522 



SPECIAL HISTOLOGY. 



rendered slightly convex by the latter, but which present no villi what- 

 soever. The remainder of the patch is occupied by common villi, or by 

 reticulated folds and by the apertures of the Lieberklihnian glands ; the 

 latter are disposed around the slight elevations produced by the follicles, 

 in circlets of 6-10 and more apertures, the coronce tuhulorum of authors. 

 ^^c\i follicle of a patch possesses a perfectly closed, thick and tolera- 

 bly strong coat of indistinctly fibrillated connective tissue, with inter- 

 spersed nuclei ; within this are the contents, which are soft and grayish 

 (never milk-Avhite). They become slowly diffused through water and 

 consist of a little fluid, with innumerable nuclei and round cells of 

 0-004-0-008 of a line, which, when recent, appear quite homogeneous 

 and of a dull gray color, but are first cleared up and ultimately de- 

 stroyed by the action of water and of acetic acid, the nuclei at the same 

 time becoming granular and very distinct. Among these elements, 

 which here and there also contain fatty granules, and which, as the 



FiR. 215. 



comparison of their various forms shows, are constantly undergoing 

 progressive and retrogressive development, Frei and Ernst have demon- 

 strated the existence of numerous, but very fine bloodvessels of 0-0015 

 -0-004 of a line, which are connected with a rich vascular network 

 surrounding the follicle, and may be readily recognized in the contents 

 of the follicles of animals (Pig, e. g.), if they be quite fresh, and have 

 been extracted with care. 



Little is known of the lymphatics of Peyer's patches. This much is 

 certain, however, that the number of lacteals wliich may he traced du- 



FiG. 215. — Horizontal section from tlie middle of three Peyer's follicles of the Rabbit, 

 in order to show their internal vessels. After an injection by Frei. 



