388 THE BLOOD AND THE BLOOD-FORMING ORGANS. 



may exhibit amoeboid movement, arid have no tendency toward the 

 formation of rouleaux. Extremely large nucleated red cells (gigauto- 

 blasts) are frequently found in advanced cases, and in these cells as well 

 as in the megaloblasts the nuclei may be rarely seen in various stages of 

 normal or pathological mitosis. "Blood crises," by which is indicated 

 the appearance of large numbers of normo- or megaloblasts in the circu- 

 lation, may occur in pernicious anaemia, but it must be remembered thnt 

 the blood picture in any severe anemia varies much from day to day 

 without any marked alteration in the general condition of the patient. 

 In the absence of complications producing leucocytosis .in pernicious 

 anaemia, the leucocytes are .usually diminished in number. There is a 

 relative increase in the number of lymphocytes, and usually a few myelo- 

 cytes may be found. 



A very rare variety of a rapidly fatal form of anaemia has been de- 

 scribed in which the number of red cells is diminished without the blood 

 showing the changes characteristic of pernicious anaemia. The bone 

 marrow in these cases has been found to be fatty instead of hyperplastic 

 as in the typical marrow of pernicious anaemia. It has been suggested 

 that the bone marrow for some unknown reason had not responded to the 

 call made upon it by the rapid haematolysis taking place in the disease, 

 and therefore did not undergo the megaloblastic changes so character- 

 istic of the bone marrow in well-marked cases of pernicious anaemia. 



LEUKEMIA (LETJCOCYTILffiMIA). 



Leukaemia is a disease in which the characteristic changes are an alter- 

 ation in the relative proportions of the different leucocytes of the blood, 

 with usually an increase in their number, and the appearance of certain 

 forms not seen in the circulation under normal conditions. The red cells 

 are diminished in number and abnormal forms appear in the blood. 

 Accompanying these alterations in the circulating blood are changes in 

 the bone marrow; less_ofteu in the spleen and in the lymph -nodes. Its 

 inciting factors are still unknown. Leukemia may be classed in three 

 types, which are fairly well defined clinically and morphologically, but 

 between these there exist many transitional forms, especially from the 

 point of view of the morphology of the blood. These three J:ypes are the 

 acute and the chronic lymphatic leukaemia and chronic myelogenous 

 leukaemia (spleuo-myelogeuous). ' 



Acute Lymphatic Leukaemia is a disease resembling clinically an acute 

 infection, with a rapidly increasing anaemia, enlargement of the lymph- 



1 A number of acute cases have been reported, in which, beside the lymphatic forms 

 prevalent in the blood, mononuclear cells containing neutrophile granules were present 

 in moderate numbers, and a claim has been made for a clinical type of acute myeloge- 

 nous leukiemia, but in view of the fact that the morphology of the blood varies greatly 

 a few days before death, and, especially as it is a matter of experience that the lympho- 

 cytes in acute lymphatic leukaemia are often very greatly diminished toward the termi- 

 nation of the disease, it would seem improper, from our present knowledge, to class 

 these cases as acute myelogenous leukjiemia. For an excellent discussion of the subject 

 see Billings and Capps, Am. Jour, of the Med. Sciences, 1903, vol. cxxvi., p. 375. 



