THE LYMPHATIC NODES 151 



puscles. They are bounded by a layer of endothelioid cells which 

 everywhere incloses the denser lymphatic cords. The function of 

 these cords would seem to be comparable to that of the peripheral 

 lymphatic follicles. 



The pulp spaces are open toward the cortex, whence they re- 

 ceive the afferent lymph after it has percolated through the folli- 

 cles, but toward the hilum the spaces are continued into the effer- 

 ent radicles of the lymphatic vessels which, in the connective tissue 

 of this part, unite into larger trunks, and finally form several 

 efferent, lymphatic vessels of considerable size. 



The reticulum of the lymphatic gland is a close-meshed net- 

 work of interlacing fibrillar bundles, which are here and there 

 clasped by flattened endothelioid connective tissue cells. Retic- 

 ulum is but poorly stained with either acid or basic dyes, is de- 

 stroyed by acids and bases, but is not digested by pancreatin. 

 After prolonged action of Weigert's specific stain for elastic tissue 

 it is but slightly colored. 



Lymphatic Corpuscles. The great majority of these cells are of 

 the small mononuclear or lymphocyte type. Large mononuclear 

 cells with a considerable cytoplasmic body are also very numerous. 

 Polynuclear neutrophile leucocytes, though of frequent occur- 

 rence, are less abundant than the previous varieties. Eosinophile 

 cells are present in small numbers, and large basophilic mast-cells 

 are occasionally seen, though according to Carlier * they are mostly 

 confined to the connective tissue. Drummond f also found large 

 multinuclear giant cells, megakaryocytes, similar to those of the 

 bone marrow ; these were, however, very rare. 



Many of these cells, after proper fixation, show mitotic figures. 

 This mitosis has been most frequently observed in the large mono- 

 nuclear type, and is most abundant in the germinal centers of 

 the follicles. The small mononuclear and polynuclear types have 

 also been shown to be capable of cell reproduction by indirect 

 division. Reproduction by direct division of leucocytes appears 

 to be rare, if indeed it ever actually occurs. 



The mononuclear as well as the polynuclear forms appear to be 

 phagocytic. Among the inclusions which have been found within 

 these cells are fat globules, pigment granules, red blood corpuscles 

 in partial disintegration, insoluble pigments, such as carbon gran- 

 ules, etc., and bacteria. 



* J. Anat. and Physiol., 1893. f J Anat. and Physiol., 1900. 



