130 NORMAL HISTOLOGY. 



work of elastic fibres surrounds each air sac and forms the septum 

 between adjoining alveoli. 



Laboratory exercise No. 41. Lungs. Fix in chromic acid, dehydrate 

 with alcohol, embed in celloidin, and stain with lithium carmine, 

 method No. 4. Make a careful study of the structures above named. 

 Demonstrate arteries, veins, and bronchioles. Distinguish between an 

 alveolus and an infundibulum. With H. P., make out the structure of 

 different portions of the pulmonary parenchyma. Drawings. 



Trachea. 



Trachea: (a) Mucous coat; (b) Ciliated epithelium; (c) Membrana propria; (d) 

 Tunica propria; (e) Submucous tissue ; (f) Hyaline cartilage showing perichon- 

 drium, matrix, and cells; (g) Muscular coat; (h) Fibrous 'coat; (i) Serous coat. 



Lungs. 



Lungs: (a) Bronchiole; (b) Alveolar duct; (c) Alveolus; (d) Infundibulum; (e) 

 Infundibular septa; (f) Alveolar wall; (g) Artery; (h) Vein; (i) Pleura. 



