XXIII.] THE SALIVARY GLANDS. 26 1 



space in the centre of the acinus, "but many acini may be so divided 

 as not to show it. It is difficult to find the connection between the 

 lumen of an acinus and a duct (fig. 250). 



(g.) Duct. This is best studied in a transverse section of one of 

 the finer ducts lying within the lobules or the 

 larger ones in the septa (fig. 251). The wall 

 consists of circularly disposed connective tissue, 

 and is lined by a single layer of tall, narrow, 

 cylindrical epithelium. The outer part of each 

 cell is distinctly striated or "rodded," and the 

 spherical nucleus is placed about the middle of 

 the cell. 



N. B. The student should compare with this FIG 251 -T.S. Salivary 



111 i- -i ! Duct showing only 



a section of a gland hardened in osmic acid or the "Rodded" Epi- 

 Flemming's fluid, or one stained by Heidenhain's ^ m Linin * ** 

 method. 



3. Sub-Maxillary Gland of Cat. In some of the acini there 

 may be a nearly complete layer of demilune cells between the base- 

 ment membrane of the acinus and the lining layer of mucous cells. 



B. Serous Salivary Glands Methods. Use the parotid of any 

 mammal rabbit, cat, or dog or the sub-maxillary gland of a 

 rabbit. Harden small parts of the gland in the same way and by 

 the same means as for mucous glands. A saturated watery solution 

 of mercuric chloride is to be pre- 

 ferred to picric acid for serous 

 glands. I find that Flemming's 

 mixture is specially good for the 

 sub-maxillary gland of the rabbit. 

 Sections are made and stained the 

 hardened gland stained " in bulk " 

 just as for mucous glands. 



4. T.S. Parotid Gland. (a.) 

 (L) Observe the capsule, septa, 

 lobes, and lobules as in the mucous 

 glands, but the alveoli or acini are 

 smaller. More sections of gland- 

 ducts will also be seen. 



// \ /i_i\ r\\~ TJ. FIG. 252. Resting Serous Gland, Babbit. 



(5.) (H) Observe an acinus. It Alcohol and carmine. 



is lined by a layer of polyhedral 



cells, leaving a very small lumen. The cells are very granular, with 

 a spheroidal nucleus placed near the centre of the cell (fig. 252). 

 Numerous sections of ducts, some cut transversely, others longitudi- 

 nally. They are like those of mucous glands. 



5. Fresh Serous Gland. Tease a fragment of a parotid gland in 

 normal saline, and observe how the cells are crowded with granules. 



