HISTOLOGY OP THE STRIPED MDSCLE-PIBRE. 
383 
dim band is traversed by a series of longitudinal lines of a 
highly refractile substance. Running across the middle of the 
bright band transversely is seen a single row of dots. The 
fine dark lines crossing the dim stripe are traceable at either 
end into the dots of the bright stripe. In this case, just as in 
the acetic acid preparations, there often appears to be a double 
row of dots in the centre of the bright stripe. Fibres are seen 
side by side, one with a single row, another with a double row 
of dots in this position. When a double row is present, the 
corresponding dots of the two rows appear to be always joined 
longitudinally by fine lines across the middle of the bright 
stripe. This is mentioned by Havcraft 1 but not by Schafer. 
Sometimes again the appearance shown in fig. 20 is observed. 
A series of short parallel longitudinal lines is seen in the 
position of the transverse network. These lines appear dotted 
on careful examination. This appearance is similar to that 
described in the acetic acid preparation (fig. 17), and may be 
explained in the same way as a perspective view of the net- 
work crossed by longitudinal bright lines, caused by refraction 
from the longitudinal rods. “ Transposition ” of the bands 
may be seen on altering the focus, similar to that already 
described. The line of dark dots, with its series of bright 
haloes forming the bright disc, becomes now a line of bright 
dots bordered by two crenated dark lines. The above obser- 
vations on the living fibre were made by means of the gas 
chamber. The chitinous integument of the leg of the bee was 
slit longitudinally, the muscle scooped out, and quickly teased 
on a cover-glass and inverted over the moist gas chamber. 
This method may be used for studying the phenomena of con- 
traction, by blowing air charged with alcohol vapour into the 
chamber, and thus causing the fibre to contract by chemical 
stimulus. 
On contraction the fibre becomes shorter and thicker, the 
transverse rows of dots approach one another and appear 
darker, probably by contrast with the now bright “ dim ” 
disc. These appearances are similar to those seen in the 
1 ‘Quart. Jouru. Micr. Sci.,’ April, 1881, p. 23. 
