8 BULLETIN 433, U. S. DEPARTMENT OP AGEICULTUEE. 



Plan of investigation.— Yov the purpose of studying the problems 

 outlined above, three distinct lines of investigation w^ere planned, 

 viz, (1) autolysis experiments with fresh beef, (2) cold-storage ex- 

 periments with fresh beef, (3) a study of the factors affecting the 

 length of time that fresh beef can be carried in cold storage. 



The changes which ordinarily take place in fresh beef, and in 

 other meats as well, during cold storage at temperatures above freez- 

 ing, may be due to one or more of three causes, viz, (1) enzyms oc- 

 curring naturally in the meats, (2) bacteria, and (3) chemical and 

 physical agencies. 



The action of the first of these agencies in causing changes in 

 meats during cold storage is probably less well understood than is 

 that of the two others, and seemed to call for special investigation. 



AUTOLYSIS EXPERIMENTS. 



The term autolysis, as applied to animals, is the name given to the 

 post-mortem changes which take place in the tissues or the fluids of 

 the body through the agency of enzyms and in the absence of bacterial 

 action. Under certain abnormal or pathological conditions auto- 

 lysis may occur in the tissues or fluids of living animals. 



The discovery of autolysis is generally accredited to Salkowski 

 (1891), who called the process " autodigestion." Previous investi- 

 gators had noted the phenomenon but had not appreciated its im- 

 portance. Salkowski studied the autolysis of the liver and striated 

 muscular tissue of the dog, using chloroform to prevent bacterial 

 action. Since then a very large number of autolysis experiments 

 have been carried on with practically every organ and tissue in the 

 body. For a resume of the literature on autolysis and intracellular 

 enzyms, the reader is referred to Jacoby (1902), Oswald (1905), and 

 Vernon (1908, 1910). 



ASEPTIC AUTOLYSIS EXPERIMENT WITH BEEF. 



The object of this experiment was to secure a measure of the 

 various changes which, in the absence of bacterial action and under 

 the most favorable conditions, might be caused in the muscular tissue 

 of beef by the action of the enzyms occurring naturally in that tissue. 



METHOD OF PROCEDURE. 



Slaughter. — A fat " high-grade " Shorthorn steer was slaughtered 

 at a local packing house by the usual methods. The operation was 

 carried on with as much cleanliness and dispatch as possible, though 

 it was recognized that it would be impossible to carry on the opera- 

 tion under strictly aseptic conditions. On the completion of slaugh- 



