50. What is pain?

51. Of what importance are the labyrinth senses (other than hearing) to man and various animals?

52. What is meant by organic sensations?

53. What are the four tastes?

54. How does the sense of smell in man compare with that of animals?

55. Why is the color pyramid superior to the color cone?

56. What are the chief symptoms of defective color vision?

57. What is not meant, and what is meant, by color mixtures?

58. Why does music use only twelve tones?

59. What is meant by the qualities of the tones of various instruments?