Elastic cartilage.—Prepared from the epiglottis, or from the cartilages of the ear, e.g., of a cat. Harden in spirit. Stain in picrocarmine or in dilute fuchsin.
White fibro-cartilage.—Obtained from intervertebral disc. Prepare and stain as for hyaline cartilage.
Bone:—
Unsoftened Bone.—Cut as thin a section as possible with a fine saw. Rub the section with the hand on a dry oil stone until it is as thin as possible. Then cement it by Canada balsam (liquefied by warming) to a piece of plate glass and continue the rubbing process with this, examining it now and then with the low power to see if it is thin enough. As soon as it is thin enough it is washed off the slide with methylated spirit, and washed to get rid of the fine bone dust. It should then be transferred to turpentine and may be mounted in balsam.
Softened bone.—Specimens may be obtained from an amputated limb or from the femur of a cat.
Specimens should be decalcified in chromic and nitric fluid, and the hardening completed in spirit. In studying the process of ossification, e.g., in the head of the humerus of a kitten, it is best to embed the specimen in celloidin before cutting sections, as the trabeculæ of bone are very delicate, and easily detached.
Very beautiful double staining effects may be obtained with either picrocarmine, or eosine and hæmatoxyline, and with eosine and methyl violet.
Bone marrow.—To obtain good sections of red bone marrow, take a piece of the clavicle or a rib, or of one of the carpal or tarsal bones. Decalcify in chromic and nitric fluid. Embed in celloidin. Stain with eosine and logwood, eosine and alum carmine, or alum carmine and picric acid. Mount in Canada balsam. The various cells present in bone marrow may also be studied by squeezing some fresh marrow from a rib, and making a cover-glass film, and preparing in exactly the same way as is directed in the case of blood films on page [116].
Tooth.—Best cut in situ from the jaw of a cat. Decalcify in chromic and nitric fluid, and cut both vertical and transverse sections. Stain in picrocarmine, or eosine and hæmatoxyline.
Developing tooth.—Extremely good specimens may be obtained from the jaw of a newly-born kitten or puppy. Sections can easily be made shewing a milk tooth and a developing permanent tooth by its side.