William Snow Miller 399 
derived from the. bronchial artery. There is usually a main arterial 
trunk on one side of a lymphatic and from this branches are given off 
which pass over and also beneath the lymphatic to the opposite side where 
they join to form a smaller vessel (Fig. 7). There is thus formed an 
arterial plexus which is placed external to the lymphatic. Along smaller 
lymphatics the two parallel arteries are usually of the same size. Here 
and there, branches can be recognized which connect the pleural vessels 
with those within the lung (Fig. 7). 
In sections taken perpendicular to the course of the lymphatics it can 
be seen, in lungs in which the bronchial and pulmonary systems have 
Fic. 8. Lung of sheep. Section taken at right angles to the pleura. Semi- 
diagrammatic. The outline, size, and position of vessels drawn by means of 
the camera lucida. ; = pleura, 9S) = septum) 28. A. = bronehiall artery. 
L. V. = lymph vessel cut obliquely. P. V. = pulmonary vein. ** = places 
where the capillaries from the bronchial artery join the radicles of the pul- 
monary vein. From one of these points the course of the venous radicle can 
be traced along a septum to a main branch of the pulmonary vein. X 50. 
been injected with differential masses, that from the plexus about the 
lymphatics capillaries are given off which unite to form radicles and 
that these radicles join branches of the pulmonary vein which are 
situated in the septa of the lung (Fig. 8). A few of the capillaries enter 
directly into the capillary network of the sacculi alveolares which are 
situated just beneath the pleura. 
That the plexus about the lymphatics is to be considered as arterial is 
shown by granular injecting masses completely filling the plexus while 
