THE HLOUD 111 



the cytoplasm. They stain strongly with basic dyes. They are 

 present in small numbers (Ehrlich, 0.2 per cent, to 0.5 per cent.) in 

 normal blood, or they may not be demonstrable. Ehrlich identifies 

 them with the "mast cells" which are found in various tissues and 

 organs, especiallx' in areolar connective tissue, but this identity has 

 been questioned. 



Upon the basis of the foregoing description the following 

 classification of leucocytes on the basis of granulation may be made. 



Leucocytes 



Xon-granular 



Granular 



Lymphocytes 22-25 per cent. 

 Mononuclear leucocytes 1-4 per cent. 



Neutrophile 65-72 per cent, (mainly polymorphonuclear, few 

 transitional and mononuclear) 



Acidophile 1-4 per cent, (mainly polymorphonuclear, few transi- 

 tional and mononuclear) 



^ Basophile 0. 2-0.5 per cent, (mononuclear and transitional) 



The function of the red cells is primarily the carrying of oxygen 

 from the lungs to the tissues and of carbonic acid from the tissues 

 to the lungs. This oxygen-carrying ability is dependent upon the 

 haemoglobin and is directly proportionate to the number of red cells 

 and to the richness of the individual cells in haemoglobin. In the 

 capillaries of the tissues and again in the capillaries of the lung the 

 haemoglobin is undergoing constant change. The haemoglobin of 

 arterial blood is known as oxy haemoglobin, of venous blood as re- 

 duced haemoglobin. The difference is readily demonstrable by the 

 spectroscope.^ 



Amcehoid Movement. — That leucocytes possess in a marked degree 

 the power of amoeboid movement has been noted (p. 52). On ac- 

 count of this motility leucocytes are able (i) to leave the blood-vessels 

 (diapedesis) and move about freely in the tissues (wandering cells), 

 (2) to surround and take up substances from without (phagocytosis). 

 (See also p. 52.) 



Diapedesis. — This power is directly dependent upon motility 

 and while possessed by all leucocytes is most markedly character- 

 istic of the polymorphonuclear forms. 



Phagocytosis. — Phagocytic powers are not possessed equally 

 by all leucocytes, but are confined largely to the mononuclear 



^Of interest in this connection is the fact that in poisoning by illuminating gas, a 

 very definite and stable combination of the carbon dioxid with the haemoglobin is 

 formed (carboxyhaemoglobin). It is this substance which determines the darker red 

 color of the blood in this condition and is apparently the cause of death. 



