CHAPTER 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 1/2 million, 7500. 



Women, 80 to 100%, 4 1/2 to 5 million, 7500. 



Children, 70 to 80%, 4 1/2 to 5 million, 9000. 



COLOR-INDEX. 



This is obtained by dividing the percentage of the haemoglobin by 

 the percentage of red cells, five million red cells being considered as 

 100%. To obtain the percentage of red cells it is only necessary to 

 multiply the two extreme figures to the left by two. Thus if a count 

 showed the presence of 1,700,000 red cells, the percentage would be 

 34. (17x2 = 34.) If the Hb. percentage in this case were 50; then 

 the color index would be 50 -H 34, or 1.4. 



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



In anaemias we have three types of color-index: (i) The perni- 

 cious anaemia type, which is above i. Here we have a greater re- 

 duction 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 haemoglobin and 90% of red cells, 40 -j- 90 = .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 



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