One or two miscellaneous objects now come before our notice. Fig. 11 is one of those curious marine plants, the Corallines, which are remarkable for depositing a large amount of chalky matter among their tissues, so as to leave a complete cast in white chalk when the coloured living portion of the plant dies. The species of this example is _Jania rubens_. Fig. 19 is part of the pouch-like inflation of the skin, and the hairs found upon the rat’s tail, which is a curious object as bearing so close a similitude to Fig. 22, the sea-mat zoophyte. Fig. 23 is a portion of the skin taken from the finger, which has been injected with a coloured preparation in order to show the manner in which the minute blood-vessels or “capillaries” are distributed; and Fig. 26 is a portion of a frog’s lung, also injected. The process of injection is a rather difficult one, and requires considerable anatomical knowledge. The principle is simple enough, being merely to fill the blood-vessels with a coloured substance, so as to exhibit their form as they appear while distended with blood during the life of the animal. It sometimes happens that when an animal is killed suddenly without effusion of blood, as is often seen in the case of a mouse caught in a spring trap, the minute vessels of the lungs and other organs become so filled with coagulated blood as to form what is called a natural injection, ready for the microscope. Before leaving the subject I must ask the reader to refer again for a moment to the frog’s foot on Plate X., and to notice the arrangement of the dark pigment spots. It is well known that when frogs live in a clear sandy pond, well exposed to the rays of the sun, their skins are bright yellow, and that when their residence is in a shady locality, especially if sheltered by heavy overhanging banks, they are of a deep blackish-brown colour. Moreover, under the influence of fear they will often change colour instantaneously. The cause of this curious fact is explained by the microscope. Under the effects of sunlight the pigment granules are gathered together into small rounded spots, as seen on the left hand of the figure, leaving the skin of its own bright yellow hue. In the shade the pigment granules spread themselves so as to cover almost the entire skin and to produce the dark brown colour. In the intermediate state they assume the bold stellate form in which they are shown on the right hand of the round spots. Very remarkable forms of these cells may be found in the skin of the cuttle-fish. Figs. 24 and 25 are two examples of coal, the former being a longitudinal and the latter a transverse section, given in order to show its woody character. Fig. 17 is a specimen of gold-dust intermixed with crystals of quartz sand, brought from Australia; and Fig. 21 is a small piece of copper-ore.