The Hunterian Oration : delivered in the theatre of the Royal College of Surgeons ... 1823 / [Sir William Blizard].

William Blizard

Date:: 1823

Credit: The Hunterian Oration : delivered in the theatre of the Royal College of Surgeons ... 1823 / [Sir William Blizard]. Source: Wellcome Collection.

154/166 page 36

$[36] If the raw materials of animal and vegetable sustenance had obviously contained the simple elements of all organic formations, it would have been more easy to account for the products elaborated by living structures; but since it is otherwise, the best method for improving this part of Phy- siology appears to be,—^that of beginning with the examina- tion of those fixed compounds, which either belong to the mineral kingdom,—such as the calcareous portions of shells, teeth, and bones, — or, those exuvial productions which clothe and protect sensitive parts,—as our cuticle, nails, and hair, and the varied apparel of birds, beasts, reptiles, fishes, and insects. The shells of the eatable Ovster exhibit examples of both mineral and animal extraneous deposits. The gross pro- portions of those two kinds of material were found, from an average of trials, to be, twenty parts of carbonate of lime, to one part of animal albuminous membrane; but this analysis is taken from the whole of the shells,—and, as I before stated, the different parts of the shells vary in com- position, and even the same shells under some circumstances possess a greater or lesser proportion of mineral matter. In a pair of fresh Oysters’ shells, weighing 3488 grains, the entire elastic ligament or spring of the hinge weighed three grains and a half; the elastic power of this spring was equal to the pressure of three pounds fifteen ounces avoir- dupois, when placed upon the centre of the flat valve, and confined to the area of the insertion of the val\mlar muscle. There is one general fact respecting the composition of bones, teeth, and shells, which may prove available in the future advances of Physiological science: it is, the occur- rence of animal gelatine, where the earthy solid proves to$