381 



The distinction between the cartilaginous types and the Doembranous 

 is best seen in a diagrammatic representation of a section taken 

 through a cartilaginous carina (Fig. 9) and through a membranous 

 carina (Fig. 10). 



Without going into a detailed description of each case the 150 

 carinae are brought together in the following table: 



Type Number of cases Percentage 



Trachea] 



Tracheo-bronchial right 

 Tracheo-bronchial left 

 Bronchial right 

 Bronchial left 

 Double bronchial 

 Mixed 

 Membranous 



The results obtained from the 

 mals are greatly at variance 

 and VON Schrötter. 

 Two of their three cases 

 were membranous while 

 I find only three out of 

 the 150 carinae in my 

 series to be membranous. 

 An interesting fact in this 

 connection is that if cases 

 12 to 16, inclusive, had 

 been the only ones studied 

 the results would have 

 been 3 membranous and 2 

 cartilaginous, — a strong 



Fig. 9. Outline of a sec- 

 tion through a cartilaginous 

 carina. The cut cartilages are 

 shown in solid black. No at- 

 tempt has been made to represent 

 histological stiiicture. 



Fig. 10. Outline of a sec- 

 tion through a membranous ca- 

 rina. Compare with Fig. 9 and 

 note absence of cartilage in the 

 carina. 



12 



19 



4 



52 



13 



41 



6 



3 



study 



8.00 

 12.70 



2.66 

 34.67 



8.67 

 27.30 



4.00 



2.00 



of this series of 150 ani- 



obtained 



Heller 



argument against drawing conclusions from the study of a limited 

 number of cases. 



The number used by Heller and v. Schrötter was too small 



