The Amphibian larynx. 281 



ferentiated arytaenoids lie on either side of the rima glottis ; whether 

 in direct contact with the tracheal elements or not, is hard to de- 

 termine. If however, the true hyaline elements are brought out by 

 the methyl-blue method, we see the now familiar appearance of ir- 

 regular, broken pieces of hyaline cartilage lying in a dense mass of 

 tissue which may be interpreted as degenerate cartilage comparable 

 to the unstained portions in Proteus (cf. Fig. 19 with Figs. 11 

 and 12). 



Here as in Proteus the point which has suffered the most from 

 the strain of growth is the region immediately below the arytaenoids. 

 In this region the remaining pieces of cartilage are the smallest and 

 and most scattered. Farther down on the sides of the trachea, how- 

 ever, they grow rapidly larger and nearer together, so that the lower 

 two-thirds of the trachea is protected by a generally continous piece. 

 This posterior lateral strip is curved around the trachea, both dor- 

 sally and ventrally, and possesses a jagged outline, which in the 

 lower part of the tracheal region, becomes often developed into well- 

 marked processes projecting towards the median line (Fig. 17). In 

 these Henle sees incipient tracheal rings, but this is rendered im- 

 probable by their extreme irregularity, and their lack of correspondence 

 on the two sides. 



That these lateral tracheal pieces are not always continuous, is 

 shown by Fig. 18, which represents a portion of one of them, flat- 

 tened out and stained by methyl-blue. 



The actual histological conditions in the region of the isolated 

 pieces is shown in Figs. 20 and 21, drawn from sections stained with 

 borax carmine, and taken in the region represented by the lower part 

 of Fig. 19. In Fig. 20 the outlines of the original 'T)ieces are seen, 

 the hyaline elements within it being readily distinguished from the 

 degenerate tissue in which they lie. Fig. 21 represents the details 

 under a higher magnification, showing the fibrous structure of the 

 intervening mass, with here and there a single isolated cell of car- 

 tilage, the whole surrounded by the perichondrium. 



To recapitulate the results here given, it would 

 seem that we have here exactly the same original con- 

 ditions as in Necturus and Proteus^ i. e. the irregular 

 breaking up of an originally continuous piece through 

 rapid growth of the surrounding parts, the greater 

 length of the trachea and the cons equent greater at- 

 tenuation of the lateral pieces resulting here in a 



