learn from our study of the vocal organs that all musical instruments and also written. music are but imitations and illustrations of the ways in which the vocal organs are naturally used.

QUESTIONS FOR TOPICAL REVIEW

What are the divisions of the lungs called?

Of what special interest in the study of tone production are the three ventricles of the lungs? What are the tone peculiarities of the three registers of the voice?

From which side of the body is the lung taken for the illustration of Plate No. 10?

What causes the dissimilarity of the two lungs? Is this dissimilarity of any importance in the study of tone production?

What condition would prevent the restoration of one of the registers of the voice?

Give some of the causes by which the registers of the voice may be lost.

Enumerate the ways by which the lost action of one of the registers of the voice can be regained. What is the power-producing muscle of the inferior register called?

What is the name of the power-producing muscles of the middle register?

What is the name of the power-producing muscles of the superior register?

How should the register newly restored to usefulness be exercised?

What is the existing condition between the power and the controlling force of the vocal organs?

What is the physical effect of their action?

What are the phenomena that may be experienced with a cold?

What is the range of the typical human lungs? What may we infer from the study of the vocal organs in regard to musical instruments and the writing of music?

CHAPTER VII

THE VOCAL CORDS AND THE HARMONICS

The air columns after their exit from the branches of the bronchial tubes have a common passageway, called the windpipe or trachea. (See G, Plate No. 1.) This tubelike part of the vocal organs, like the bronchial tubes, is lined with mucous membrane. It ends at the top with a slit-like opening, called the glottis. (See J, Plate No. 1.) A membrane, called the epiglottis, fits over it like the lid of a box and closes it during the act of swallowing, so as to protect the lungs from the food and liquid which are intended for the stomach.

The slit-like opening at the superior end of the trachea, the glottis, reminds one of the openings in the pipes of an organ. Im

mediately below the glottis are the vocal cords, H, Plate No. 1, and the false vocal cords, I, Plate No. 1. They are parallel and, beginning at the larynx, K, Plate No. 1, extend back of the trachea on each side for about half to three-quarters of an inch.

The false vocal cords are so called because they have the appearance of the vocal cords but have none of their attributes. Their purpose may be the ready nutrition that the vocal cords can derive from the generous supply of blood vessels they contain.

These important parts of the vocal organs, the vocal cords, are not under the control of the conscious mind. As the eyes. glitter from the effect of happiness, as the saliva comes to the mouth at the anticipation of something tasty, through reflex action, so at the thought of a tone the

vocal cords swell out to the extent of shutting off the exit, until the outward traveling air columns cause a blow or a friction impelling them to vibrate. The extent of the vibration of the vocal cords is determined by the intensity of the blow they receive. An air column resulting from the action of the inferior register causes a deep tremor of the vocal cords and this sends forth the long and slow sound waves which constitute low tones. An air column of the middle register causes a tremor of only half the depth in the vocal cords of that of the inferior register, so the sound waves are only half as long, but they are doubled in quantity. Consequently the pitch of these tones is one octave higher than that of the corresponding tones of the inferior register.

The air columns which are caused by the superior register affect the vocal cords only superficially, so the sound waves are again