THE CORPUSCLES OF THE BLOOD 97 



made from ox-blood which had the power to combine with 18-i volumes 

 of oxygen when shaken with air. Blood of the same strength as this 

 can combine with the same amount of oxygen. 



Taking the percentage of haemoglobin in man as 100, woman nor- 

 mally has 90 per cent., children 85 per cent. The new-born infant 

 has a high percentage, 140 per cent., which quickly decreases in the 

 first few months of life to just below normal. The effect of altitude 

 has been mentioned. 



The Pale Corpuscles. The pale corpuscles of the blood have been 

 variously classified. At present the best classification appears to 

 be that based upon their supposed origin and their staining properties. 

 According to the origin, the pale corpuscles may be divided into leuco- 

 cytes (amoeboid cells), arising in the bone marrow and passing primarily 

 into the blood essentially, therefore, blood-corpuscles; lymphocytes, 

 probably non-amoeboid or but faintly amoeboid cells, arising in 

 lymphoid tissue and passing primarily into the lymph essentially 

 lymph-corpuscles. 



By staining reactions the leucocytes are classified under three 

 headings : * 



Neutrophil. 



Eosinophil, or acidophil. 



Basophil. 



The lymphocytes are divided into two groups the large and the 

 small. The various staining properties can be seen in a well-made 

 blood-film, which can be prepared as follows: 



Two clean slides are taken with well-cut edges. The slide upon 

 which the film is to be made is gently rubbed with fine emery-paper 

 to give it a very slightly roughened surface. The edge of the other 

 slide is applied to a small drop of blood obtained by pricking the finger; 

 this edge is applied to the roughened slide at an angle of 45 degrees, 

 and by a sweeping movement the blood is lightly and evenly spread 

 over the roughened surface. To this film Leishman's stain is added ; it 

 consists of equimolecular weights of methylene blue and eosin dissolved 

 in methyl alcohol, and is a fixing agent by virtue of the methyl alcohol. 

 After fixing for thirty seconds the stain is diluted with water, 1 : 2, 

 when it assumes a pinkish tint and acts as a stain. The film is stained 

 for about five minutes, and is then washed with distilled water. It is 

 finally dried with blotting-paper. The methylene blue acts as a basic 

 dye because the base in this salt is the active group, and it reacts 

 with nucleic acid in the iiucleo-protein of the cell. Eosin is an acid 

 dye because the acid in this salt is the active group, and it reacts 

 with the basic substances of the cell. 



Stained in this way the neutrophil corpuscles appear two and a 

 half times as wide as a red corpuscle, with a fragmented nucleus stained 

 blue and the fragments joined together with faintly stained pieces of 

 chromatin. For this reason it is called polymorphonuclear. With 

 the magnification of a ^ objective small pinkish granules may be just 

 visible; these are well seen with an oil-immersion (J^) lens. 



7 



