448 



divisions of the ducts. In the inner row of cells of the primitive acini, 

 a mucous transformation takes place (Fig. 7, Ä), which is first indicated 

 by the appearance of deep staining blue masses in these cells. These 

 increase in size pushing the nucleus of the cells towards the pole ad- 

 jacent to the basement membrane. At the same time, the outer row 

 of cells is pressed against this structure in quite the same way that 



.^■^:^ 



PVJ 







Fig. 5. Cross section of the Oesophagus of a pig 13 cm long, at the level of the 

 bifurcation of the Trachea. Same preparation as Fig. 1. X 105. M Mucosa. MP 

 Basement membrane. SM Submucosa. MM Muscularis mucosae. IC Inner layer and 

 OL Outer layer of the Tunica muscularis. 



mucous acini are formed in the submaxillary gland of the pig ^). The 

 duct retains its double layer of low cubical epithelium, while the alveoli 

 are ultimately transformed into typical mucous glands, lying in the 

 Submucosa beneath the Muscularis mucosae. 



1) Vide Flint, Arch. f. An at. u. Phys., Anat. Abt., 1903. 



