60 THE LUNGS, BY FRANZ EILHARD SCHULZE. 



into the passages, or first unite in the infundibula. Delicate 

 isolated elastic fibres extend from these again, which divide 

 dichotomously, and unite to form arches distributed in a retiform 

 manner over the alveoli. 



Fig. 130. 



b 



i 



I 



Fig. 130. Section made through a lateral infundibulum. From the 

 lung of an adult Man, injected and hardened by maceration in alcohol 

 containing a little acetic acid, a, Orifice of the infundibulum in the 

 alveolar passage the upper border has been partially removed by 

 the cut ; 6 6, nuclei of smooth muscular fibres. Magnified 80 dia- 

 meters. 



The septa for the most part projecting into the lumen of the 

 alveolar passages, especially in the first portions of the main 

 ones, where their free margins can still be regarded as a direct 

 continuation of the bronchial wall, contain here and there 

 between the more superficial layers of elastic fibres delicate 

 scattered bands of smooth muscular tissue which often consist 

 merely of isolated fibres imbedded in a delicate connective 

 tissue. The membranous walls of the alveoli themselves are 

 entirely destitute of muscular tissue, nor have I been able to 



