HISTOLOGY OF THE STRIPED MUSCLE-FIBRE. 
375 
Optical Effects produced by the Network. 
Fig. 12 represents a small piece of the network isolated from 
the rest of the fibre, consisting of nine or ten rows of dots and 
the connecting longitudinal bars. There is a single layer only 
of network and dots. This isolated piece seems to be a portion 
of sarcolemma stripped off the fibre, along with the portion of 
network immediately below the sarcolemma, and attached to it 
by each transverse network. 
When exactly focussed (fig. 14, l) each dot appears as a dark 
granule surrounded by a bright halo. The blending of these 
haloes causes a crenated bright transverse band. The effect of 
alternating light and dim bands is thus obtained, the bright 
band being crossed transversely by a row of dots, the dim band 
longitudinally by a series of fine lines. 
On altering the focus (raising •0025 millimetre, about), the 
refractive effects are to a certain extent transposed (fig. 14, u). 
The dots now appear bright, surrounded by a dark border. 
By coalescence the appearance of a narrow bright disc is pro- 
duced, separated from the dim disc at each side by a dark 
crenated line. 
Similar refractive effects and transposition on focussing 
are seen in the discs isolated by transverse splitting of the 
fibre. 
Transposition of the Bands. 
The effect known as “ transposition ” of the bands has been 
noticed by many observers. On raising the objective what was 
previously the bright band appears now darker than the dim 
band. 
This so-called transposition is seen in fibres prepared by the 
gold method, better in fibres prepared with osmic acid ; diag. 6, 
u represents a fibre at the upper focus. The light band in the 
position of Krause’s membrane appears very bright, and is 
bordered by a dark line at the junction of the light and dim 
bands. On focussing about '0025 mm. lower down (with 
Zeiss d obj.) the appearance seen in Lis obtained. The darkest 
VOL. XXV. NEW SEE. 
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