THE HISTOLOGY OF THE STRIPED MUSCLE FIBRE. 227 



from five to fifteen seconds, then into gold chloride solution 1 per cent 

 for forty-five minutes, and leave in formic acid 25 per cent for 

 forty-eight hours in the dark. Tease and mount in glycerine. 



If now examined with a magnifying power of about 700 diam. the 

 appearance shown in figs. 1, 2, 3, 12, 13, and 14 will be seen in certain 

 of the fibres. The method of preparation has a great tendency to 

 soften the fibre, so that it becomes much expanded on compression 

 by the cover-slip ; it also has a great tendency to split the fibre into 

 transverse discs. 



Fig. 1 represents a fibre which has retained its natural size and form. 

 Narrow transverse bands of granular substance, deeply stained with 

 the reduced gold, are seen crossing the fibre, separated by wider bands 

 of lighter substance. These deeply-stained granular bands correspond 

 in position to Krause's "membranes." The usual separation into light 

 and dim discs of about equal thickness is lost by this method of 

 preparation. Traversing the wider unstained discs, and giving the 

 fibre the appearance of longitudinal striation, are seen fine longitudinal 

 lines. 



In fig. 2 is seen a portion of a fibre which has been more flattened 

 out by pressure. In it the deeply-stained, narrow granular band is 

 seen to consist of a transverse row of dots. The longitudinal lines are 

 seen to represent fine rod-like bodies traversing the position usually 

 occupied by the dim stripe, and being continued into the dots at 

 either end. In some fibres a minute thickening of the rod is apparent 

 midway in the position of the so-called "Hensen's disc" (in the middle 

 of the dim stripe). 



This method, as was before stated, has a tendency to split the fibre 

 into transverse discs. These isolated discs are found in many parts of 

 the preparation ; they present the appearances seen in figs. 4 and 5. 

 They are seen plainly in all cases to consist of two parts — (1) a net- 

 work of fine highly refracting lines, stained by the gold, and having 

 thickenings at the nodes ; and (2) an unstained substance lying in the 

 interstices of the network. 



The appearance of this network differs somewhat with the degree of 

 compression of the discs. When much compressed the network appears 

 more open, and the nodal dots less marked. Towards the outside of 

 the fibre the meshes appear more oblong, the network extending 

 mostly in a radial direction. This network evidently corresponds 

 when it is in its transverse position in the fibre with the deeply-stained, 



