150 veti:rinarv I'atiiology. 



peripheral stream. The curpiiscles cicciip\- the axial stream 

 because the\' ha\-e a [greater specific ,<4Ta\'it\- than the plasma. 

 Whv the leucocytes enter the peripheral nr plasmatic stream in 

 inflammation has not l)een clearl_y determined. ])ut it is probable 

 that this margination is a result of chemotactic influences. 

 After the leucocytes become marginatcd the\- pass through the 

 vessel wall as follows; Small protoplasmic processes extend 

 and priiject through the \-essel wall. These processes gradually 

 increase in size until the entire leucocyte has. by protoplasmic 

 extension, passed through. The leucocytes usually pass be- 

 tween the endothelial cells Init the\- nia\- p.ass directly through 



"1 





5^' 



t'i£; ^a. — Blood vussel showing' diapedesis of luuciicj-tts t.\-picat ui tho (.■xudative 



stat,"u of inllammation, 



them. The exudation of erythrocytes is ])assiye, the cells being 

 forced through the vessel wall b^• pressure. To recapitulate: 

 fluid exudation is either a physical process, such as filtration, or 

 a physiologic process, a secretion ; leucocytic exudation is a 

 physiologic process depending largely upon the chemic influ- 

 ences of the adjacent tissues, i. e., chemotaxis; exudation of 

 erythrocytes is a physical process resulting from intravascular 

 pressure plus diminished resistance of the vessel wall. 



Exudate. 1. Composition. — Inflammatory exudate contains 

 varying quantities of cells suspended in a fluid (plasma, tissue 

 juice, etc). The fluid part of the exudate contains proteids 

 (serum albumin and serum globulin) in excess of normal plasma. 

 It has a specific gravity of 1018 or more. The quantity of pro- 

 teid is directly proportional to the severity of the process and 



