394 



THE LYMPH-NODES. 



a more or less deeply pigmented mass of dense connective tissue. The 

 function of the node may be, of course, in this way partially or entirely 

 destroyed. The pigment in these cases appears to reach the node, in 

 part by being carried along free in the lymph current, in part through 

 transportation by leucocytes in which the particles have become enclosed. 

 Pigmentation of the nodes is most marked in those about the root of the 

 lungs, which are frequently of a mottled gray or a black color, but it 

 may occur in the meseuteric and other nodes. Under similar conditions 

 the diffuse lymphatic structure in the lungs and liver may be pigineiited. 



INFLAMMATION. 



Acute Inflammation of the lymph-nodes is commonly due to the pres- 

 ence of pathogenic micro-organisms or of toxic substances, usually bac- 

 terial in origin, which may be formed in the node or brought to it in the 



A -^ZS= 



Cr 



FIG. 204. ACUTE HYPERPLASTIC INFLAMMATION' OF LYMPH-NODE IN TYPHOID FEVEU. 



Showing a portion of one of the mesenteric nodes. A, Capsule ; B, perifollicular space or lymph sinus, 

 containing in its meshes many large cells ; C, portion of one of the follicles, with large and small cells in 

 the meshes of its reticulum. 



lymph current from the tributary region of the body. Under these con- 

 ditions the nodes are usually swollen, reddened, and softer than normal, 

 and are often the seat of small haemorrhages. One or all of the nodes of 

 a cluster may be affected. 



Two forms of the acute inflammatory process may conveniently be 

 recognized, an HYPERPLASTIC and an EXUDATIVE. 



In the HYPERPLASTIC form a microscopical examination shows the 

 lesion to bejargely due, in addition to the hypersemia and haemorrhage, 

 to a proliferation of the cells of the node ; the spheroidal mououuclear 



