HISTOLOGY OP THE STRIPED MUSCLE-FIBRE. 
381 
the sarcolemma at the edges, and appear to divide the fibre into 
compartments. If the near edge of one of these discs be 
focussed it appears as a transverse row of dots crossing the 
fibre, and in many fibres fine longitudinal lines may be seen 
joining the dots of two adjacent discs. 
In some fibres the appearance of a double row of dots 
crossing the fibre in the position of the transverse network is 
seen. This is represented in fig. 16. It is noticed in the pre- 
parations made with acetic acid, that the double rows of dots 
are met with, as a rule, in those fibres which have undergone 
least pressure. In fibres expanded by pressure a single row of 
transverse dots is alone observed. 
Fig. 17 represents a fibre treated with acetic acid and after- 
wards stained in watery solution of logwood. At the upper 
part of the fibre the thin dotted transverse discs are not seen 
edgeways but partially from below. Lower down in the fibre 
the discs are seen more nearly edgeways, and appear in pers- 
pective view as narrow granular bands. These granular bands 
appear crossed longitudinally, and more or less broken up into 
short parallel longitudinal segments, by fine bright lines. These 
bright lines are caused by refraction from the longitudinal 
rods of the network. 
Ill, Osmic Acid Preparations. 
Preparations made by placing living muscles from the bee in 
osmic acid 1 per cent, for ten minutes, and mounting in balsam, 
give on examination the appearances figured in fig. 18 and 
diag. 6. Thickenings (Engelmann’s “ fixed waves of contrac- 
tion'”) are seen on many of the fibres. 
In diag. 6, l the fibre is seen crossed at intervals by a 
dark well-marked line, Krause “ membrane ” or the horizontal 
network. On focussing upwards this line appears as a thin 
bright disc, and the appearance u is obtained. 
In certain fibres (fig. 18), by careful examination, it can be 
seen that this dark line consists of a row of dots, and occa- 
sionally fine longitudinal lines may be seen joining them. 
A fixed wave of contraction is shown in this figure. 
