[AFTER XIV 

 NORMAL AND PATHOLOGICAL BLOOD 



IN considering what may be termed normal blood, it must be borne 

 in mind that the normal varies for men, women, and children: 



Hb. Red cells Leukocytes 



Men, 90 to 110%, 5 to 5^ million, 7500 



Women, 80 to 100%, 4}^ to 5 million, 7500 

 Children, 70 to 80%, 4^ to 5 million, 9000 



COLOR INDEX 



This is obtained by dividing the percentage of the haemoglobin by 

 the percentage of red cells, 5,000,000 red cells being considered as 

 100%. 



To obtain the percentage of red cells it is only necessary to multiply the two ex- 

 treme figures to the left by two. Thus if a count showed the presence of 1,700,000 

 red cells, the percentage would be 34(17 X 2 = 34). If the Hb. percentage in this 

 case were 50; then the color index would be 50 -5- 34, or 1.4. 



In normal blood the color index is, approximately, i. 



In anaemias we have three types of color index: i. The pernicious anaemia type, 

 which is above i. Here we have a greater reduction in red cells than we have of the 

 haemoglobin content of each cell. 2. The normal type, when both red cells and 

 haemoglobin are proportionally decreased, as in anaemia following haemorrhage. 

 3. The chlorotic type. Here there is a great decrease in haemoglobin percentage, 

 but only a moderate decrease in the number of red cells. Hence the color index 

 is only a fraction of i. For example, in a case of chlorosis we have 40% of haemo- 

 globin and 90% of red cells, 40 -f- 90 = 0.4. 



RED CELLS 



In considering the corpuscular richness of a specimen of blood, it 

 must be remembered that this does not necessarily bear any relation to 

 the quantity of blood in the body. Thus, a more or less bloodless- 

 looking individual, the total quantity of whose blood is greatly reduced, 



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