420 Dr. F. Semon. On the Position of the 



any considerable error, the space above and below the vocal cords and 

 ventricular bands might be looked upon as a circle. Selecting now 

 the average radius resulting from the comparison of my measure- 

 ments as the representative of the circle, we'find in the five measure- 

 ments of male larynges that its average would be about 8 mm. The 

 area, therefore, in adult men of the air-tube above and below the 

 phonatory apparatus would be about 200 square mm. In women the 

 average radius would be 6*5 mm. ; the area of the air-tube above and 



O 



below the phonatory apparatus would be therefore about 133 mm. 



Now, the average length of the glottic triangle in men after death 

 is a little more than 23 mm., its base, as shown before, is 5 mm. ; the 

 area of the space included by the sides of the glottic triangle in men 

 after death, therefore, is about 57 mm. 



In women, the average length of the glottis would be 20 mm., its 

 width, as shown before, is 4 mm. ; the area of the glottic space, there- 

 fore, 40 mm. This means, in other words, that in adult individuals of 

 both sexes the space for the entry of air is reduced by the interpola- 

 tion of the phonatory apparatus when its constituent parts are at 

 perfect rest to less than one-third of its natural area. 



Anatomically, therefore, there can be no question as to the gravity 

 of the diminution of the air channel, and the more so because it must 

 not be forgotten that, even apart from the interpolation of the 

 phonatory apparatus, the larynx and trachea represent the narrowest 

 part of the whole air passages, both the uppermost part of the air 

 passages and the aggregated diameter of the bronchi being consider- 

 ably larger, than the calibre of the first-named parts. 



Physiologically, the question immediately arises :. Is so considerable 

 a diminution of the lumen of the air passages as that produced by 

 the interpolation of the phonatory apparatus when at complete rest 

 compatible with what we call at present the normal type of quiet 

 respiration ? 



In this sentence the expression " normal type of quiet respiration " 

 demands further explanation. It is by no means the purpose of this 

 paper to show that, even if the glottis during life was identical with 

 that seen after death, necessarily that state of laboured respiration 

 which we call "dyspnoea" would arise. Obviously, if the inter- 

 ference caused by the diminution of the calibre be not excessive, a 

 condition of things could be imagined in which this diminution was 

 counterbalanced merely by what is called " hyperpncea," i.e., either 

 an increased labour of the muscles normally engaged in quiet respira- 

 tion (diaphragm, intercostal muscles, and* scaleni), or additional 

 efforts of the so-called " accessory " muscles of respiration. Under 

 such circumstances, though one could hardly speak of the presence of 

 actual dyspnoaa, yet, undoubtedly, the state of things thus created 

 would be different from what is at present the general idea of quiet 



