154 SPECIAL PHYSIOL OGY 



number. By the scale on the mechanical stage, measure the 

 width of the microscopic field and then move the specimen to the 

 next field to the right. Count and keep a record of all the various 

 corpuscles in this field. Continue counting each field to the right until 

 across the specimen; then drop down to the next row of microscopic 

 fields and count to the left, and so on until the whole specimen has 

 been counted and a record of the various corpuscles on the specimen 

 has been obtained. Usually there are not enough white cells on one 

 specimen to take an average from; in that case continue counting 

 specimens until at least 100 white cells in all have been counted. 

 They normally occur in the percentages as given in the table below. 

 If there is difficulty in keeping the microscopic field because it is 

 round, take a piece of stiff paper and cut a square hole in it just the 

 size to make the field square, and place the paper on the diaphragm 

 in the eye-piece of the microscope. 



Corpuscles of Normal Blood. 



1. Red, 5,000,000 per cubic millimetre. A biconcave disk 7.7 

 microns in diameter. 



2. White, 8000 per cubic millimetre. 



Classification of Leukocytes. 



I. Small Mononuclear. Irregularly spherical, 8 to 10 microns 

 in diameter; 20 to 30 per cent, of white cells. The nucleus nearly 

 fills the cell and may or may not stain deeply blue according to 

 technique, though it usually stains well. The protoplasm forms a 

 thin rim around the nucleus, stained faintly blue. 



II. Large Mononuclear. Irregularly spherical, 12 to 13 microns 

 in diameter, 4 to 8 per cent, of white cells. The nucleus, about 

 half the size of the cell, lies eccentrically, takes the blue stain lightly, 

 and is surrounded by protoplasm very faintly blue, with the layer 

 next the nucleus being almost unstained. 



Transitional Forms. Same as above, except that the nucleus is 

 indented or horseshoe-shaped. 



III. Polynuclear. (a) Neutrophile. Irregularly spherical, 12 

 to 14 microns in diameter; 60 to 70 per cent, of white cells. . Two 

 or more nuclei in an irregular group. Nuclei are stained clearly. 

 Protoplasm is partially filled with fine granules that stain red or 

 pink, with a bluish or pinkish background. 



(b) Eosinophile. Irregularly spherical, 12 to 14 microns in 

 diameter; J to 4 per cent, of white cells. Two or more nuclei, faintly 

 stained. Protoplasm is filled with coarse granules stained a bright 

 red with pinkish or unstained background. 



