294 MORPHOLOGICAL STUDY OF TRACHEAL AND BRONCHIAL CARTILAGES. 



lateral direction. An elongated oval opening is seen in the portion of the cartilage 

 situated between the first and second branches. Inadvertently the apical bronchus 

 was not carried out far enough in the drawings of the reconstruction to show 

 clearly that both the mesial and the lateral portions of this cartilage are also 

 associated with the origin of this branch from the eparterial bronchus. This 

 cartilage demonstrates a relationship between a cartilage and bronchi which 

 has already been noted and which will frequently recur; namely, a cartilage may 

 be associated with two or more bronchi. 



Only a single cartilage is found between the eparterial bronchus and the bron- 

 chus going to the lobus medius that is exclusively a cartilage of the stem bronchus. 

 This cartilage is deficient dorso-laterally, the interval between its two extremities 

 being occupied by two small and one large, bizarre shaped, intercalated cartilages. 

 Both extremities of this cartilage are broad ; the dorsal extremity is perforated by a 

 foramen for the passage of a branch of the bronchial artery. 



The description of the cartilages has now reached the point where the bronchus 

 going to the right lobus medius arises from the right stem bronchus, and the bron- 

 chus going to the left lobus superior arises from the left stem bronchus. These two 

 bronchi arise nearly opposite each other from their respective stem bronchi. Figure 

 10 shows the outline of a section taken through the right and left stem bronchi, 

 the greater part of the bronchus going to the right lobus medius, the bronchus going 

 to the left lobus superior, and the position of the cartilages. In the outline drawing 

 the cartilages appear as "plates;" that they are not plates but portions of well- 

 formed cartilages is shown in figure 12 and 13, in which they are represented plastic. 



It is not necessary to describe each cartilage in detail; a careful study of the 

 ventral and dorsal views (figs. 12 and 13) will enable the reader to follow them individ- 

 ually without difficulty. It will be noticed that on both the upper (anterior) and 

 lower (posterior) wall of each bronchus there are small cartilages which extend only 

 a short distance around the circumference of the bronchus. These might, not 

 inaptly, be called "plates," though the name introduced by Luschka, "intercalated 

 cartilages," best describes them. 



One cartilage belonging to the bronchus going to the left lobus superior deserves 

 special consideration, for its form is unlike any other cartilage the author has studied. 

 The first branch given off from the bronchus supplying the left lobus superior is the 

 apical bronchus. This does not arise from the cephalic (upper) surface of the bron- 

 chus, but its origin is slightly rotated to the dorsal side of the bronchus. The car- 

 tilage in question is associated with this bronchus and can be easily followed in the 

 ventral and dorsal views of the reconstruction (figs. 12 and 13), but is best seen in 

 figure 19, which is a ventro-mesial view. 



For convenience of description the cartilage may be said to begin near the 

 posterior border of the bronchus as a slender bar which passes obliquely along the 

 ventral surface of the bronchus. Arriving at the origin of the apical bronchus it 

 divides into two broad arms which pass one on either side of the apical bronchus. 

 The mesial arm arches over the main bronchus, then rotates so that its broadest 

 surface is turned towards the main bronchus, and, passing along the corresponding 



