Page:Proceedings of the Royal Society of London Vol 1.djvu/436

Rh Within the cavity of the tympanum is a part peculiar to the whale. This is a membranous fold, or broad ligament, stretched across the cavity, having the form of a triangle, or rather the sector of a circle, the apex of which is attached to the short handle of the malleus, having one side detached, and passing across the centre of the membrana tympani, and its base attached to the concave surface of the hollow bone, at a small distance from the bony rim to which that membrane is connected.

The long handle of the malleus has no connexion with any other part; but the forms of this bone, of the incus, and stapes are much the same as in the human ear; there being no considerable differ- ence excepting in the want of the os orbieulare.

The vestibulum, semicircular canals, cochlea, &c., differ in nothing material from the usual construction of these parts.

From this structure it appears to the author that the membrana. tympani, which is subject in the whale to vast differenca of pressure from without, is not well ﬁtted, under all circumstances, to convey the nicer vibrations of sound to the ossicula auditﬁs, but that the membrane which projects across the cavity, being exposed to the same medium on both sides, will freely continue, and communicate the impressions it receives, unaffected by any differences of pressure.

The author, after referring to those authorities by which he had been misled into the supposition that the colour of the blood depended on the presence of iron, until he had tried how slight effect it pro- duced by infusion of galls. proceeds to a series of experiments which he has made upon chyle and on lymph, for the purpose of comparing their composition with that of blood, the examination of which is divided into three sections, in which he treats separately of the serum, the coagulum, and the colouring matter.

The chyle employed in these analyses was collected by Mr. Brande while assisting Mr. Home and Mr. Brodie in their experiments on different animals; attention being always paid to the interval that had elapsed since the last meal; upon which circumstance its qualities were found to depend more than upon the animal from which it was taken. About four hours after a meal, the chyle is supposed to be in its most perfect state, and is then uniformly white, like milk. At longer periods it becomes more dilute, like milk and water, till at length, when an animal has fasted twenty-four hours, the ﬂuid contained in the thoracic duct is reduced to the state of mere lymph.

The taste of chyle is rather salt, with a degree of sweetness, and, by the test of violets, appears very slightly alkaline. In about ten minutes after removal from the thoracic duct. it coagulates, and ulti-