370 RETROGRESSIVE CHANGES 



a series of plates, together with the chemical details' thus establishing a standard 

 whereby the histological changes can be interpreted in terms of the chemical 

 changes which cause them. 



Autolysis of asepfcically preserved tissues outside the body is 

 much more rapid than is the autolysis of infarcts and similar aseptic 

 necrotic areas within the body. This may be due to either or both of 

 two factors:^ First, autolysis is much slower in alkaline than in acid 

 media; outside the body autolyzing tissues develop an acid reaction 

 which favors their autolysis; within the body this is checked by the 

 plasma. Second, the plasma contains inhibiting substances, which 

 also may interfere with self -digestion in the body. In corroboration 

 of the above may be recalled the fact that large necrotic areas show 

 autolysis first in the center, where the alkaline, antagonistic body 

 fluids presumably cause the least effect. Furthermore, it has been 

 found by Wells^ that the histological changes of autolysis proceed 

 much faster in tissues placed in serum that has been heated to destroy 

 the antibodies than in unheated serum. Leucocytes, as Opie has 

 shown, contain autolytic enzymes acting best in an alkaline medium, 

 hence they perform their digestive function readily at the periphery 

 of necrotic areas, and coagulated tissue proteins, when acted upon by 

 body fluids, produce chemotactic substances which attract leucocytes 

 to dead areas. ^° 



When a cell dies, certain physical changes occur that are probably 

 of considerable importance. Bechhold says: "With the occurrence 

 of death, protoplasm gelatinizes, Brownian movement of the smaller 

 particles ceases, and the structure of the gel appears in the ultramicro- 

 scope as a conglomeration of many reflecting platelets. It makes a 

 substantial difference whether the protoplasm slowly dies or is suddenly 

 killed by a fixative (alcohol, formalin, etc.). In the first instance 

 there is a precipitation (flocculation), whereas, in the latter there is 

 a stiffening; this difference may be readily recognized under the 

 ultramicroscope." 



The permeability of the cell wall is almost immediately increased, 

 so that all diffusible substances readily pass through, i. e., its semi- 

 permeable character is lost. This we see particularly in plant cells, 

 which lose their turgor with their semipermeability, and therefore 

 the plant wilts. The cell structure is also disintegrated, and as a 

 result coordination of the cell chemistry is at once destroyed. ^^ In- 

 tracellular enzymes escape into the blood from areas of local death of 

 cells, ^2 or as an agonal manifestation in general death. ^^ Various 



* Literature and more complete discussion under "Autolysis." 

 9 Jour. Med. Research, 190G (15), 149. 

 10 Burger and Dold, Zeit. Immunitiit., 1914 (21), 378. 



" See V. Prowazek, Biol. Centrbl., 1909 (29), 291. Pictet suggests that in 

 dead proteins, aldehydes and amino radicals unite with one another to form cyclic 

 compounds (Arch. sci. phys. nat., 1915 (40), 181). 



12 Mandelbaum, Munch, med. Woch., 1914 (()1), 461. 



13 Schultz, Miinch. med. Woch., 1913 (GO), 2512. 



