THE INTESTINES. 103 



by the latter, but which present no villi whatsoever. The 

 remainder of the patch is occupied by common villi, or by 

 reticulated folds and by the apertures of the Lieberkiihnian 

 glands -, the latter are disposed around the slight elevations 

 produced by the follicles, in circlets of 6 — 10 and more 

 apertures, the corona tubulorum of authors. 



Each follicle of a patch possesses a perfectly closed, thick 

 and tolerably strong coat of indistinctly fibrillated connective 

 tissue, with interspersed nuclei ; within this are the contents, 

 which are soft and greyish, (never milk-white). They 

 become slowly diffused through water and consist of a little 

 fluid, with innumerable nuclei and round cells of 0004 — 

 0008'", which, when recent, appear quite homogeneous and of 

 a dull grey colour, but are first cleared up and ultimately des- 

 troyed 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 



Fig. 215. 



which, as the comparison of their various forms shows, are 

 constantly undergoing progressive and retrogressive develop- 



Fig. 215. Horizontal section from the middle of three Peyer's follicles of the 

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



