433 



Up to the time of Guillot there was a general agreement that 

 the bronchial artery formed an anastomosis with the pulmonary artery. 

 Guillot found as the result of his studies that the two arterial systems 

 were independent, and that injections made into the bronchial artery 

 returned by the pulmonary vein. This radical change of opinion at 

 first met with strong opposition, but later investigations have supported 

 his statement. 



From this brief introduction I pass to the results obtained by my 

 own investigations, confining myself in this preliminary communication 

 to the arrangement of the bronchial vessels in the bronchi and their 

 relation to the pulmonary blood vessels. 



The bronchial artery as soon as it has entered the hilus of the 

 lung penetrates into the fibrous layer of the bronchus, giving off' two, 

 sometimes three, main branches. With the division of the bronchus a 

 corresponding division of the artery takes place. 



In the fibrous layer the main arterial trunks give off smaller 

 branches the greater part of which unite to form an irregular plexus, 

 in general arranged at right angles to the circular layer of smooth 

 muscle (Fig. 1 4). It is from these smaller branches that the arterioles 

 arise which pass to the mucosa and there form a rich plexus of 

 capillaries. Occasionally arterioles pass directly from the main trunks 

 to the mucosa. Besides the branches which pass to the mucosa other 

 branches are given off which are distributed to adjacent structures, 

 6, g., the connective tissue septa, glands, etc., or they become the 

 vasa vasorum of the pulmonary blood vessels. In general the larger 

 trunks pursue a direct course along the bronchi. When the lungs are 

 in a collapsed condition and the bronchi correspondingly shortened 

 they have a more or less tortuous course. The smaller the bronchi 

 the more noticeable the sinuations. 



The arterioles which give origin to the capillary plexus in the 

 mucosa (Fig. 1 5) pass from the larger vessels situated in the fibrous 

 layer obliquely through the muscular layer and having reached a 

 position in close juxtaposition to the epithelial layer turn and run for 

 a short distance parallel to the muscular layer giving off a number 

 of capillaries which run parallel to each other and to the long axis 

 of the bronchus (Fig. 1 * and Fig. 2). At intervals, approximately 

 regular, these capillaries join venous radicles which are also situated 

 in the mucosa. These venous radicles form a plexus whose mesh is 

 irregularly rectangular in shape and generally correspond to the long 

 axis of the bronchus (Fig. 1 1). From this superficial venous plexus 

 branches pass through the muscular layer and form a second plexus 



Anat. Anz. Aufsätze. XXVin. 28 



