114 HUMAN PHYSIOLOGY. 



greater is the quantity of oxygen absorbed, and, consequently, all the vital 

 functions of the body become more active. 



The white corpuscles are far less numerous than the red, the proportion 

 being, on an average, about i white to from 350 to 400 red; they are globular 

 in shape, and are ^QQ of an inch in diameter, and consist of a soft, granu- 

 lar, colorless substance, containing several nuclei. 



The number per cubic millimeter varies from 7,000 to 10,000. 



Five distinct varieties of white corpuscles are now recognized, viz.:- i. 

 small lymphocytes; 2. large lymphocytes; 3. Polymorphonu clear leuko- 

 cytes; 4. Eosinophiles; 5. Basophiles. 



The white corpuscles possess the power of spontaneous movement, alter- 

 nately contracting and expanding, throwing out processes of their substance 

 and quickly withdrawing them, thus changing their shape from moment to 

 moment. These movements resemble those of the ameba, and for this 

 reason are termed ameboid. The white corpuscles also possess .the capability 

 of passing through the walls of the capillaries into the surrounding tissue 

 spaces; to this process the term diapedesis is given. 



The white corpuscles are identical with the leukocytes, and are found in 

 milk, lymph, chyle, and other fluids. 



The function of the leucocytes is imperfectly known. It has been sug- 

 gested that they are engaged in the removal of dead tissue, of attacking and 

 destroying bacteria. For this reason they have been termed phagocytes. 



Origin of Corpuscles. The red corpuscles are developed out of nucle- 

 ated cells, the erythroblasts found in the red marrow of the long bones. 

 The latter increase by karyokinesis and increase in their hemoglobin content. 

 The nucleus is finally extruded, after which the cell assumes the form char- 

 acteristic of the red corpuscle. 



The white corpuscles arise from two different sources. The lymphocytes 

 take their origin from the lymph-adenoid tissues, e. g., lymph glands, solitary 

 glands, etc. The leucocytes are derived from the myelocytes found in the 

 marrow of long bones. 



COAGULATION OF THE BLOOD. 



When blood is withdrawn from the body and allowed to remain at rest, 

 it becomes somewhat thick and viscid in from three to five minutes; this 

 viscidity gradually increases until the entire volume of blood assumes a jelly- 

 like consistence, which process occupies from five to fifteen minutes. 



As soon as coagulation is completed, a second process begins, which con- 

 sists in the contraction of the coagulum and the oozing of a clear, straw- 



