7. What is the necessity for a nutrient fluid in the body?
8. Why is the maintenance of life necessarily the chief aim of all the activities of the body?
9. State the two main problems in the study of the body.
PRACTICAL WORK
Observations.—1. Make some scrapings from the inside of the cheek with a dull knife and mix these with a little water on a glass slide. Place a cover-glass on the same and examine with a compound microscope. The large pale cells that can be seen in this way are a variety of epithelial cells.
2. Mount in water on a glass slide some thin slices of cartilage and examine first with a low and then with a high power of microscope. (Suitable slices may be cut, with a sharp razor, from the cartilage found at the end of the rib of a young animal.) Note the small groups of cells surrounded by, and imbedded in, the intercellular material.
3. Mount and examine with the microscope thin slices of elder pith, potato, and the stems of growing plants. Make drawings of the cells thus observed.
4. Examine with the microscope a small piece of the freshly sloughed off epidermis of a frog's skin. Examine it first in its natural condition, and then after soaking for an hour or two in a solution of carmine. Make drawings.
5. Mount on a glass slide some of the scum found on stagnant water and examine it with a compound microscope. Note the variety and relative size of the different things moving about. The forms most frequently seen by such an examination are one-celled plants. Many of these have the power of motion.
6. Examine tissues of the body, such as nervous, muscular, and glandular tissues, which have been suitably prepared and mounted for microscopic study, using low and high powers of the microscope. Make drawings of the cells in the different tissues thus observed.