382 



to give definite results and the liability of error was correspondingly 

 increased. 



In general the description given of the carina in man may be 

 applied to the cat. This is especially true of Luschka 's excellent ac- 

 count of the manner in which the carina is formed i). 



The ])rincipal ditference between the carina of the cat and man 

 consists in the absence in the cat of a long, narrow spur derived 

 from the last tracheal ring, which enters into the formation of the 

 carina. 



The right bronchial cartilage formed the carina in one third of 

 the cases and bronchial cartilages from both sides entered into the 

 carina in nearly another third of the cases (double bronchial). Of the 

 remaining types the tracheo-bronchial in which fusion took place be- 

 tween the last tracheal ring and the first right bronchial cartilage or 

 cartilages was the most frequent; the tracheal and bronchial left type 

 had practically the same number of cases. 



Most interesting of all is the small number of cases that could 

 be called membranous. In every instance where there was a doubt 

 whether a carina was membranous or not the carina was embedded in 

 celloidin and sectioned. It was by means of this method that the three 

 cases of membranous carinae were positively identified. 



Resum6. 



1) From this study of 150 cat tracheae it can be stated that the 

 carina is rarely membranous. 



2) There is an absence of the long, narrow, tracheal spur common 

 in man. 



3) In the cat bronchial cartilages either alone or in combination 

 with the tracheal cartilage form the great majority of the carinae. 



1) H. Luschka, Die Anatomie des Menschen, Tübingen 1863. 



