. Combinations of Cellulose with other bodies 

 are not yet known ; there thus remains, to explain the easy transition of 

 Cellulose into Sugar, Dextrin, and Starch, only the hypothesis of Iso- 

 merism. All other formulae appear purely arbitrary, and explain nothing, 

 for the elementary analyses vary from 43*22 to 52-01 of carbon, 5-9 to 

 6*91 hydrogen, 41-57 to 50-38 oxygen, or of analyses of the same cellular 

 tissue taken into account C 43-2 447, H 6-06-5, O 49-350-59, which 

 agree perfectly with the formula given above. On the other hand, the 

 whole doctrine of an incrusting matter (Payen), although supported by 

 the profundity of Mulder (Physiol. Chem. Moleschott, p. 209.), is a mere 

 castle in the air, that must be rejected a priori. On the application of 

 the ordinary re-agents, the thickness of the cell-walls is not diminished, 

 but they become loosened and swell up. What the reagents take up are 

 the contents of the cell, and matters which the cell-wall contain, and 

 which, according to the age of the cell, would become colouring matter, 

 tannin, hurnic acid, and humates. The wood-cells are, in comparison 

 with other cells, decaying, and are constantly forming out of the cellulose 

 substances, which are more and more rich in carbon, which remain dis- 

 solved in the cell-walls, and which are taken up by means of re-agents. 

 The successive layers of the cell-wall are composed chemically out of the 

 same or an isomeric matter as the primary cell, which explains its whole 

 deportment, and even Payen's elementary analysis of the spiral fibres 

 in Musa sapientum. A knowledge of the cell-layers is especially 

 important physiologically ; a knowledge of the substances which convert 

 sap-wood into heart-wood is only technical, as here life is almost wholly 

 extinct. 



Cellulose presents itself under many modifications. In its pure state 

 it appears to vary chemically, according to the quantity of water it con- 

 tains. Independently of this, it varies greatly in its physical properties, 

 such as brittleness, viscosity, density, and especially in its perviousness 

 to water, which the less it is the more it appears to approach in its 

 nature amyloid and jelly ; and there are, in fact, very many transitionary 

 bodies between these three.* 



In the impure state in which it ordinarily occurs, it varies yet more 

 from the passage through it of other matters ; perhaps through some de- 

 composition which they induce. Its colour is especially various, passing 

 from perfect transparency to the darkest brown (as in ferns) ; and occa- 

 sionally all other possible colours are present, as is seen in the epidermis 

 of the seeds of Leguminosce y a golden yellow colour in the leaves of Phor- 

 mium tenax, &c. 



2. Amyloid*( is, when dry, a cartilaginous, but moist, gelatinous, clear, 

 transparent body, soluble in boiling water, strong acids, and caustic 

 alkalies, but not in ether and alcohol in a concentrated state. It is 

 coloured blue by iodine, and the combination is soluble in water, giving 

 it a golden-yellow colour. It is found only in the layers of the primary 

 cell-membrane. There is no chemical analysis of this substance. It 

 has been found at present only in the cotyledon-cells of Schotia latifolia, 

 S. speciosa, Hymencea Courbaril, Mucuna urens, M. gigantea, and Tama- 

 rindus indica. Perhaps many of the observations olf Hugo Mohl belong 

 to this substance. 



3. Vegetable Jelly (Vegetable Mucilage, in part, of the chemists, Bas- 



* See Hugo Mohl, Some Observations upon the blue Colouring of vegetable Cell 

 Membrane, through Iodine. Flora, 1840. 

 f See Poggendorff's Annalcn, 1839. 



