THE SEXSES 1 43 



foods that have a flavor (see text) : vanilla, apple, lemon, beef, 

 peaches, grapes, coffee, onion. potato, cinnamon. 



Experiment 8. A Smelling Contest. — Place the following and other 

 things having taste in vials around which paper has been pasted to con- 

 ceal their contents : pepper sauce, vinegar, kerosene, flavoring extracts 

 (diluted), several perfumes, iodine, bits of banana, lemon, apple, etc. 

 Number the vials and have pupils test and write results in a list. 

 Correct the lists and announce pupil having keenest sense of smell. 



Experiment 9. A tasting contest may be arranged in a similar 

 way. Smelling and tasting tests should be made quickly as these 

 senses are soon dulled by repeating a sensation. 



Experiment 10. Advantage of Two Eyes over One. — Try to touch 

 forefinger to something held by another at arm*s length from you, 

 bringing the finger in from the side: (1) with one eye closed; 

 (2) with both eyes open. Result ? Conclusion ? We tell the dis- 

 tance of an object by the amount of convergence of the eyeballs needed 

 to look at it. 



Experiment II. Duration of Impression. — Whirl a stick with a 

 glowing coal on one end (see Fig. 123). 



Experiment 12. Color Blindness. — Provide a number of yarns of 

 different tints, and the same tints. Test color blindness by having each 

 pupil match tints and assort the yarns. 



Experiment 13. Fatigue of Optic Nerve. — Gaze long and steadily at 

 a moderately bright object, then close the eyes. Result ? Conclusion ? 



Experiment 14. Dissection of Eye. — The eye of an ox is an in- 

 teresting subject for dissection. The lens is like a clear crystal. Make 

 out all parts named in the text (see Fig. 122). 



Experiment 15. Image formed by a Convex Lens. — For a few 

 cents obtain from a jeweler a convex lens, or use a strong pair of 

 spectacles worn by an old person. Hold the lens a few feet from a 

 window (darken any other windows near). A little beyond the lens 

 hold a white card or book open at a blank page to catch the image. 

 Have some one walk before the window. 



Experiment 16. Work of Iris. — Notice the size of the pupils. 

 Cover one eye with the hand for a few minutes. Uncover and look in 

 a mirror. Gaze at bright window and look again in the mirror. Con- 

 clusion ? Do the two pupils still keep the same size when one eye is 

 shaded ? 



Experiment 17. Accommodation. — By holding your finger or a 

 pencil in line with writing on the blackboard, you find that you cannot 

 see both finger and blackboard distinctly at the same time — first one 

 and then the other is distinct. Explain (see text). 



