G4 THE CELL 



frog the heart is opened and the blood allowed to drop into a tube containing 

 Hayem's fluid (sodium chlorid i gm., sodium sulphate 5 gm., mercuric chlorid 

 0.5 gm., distilled water ico c.c). After shaking, the cells are allowed to settle 

 for from twelve to twenty-four hours. The fixative is then replaced by water, 

 the tube again shaken, the cells allowed to settle, and the water is replaced with 

 80 per-cent. alcohol tinged with iodin. After from twelve to twenty-four hours 

 the alcohol is decanted and the tube partly filled with alum-carmine solution 

 (page 19). About twenty-four hours usually suffices for staining the nuclei. 

 The alum-carmine is then poured oft' and the cells well shaken in water. After 

 settling, the water is replaced by glycerin, to which a small amount of picric 

 acid has been added. In this the cells may be permanently preserved. The 

 nuclei are stained red by the carmine, the cytoplasm yellow by the picric acid. 



3. Surface cells from the mucous membrane of the bladder. The bladder 

 is removed from a recently killed animal, pinned out mucous membrane side 

 up on a piece of cork and floated, specimen side down, on equal parts MiiUer's 

 fluid and Ranvier's alcohol (technic, 5, p. 7, and a, p. 4) for from twenty-four 

 to forty-eight hours. The specimen is then washed in water and the cells re- 

 moved by gently scraping the surface. These may then be stained and pre- 

 served in the same manner as the preceding. Cells from the different layers 

 should be studied; also the appearance of the large surface cells seen on flat and 

 on edge, showing pitting of under surface by cells beneath. 



4. Amoeboid movement may be studied by watching fresh-water amoebae or 

 white blood cells. A drop of water containing amoebae is placed on a slide, 

 covered, and a brush moistened with oil is passed around the cover to prevent 

 evaporation. The activity of the amoebae may be increased by slightly raising 

 the temperature. An apparatus known as the warm stage is convenient for 

 demonstrating amoeboid movement. A drop of blood, human, or better from 

 one of the cold-blooded animals, may be used for the study of amoeboid move- 

 ment in the white blood cells. It should be placed on a slide, covered, and 

 immediately examined on the warm stage. 



5. Ciliary movement is conveniently studied by removing a small piece of 

 the gill of an oyster or mussel, teasing it gently in a drop of normal salt solution 

 and covering. The cilia being very long, their motion may be easily studied, 

 especially after it has become slow from loss of vitality. 



6. Mitosis. The salamander tadpole and the newt are classical subjects 

 for the study of ceU-division. The female salamander is usually full of embryo 

 tadpoles in January and February. The embryos are removed and fixed in 

 Flemming's fluid (technic 8, p. 8), after which they may be preserved in equal 

 parts of alcohol, glycerin, and water. Mitotic figures may be found in almost 

 any of the tissues. Pieces of epidermis from the end of the tail, the parietal 

 peritoneum, and bits of the gills are especially satisfactory. If the newt's tail 

 is used, it should be fixed in the same manner, embedded in parafiin and cut 

 into thin sections. These are stained with Heidenhain's haematoxylin, technic 

 3, p. 18. 



Certain vegetable tissues, such as the end roots of a young, rapidly growing 

 onion or magnolia buds, are excellent for the study of mitosis. The technic is 

 the same as for animal tissues. 



