STRIPED MUSCLE OF WASP 19 
tration emphasizes a cardinal point regarding striped muscle 
structure, namely, that, under certain conditions, optically 
different substances or portions of the sarcostyle are stratified 
so that an isotropic disc alternates regularly with an anisotropic 
Fig. 6 Three sarcostyles from the wing muscle of the wasp prepared accord- 
ing to Rollet’s method, and magnified about 2000 diameters (after Schaefer). 
Schaefer interprets A as a contracted fibril, B as a stretched fibril, and C as an 
uncontracted fibril. In C, above, are shown numerous circles which Schaefer 
regards as ‘pores’ through which the lightly staining hyaline substance of the 
J-dise is supposed to pass into the deeply staining ‘sarcous’ substance of the 
Q-dise during contraction. These illustrations are regarded as demonstrating 
the illusion of a reversal of striation during contraction. The writer interprets 
sarcostyle C as at the beginning of contraction (since the H-disc is beginning to 
make its appearance), and its ‘pores’ as fixation artifacts; sarcostyle B he regards 
as the stretched condition of C, not a stretched relaxed sarcostyle, and sarcostyle 
A as one which has become swollen and in consequence artificially but not func- 
tionally contracted (shortened) through the osmotic action of the hypotonic 
formic-acid-water solution employed in the Rollet’s technic. Sarcostyle A ac- 
cordingly can give no evidence regarding a reversal of striation during contraction, 
because it is in an artificially modified relaxed condition. 
