FAT NECKOSIS 321 



supports the belief that it has wandered in from the outside. 1 

 A certain proportion of the fat is probably derived from the 

 bodies of the tubercle bacilli, which usually contain about 40 

 per cent, of fatty matter ; but it has not been determined 

 whether the fat from this origin forms an appreciable part of 

 the fatty matter of caseous material. 



Caseous areas persist for extremely long periods of time with- 

 out undergoing absorption, which indicates that the autolytic 

 enzymes are destroyed early in the process, presumably by the 

 toxins of the tubercle bacillus ; corresponding to this Schmoll 

 found autolysis very slight indeed in caseous areas. Because 

 of a lack of chemotactic substances no leucocytes enter to 

 remove the dead material. That the failure of absorption is 

 not due to a modification of the proteids into an indigestible 

 form is shown by the rapid softening of caseous areas when, 

 through mixed infection, chemotactic substances are once de- 

 veloped and leucocytes enter. 



FAT NECROSIS. 2 



Through usage this term has come to indicate a specific form 

 of necrosis of fat tissue, which is characterized by a focal, cir- 

 cumscribed arrangement, and by the splitting of the fat in the 

 necrotic area into fatty acids and glycerin, the latter disappear- 

 ing, the former combining with bases to form soaps. 3 In all 

 cases fat necrosis is produced by the action of pancreatic juice 

 upon fat tissue, 4 presumably through the action of the enzymes 

 it contains, and the condition can be produced experimentally 

 by any procedure that causes escape of the pancreatic juice 

 from its natural channels. 



Langerhans 5 made the first studies of the nature of the 

 changes in fat necrosis, and established the fact that the fat of 

 the cells is split into its components, and that the fatty acids 

 combine (at least in part) with calcium. Dettmer 6 found that, 



1 Fischler and Gross (Ziegler's Beitr., 1905 (7th suppl.), 344) could find 

 no fatty acids in caseous areas by histological methods. 



2 General literature will be found in the articles cited in the text ; also in 

 Opie's " Diseases of the Pancreas," 1903 ; and in Truhart's " Pankreas-Pathol- 

 ogie," Wiesbaden, 1902. 



3 The fatty acids form masses of crystals in the fat-cells, and they can also 

 be demonstrated microchemically by Benda's method (Virchow's Arch., 1900 

 (161), 194), which consists of staining with a copper acetate mixture, blue- 

 green copper salts of the fatty acids being formed. 



4 Wulff (Berl. klin. Woch., 1902 (39), 734) claims to have observed an 

 exception to this rule, but his account is not by itself convincing. 



5 Virchow's Arch., 1890 (122), 252. 



6 Dissertation, Gottingen, 1895. 



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