A simple injection, adequate to all useful purposes, where it is only intended to illustrate the bloodvessels, consists of tallow, melted and coloured. Or the following, which is in general use in the Parisian dissecting rooms: Lamp-black, ground in oil, adding the lime water and turpentine as above mentioned in the cold coarse injection. It is difficult, at the present time, to ascertain to whom anatomy is justly indebted for the discovery and first introduction of arterial injections, &c. The first use of wax injections has been attributed to Swammerdam, in 1672, although it is probable that De Bils and Ruysch preceded him. The Sieur Disenclosses possessed a cabinet furnished with over one hundred pieces, many consisting of injected vessels, a description of which was _published_ in 1727, but the collection must have existed many years previously. Corroded preparations have been attributed to Francis Nichols, Professor of Anatomy, at Oxford, about the beginning of last century; size injections to Rouhaut, surgeon to the King of Sardinia; the fusible metal, to Homberg, of Paris, (this metal is composed of an equal proportion of tin, bismuth, and brass,) who used a pneumatic apparatus for forcing it into the vessels; the origin of Spalding’s cold injections has more recently been attributed to Mr. Allan Ramsay, a Scotch anatomist. (_Vide Horner’s Practical Anatomy_, p. xviii, _Introduction_.) _Mercurial Injections._ These exact great skill and care in the operator. It requires an iron tube with a finely drawn glass pipe attached, supplied with a stop-cock--they are chiefly used for filling the lymphatics: the pipe must be introduced into these vessels at numerous points most distant from the heart, and these successively charged with the quicksilver. The lymphatic vessels of the liver, the parotid glands, the vesiculæ seminales, the testicles, the mesentery of the tortoise, the lactiferous ducts of the mammæ, the kidneys of a cat, &c., form the best objects for a successful display of this kind of injection. The hand of an emaciated individual may be readily injected, both arteries and veins, by fixing the pipe in the radial artery. The vessels are very apt to rupture during this operation, when it had been the custom to throw away the preparation as spoiled. But this accident we have found very readily remedied, by simply touching the ruptured vessel with a red hot wire, when, by the contraction of tonicity, the effusion of the quicksilver is suppressed. After the injection has been completed, the hand must be macerated in water, frequently changed, until the blood and cuticle are removed, when it may be dried and varnished, or suspended in spirits of turpentine.