sue. The acini of the mucous ghuids are Larger tlian those 

 of the serous glands. Stud\' tlie structure of tlie aoini 

 under high power. 



In tlie mucou,^ (jUiitds the acini are surrounded by a 

 membrana propria which is nearly filled with clear mucous 

 cells stained a steel -iiray. The nuelei are in the jjeripheral 

 part of the cells. Many of the acini will y\\o\\ a crescent 

 of more deeply stained cells, tlie demilunes of Heidenhain, 

 lying between the mucous cells and the membrana propria. 

 The ducts are regularly round or oval with relatively largo 

 lumina. They are lined by a single layer of columnar 

 cells witii striated protoplasm. 



The acini of the serous (jlands also have a limiting 

 membrana pro[)ria. They are lined 1)}' cuboidal or 

 polyhedral cells with the nuclei near tin; center of the 

 cells. They often have a granular i)r()toi»lasin. The 

 structure of the ducts is the same as in the mucous glands. 



Sketch a duct and a number of acini surrounding it, 

 from both mucous and serous glands as seen under high 

 j)Ower. 



(f) Mucous and Serous Salivary Glands Stained 



in Delafield's Haeniatoxylin. 



Pieces of tlie submaxillary and parotid j^laiids of a dog were 

 liardened in niercuric chloriile, stained in Delafield's lifematoxyiin, 

 and a piece of eacli gland embedded siile by side in a block of 

 paraffin, and sectioned. I"ix to the slid(> an<l mount in balsam. 



The structure seen in (e) will again be observed. 



(g) Mucous and Serous Salivary Glands Stained 



in Borax Carmine. 



Pieces from the sul)maxillary and parotid glands of a dog were 

 hardened in al)solute alcohol, stained in borax carmine, pieces of 

 each gland embedded as above, and sectioned. Fix and mount. 



The last two preparations are given to the student to 

 show the structure of mucous and serous glands as shown 

 by htematoxylin and carmine stains to facilitate their 

 recognition in sections to be given later on in the work. 



