THE STRUCTURAL CHANGES IN STRIPED MUSCLE DURING CONTRACTION

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Abstract
From an extensive review the author concludes that in essence, contraction is a matter of the equal division of the dark, stainable materials of the Q discs and the movement of the resultant semi-discs in opposite direction against the limiting telophragmata of a sar-comere. Relaxation is the reversal of this process, the halves of respective Q discs returning to their originally bisecting mesophragmata. Thus, 2 limiting membranes (terminal Z and median M), a laterally confining pellicle (sarcostylic membrane) and a dark substance (salts of Q) moving through a colloidal clear substance, are the only essential morphologic elements involved in contraction. How this shuttle-like movement of a dark substance between successive telophragmata effects contraction and relaxation would seem to be the central problem of the physiologist in formulating an adequate explanation of muscle contraction.