292 MORPHOLOGICAL STUDY OF TRACHEAL AND BRONCHIAL CARTILAGES. 



The angle which the bronchi form with the trachea differs from that which 

 they form with the human trachea, in that it is practically the same for each bron- 

 chus; on the other hand, in man the right bronchus continues in nearly the same 

 direction as the trachea, but the left bronchus has a more oblique direction. As a 

 control for this point a number of celloidin corrosions were made and all showed the 

 same mode of division. Narath's figure of a celloidin corrosion of the trachea and 

 bronchi of Cavia (Ccelogenys) paca also shows the same characteristic. In still another 

 point the bronchi differs from the human bronchi; in man the right bronchus exceeds 

 the left in diameter, while in the guinea pig the two have practically the same 

 diameter. 



On the mesial surface of the left bronchus, just before the bronchus going to 

 the left superior lobe is given off, there are present, in the interval between the ends 

 of the main cartilages, two cartilaginous plates which are independent of any connec- 

 tion with the main cartilages. Such plates have been named by Luschka "inter- 

 calated cartilages." The more anterior of these two cartilages is long and nar- 

 row and is placed obliquely in the membranous intercartilaginous space; the other 



Ep.b 



Flo. 8. Outline of a section taken along the line indicated on figure 12 showing the position of the various pieces of cartilage 



which enter into the formation of the cartilages shown in figures 12 and 13 along the eparterial bronchus. R. B., 



right bronchus. L. B., left bronchus. Ep. B., eparterial bronchus. X6. 

 Fia. 9. Outline of a section taken along the line indicated in figure 13. The plane of the section takes in a portion of the 



bronchus going to the left lobus anterior and portions of the cartilage (.4) shown in figure IS. L. B., left bronchus. 



L.I. a., bronchus going to left lobus anterior. X6. 



cartilage, placed transverse to the long axis of the bronchus, is broad on the dorsal 

 side of the bronchus, tapers as it arches around the mesial surface of the bronchus, 

 and ends on its ventral surface just behind the seventh bronchial cartilage. 



Cartilages of the eparterial bronchus. The eparterial bronchus arises from the 

 right bronchus opposite its third cartilage and quickly divides into five branches, 

 which are distributed to the superior lobe of the right lung. The main stem of the 

 eparterial bronchus, at the place where it leaves the right bronchus, is partially 

 surrounded by two large cartilages. The one on the anterior (cephalic) surface 

 consists of two elements, one of which belongs to the right bronchus, the other to 

 the eparterial bronchus. In a ventral view of the bronchus (fig. 12) the bronchial 

 element appears to be an independent cartilage, but when seen from the dorsal 

 side (figs. 13 and 15) the fusion of the two elements becomes at once apparent. 



The bronchial element differs from any of the preceding bronchial cartilages 

 in that it encircles the stem bronchus spirally. It is irregular in outline and the 

 lateral end tapers to a blunt point where it overlies the cleft mesial end. From 

 the posterior surface of the lateral end there is a prolongation outward which fuses 

 with a mesial prolongation from the dorsal surface of the element belonging to 

 the eparterial bronchus. 



