BLOOD 199 



The third type of granular cell, unlike the eosinophiles and mast cells, 

 contains fine granules, and these stain purple or lilac by taking both acid 

 and basic stains simultaneously. They are called neutrophiles, and form 

 between 70 and 72% of the leucocytes in the blood. They are actively 

 amoeboid and are the principal wandering cells of the body, leaving the 

 blood vessels more readily than other forms. In suppurative processes 

 they accumulate around the centers of infection, and they are of very 

 great clinical importance. 



SUMMARY OF THE FORMS OF LEUCOCYTES. 



Lymphocytes, 22 to 25% of the leucocytes, are small (about the. size 

 of a red corpuscle) or large (perhaps twice the diameter of a red corpuscle), 

 non-granular, with round checkered nuclei. 



Large mononuclear leucocytes, i to 3%, may be two or three times the 

 diameter of red corpuscles. They are non-granular, or with few granules, 

 and have pale vesicular nuclei, round or crescentic. 



Polymorphonuclear leucocytes, larger than red corpuscles, are gran- 

 ular, with nuclei variously constricted or bent. They include 



Mast cells, 0.5%, with very coarse basophilic granules obscuring 



the nucleus. 



Eosinophiles, 2 to 4%, with coarse eosinophilic granules. 

 Neutrophiles, 70 to 72%, with fine neutrophilic granules. 

 Blood plates (Fig. 188) are small granular bodies (Kb'rnchenplaques) 

 which were recognized as a normal constituent of the blood by Schultze 

 in 1865. Previous references to them occur, and Zimmer- 

 mann described them as "elementary corpuscles," be- 

 lieving that they gave rise to red corpuscles (Arch. f. 

 path. Anat., 1860, vol. 18, pp. 221-242). They are 2-4 n 

 in diameter, and between 245,000 and 778,000 have been 

 estimated to occur in a cubic millimeter of human blood. 



They are readily reduced to granular debris in ordinary 



PUSCLE. 



sections, but when well preserved and properly stained, 

 they are found to consist of a central granular core and a hyaline outer 

 layer. Often they appear stellate, and on a warm stage they exhibit 

 amoeboid movements. They are concerned in the clotting of the blood, 

 or thrombus formation, and during coagulation threads of fibrin extend 

 out from them as seen in Fig. 182. It is possible, however, that they are 

 only passively involved in this process. In the amphibia certain small 

 spindle-shaped cells appear to be similarly related to fibrin-formation, 

 and they are called thrombocytes; the same term is sometimes applied to 

 the blood plates. In blood clots several days old, blood plates are still 

 found, indicating that they have more than a transient existence. 



