278 COORDINATION AND SENSATION 



8. How does alcohol cause one to feel warm when he may be losing 

 too much of his heat ? 



9. What precaution should be observed by one in poor health, in 

 taking a bath ? 



10. How may the cold bath be a means of improving the general 

 health ? 



PRACTICAL WORK 



Observations on the Skin and its Appendages. Examine the palm of 

 the hand with a lens. Note the small ridges which correspond to the 

 rows of papillae beneath the cuticle. In these find small pits, which are 

 the openings of the sweat glands. 



2. Examine the epidermis on the back of the hand and palm. At 

 which place is it thickest and most resisting ? Is it of uniform thick- 

 ness over the palm ? Try picking it with a pin at the thickest place, 

 noting if pain is felt. Inference ? 



3. Examine a finger nail. Is the free edge or the root the thickest ? 

 Trim closely the thumb nail and the nail of the middle finger of one 

 hand and try to pick up a pin, or other minute object, from a smooth, 

 hard surface. The result indicates what use of the nails ? Suggest 

 other uses. 



4. Examine with a microscope under a low power hairs from a 

 variety of animals, as the horse, dog, cat, etc., noting peculiarities of 

 form and surface. 



To illustrate Cooling Effects of Evaporation. i. Wet the back of 

 the hand and move it through the air to hasten evaporation. Observe 

 that, as the hand dries, a sensation of cold is felt. Repeat the experi- 

 ment, using ether, alcohol, or gasolene instead of the water, noting the 

 difference^ in results. These liquids evaporate faster than water. 



2. Wet the bulb of a thermometer with alcohol or water. Move it 

 through the air to hasten evaporation. Note and account for the fall 

 of the mercury. 



