SEMIOLOGY OF THE ORGANS OF CIRCULATION. 373 



white blood corpuscles and haematoblasts ; the existence or non-existence 

 of leucocytosis and its degree, as well as the existence, for instance, of 

 leucocythaemia. 



The blood corpuscles may also be counted. 



Histological examination, supplemented by suitable staining, reveals 

 the presence of normal or abnormal blood corpuscles, parasites such as 

 piroplasma, or microbes such as bacteria. 



Such examination necessarily presupposes a knowledge of what 

 should be looked for in the normal state. 



In normal blood the red blood corpuscles predominate. They are all 

 similar in form and, with few exceptions, of the same size. They stain 

 strongly with acid solutions such as eosine. In pathological conditions, 

 large or giant corpuscles may be found (macrocytes), as well as those of 

 medium size (normal) and small size (microcytes). Some are vigorous 

 and stain deeply; others, on the contrary, are degenerating or dead, and 

 have no greater affinity for one constituent than for another of the 

 double or triple stains commonly employed. 



In pathological conditions the haematoblasts occur in very varying 

 numbers. 



The white blood corpuscles found in health may be classified as 

 follows : — 



Large and small lymphocytes, each of which has a round volu- 

 minous nucleus and a narrow border, and contains a non-granular 

 protoplasm ; their proportion varies between 22 per cent, and 25 per 

 cent. : 



Polynuclear leucocytes or polymorphous leucocytes with a single 

 nucleus, which originate in bone marrow, stain best with neutral colours, 

 and are present in the proportion of 70 per cent, to 72 per cent. : 



Mononuclear leucocytes with an ovoid eccentric nucleus stain best 

 with basic colours, and form about 1 per cent. : 



Polynuclear leucocytes stain best with eosine or acid colours, and 

 form about 1 per cent, to 2 per cent. 



When these white blood corpuscles are in larger number the con- 

 dition is known as leucocytosis, and when one or other variety is in 

 very great excess the condition is known as leucaemia. 



