THE WHITE BLOOD-CORPUSCLES. 45 



THE WHITE BLOOD-CORPUSCLES (LEUKOCYTES), THE BLOOD- 

 PLATES AND ELEMENTARY GRANULES. 



Through the lymph-stream colorless cells, designated white blood- 

 corpuscles or leukocytes, are swept into the blood. In addition to the 

 blood they are found in the lymph, in adenoid tissue, in bone-marrow 

 and as wandering cells in the connective tissues of various parts, as well 

 as between glandular and epithelial cells. They consist of globular 

 masses of viscid, bright or granular, highly refracting, soft, motile, 

 unencapsulated protoplasm (Fig. 6). In the fresh state (A) they 

 exhibit no nucleus, which appears only after addition of water or acetic 

 acid (B), and in consequence of which also the definition becomes more 

 distinct. Water, besides, renders the contents more granular and more 

 turbid, while acetic acid causes them to clear up. The nucleus contains 

 one or more nucleoli. The diameter of the cells varies from 4 to 13 //. 

 The leukocytes are dissolved by peptone. 



In accordance with their form and size leukocytes are differentiated 

 as follows: (i) Small lymphocytes, approximating erythrocytes in size, 

 with a large, round, deeply staining nucleus and a thin margin of proto- 

 plasm. (2) Large cells, with 

 an extensive oval, feebly 

 staining nucleus and a heavy 

 cortical layer of protoplasm. " ^. 



(3) Cells resembling those jg^ HP 

 last described except that the 

 nucleus is constricted. (4) 

 Somewhat smaller cells, con- 

 stituting about three-quar- FlG 6 _ A) human white ^00^0^,^, wit hout any re- 



terS Of the total number, agent; B, after the action of water; C, after acetic acid; 



. , , , 111^-1 D. frog's corpuscles, changes of shape due to ameboid 



with polymorphous, lobulated movement, 



or variously convoluted nu- 

 clei, or nuclei separated into from one to four parts. The last three 

 forms of cells have a genetic connection. 



The leukocytes increase by division, in part by mitosis, in part by 

 amitosis especially in their germ-centers, that is, the lymphatic glands 

 and adenoid tissues. Division has not as yet been observed in the small 

 lymphocytes found in the lymphatic glands (Fig. 8,00). Perhaps these 

 represent juvenile forms. Also sessile cells in the^ connective tissue 

 may undergo multiplication by division and send their offspring into the 

 blood through the lymph-stream. 



The number of leukocytes in a given division of the vascular system 

 may differ widely. At times they may be found increased in one place 

 or another, as, for instance, as a result of chemotaxis, while at other times 

 a large number may be sent into the blood-stream from the lymphatic 

 apparatus. The increase is designated leukocytosis. 



The number of leukocytes is considerably less in shed blood than in 

 circulating blood. Immediately after removal from the vessels nine- 

 tenths of all of the leukocytes are destroyed (fibrin-formation). 



Local heat diminishes, and cold increases, the number of leuko- 

 cytes in the vessels of the part of the body treated, as they are re- 

 strained in the blood-vessels contracted by cold. 



