^{page 377 note *} Smith's Optics, vol. ii. Rem. p. 5.

^{page 377 note †} Treatise on the Eye, vol. ii. p. 74–80.

^{page 378 note *} Practical Treatise on the Diseases of the Eye, 1830, pp. 748, 750.

^{page 382 note *} This may be done by projecting it upon a luminous surface, and marking its apparent size; or by comparing it with the images of objects of known dimensions seen with a fine microscope.

^{page 383 note *} The vitreous humour, when slowly dried, either by itself, or along with parts of the septa in which it may be contained, shoots into beautiful crystalline ramifications proceeding from the four angles of a quadrilateral crystal. Thin six-sided plates frequently occur, but they seem to exercise no action upon polarised light, probably on account of their thinness. The same effects were produced when the vitreous humour from a fresh eye was well washed in distilled water.

^{page 383 note †} Medico-Chirurgical Trans., 1814, vol. v., p. 255.

^{page 383 note ‡} Id. Id., p. 266.

^{page 384 note *} Lond. and Edin. Phil. Mag., 1832, vol. i., p. 172, vol. ii., p. 168.

^{page 384 note †} Practical Treatise, &c, p. 751.

^{page 384 note ‡} Professor Plateau mentions that he had been led to suppose that the Muscæ had their seat in the vitreous humour rather than in the aqueous; but that he had been stopped by the difficulty of reconciling this opinion with the viscosity of the vitreous humour. As the vitreous humour is perfectly fluid within each cell, the viscosity here supposed being only apparent, no longer presents any difficulty.