378 



fused tracheal and bronchial ring entered the carina; in such cases 

 the carina was described as "tracheo-bronchial" and like the simple 

 bronchial it could be either "right" or "left". 



Their series consisted of 125 human tracheae and 48 tracheae 

 taken from other mammals. Out of the 125 human tracheae inves- 

 tigated the carina was cartilaginous in 56 %; membranous in 33%; 

 partly membranous in 1 1 ^/o- In 27 7o where cartilage was present it 

 was tracheal; in 21% it was bronchial, divided as follows: 15 Vo bronchial 

 right, 3"/o bronchial left, 3,5 double bronchial. 



Of the 48 tracheae investigated, other than human, 3 were from 

 the domestic cat (Felis domestica), which they describe as follows: 



"12. Carnivora. Felidae. Felis domestica L. 



Die 47 Trachealringe häufig gegabelt und Inselbildung an den- 

 selben. Der letzte Ring unregelmäßig gegabelt und geknickt. 



Der Sporn von den ersten Bronchialringen seitlich gestützt; der 

 rechte Bronchialring breiter. — Membranös. 



13. Carnivora. Felis domestica L. — Länge der Trachea 

 7,2 cm. Durchmesser der Trachea 5 mm, des rechten Bronchus 4 mm, 

 des linken Bronchus 3 mm. 



Zahl der Ringe 48 , nach unten zu schmäler werdend. Der 

 48. Trachealring doppelt so breit wie die oberen. Sein unterer Rand 

 besitzt nahe der Medianen jederseits zwei kleine Zacken, die den 

 Teilungsfirst begrenzen. 



lieber die häutige Carina zieht eine feine, nach hinten zu höher 

 werdende Schleimhautfalte. — Membranös. 



14. Carnivora. Felis domestica L. Länge der Trachea 

 7,4 cm. 



Zahl der Trachealring 50. Der letzte bildet durch drei nach ab- 

 wärts konvergierende und an ihrem unteren Ende miteinander ver- 

 wachsene kurze Spangen ein durchbrochenes Knorpeldreieck. 



Sporn knorpelig, durch Konvergenz und Vereinigung des rechten 

 1. und linken 2. Bronchialringes gebildet. — Knorpelig-bronchial." 



From the above three cases noted by Heller and v. Schrötter 

 one would draw the conclusion that the membranous type of the carina 

 predominated in the cat. 



Having occasion to examine the carina of a number of cats in 

 connection with a general study of the trachea my attention was 

 directed to the fact that in none of the tracheae studied was the carina 

 membranous but in every instance it was cartilaginous. This led to 

 a more extended study and eventually embraced the trachea of 150 

 animals. 



