Ill 



145 



fact that there is adduction of the vocal cords in the formation 

 of sounds, so that the glottis assumes the form of a slit. 



The discovery of the laryngoscope by the famous singing- 

 master Manuel Garcia (1854) made it possible to observe the 

 human glottis directly under normal conditions, during the 

 emission of laryngeal sounds of different pitch. 



The original laryngoscope used by Garcia was a simple metal mirror 

 fixed to a handle at a suitable angle. After warming it gently over a spirit 

 lamp to prevent the deposition of moisture, it was introduced into the isthmus 

 of the fauces, so that a beam of light could be thrown on to the glottis, which 

 thus becomes visible to the observer, who is looking into the mirror. The 



Fio. 97. Examination of larynx by laryngoscope, a, 6, two metal mirrors ; illuminated by a lamp, 

 which is reflected from a mirror with a central aperture which is fixed in front of the 

 observer's eye. 



latter may be directly illuminated by sunlight, which was Garcia's original 

 method, or by a lamp at the side of the observer in front of which a large 

 lens is placed to increase the strength of the illumination ; or by a lamp 

 placed behind the shoulder of the person observed, which illuminates a 

 concave mirror, and reflects a beam of light upon the mirror of the laryngo- 

 scope. The observer watches the latter through a central aperture in the 

 concave mirror (Fig. 97). 



Oertel employed a rapidly intermittent illumination by placing a Mach's 

 stroboscopic disc in front of the lamp. It is then possible to follow the 

 vibration of the vocal cords by direct vision. 



Szimanowsky obtained instantaneous photographs of the glottis during 

 the production of the different tones by substituting a photographic apparatus 

 for the eye of the observer. 



The whole of the laryngeal vestibule cannot be seen simultaneously on 

 the laryngscopic mirror, but by moving the mirror it is possible to see the 

 different parts in succession (Fig. 98). 



Laryngoscopical observation shows that voice production is 

 VOL. in L 



