571 
an inferior pair. The superior pair are the Arytaenoids, from which 
‚may arise by a further segmentation, the cartilages of Sanrorını. The 
Cricoid as well as the tracheal rings are formed from the lower pair, 
by a fusion in the middle line of medially extended processes, and 
the subsequent absorption of the lateral connections. In support of 
this theory he describes different adult conditions, found mainly 
among the Urodeles, which he considers to represent stages in this 
process !). 
BALFOUR ?) briefly states that “the larynx is formed as a simple 
dilatation of the trachea. The cartilaginous structures of the larynx 
are of the same nature as those of the trachea”. 
Hertwic*) says that “Ring- und Stellknorpel sowie die Halb- 
ringe der Luftröhre sind selbständige Verknorpelungen in der Schleim- 
haut”. 
Dusors considers both Arytaenoids and Cricoids to be morpho- 
logically similar, and refers all to a segmentation and subsequent differen- 
tiation of a primitive pair of lateral cartilaginous rods, extending along 
the air-passages. Concering the Arytaenoids he says: “Die Arytae- 
noidea stellen, entsprechend ihrer großen funktionellen Bedeutung, die 
frühesten Abgliederungen aus dem Trachealsystem dar” *). 
WIEDERSHEIM does not believe that the several cartilages were 
formed by the segmentalion of a previously formed rod, but finds as 
the most primitive condition an anterior pair of cartilages, at the sides 
of the Rima glottidis. To these, the most primitive cartilages, succeed 
from time to time other pairs of cartilages, arising secondarily accord- 
ing to need, and developing in a posterior direction. He states: 
“Somit handelt es sich nicht erst bei héheren Urodelen um eine ‘Ab- 
gliederung’ jener, den Luftröhreneingang begrenzenden Knorpel, son- 
dern letztere (Arytaenoidea) sind die phyletisch ältesten Knorpel- 
gebilde des ganzen Kanalsystems, an welche sich kaudalwärts die 
eigentlichen Tracheal- beziehungsweise der Ringknorpel erst sekundär 
anschließen” 5). 
1) J. Hentz, Vergl.-anat. Beschreibung d. Kehlkopfs, 1839. Resul- 
tat, p. 71. 
2) F. M. Barrour, Comparative Embryology, Vol. II, 1881, p. 630. 
3) Oscar Herrtwic, Lehrbuch der Entwickelungsgeschichte, 1890, 
p. 272. 
4) Duzors, Zur Morphologie d. Larynx, Anat. Anzeiger, 1. Jahrg,, 
No. 7 u. 9, 1886. 
5) WIEDERSHEIM, Lehrbuch d. vergl. Anatomie, 1886, p. 625. 
