94 ENZYMES 



that in nerve destruction lecithin is spht up with-hberation of cho- 

 line (see "Choline")- Koch and Goodson^* found that degenerated 

 nervous tissue is characterized, chemically, by containing a relatively 

 increased amount of nucleo-proteins, with an absolute decrease in 

 solid constituents, while the lecithins are greatly altered. 



In caseation autolysis is very slight, as is shown by the persistence 

 of the caseous material for long periods of time without absorption. 

 Presumably the toxin of tuberculosis destroys the autolytic ferments 

 of the cells it kills, ^^ and as there is little chemotactic influence, leuco- 

 cytes do not enter the caseous area. Jobling and Petersen^^ find 

 evidence that the soaps of unsaturated fatty acids present in tubercles 

 are responsible for the inhibition of digestion. Spiethoff^'' found 

 that pure caseous material is usually free from even traces of albumose 

 and peptone, but the caseous material at the periphery mixed with 

 tissue elements contains them in very small quantities, suggesting that 

 at the periphery of caseous areas some slight autolysis does occur. The 

 fact that B. tuberculosis is, itself, very poor in proteolytic enzymes as 

 compared with most other bacteria may be another factor. When 

 leucocytes are attracted into a tuberculous focus softening goes on 

 rapidly, showing that there is no loss of digestibility of the caseous 

 material, but merely a lack of enzymes. Pus from a cold tuberculous 

 abscess will not digest fibrin, but if iodoform is injected, leucocytes 

 enter in great numbers, softening is rapid, and the pus will then di- 

 gest fibrin (Heile^^). On serum plates tuberculous pus produces no 

 digestion unless a secondary infection or other cause has resulted in 

 a local accumulation of leucocytes. ^^ Tuberculous material contains, 

 like the lymphocytes, an enzyme which is proteolytic in acid media 

 and which is inhibited by normal serum (Opie and Barker'*^). 



Correlation of Histological and Chemical Changes. — A careful study of the 

 relationship of the chemical chan}.';es produced by autolysis, to the histological 

 changes of necrosis and autolysis, has been made by H. J. Corper,^" and colored 

 plates published together with analytical figures make it possible to correlate at 

 a glance the structural and chemical changes of necrobiosis. Corper found that 

 in the early stages, characterized by a high grade of pycnosis but no further nu- 

 clear changes, the nucleins are still intact; but with well developed karyorrhexis 

 and beginning karyolysis, some ten per cent, of the nuclein nitrogen has become 

 soluble in the form of purine bases. When karyolysis is completed so that no more 

 nuclei remain in a stainable condition, only twenty-eight ])er cent, of the nucleo- 

 proteins was found to have been dccom])oseil to free purine bases,^' the remaining 

 seventy-two per cent, being intact although unstainable. This rather surpris- 

 ing observation indicates that the stainable chromatin rejjresents but about one- 

 fourth of the nucleins of the cell, which is in accord with the views of Hamnuirsten 



«Amer. .Jour. Physiol., 1906 (15), 272. 



" However, Pesci (Pathologica, 1912 (3), 144) states that tuberculin increases 

 autolysis in vitro. 



"Uour. Exp. Med., 1914 (19), 383. 



■" Cent. f. inn. Med., 1904 (25), 481. 



"8 Zeit. klin. Med., 1904 (55), 508. 



"Jour. Exper. Med., 1909 (11), 686. 



^"Jour. Exper. Med., 1912 (15), 429. 



" Marshall (Jour. Biol. Chem., 1913 (15), 81) has also found that much of 

 the nucleic acid remains unaltered in autolysis of thymus. 



