MORPHOLOGY OF LEUCOCYTES AND RED CORPUSCLES 201 



of moisture from the fingers, which may distort the corpuscles. 

 Except when the operator's fingers are very moist it is quite 

 unnecessary, and perfect films, may be obtained with the cover- 

 glasses held in the fingers. 



The blood may be taken by means of the platinum loop, and 

 this is a good plan, as all danger of smearing the cover-glass 

 upon the skin is avoided. If several films are to be taken, a 

 number of platinum loops should be provided, as the blood upon 

 them soon coagulates. The exact size of the loop can only be 

 learnt by experiment, and when one has been found to deliver 

 a drop of the right size it should be kept entirely for this work 

 and carefully protected from injury. 



Fig. 52. — Method of spreading Films with Cigarette-paper. 



II. Method with Cigarette-papers. 



Requisites. — i. Perfectly clean slides. 



2. Some fairly stiff cigarette-papers cut in half longitudinally. 

 Paper which is decidedly ridged or ribbed will not answer. 



3. Needle. 



Method. — The patient is pricked, and the first drop of blood 

 wiped away as before. One of the half strips of cigarette-paper 

 is now held in the right hand, the index-finger being placed 

 above the strip, and the edges held between the thumb and 

 index-finger and the index and middle fingers respectively ; this 

 converts it into a gutter, the convex edge of which is downward. 

 The edge of this gutter which points away from you (and which 

 is formed by a machine-cut edge of the paper) is now dipped into 

 the drop of blood, and a small quantity picked up on its lower 

 surface. This lower surface is then placed on a clean slide 

 parallel to one of its shorter edges and about J inch from it, and 

 pressed gently upon it so as to flatten out the paper gutter ; as 

 this flattens out the edge of the drop of blood on its under 

 surface will follow it. The strip of paper is now drawn towards 



