HISTOLOGY OF THE STRIPED MUSCLE- FIBRE. 
373 
Demonstration of an Intracellular Network in the 
striped Muscle-Fibre. 
I. The Muscle-Fibre prepared with Gold Chloride. 
(a) Dvtiscus marginalis. 
Method of Gold Staining. — Decapitate a Dytiscus, open 
the thorax, remove a portion of a leg muscle, and place in 
I per cent, acetic acid for 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 appearances seen 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 “membrane.” 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 lougitudinal 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). 
