316 DISEASES OF THE BLOOD. 



blasts. The presence of these nucleated red blood-cells is 

 especially characteristic when the oligocythsemia is slight- 

 in fact, it is the only disease in which they are present under 

 that condition. The manner in which this excessive accumula- 

 tion of leukocytes is brought about, whether due to an increased 

 proliferation or a diminished destruction of these elements, is 

 not known. Some maintain that it is primarily a disease of 

 the blood-making organs the spleen, lymphatic glands, and 

 bone-marrow while others believe the changes in these 

 organs to be secondary to the alterations in the blood. The 

 enlargement of the spleen, which is nearly always present, is 

 the result of an enormous increase of the lymphatic elements. 

 The marrow of spongy and long bones becomes yellowish in 

 color; microscopically the marrow-cells are found to be 

 greatly increased in number. The lymphatic glands are also 

 sometimes involved ; in fact, any lymphatic tissue in the body 

 may be affected. 



In the lymphatic variety of leukaemia, which is of much 

 less frequent occurrence, the enlargement of the lymphatic 

 glands is especially marked. A pure lymphatic form is rare, 

 usually there being some involvement of the spleen and bone- 

 marrow. The leukocytes are never increased to the same 

 extent, the large and small mononuclear elements making up 

 95 per cent, of their number. Myelocytes are present in very 

 small numbers only, if at all ; the eosinophiles and polynu- 

 clear neutrophiles are relatively and absolutely reduced. 



The oligocythaBmia is much more marked than in the spleno- 

 myelogenous variety ; nucleated red blood-corpuscles, how- 

 ever, are extremely infrequent. 



Hodgkin's disease, malignant lymphoma, lymphosarcoma , or 

 pseudoleukcemia, resembles leukaemia in all respects except in 

 that there is no increase in the number of leukocytes in the 

 blood. The lymphatic glands throughout the body are 

 enlarged as a result of a hyperplastic proliferation of the lym- 

 phatic elements. As in leukaemia, the spleen, bone-marrow, 

 tonsils, lymphatic follicles of the intestinal mucous membrane, 

 and all the other lymphatic tissues in the body may be affected. 

 Nodules, from the size of millet-seed to that of a walnut, 

 composed of lymphoid cells, may occur in the liver, kidneys, 



