PAPERS ON ZOOLOGY AND PHYSIOLOGY 335 
in the oxidative processes of skeletal muscles and fat during 
starvation the check on the autolyzing enzymes is removed and 
they are thus left free to digest these tissues. 
Conradi (3), Rettger (4), and Effront (5) showed that 
when bacteria and yeasts were starved by being placed in a 
physiological salt solution, where there was no food, they were 
autolyzed. The explanation usually offered this bacterial auto- 
lysis is that ‘‘the normal existing autolytic processes are not 
counteracted by synthesis of new protein material.’’ A more 
plausible explanation would seem to be that by starvation the 
oxidative processes are decreased, thus removing the normal 
check on the autolytic enzymes, with resulting digestion of the 
cells. 
Neuberg (6) found that when cancer tissue was exposed to 
radium rays the rate of autolysis of this tissue was 
greatly increased. He also found that the autolyzing en- 
zymes of this tissue were not destroyed as were the 
oxidizing and other enzymes by the exposure. On the 
basis of these experiments it is assumed that the great 
increase observed in the activity of the autolyzing en- 
zymes in the cancer tissue when exposed to radium rays was 
made possible by the decrease in oxidation in this tissue which 
in turn was due to the destruction of the oxidizing enzymes 
by the rays, thus leaving the autolyzing enzymes free to digest 
the cancer tissue. 
It has been shown that the resistance to the digestive action 
of trypsin of unicellular organisms, paramecia, living in a so- 
lution of this enzyme can be decreased by decreasing the oxi- 
dative processes so that these organisms are literally digested 
alive and that they are revived provided digestion has not pro- 
ceeded too far, when normal oxidation is restored (7). From 
these and similar experiments (8) the authors conclude that 
the means by which living cells protect themselves from being 
digested by intracellular as well as extracellular enzymes is 
oxidation, 
CONCLUSIONS 
From the evidence presented in this paper the conclusion is 
drawn that the catalase content of the heart, which is not 
autolyzed during starvation, remains normally high while the 
catalase content of the fat and skeletal muscles, which are auto- 
