LYMPHATIC GLANDS. 441 



we shall first take up the appearances which are observed in 

 the fresh structures, and afterward those points which have 

 been demonstrated by minute injections. 



The perfect healthy glands are of a grayish- white or red- 

 dish color, of about the consistence of the liver, presenting a 

 hilum where the larger blood-vessels enter and the efferent 

 vessels emerge, and covered, except at the hilum, with rather a 

 delicate membrane, composed of inelastic, with a few elastic 

 fibres. Their exterior is somewhat tuberculated, from the 

 projections of the follicles just beneath the investing mem- 

 brane. The interior of the glands is soft and pulpy. It pre- 

 sents a coarsely granular cortical substance, of a reddish- white 

 or gray color, which is from one-sixth to one-fourth of an inch 

 in thickness in the largest glands. The medullary portion, 

 which comes to the surface at the hilum, is lighter colored and 

 coarser than. the cortical substance. Throughout the gland 

 are found delicate fasciculi of fibrous tissue connected with 

 the investing membrane, which serve as a fibrous skeleton 

 for the gland, and divide its substance into little alveoli. The 

 structure is far more delicate in the cortical than in the me- 

 dullary portion. Leydig compares this tissue to that of a 

 sponge, and says that " the connective tissue of the cortical 

 region corresponds to a very fine sponge, and that of the 

 medullary region to a coarse sponge." 1 



Within the alveoli, are irregularly oval, closed follicles, 

 about 2^0- of an inch in diameter, 2 filled with a fluid and 

 with cells like those contained in the solitary glands of the 

 intestines and the patches of Peyer. These follicles do not 

 seem to occupy the medullary portion of the glands, which, 

 according to Kolliker, is composed chiefly of a net-work of 

 lymphatic capillaries, mixed with rather coarse bands of 

 fibrous tissue. 3 The follicular structures in the lymphatic 



1 LEYDIG, Traite d 1 Histologie de VHomme et des Animaux, Paris, 1866, p. 

 457. 



3 ROBIN, Dictlonnaire de Nysten, Paris, 1865, article Lymphatique. 



3 KOLLIKER, Manual of Human Microscopic Anatomy, London, 1860, p. 507. 



