SOME FACTORS IN THE LIFE-HISTORY 

 OF THE LEUCOCYTE 



By FRANK E. TAYLOR. M.Sc. M.A., M.D.. B.S.. F.R.C.S., M.R.C.P., D.P.H. 

 Lecturer on Bacteriology, University of London, King's College 



A MICROSCOPIC examination of fresh normal human blood 

 reveals the fact that it consists of a colourless fluid part, the 

 blood-plasma, in which are suspended enormous numbers of 

 non-nucleated circular biconcave discs, the red blood corpuscles 

 or erythrocytes, and a much smaller number of nucleated more 

 or less amoeboid cells, the white blood corpuscles or leucocytes. 

 The much smaller blood platelets are usually undiscernible by 

 this method of examination. 



In health, whilst the erythrocytes are all uniform in 

 character and appearance, the leucocytes, on the other hand, 

 show many differences among themselves. Thus they vary in 

 size, in the size and shape of the nucleus, and in the amount 

 and appearance of the cytoplasm, which may be hyaline or 

 finely or coarsely granular. Hence several varieties can 

 readily be distinguished and recognised. 



It is, however, chiefly upon stained preparations of blood 

 films that we rely for the recognition and accurate differentiation 

 of the various kinds of leucocytes. A great advance in the 

 study of the morphology and functions of these cells was made 

 by Ehrlich when he applied to them special methods of 

 fixation and staining, chief amongst which was the employ- 

 ment of his triacid stain. The discovery of the Romanowski 

 double stain and its more recent modifications in Jenner's, 

 Giemsa's, and Leishman's stains have added greatly to our 

 knowledge of this subject, and to the ease and accuracy with 

 which the various types of leucocyte can be recognised. 



To prepare stained blood films after this method one may 

 proceed as follows : After cleansing the skin of the finger or 

 of the lobe of the ear with ether, the specimen of blood is 

 obtained by sharply pricking the skin in the cleansed area 

 with a Hagedorn needle sterilised by passing through the 

 flame of a Bunsen burner or spirit lamp. The drop of blood so 

 obtained is placed on a clean slide, and a uniform film is made 

 by spreading it with another clean slide pushed along at an 



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