MILLER — CONTRIBUTIONS FROM ANATOMICAL LABORATORY. 207 



This does not hold true for the lung of Necturus, since both the 

 artery and the vein lie superficially, the greater part of the 

 muscle fibers lying internal to them. PL 8, figs. 11, 12, shows 

 the relation between the blood-vessels and the muscular fibers. 

 It will be noted that the relation is the same in both the artery 

 and vein. 



THE NERVE FIBERS. 



The distribution of the nerves in the lung is shown in PL 6, 

 fig. 10, and PL 8, fig. 15. Contrary to the usual opinion, we do 

 not find the main branches along the blood-vessels, but rather 

 between them. To be sure, there are nerve trunks lying over 

 the blood-vessels, yet they are not so large as those forming the 

 elongated meshwork between them. The anastomoses between 

 the trunks are quite numerous, increasing as they diminish in 

 size until we come down to the ultimate fibers. 



This distribution is contrary to that found by Stirling in the 

 lung of the newt. He savs : 



"The nerves enter the lung in three or four main strands at its base. 

 These strands are of unequal thickness, i. e., a varying number of 

 nerve-fibers enter into their composition. At once they proceed 

 towards the pulmonary vein, which they follow very closely in their 

 distribution. They form a plexus along the course of the vein. Only 

 a few non-medullated nerve-fibers pass on to the pulmonary artery. 

 The nerve-strands lie outside the muscular coat, and as they pass 

 onwards in the pulmonary walls they give off branches right and 

 left. A large number of multipolar nerve-cells exist in the course 

 of the nerve-strands, and they are especially numerous where a branch 

 is given off." 



Both medullated and non-medullated fibers are found in the 

 main trunks. From this main network we get a second network 

 with fewer fibers in a branch, but still containing both kinds of 

 fibers. From this secondary network we have a fine network of 

 non-medullated fibers given off which breaks up into the ulti- 

 mate fibrils. These last I did not try to follow out to their 

 endings. Along the course of the fibers, as well as the trunks, 

 nerve-cells are present, and my observations in Necturus coin- 



