CHAPTER II 



THE SKIN 



NOTE TO TEACHER.- -The experiments should be assigned in turn 

 to the pupils as each chapter is reached : e.g. this set of 13 will leave 3 

 pupils in a class of 39 to stand responsible for each experiment. Each 

 pupil should do the work separately and credit may be given for the 

 best results. Encourage (or require) each pupil to try every experi- 

 ment and record them in a note book. 



Experiment i. (At home or in class.) Albinism. --Study a white 

 rabbit as an example of albinism. Does albinism affect only the skin? 

 What evidence that its blood is of normal color? 



Experiment 2. Use of Hairs on the Skin. - - Let one pupil rest his 

 hand upon the desk behind him while another touches a hair on his 

 hand with a pencil. He should speak at the moment, if it is felt. Do 

 the hairs increase the sensitiveness of the skin? What was their use 

 with primitive man? Are the hands of all your acquaintances equally 

 hairy? Are the hairs to be classed as rudimentary? Will they disap- 

 pear? Will the race become baldheaded? 



Experiment 3. (Home or school.) Invisible Perspiration. -- Hold 

 a piece of cold glass near the hand or place the cheek near a cold win- 

 dow pane and notice for evidence of moisture. Its source? 



Experiment 4. Effect of Evaporation on Temperature. Read a 

 thermometer and cover its bulb with a moist cloth. Read again after 

 twenty minutes. Repeat experiment in breeze. 



Experiment 5. Moisten one hand and allow it to dry. Touch the 

 other hand with it. Explain result. 



Experiment 6. Absorbing Power of Fabrics. - - Wet the hands and 

 dry them upon a piece of cotton cloth. Repeat with woolen, linen, and 

 silk. Arrange in list according to readiness in absorbing water. 



Experiment 7. Rates of Drying. -- Immerse the cloths in water and 

 hang them up to dry. Test their rates of drying with dry powder or by 

 touch. 



Experiment 8. Test Looseness of Weave of above cloths by measur- 

 ing the distance pieces of equal length will stretch. 



Experiment 9. Does Cotton or Wool protect better from Radiant 

 Heat? --Lay a thermometer in the sun for ten minutes, first covering 



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