566 
MR. BISHOP ON THE PHYSIOLOGY 
notes, a great facility is afforded to their action in modulating the voice. The vocal 
tube, like any other tube open at both ends, is said to be capable of producing the 
harmonics of its fundamental tone in the ratio of the series of natural numbers, 1, 
2, 3, 4. These harmonic sounds have been described by Knecht of Leipsic, and by 
Dr. Young. I have occasionally thought that I have heard them during the forcible 
expiration which attends the boisterous laughter of children. The density of the air 
inspired is said to affect the pitch of the voice as in rigid tubes. 
The influence of the epiglottis on the voice has been the subject of divers hypotheses. 
MM. Biot, Majendie, and Mayo have inferred from the experiments of Grenie, that 
the epiglottis prevents the tones from becoming more acute when they increase in 
intensity. Liscovius, on the other hand, states that neither its depression, elevation, 
nor even its entire removal has any effect on the voice*. Haller appears to have 
deduced the same opinion from the circumstance of birds being destitute of this organ. 
“Epiglottis equidem nihil facit ad vocem, cum ea (vox) nata sit et perfecta quam- 
prixnum aer ex glottidis rima prodit, et absque epiglottide aves suavissime canant.” 
According to Muller, the influence of this organ on the pitch of the voice is exer- 
cised during its depression only, rendering the tones graver, and at the same time 
duller. He thinks we evidently employ it in this way during the production of very 
deep tones ; and observes that, by introducing the finger at the side of the mouth, the 
epiglottis will be found to maintain the same position during the utterance of musical 
notes, whether they be of the falsetto character, or of the ordinary scale. I am 
disposed to ascribe to the functions of the epiglottis much the same value as Muller; 
since it is clear that its presence is not essential to the mere formation of voice, for it 
may be removed, together with the superior ligaments of the glottis, the ventricles of 
the larynx, and the capitula laryngis of Santorini, without impeding the vibratory 
movements of the glottis. 
The art of singing consists in the application of the vocal organs to produce a 
certain succession of tones in some determinate order, which constitutes melody. 
This can be accomplished with precision by those only who can accurately discern 
with the ear, and imitate with the voice, the variations of a musical instrument, or other 
sounding body. In many persons the perception of sound is defective ; so that, what- 
ever may be the purity and intensity of their notes as single unconnected musical 
sounds, they can never be used for musical purposes, that is, for sounds succeeding 
each other at regular intervals, governed by fixed rules. Many persons can imitate 
the voices of birds and beasts, and diversify the character of their tones to an inde- 
finite extent. These performances illustrate the perfection of the human voice, but 
the artifices by which they are effected have no reference to the subject under in- 
vestigation. The musical varieties of the human voice are classed according to their 
pitch, or the middle note of their primary register, which depends on the dimensions 
and physical constitution of the vocal ligaments. These varieties are, the Bass , the 
* Physiology, lib. ix. p. 572. 
