492 WILLIAM A. LOCY AND OLOF LARSELL 



(fig. 36, Lat. 4 and 5), they follow a course parallel to that of 

 laterobronchiis number three. In their subsequent history they 

 form branches by the customary bifurcation and give rise to para- 

 bronchi in the posterior lateral region of the lung. 



A small inconspicuous bronchus arises more caudally on the 

 mesobronchus, and although it resembles quite closely some of 

 the larger dorsobronchi, we have considered it as the sixth latero- 

 bronchus (fig. 36). 



The dorsobronchi. These embrace the bronchi of Campana's 

 fourth division of secondary bronchi and by him designated 

 ''bronchesposterieurs ou dorsales" (dorsilateribronchi of Schulze, 

 '10). They are smaller and more numerous than the other bron- 

 chi arising from the central lung tube. Their orifices are some- 

 what variable as to position, and some members of the group 

 arise on the stems of the latero- and ectobronchi, and this im- 

 parts to them the character of being transitional between the 

 bronchi of the second and of the third order. On strictly ana- 

 tomical grounds those that spring from the latero and ectobron- 

 chi are of the third order, but there are always many, especially 

 of the smaller ones (and frequently large ones), that connect 

 directly with the mesobronchus. Campana thinks that it in- 

 troduces a useless morphological complication to exclude them 

 from the group of the secondaries. On account of their transi- 

 tional character and their (sometimes) connections with latero 

 and ectobronchi, Juillet sets them at one side. Our observations, 

 however, lead us to agree with Campana, that, after recognizing 

 that some of them merge into bronchi of the third order, and 

 that they are so small as to resemble parabronchi, nevertheless, 

 there are always a considerable number arising from the walls 

 of the mesobronchus, and therefore, they should be retained in 

 the group of the secondaries. 



So far as we are aware no previous em])ryological observations 

 have been recorded on these bronchi. 



There are two groups of the dorsobronchi, four or five larger 

 ones and approximately twenty smaller ones. Figure 86 exhibits 

 three small spur-like projections from the lateral side of the meso- 

 bronchus just dorsal to the bases of the first, second, and third 



