384 
A vgas persicus 
of the shrinking of the muscular tissue. Each muscle fibre is closely 
invested by an exceedingly thin structureless sarcolemma, immediately 
beneath which elongated nuclei are distributed at more or less wide 
intervals in the superficial sarcoplasma. In the ordinary preparations 
the interior of the muscle fibre generally appears to consist of very fine 
longitudinally arranged parallel fibrils. In transverse section, the whole 
interior of the muscle fibre with the exception of a very thin superficial 
zone is filled with the contractile substance, this being surrounded by a 
matrix of sarcoplasm which fills in the space between the sarcolemma 
and the contractile portion, constituting the thin superficial zone referred 
to above (see Text-fig. 1). 
nc. 
l/100ths mm. 
Fig. 1. Argas persicus S . Transverse section of a muscle fibre (from the retractor 
muscle of the chelicera). Gilson’s fluid; Heidenhain’s iron alum haematoxylin and 
orange G. 
nc. nucleus; s.c. contractile substance (sarcostyles); scl.sh. sarcolemma sheath; 
scpl. sarcoplasm. 
Material fixed in Gilson’s modification of Carnoy’s fluid 1 and stained 
with Heidenhain’s iron alum haematoxylin and orange G. shows the 
finer structure of the muscle fibres iu a most admirable manner. The 
contractile elements of the fibre retain the basic dye much more per¬ 
sistently than the sarcoplasm, and by careful differentiation with the iron 
alum solution, the detailed structure is perfectly displayed. In suitably 
prepared sections, therefore, the contractile substance, being more 
deeply stained than the sarcoplasm, is readily distinguished. It is then 
seen to consist of small elements which, in cross section, appear as more 
or less coherent granules aggregated in clumps, which radiate from the 
central portion of the muscle fibre. Between these radial masses of 
the contractile substance, the sarcoplasmatie matrix penetrates. These 
1 See Lee, A. Bolles, The Microtomist's Vade-Mecum, 5th ed., J. and A. Churchill, 
Loudon, p. 64. 
