THE CIRCULATORY SYSTEM. 433 



iii the spaces between the trabeculae ; or have a polypoid shape and are 

 attached by a narrow pedicle (Fig. 228), or very rarely are globular aiid 

 free iii the cavity of the auricle (Fig. 229). Cardiac thrombi are most 



FIG. 229. LARGE GLOBULAR THROMBUS IN THE RIGHT AURICLE OF THE HEART. 



frequent in the auricular appendages and between the columnse carnese 

 near the apices of the ventricles. 



They are usually found in connection with some valvular lesion (Fig. 

 230), which involves a roughening of the surface, or prevents the free 

 circulation of blood through the heart. ' 



Old cardiac thrombi are firm, dry, and of a whitish color ; they may 

 soften and break down at their centres, so as to look like cysts filled 

 with pus, or they may calcify. They are usually entirely unorganized, 

 consisting simply of fibrin, but may become organized. 



Cases are reported of organized thrombi in the auricles, the seat of 

 tuberculous inflammation. * 



1 For a study of cardiac thrombosis see Martin and Rennie, Lancet, 1899, ii., p. 782. 

 See also Welch in Allbutt's "System of Medicine," vol. vi., p. 182. 



*KoUar, Ref. Cbl. f. Bak., Abth. 1, Bd. xv., p. 498, 1894; also Moser, I. c., p. 406. 

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