CHANGES IN THE CIRCULATION OF THE BLOOD. 



73 



OK RED THROMBUS. 



, and a few 



circulation. So long as the eudothelial lining of the vessels is intact, 

 simple retardation of the circulation does not usually alone suffice to in- 

 duce coagulation ; but changes in the en- 

 dothelium, in a great variety of condi- 

 tions, such as inflammation, degeneration, 

 atheroma, calcification, and the presence 

 of bacteria, ' tumors, and foreign bodies, 

 favor its occurrence, especially when as- 

 sociated with changes in the circulation 

 or in the character and contents of the 

 blood. Thrombosis is a not infrequent 

 complication of the infectious diseases as 

 well as of the cachectic conditions associ- 

 ated with various acute and chronic gen- . 

 eral diseases. 



Thrombi may be composed of fibrin 

 and of red and white blood cells, inter- 

 mingled in about the same proportion as 

 in an ordinary extravascular blood clot Thlsshows 

 (Fig. 9). These are called red thrombi, 

 and usually occur from some sudden stoppage of the circulation. Other 

 thrombi, usually such as form while the blood is in motion, may consist 

 almost entirely of white blood cells with a little fibrin, or of these inter- 

 mingled with blood platelets, or they may consist almost entirely of 

 blood platelets ; all of these forms are called white thrombi. Red thrombi, 

 when decolorized by changes in the blood pigment, may somewhat re- 

 semble genuine white thrombi. Mixed thrombi are usually lamellated 

 (Fig. 10) and contain varying proportions of fibrin, red and white blood 

 cells, and platelets. The fibrin fibrils in thrombi, as elsewhere, often 

 coalesce, forming hyaline masses. A similar change may take place in 

 the blood platelets. 



After a certain amount of shrinkage by which the fluids are squeezed 

 out and the thrombus becomes denser and drier, the changes which 

 occur in the thrombus may be either in the direction of degeneration 

 and absorption or organization. The leucocytes, the fibrin, and the 

 blood plates may degenerate, forming a granular material which may be- 

 come infiltrated with salts of lime, forming the so-called phleboliths, or 

 vein stones. In other cases the thrombi may soften and disintegrate. 

 This softening may be simple and the result of fatty or other form of tis- 

 sue degeneration, resulting in a white or reddish or brown grumous 

 mass, which may resemble, but is not, pus. Or, in many instances, 

 softening probably occurs through the autolytic processes, 2 initiated and 

 sustained largely by leucocytes. On the other hand, softening of the 

 thrombus may be associated with bacteria or other infectious material 



1 For a study of the role of micro organisms in the formation of venous thrombi see 

 Jakowski, Cbl. f. Bak., Abth. I ., Bd. 28, p. 801, 1900, Bibl. Consult also Welch on .in- 

 fective thrombi, Albutt's "System of Medicine," vol. vi , p. 169. 



4 See p. 92. 



