. Electro-physiology. Electrophysiology. ORGANISATION AND STRUCTURE OF MUSCLE 15 is excessively developed, and produces very complicated figures in transverse section. Certain Polychceta?, in particular, exhibit an extraordinarily complex arrangement of the flat band-like muscle- cells, which are individually of very insignificant proportions. The cross-section of the longitudinal muscle-layer not infrequently acquires a characteristic appearance. The muscle-fibres of Cephalopoda should be mentioned as affording in many respects a remarkable instance of muscle-cells in Invertebrates. Their pec
. Electro-physiology. Electrophysiology. ORGANISATION AND STRUCTURE OF MUSCLE 15 is excessively developed, and produces very complicated figures in transverse section. Certain Polychceta?, in particular, exhibit an extraordinarily complex arrangement of the flat band-like muscle- cells, which are individually of very insignificant proportions. The cross-section of the longitudinal muscle-layer not infrequently acquires a characteristic appearance. The muscle-fibres of Cephalopoda should be mentioned as affording in many respects a remarkable instance of muscle-cells in Invertebrates. Their peculiar structure has recently been investigated by Ballo- witz (10)- With both the high and low power a system of parallel lines appears, running obliquely in opposite directions, and seem- ing with the medium power to cross directly over one another (Fig. 8). The ex- amination of partially destroyed muscle-cells shows this to be the optical expression of fibres which " run in a continuous spiral in the COrteX round the FIG. 7.—Transverse section of body-muscles of Protula „ (Rhode.) medullary substance. The steepness of the spirals varies considerably with the state of contraction. In very flat muscle-cells both systems of striation appear to lie almost in the same plane, giving an appearance of "double oblique striation," first described by Schwalbe (11) for several of the Invertebrates. Schwalbe explained these figures on the assumption that the fibres were composed of rhombic " sarcous elements," while Engelmami (12) at a later period pointed out their fibrillated structure, and maintained " that every fibre with double oblique striation consists of two systems of fibrils in concentric layers parallel to the surface of the fibre, which describe a spiral in opposite directions round its ;. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appea
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