312 DISEASES OF THE BLOOD. 



haemoglobin per red corpuscle ascertained by comparing the 

 number of red cells per cubic millimetre with the percentage 

 of haemoglobin. 



THE ANAEMIAS. 



The term anaemia includes a variety of conditions in which 

 there are qualitative alterations in the blood, the most con- 

 spicuous evidence of which, clinically, is pallor of the skin 

 and mucous membranes, due to a reduction in the amount of 

 haemoglobin, whether from a reduction in the amount of 

 blood, in the number of red corpuscles, or in the coloring- 

 matter alone. 



Reduction in the number of red corpuscles oligocythcemia, 

 and of the amount of haemoglobin oligochromcemia, are usu- 

 ally associated, though the latter may be present without 

 alteration in the number of red cells, as is seen especially in 

 chlorosis. 



The anaemias are usually divided into two classes clinically 

 the primary or essential, and the secondary or symptomatic. 



The former include simple primary anaemia, pernicious 

 anaemia, chlorosis, leukaemia, and Hodgkin's disease, neither 

 of which is dependent on any preceding affection. 



The latter include those anaemias produced by disturbances 

 outside of the haemopoietic system e. g., tuberculosis, malig- 

 nant disease, etc. 



Primary Anaemias. 



Chlorosis is a primary anaemia, occurring principally in girls 

 about the time of puberty, characterized by an excessive reduc- 

 tion in the amount of haemoglobin and, in most cases, a peculiar 

 sallow complexion having a somewhat greenish tinge, which 

 has won for it the term green-sickness. The red corpuscles may 

 be normal in number, but generally in prolonged cases there 

 is a considerable reduction never so great, however, as the 

 percentage-reduction of haemoglobin ; in other words, the 

 amount of coloring-matter in each individual corpuscle la 

 valeur globulaire is reduced. This difference may be as 

 great as 30 per cent. ; while the number of corpuscles in a 

 given case may be reduced to only two or three million per 

 cubic millimetre, the quantity of haemoglobin may be less 

 than 20 or 30 per cent, of normal. 



