314 DISEASES OF THE BLOOD. 



nicious anaemia are absent. The red blood-corpuscles and 

 haemoglobin are usually reduced to the same degree ; the leuko- 

 cytes undergo no important change either in number or kind. 



Leukaemia or leukocythsemia : The term leukaemia white 

 blood was first proposed by Virchow 7 , in 1845, for cases in 

 which there was an enormous increase in the number of leuko- 

 cytes in the blood, associated with enlargement of the spleen 

 and lymphatic glands. The condition had previously been 

 regarded as an inflammation or suppuration of the blood. 



The disease is well named, for at times the blood is so 

 white it resembles milk or pus. The older writers were 

 accustomed to speak of the relations existing between the 

 number of white and red corpuscles ; but as this depends also 

 on fluctuations in the number of red corpuscles, it is more im- 

 portant to know the exact number of leukocytes per cubic 

 millimetre. Instead of one leukocyte to five or six hundred 

 red cells, the proportion is frequently one to eight, even one 

 to two or three ; in cases of moderate severity there are one 

 to three hundred thousand per cubic millimetre five hundred 

 thousand per cubic millimetre not being infrequent. 



Yet it is not so much the number of leukocytes, which is 

 characteristic of this disease, as the character of the predomi- 

 nant variety ; for the proportion of one to eight has been 

 noted in non-leukaemic anaemias, and in some cases of leuko- 

 cytosis there may be as many as one hundred thousand white 

 blood-corpuscles per cubic millimetre. 



Virchow recognized two forms of the disease, one character- 

 ized by enlargement of the spleen, in which the blood showed 

 an excessive number of large white cells ; and another charac- 

 terized by enlargement of the lymphatic glands, in which the 

 small variety of leukocyte predominated. 



A third form of the disease was later described by Neu- 

 mann, in which there were marked changes in the marrow of 

 the bones. 



Though it is customary to speak of lymphatic, splenic, and 

 myelogenous varieties of the disease, these different forms are 

 often associated. There is some doubt as to a pure splenic 

 variety existing without accompanying changes in the bone- 

 marrow. 



