390 THE POPULAR SCIEXCE MONTHLY. 



in an appendage called the uvula. When the velum palati, or soft 

 palate, does not discharge its functions properly, the voice assumes a 

 specially disagreeable character it becomes nasal. The two rows of 

 teeth act a part in producing speech ; a breach once made in this 

 rampart, the pronunciation becomes defective, the air escapes through 

 the unguarded space, and the result is a hissing sound. 



The plan of action of the whole vocal apparatus being under inves- 

 tigation, in the absence of the means of direct observation, recourse 

 has been had to endless stratagems, in order to have a glimpse of the 

 play of the organs and to explain the mechanism of voice-production. 

 It has been a struggle with incredible difficulties, in which the human 

 mind, though it has not won a complete victory, has nevertheless ac- 

 quitted itself with honor. Some of the investigators succeeded in 

 forming theories which are not very far from the truth, but these 

 theories are now only the monuments of a period whose science is 

 antiquated. 



Galen, in comparing the organ of voice to a flute with double 

 mouth-piece, referred the production of the sound to the vocal cords. 

 Fabrizio d'Acquapendente, the famous professor of the University of 

 Padua, held that the dilatation and contraction of the glottic ori- 

 fice determined whether sounds shall be grave or acute. Dodart. a 

 member of the old Academie des Sciences, held that the tone depends 

 upon the greater or less number of vibrations of the vocal cords. 

 Ferrein, one of the famous anatomists of the eighteenth century, con- 

 ceived the idea of causing the larynx of a dead body to produce 

 sounds by blowing through the trachea. He affirms that the lips of 

 the glottis vibrate and emit sound like the strings of a violin. Ma- 

 gendie made experiments upon living animals ; having laid bare the 

 glottis, he saw the vocal cords vibrating when the animal uttered a 

 cry. Savart, famed for his researches in acoustics, compared man's 

 vocal apparatus to an organ-pipe. Lehfeld, a German author, laid 

 stress upon the special effects of the cords, as vibrating through their 

 entire substance, or only at their free edges. Cagniard de Latour 

 constructed artificial larynges with mouth-pieces of membrane. John 

 Miiller, the physiologist, after a series of diversified researches, was 

 of the opinion that " the vocal organ is a mouth-piece consisting of 

 two lips, and that the vibrations of these is the chief cause of the 

 sound the pitch being determined by the width and length of the 

 orifice of the glottis." Longet, who made numerous experiments on 

 the actions of the muscles of the vocal organ, threw new light upon 

 the conditions modifying the vibrations. In short, the result of all 

 these researches, made by investigators who never had seen the larynx 

 of a living man, was firmly to establish one point, namely, that the 

 voice is formed in the glottis. The proofs of this are conclusive, for, 

 if an opening be made in the trachea, the voice ceases ; it reappears 

 when we close the opening again ; it persists though the superior parts 



