613 
(Querscheibe or Brücke’s doubly refractive substance), separated by 
bands which stain less deeply. Further it is seen that this clear sub- 
stance or sarcoplasm is not a homogeneous mass, but is divided into 
compartments or discs. These discs are bounded in preparations 
stained with KoLossow’s method by dark surfaces. The peripheries 
of such sarcoplasmic discs, as they may be called, may be in contact 
with one another (Fig. 3 A), while the line of junction of the succes- 
sive discs on one fibril bundle, correspond precisely as the figure shows 
to Krause’s line. At the periphery of the cell one sees the sarco- 
plasmic discs projecting as clear masses beyond the fibril bundles, 
their outlines forming the cell surface. 
In some cases each fibril bundle has a complete set of these 
sarcoplasmic discs, the partitions between them in every case being 
continuous, as has been said, with the Zwischenscheiben of the fibrils; 
while in other instances, two adjacent fibril bundles may have a series 
of discs in common. Where the former condition is present, the sarco- 
plasmic discs of one fibril bundle come in contact with those of other 
fibril bundles in such a way that the Zwischenscheiben do not extend 
in a straight line across the whole cell (Fig. 3). That the sarcoplasmic 
discs are undoubtedly intimately connected with the fibril bundles is 
further shown by the fact that in some places where the discs have 
become broken, the Zwischenscheiben are seen still projecting for a 
short distance from the surface of the fibril bundles (Fig. 3C). The 
fibril bundles are not homogeneous, but show narrow bright longitu- 
dinal markings, indicating a separation into constituent fibrils. 
The most characteristic features, then, to be observed in a longi- 
tudinal section, are the following: 
1) The presence of fibril bundles separated by sarcoplasm. 
2) The division of this sarcoplasm into discs, whose horizontal 
lines of separation correspond with definite transverse striae on the 
fibril bundles. 
3) The occurrence of a double transverse striation on the fibril 
bundles, a broad striation belonging to the fibrils alone (Querscheibe), 
and a narrow line (Zwischenscheibe) which stands in relation to both 
sarcoplasm and fibrils, and is continuous with the flat surfaces of the 
sarcoplasmic discs. 
4) The limiting surface of the cell is formed by the membranes 
of those sarcoplasmic discs, which reach the periphery of the cell body. 
In transverse section the cells vary widely in form, owing to the 
presence of branches which are cut at different angles. The fibril 
bundles occupy the periphery of the cell, while in the centre is 
