INFARCTION 275 



ever, seems to be accomplished rather by the invading leuco- 

 cytes, through heterolysis. The relatively small part taken by 

 the intracellular enzymes may possibly be due to the seeping 

 through them of alkaline blood-plasma, for autolytic enzymes 

 are not active in an alkaline medium ; the leucocytic enzymes, 

 however, act best in an alkaline medium. 1 



About the periphery of infarcts is usually observed more or 

 less fat formation (Fischler 2 ), particularly in the endothelial 

 cells (Ribbert). This is not peculiar to infarcts, however, for 

 Sata 3 found a similar peripheral fatty metamorphosis common 

 to all necrotic areas. The basis of this is probably the persist- 

 ence of the cell lipase, which acts upon fatty acid and glycerin 

 diffusing into the necrotic area with the plasma, unchecked by 

 the normal oxidative destruction of these substances. (See 

 " Fatty Degeneration," Chap, xiv.) 



Hemorrhagic infarcts offer, in addition to the changes com- 

 mon to anemic infarcts, the alterations occurring in the blood- 

 corpuscles. Panski 4 found that after ligation of the splenic 

 vein of dogs the red corpuscles begin to give up their hemo- 

 globin in about three hours. After twelve hours fibrin for- 

 mation begins in the tissues, the corpuscles continue to give 

 up hemoglobin and become cloudy in appearance. Later, iron- 

 containing pigment is formed in the cells beneath the capsule, 

 but in the deeper tissue even the iron normally present in the 

 spleen tissue seems to disappear ; this probably depends upon 

 the fact that pigment reacting for iron, hemosiderin, is formed 

 only in living cells under the influence of oxygen. The 

 hemolysis is probably produced either by the action of autolytic 

 products, which are notoriously hemolytic, or perhaps also by 

 direct attack of tissue and blood proteases upon the corpuscles. 



Other retrogressive changes that may occur in infarcts, such 

 as septic softening and calcification, are not greatly different 

 from the same processes occurring in other conditions, and will 

 be considered with the discussion of these processes. 



1 More fully discussed by Wells, loc. cit. 



2 Cent. f. Path., 1902 (13), 417. 



3 Ziegler's Beitr., 1900 (28), 461. 



4 " Untersuchungen iiber den Pigmentgehalt der Stauungsmilz," Dorpat, 

 1890. 



