Outlines of practical physiology : being a manual for the physiological laboratory, including chemical and experimental physiology, with reference to practical medicine / by William Stirling.

  • William Stirling
Date:
1902
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of practical physiology : being a manual for the physiological laboratory, including chemical and experimental physiology, with reference to practical medicine / by William Stirling. Source: Wellcome Collection.

    48/690 (page 18)
    In absolute alcohol (and ether) almost all are soluble with difficulty, or insoluble. (h) When strongly heated they char, decompose, and yield a variety of products. Classification of some Carbohydrates. I. Glucoses or Monosaccharides (C6h12o6). (Hexoses.) II. Saccharoses or Disaccharides (C12H22Ou). III. Amyloses or Polysaccharides (?i(C6H10O5) ). + Dextrose. - Laevulose. + Galactose. -1- Cane-sugar. + Lactose. + Maltose. + Iso-maltose. + Starch. + Soluble starch. + Dextrins. + Glycogen. Cellulose. Animal gum. The + and - signs indicate that, as regards polarised light, the substances are dextro- and laevorotatory respectively. Those in italics occur in the organs or secretions. The amyloses are anhydrides of the glucoses [w(C6H1206) - wH20 = (C6H10O5)„ ], while the saccharoses are condensed glucoses (C6H1206 + CgH^Og-HoO = C12H22On)]. The saccharoses are converted into glucoses on boiling with dilute sulphuric acid. 0 | c'hJa + H-° = 2C«h^°6- Emil Fischer has shown that the monosaccharides are aldehydes or ketones of a hexatomic alcohol, C6H8(OH)6. Just as aldehyde, C2H40, is formed by oxidising ethylic alcohol, C2H60, so from mannitic alcohol the simplest carbohydrate, C6H1206, is formed. When two molecules of such monosaccharides polymerise with the loss of water, they form the disac¬ charides, which may split up again and yield monosaccharides. When there is further polymerisation with loss of water we get bodies with mole¬ cules of greater molecular weight—the simpler members being dextrins, the more complex starch and glycogen, forming the group of polysaccharides. These in turn may break down and yield monosaccharide or disaccharide molecules. Thus the transformation undergone by carbohydrates in the organism, their conversion from one form to another, are rendered more easy of comprehension. I. MONOSACCHARIDES. 1. Glucose, Dextrose, or Grape-sugar (C6H1206).—In commerce it occurs in warty uncrystallised masses ol a yellowish or yellowish-brown colour. It exists in fruits, honey, and in small