164 NORMAL AND PATHOLOGICAL BLOOD. 



Young children have normally an excessive proportion of lympho- 

 cytes. This is apt to be particularly marked in hereditary syphilis. 

 Enlarged tonsils may give rise to a lymphocytosis of 10,000 to 15,000, 

 when more than 50% of the white cells will be lymphocytes. Rickets 

 and scurvy give a lymphocytosis. 



DISEASES IN WHICH THERE is A NORMAL LEUKOCYTE COUNT. 



Uncomplicated tuberculosis, influenza, Malta fever, measles, 

 trypanosomiasis, malaria, syphilis and chlorosis. In malaria we have 

 a leukocytosis at the time of the rigor, while during the apyrexial 

 period there is a moderate leukopenia. In malaria we have a marked 

 increase in the percentage of the large mononuclears and transitionals. 

 These may form from 25% to 35% of the leukocytes. When bearing 

 particles of pigment they are known as melaniferous leukocytes 

 macrophages which have ingested malarial material. In dengue, at 

 the time of the terminal rash, we may have as great a percentage of 

 large mononuclears. In this disease, however, we have a great dimi- 

 nution of polymorphonuclears from the start (25 to 40%). Instead of 

 a large mononuclear we have at the onset a lymphocytic increase. 

 There is an increase of large mononuclears in trypanosomiasis. 



THE PRIMARY ANEMIAS. 



Chlorosis. In chlorosis it is the reduction of haemoglobin with the 

 slight numerical variation from normal of the red cells that makes for 

 a diagnosis. The color-index is very low. There is nothing abnormal 

 about the leukocytes. Microcytes may be present, and very occasion- 

 ally a normoblast. Macrocytes and megaloblasts are always absent. 

 Blood of chlorotics is very pale and very fluid and coagulates rapidly, 

 hence frequency of thrombosis. 



Simple Primary Anaemia. This condition is not recognized by 

 many authors, but is a convenient term under which to group anaemias 

 which are neither chlorosis nor pernicious anaemia and for which no 

 assignable cause can be designated. It is a secondary anaemia with- 

 out a cause. In it color-index is about normal, there is no change in 

 the leukocytes and cases go on to recovery. 



Pernicious Anaemia. In pernicious anaemia we obtain a very 



