\$f> NORMAL HISTOLOGY. 



blood- and lymph-vessels and nerves. The alveoli, 

 depending upon the gland-epithelium which lines 

 them, present two distinct forms : in one form, the 



smaller of the two, we find the cavity of the alveoli 



nearly filled by cuboidal or polyhedral cells, whose 

 bodies are cloudy or granular, and which have 

 spheroidal or ellipsoidal nuclei. In the other form 

 of alveoli the larger we find in the first place, 

 surrounding the cavity of the alveoli, large, irregu- 

 lar-shaped, transparent cells, having a gelatinoid ap- 

 pearance, with an often .flattened nucleus lying at 

 the peripheral side; these cells are not readily 

 stained by eosin, and are called mucous cells. In the 



second place, in the periphery of the alveoli, be 



twecn th< cells just described and the membrana 

 propria, lie large, in cross-section, crescentic, strongly 

 granular masses, usually containing several nuclei ; 

 1 1x-se are called the crescents of GianuzzL They are 

 helirved t<> I > formed by a number of small angular 

 cells closely crowded together ; they are readily 

 stained with eosin, and are apparently analogues of 

 the granular peptic cells of the stomach. Like the 

 latter, they are most abundant when the gland is in 

 a condition of functional activity, and are believed 

 to be destined to replace the inner layer of trans- 

 parent cells as these are destroyed or changed in 

 furnishing the specific secretion of the gland. 



The excretory ducts differ in structure and in t In- 

 dia meter of the Imm-M, in dill ere nl par Is <>f the 



