104 



ANIMAL 



a set of structures of obscure function, found in every part 

 of it, may be mentioned, namely, the closed follicles. These 

 are bodies the size of small millet grains, imbedded in the 

 mucous membrane, and containing corpuscular matter and 

 loops of capillary blood-vessels. A number of such struc- 

 tures, grouped round recesses of the mucous membrane of 

 the fauces, constitute the tonsils (p. 88) ; they are also 



numerously scattered in the 

 pharynx, and are called lenti- 

 cular glands in the stomach. 

 In the ileum they are gathered 

 in elongated and rounded 

 groups about half an inch 

 broad, called Peyer's patches, 

 or agminated glands; and in 

 the great intestine they are 

 very plentifully scattered all 

 over, and called solitary glands. 

 In recent years they have been 

 very generally supposed to be 

 connected with the absorbent 

 system; but there is no suffi- 

 cient proof that their function 

 is not secretory, although their 

 Fig. 59. Two PEYER'S PATCHES, structure differs from that of 

 natural size. secreting glands. Peyer's 



patches are interesting as being the seat of a deposit in 

 typhoid fever, and subject to ulceration in that disease. 



