406 CARDIAC GLANDS. [BOOK n. 



other by a considerable space equal probably to about their own 

 diameter. 



The outline of each gland is denned by a distinct basement 

 membrane which appears to be formed by a number of flat 

 transparent connective-tissue corpuscles fused together into a 

 sheet ; in a section of a gland, longitudinal or transverse, some of 

 the nuclei belonging to the constituent cells may be seen embedded 

 as it were in the basement membrane. 



Each gland may be divided into a mouth,' by which it opens 

 into the cavity of the stomach, and which reaches about a third or 

 a quarter down the length of the gland, and into a ' body ' which 

 forms the rest of the gland, the junction of the two being called 

 the ' neck.' These two parts differ fundamentally in structure. 



The mouth has a wide open lumen and is lined with a single 

 layer of long slender conical cells called ' mucous cells.' The lower 

 two-thirds of each mucous cell, including the pointed or blunt or 

 sometimes slightly branched end resting on the underlying base- 

 ment membrane, is composed of ordinary granular protoplasmic 

 substance, staining with the ordinary staining reagents ; embedded 

 in the lower part of this is a small oval nucleus placed vertically. 



The upper third is more clear and transparent, does not stain 

 readily and differs in appearance at different times. At one time 

 this part of the cell is occupied by mucus ; at another time the 

 mucus has been discharged by a rupture of the outer face or lid of 

 the cell, leaving a small cup-shaped cavity (containing fluid and a 

 remnant of mucus) the fairly distinct walls of which are continuous 

 with the protoplasmic lower two-thirds of the cell. We shall shortly 

 have to discuss more fully the nature of mucous cells in connection 

 with the salivary glands, and may here simply say that in the 

 upper third of the cell, the cell-substance of the cell, except for a 

 portion which remains as the cell wall of this part of the cell, is 

 transformed into mucus, and that the mucus so formed is sooner 

 or later discharged from the cell, its place being in time occupied 

 by new cell-substance, which again in turn is converted into 

 mucus. 



These mucous cells not only line the mouths of the glands, 

 becoming shorter where the mouth joins the neck, but also 

 cover the ridges between the glands and so form the immediate 

 lining of the interior of the stomach. The free surface or lid of 

 each cell is more or less hexagonal or polygonal in outline, and in 

 sections of hardened stomach the hardened cell-walls of the tops 

 of the cells give rise to the appearance of a mosaic of hexagonal 

 or polygonal areas where the section presents a number of these 

 cells seen on end. Lying between the bases of the mucous cells 

 above the basement membrane may be seen in verti<^al sections a 

 certain number of the small cells referred to in 2i}8 as either 

 reserve cells or leucocytes. 



212. The body of the gland is not only in itself distinctly 



