206 



MUSCULAR CONTRACTION IN TISSUE-CULTURES. 



minute quantities of certain substances, such as acid, alkali, chloroform, nucleic 

 acid, pancreatin, or magnesium sulphate (fig. 6). 



Although the addition of weak acid, etc., to the medium did cause the side 

 wall to bulge out, such swelling was not necessarily accompanied by a coincident 

 shortening of the height of the individual sarcomere. Neither was the shortening 

 and thickening of the entire sarcostyle always accompanied by a protrusion of the 

 wall of the sarcomeres. Either the membrane of Krause or the line of Hensen may 

 become extended to a marked degree. Various degrees of extension of the Krause 

 membrane were shown in the same sarcostyle. When the sarcostyle was placed 

 in certain solutions all cross markings disappeared. The details of these experiments 

 will be published in a separate paper, since they throw no light upon the phenome- 

 non of contraction exhibited by muscular tissue in cultures. 



Exceedingly thin pieces of the skeletal muscle of the cat, dog, chicken, or turtle, 

 cut with sharp scissors along a line parallel to the length of the fibers, were mounted 

 in a drop of warm Locke-Lewis solution. When such preparations were examined 



FIG. 6. Somewhat diagrammatic 

 representations of a few of the 

 many interesting shapes exhibited 

 by the isolated sarcostyles of the 

 house fly. A, normal sarcostyle 



in fly plasma. B, swollen sarco- 



vl"5~- meres in slightly acid Locke's 



"..J^IT" 1 ""* solution. C, isolated membranes 



_T""""""" of Krause floating in Locke's 



solution saturated with magnes- 

 """"""..,17 ' um sulphate. D, fibrillated sarco- 



meres in Locke's solution con- 



^ , E taining nucleic acid. E, extended 



B I P. lines of Hensen in diluted white of 



egg. to which a minute crystal of 

 sodium chloride was added. 



under the microscope in the warm box, contraction waves were found occurring in 

 the individual fibers. The contraction was caused by movement of the substance 

 of a given muscle-fiber rather slowly toward a given region, where it became piled up 

 in an area much broader than the width of the muscle fiber. The cross-striations 

 in this region were nearer together than were those in other parts of the fiber. There 

 was no question of the fact that the material of the fiber moved toward this region, 

 for a granule or a foreign body upon such a flowing fiber finally reached and became 

 included within the broader area. The fiber became stretched out at the end from 

 which the protoplasm was flowing, so that the cross-striations in this region became 

 extended far apart. In some cases, while the movement of the protoplasm was 

 taking place, the direction of the current was suddenly reversed, so that the flow 

 occurred in the opposite direction. This lasted only a very short period of time 

 but caused all sorts of distortion of the cross-striations just at the beginning of the 

 broader region (contracted area). In some cases they were drawn out on either 

 side and presented an appearance such as that shown by Schiifer (1912, fig. 286); 

 in others there resulted a tearing of the region adjacent to the contracted area 

 which caused the formation of a homogeneous one resembling that depicted by 

 Meckel. In a number of cases the distortion appeared to be caused by the uneven 



