32 BULLETIN 433, U. S. DEPAETMENT OF AGRICULTUEE. 



than in the other quarters. This was probably due to irregularities 

 in the storage temperature during this experiment, the temperature 

 rising sufficiently high at times to permit of multiplication of the 

 organism. 



The micrococcus encountered in the carcasses was tested on labora- 

 tory animals and was found to possess no pathogenic properties. The 

 absence of pathogenicity is further borne out by the fact that steaks 

 cut from all of the quarters were eaten by the investigators without 

 any ill effects. 



In addition to the micrococcus described above, a small Gram- 

 positive bacillus was noted in one of the fresh (i. e., chilled) quar- 

 ters. This organism grew chiefly along the line of stab, but was not 

 a strict anaerobe. It also was of no pathogenic significance. 



Histological studies were made by taking bits of muscular tissues 

 at points about 2 inches below the outer surfaces of the rounds. 

 The tissues were hardened in alcohol, embedded in celloidin, and 

 sectioned. The sections were stained with hematoxylin and eosin 

 and examined as to histological structure. 



CONCLUSIONS FROM BACTERIOLOGICAL AND HISTOLOGICAL STUDIES. 



The following conclusions would seem warranted: (1) Certain 

 bacteria (chiefly micrococci) may be normally present in the car- 

 casses of healthy animals slaughtered for beef; (2) these bacteria 

 possess no pathological significance and do not appear to multiply in 

 the cold-stored carcasses, provided the cold-storage room is main- 

 tained at the proper temperature; (3) bacteria and molds grow on 

 the surface of cold-storage carcasses, but do not penetrate to any 

 great depth (less than 1 inch in 177 days) ; (4) bacteria apparently 

 are not concerned in the changes leading to increased tenderness in 

 cold-stored meats; (5) microscopic sections failed to show any 

 noticeable histological changes in the muscular tissue after 77 days 

 of storage. 



CHEMICAL AND PHYSICAL STUDIES. 

 PREPARATION OF MATERIAL. 



Shortly after the beef had been received from the packing house 

 one of the quarters was transferred to cold-storage room No. 2 and 

 was there cut up into several parts, viz, round, loin, rump, and flank, 

 which were then prepared for analysis. 



Round. — Two cross sections, each about 2.5 inches thick, were cut 

 from the round, one at the butt and the other at a place about half 

 way between the butt and the hock joint. These sections were trimmed 

 free of fat, bone, and connective tissue; the resulting lean meat was 

 ground three times through a meat grinder ; and samples were trans- 

 ferred to glass jars which were then tightly stoppered and stored at 

 34° F. until analytical work was begun. 



