MARKET COLD-STORAGE CHICKENS. 81 



EXAMINATION OF FRESH AND COLD-STORAGE CHICKEN MUSCLE. 



The histological structure of fresh chicken muscle, as seen in the 

 Pectoralis major, is shown in Plate VI. The fibers in the fresh muscle 

 have a wavy outline, lie close together in bundles of six to ten, and 

 often are so tightly adherent that their individuality is difficult to 

 trace. The endomysium stains sharply and clings to the bundles. 

 There is no evidence of a structureless, coagulable material between 

 either the bundles or the individual fibers. While the cross markings 

 are visible, they are not especially distinct, and appear as short seg- 

 ments instead of the clear, dark bands which text-book illustrations 

 are apt to show. 



The cross section of the muscle emphasizes the close packing of the 

 fibers and the lack of material between them. 



The examination of the longitudinal section of the breast muscle 

 of chicken No. 84, which had been in storage 14 months, yields a 

 picture varying greatly from that of the fresh tissue. The integrity 

 of the small bundles is very largely obliterated, the individual fibers 

 being pulled apart and in many places separated by wide spaces. 

 Throughout this tissue lying between the bundles there is a markedly 

 granular material, the origin of which can be traced to the muscle 

 fiber itself, and is undoubtedly a product of its degeneration. This 

 material has taken on a stringy, reticulated character, so much so 

 that without careful study it might be confounded with a degen- 

 erated reticular tissue. It is constantly found, however, running 

 back to the fiber itself, the structure of which becomes gradually more 

 distinct until finally the cross markings and general outline of it are 

 unmistakable. 



In the muscle of this tissue there is also a tendency to a longitu- 

 dinal gathering of the fibrils into masses sometimes one-third or one- 

 quarter the size of the original fiber, with a space between the bundles, 

 and the whole still surrounded by the sarcolemma. While the wavi- 

 ness of the normal muscle and the appearance of contractility are 

 entirely lost in these muscles kept in cold storage, there is, however, 

 a tendency to a twisting of the muscle fiber, making " knees/' as they 

 may be designated, along its length and giving it a very irregular 

 appearance. With the longitudinal splitting there is also a marked 

 tendency to a transverse fracture, in many places the fibers being 

 split into short fragments. (Plate VII, fig. 1.) 



The cross section of the muscle illustrates well a number of the 

 points which were observed in the longitudinal section. It shows, for 

 instance, the breaking of the small bundles by many transverse lines, 

 which are probably the indications of the bundles of fibrils before 

 noted. The reticulated structure is seen between the muscle bundles 

 49078— Bull. 115—08 6 



