400 THE LYMPH-NODES. 



leucocytes in the blood. This is called Hodgkin's disease, or pseudo-leu- 

 Jccvmia, aud the enlarged lymph-nodes may in this case be called psemlo- 

 leukcemic tymphomata. The lesions of the lymph-nodes are apparently 

 similar in both diseases, but it is convenient to assign different names to 

 them because they seem to arise under different conditions and to be 

 associated with a constant difference in the character of the blood. 

 There is some reason for the conjecture that Hodgkin's disease may be 

 infectious in its nature. Whether the pyogenic cocci and the pneumo- 

 coccus which have been found in the lesions are the excitants or not is 

 not yet certain. 



Le Count has recently described a benign tumor lymphoma in the 

 groin having the structure of a lymph-node. 1 A form of generalized 

 tuberculous lymphadenitis which may be mistaken for Hodgkin's dis- 

 ease is described above. 



TUMORS. 



Sarcoma occurs in the lymph-nodes as a primary and secondary tumor, 

 aud may be of various forms: spindle-celled, large and small round- 

 celled, and augio-sarcoma. It is not easy in many cases to distinguish 

 morphologically between the small round-celled sarcomata and the above- 

 described lymphomata, but in general the leuksemic and pseudo-leukaemic 

 lymphornata remain circumscribed, while the sarcomata tend to break 

 through the node capsule and invade the surrounding tissues. Fibroma, 

 myxoma, and chondroma occur in the lymph nodes, but are rare. Endothe- 

 liomata are described, but are not common. Secondary carcinomata are 

 of frequent occurrence, the form of the cells and the nature of their 

 growth depending upon the seat and character of the primary tumors. 



PARASITES. 



Aside from the various forms of bacteria which are not infrequently 

 found in the lymph-nodes in infectious diseases, among the animal para- 

 sites filaria, trichina, and pentastomum have been described. 



H^MOLYMPH NODES. 



Numerous observers have described the occurrence in man and certain of the lower 

 animals, under normal as well as pathological conditions, of structures which resemble 

 lymph-nodes, but are usually smaller and are red or mottled red and white. In man 

 they are found especially in the prevertebral fat, in the deep cervical region, in the 

 retroperitoneal region, near the renal vessels, and about the rim of the pelvis. They 

 are normally present, but they mny be more conspicuous under certain pathologi- 

 cal conditions pernicious anaemia, acute infections, intoxications, etc. Their color is 

 due to the presence of blood in the sinuses of the nodes. There are numerous transi- 

 tional forms between nodes containing lymph sinuses only and those which more nearly 

 resemble the spleen in character. They become more prominent and are increased in 

 number after splenectomy in animals.' 2 These structures do not appear to be lymph- 



1 Jour. Exp. Med., vol. iv., p. 559, bibliography of lymphoma. 



2 See Warthin, "Vaughan Anniversary Contributions to Medical Research," 1903, 

 p. 216. 



