338 RETROGRESSIVE PROCESSES 



invisible fat becomes visible through autolysis of the cell pro- 

 teids. (3) Finally, of course, both factors may occur together. 

 Of these various forms, in only the first and last can we properly 

 consider the organ " fatty," and the form that will occur seems 

 not to depend upon the cause of the cell injury, but rather 

 upon the organ under consideration. In a study of the relation 

 of the morphological to the chemical changes Rosenfeld 1 arrived 

 at the following results : 



Normal human hearts contain, on an average, 15.4 per cent, 

 of fat ; the hearts showing fatty degeneration contain 20.7 per 

 cent., on an average. The pancreas, which normally contains 

 15.817.4 per cent, of fat, also contains an increased amount of 

 fat when showing fatty degeneration. The liver, however, takes 

 on by far the greatest amount of fat after " steatogenetic " poi- 

 sons, and the microscopic picture gives a very good approxi- 

 mation of the amount of fat it contains. 2 Apparently in these 

 organs any excessive fat above the normal is observable micro- 

 scopically, although the normal fat content is not, and only in 

 these three organs could Rosenfeld find an actual increase in fat 

 after poisoning with phosphorus, etc. It would seem, on the 

 other hand, that there is not often a real increase in the fat 

 content of the "fatty" kidney. 3 Normal spleen contains 14.2 

 per cent, of fat, and lung 17.3 per cent., but in both, " fatty degen- 

 eration " results in a lowering of this quantity. Degenerations 

 in the nervous tissue, which Yirchow considered the best evi- 

 dence of the conversion of protoplasm into fat, also show a marked 

 decrease in fat, and voluntary muscle shows no increase in the 

 normal quantity after poisoning. In general, these experiments 

 support the contention of Taylor concerning the disclosure of the 

 invisible fat through autolysis. 4 



1 fieri, klin. Woch., 1904 (41), 587. 



2 In fatty livers in phosphorus-poisoning the amount of fat may reach 75 

 per cent, of the dry weight. Accompanying the fat increase are increase in 

 water and a relative or absolute decrease in proteids, probably due to cell autol- 

 ysis. In acute yellow atrophy a similar decrease in proteid occurs, but without 

 an increase in fat. (See v. Starck, Deut. Arch. klin. Med., 1884 (35), 481.) 



3 This is contradicted by Landsteiner and Mucha (Cent. f. Path., 1904 (15), 

 752) and by Lohlein (Virchow's Arch., 1905 (180), 1) and Rosenthal (Deut. 

 Arch. klin. Med., 1903 (78), 94), but is supported by Orgler (ibid., 1904 (176), 

 413). See also the recent studies by Rosenfeld on "the effects of various 

 steatogenic poisons on different organs, in Arch. f. Exp. Path. u. Pharm., 1906 

 (114), 179 and 344. It is probable that the truth lies between the opposing views, 

 namely, the kidney may under some conditions take up fat from the blood, but it 

 does so to a much less extent than the liver, and it may sometimes show 

 marked fatty change anatomically without corresponding increase chemically. 



4 Pieces of tissue implanted into animals may show a peripheral fatty meta- 

 morphosis or infiltration, yet show upon analysis a decreased fat content 

 (Dietrich, Verh. Deut. Path. Gesellsch., 1905 (9), 212). 



