Stun a frog by striking its head, or by chloroforming it. Fix it on a piece of card with a V shaped notch at one end. Tie one of the hind feet by means of threads attached to its toes so that the web of the foot is gently stretched over the V. The foot can then be readily examined under a 1/2 inch objective. The foot must be brushed from time to time with normal salt solution to keep it moist. The movement of blood in the capillaries, &c., can then be studied for an hour or two. After death the mesentery should be spread out on a piece of wood, and hardened for a few days in Müller’s fluid.
Stain with eosine and hæmatoxyline.
Lymphatics.—Commencement of lymphatics in serous membrane. Stain a piece of cat’s omentum in nitrate of silver (p. [82]) for some minutes. After washing keep in glycerine for about a week and then stain in hæmatoxyline and mount in Farrant’s medium.
Lymphatic glands.—The lymphatic glands of the neck of the cat may be used. Harden in Müller’s fluid. Stain in picrocarmine, eosine and hæmatoxyline.
Skin and sweat glands.—Sections should be made from pieces taken (a) from the sole, (b) from the skin of the body, (c) from the axilla of an adult to study the pigment. Harden in Müller’s fluid. Stain in picrocarmine or eosine and hæmatoxyline.
Hairs and sebaceous glands.—Take a portion of the scalp, or of the skin of a puppy. Harden in Müller’s fluid. Stain in eosine and hæmatoxyline, and mount others unstained.
Hairs from various parts of the body should also be soaked for some hours in liq. potassæ and mounted unstained in Farrant’s medium. They may be bleached subsequently by treatment with eau de Javelle (p. [27]).
Brain and spinal cord.—Must be removed from the body with extreme care, all stretching or squeezing being avoided. Harden slowly in Müller’s fluid to which a fourth of its bulk of water may be added.