256 TEXT-BOOK OF PHYSIOLOGY. 



ameboid movements the corpuscle can appropriate small particles 

 of pigment, such as indigo or carmine, and after a short time 

 eliminate them from various parts of the surface. It is also capable 

 of thrusting a process into and through the wall of the capillary 

 vessel, after which the remainder of the corpuscle follows (Fig. 

 no). This continues until the corpuscle is outside the vessel and in 

 the lymph-space, where it resumes its original shape and movement. 

 This process is best observed in inflammatory conditions, when the 

 blood has come toirest and the vessels are occluded with both red and 

 white corpuscles.| To this passage of the white blood-corpuscles 

 through the capilrary wall the term diapedesis is given. I The move- 

 ments of the white corpuscles are increased by a rise in Temperature 

 up to 40 C., beyond which they cease, owing to the coagulation of 

 the cell-substance. A low temperature also arrests the movements. 

 Induced electric currents also cause contraction and death of the cell. 

 Moisture and oxygen are necessary to their activity. From their 

 similarity to lower organisms the white corpuscles may be regarded 

 as independent organisms living in the animal fluids, just as the 

 amoeba lives in its natural liquid medium. 



Classification. With the aid of the tricolor staining fluid of 

 Ehrlich four distinct forms of white corpuscles or leukocytes can be 

 demonstrated to be present in the blood, viz.: 



1. Small lymphocytes, so called from their resemblance to the cor- 



puscles of the lymph-glands, consisting of a small dark nucleus 

 surrounded by a very thin layer of cytoplasm. 7V<4 fcuunjfa 



2. Large mononuclear lymphocytes, which represent the preceding type 



at a later stage of development and in the possession of a large 

 amount of perinuclear cytoplasm more or less hyaline and devoid 

 of granules. The nucleus is often deeply notched, resembling a 

 horseshoe in shape. Xhis_cel^ is capable oLexecuting ameboid 

 movements. 



3. Polymorphonuclear leukocytes or neutrophiles, which represent 



the adult condition of the cell. The nucleus is irregular and 

 assumes a variety of shapes in different cells, a. feature which 

 has suggested the name given to the cell. The perinuclear cyto- 

 plasm contains a number of granules which are made evident 

 when stained with the neutral mixture of Ehrlich. These 

 cells exhibit active ameboid movements. They make up about 

 60 to 70 percent, of the whole number of the white blood-cells. 



4. Eosinophile cells, the granules of which stain most readily with 



acid stains like eosin. The granules are spheric and larger 

 than in the previous cell. The nucleus is pale and irregular 

 in shape. TJiejQsjnp^tole.Cfi^^ 



ne__jlLand is the most actively ameboid of all tlig rails Tt 

 is present to the extent of from } to 4 per cent 



