243 



membrane. Each gland is surrounded by openings like those 

 of Lieberkiihn's follicles (see Fig. 77) except that they are 

 more elongated ; and the direction of the long diameter of 

 each opening is such that the whole produce a radiated ap- 

 pearance around the white sacculus. These openings appear 

 to belong to tubules identical with Lieberkiihn's follicles : 

 they have no communication with the sacculus, and none of 

 its contents escape through them on pressure. Neither can 

 any permanent opening be detected in the sacculus or Peyer's 

 gland itself (see Fig. 78). 



Each gland is an imperfectly closed sac or follicle formed 

 of a tolerably firm membranous capsule of fine connective 

 tissue, imbedded in a rich plexus of minute bloodvessels, 

 many fine branches from which pass through the capsule and 

 enter, chiefly loopwise, the interior of the follicle (Fig. 79). 

 Entering into the formation of the sacculus, moreover, and 

 forming a stroma or supporting framework throughout its in- 

 terior, is lymphoid or adenoid tissue (Fig. 72), continuous with 

 that which forms a great part of the mucous membrane out- 

 side of it. The contents of each sac consist of a pale grayish 



FIG. 78. 



a- /,' 



Side view of a portion of intestinal mucous membrane of a cat, showing a Peyer's 

 gland (a) : it is imbedded in the submucous tissue (/), the line of separation between 

 which and the mucous membrane passes across the gland ; 6, one of the tubular fol- 

 licles, the orifices of which form the zone of openings around the gland ; c, the fossa 

 in the mucous membrane ; d, villi ; e, follicles of Lieberkuhn (after Bendz). 



opalescent pulp, formed of albuminous and fatty matter, and 

 a multitude of nucleated corpuscles of various sizes, resembling 

 exactly those found in lymphatic glands. 



The real office of these Peyerian glands or follicles is still 

 unknown. It was formerly believed that each follicle was a 



