RELEASE OF CYTOST 49 



structural elements; hence, if such action is unduly 

 prolonged the cell structure becomes disorganized 

 and death ultimately results. This process of self- 

 digestion was first pointed out by Hoppe-Seyler, who 

 noted that the tissues of dead animals underwent lique- 

 faction even though there was no apparent evidence 

 of bacterial action. Some twenty years later Salkow- 

 ski (1890) found the end products resulting from 

 such liquefaction to be nearly identical with the 

 end products produced by the action of pancreatic 

 trypsin on proteins. While today it is known that the 

 intracellular proteases differ in their properties from 

 the intestinal proteases, their actions are nevertheless 

 analogous as first surmised by Salkowski. The essen- 

 tial difference between these two classes of enzymes 

 appears principally in the optimal hydrogen ion con- 

 centration for their activities — the intracellular pro- 

 teases exhibiting their maximal activity in faintly acid 

 media whereas trypsin is inactivated in the presence 

 of acids. 



In 1900 Jacoby observed that when a portion of 

 liver was ligated in situ it underwent changes analo- 

 gous to those previously found by Hofmeister and 

 Salkowski in dead tissues. Jacoby coined the word 

 autolysis to describe the self-digestion of tissues both 

 in vivo and in vitro. It has been pointed out above 

 that starving tissues undergo autolysis. In this con- 

 nection it is worthy of note that Cusa-Bianche states 

 that tissues taken from starving animals and tissues of 

 normal animals which have undergone in vitro autol- 

 ysis present much the same histological picture. 



Analogous conditions are found in unicellular 

 organisms; for Condradi (1903), Rettger (1904) 



