XX] SALIVARY GLANDS 159 



and there a pear-shaped mucous cell will be seen with 

 a nucleus and small amount of protoplasmic cell 

 substance at the narrow end, and a network of cell 

 substance stretching through the swollen, mucous 

 portion. 



6. Section of dog's resting sub-maxillary gland 



(alcohol ; picro-carmine 1 to 24 hours ; htematoxylin 

 and eosin ; or Ehrlich-Biondi fluid). Mount with it 

 the specimen of active gland ( 7). 



Note under the low power that the general features 

 are the same as those of serous glands, 3 (a) ; the alveoli 

 however are more distinct. 



Note under a high power that two kinds of cells 

 are present in the alveoli, the mucous cells and the 

 serous or demilune cells (the latter are not present in 

 all mucous glands). 



The mucous cells are comparatively large, and 

 often have rounded outlines ; most have a disc-shaped 

 nucleus close to the basement membrane ; in a few 

 the nucleus is spherical and farther from the basement 

 membrane. Much the greater part of the cell is clear 

 and homogeneous, consisting of mucin (or mucigen) 

 resulting from the running together of the mucous 

 granules (cp. 5). The mucin is unstained in the 

 carmine specimens. The protoplasmic cell substance is 

 arranged much as in the cell swollen by acid (cp. 5). 



The demilune cells occur usually in half-moon 

 shaped groups, at the ends of the alveoli ; they are 

 more or less overlapped by the swollen mucous cells. 

 The outlines of the several cells are not very distinct. 

 The nuclei are spherical, the cell substance, which 



