. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Fig. 290. Transverse section of three elementary fibres of the dried pectoral muscle of the Teal, (Querquedula crecca,) treated with weak citric acid, shewing the round refracting particles separated from one ano- ther. The cut edge of the tubular sheath of each fibre is also seen. It is in these sarcous elements that the con- tractile power resides, and, as they are apt to retain after death the varying effects of the con- traction they have undergone during the rigor mortis, it is not easy to give an exact measure- men
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. Fig. 290. Transverse section of three elementary fibres of the dried pectoral muscle of the Teal, (Querquedula crecca,) treated with weak citric acid, shewing the round refracting particles separated from one ano- ther. The cut edge of the tubular sheath of each fibre is also seen. It is in these sarcous elements that the con- tractile power resides, and, as they are apt to retain after death the varying effects of the con- traction they have undergone during the rigor mortis, it is not easy to give an exact measure- ment of their size or shape. An average drawn from very numerous observations shews, how- ever, that they are very nearly alike in these respects in all animals and at all periods of life. Their diameter in the longitudinal direction of the fibre, as indicated by the distance between the transverse lines, is thus shown to be :* No. of Observations. In the Human subject. In Mammalia generally In Birds ............ In Reptiles .......... 700 In 1T'TM 27 15 7 7 2o 8 Their diameter in the opposite direction or that marked by the distance between the long- itudinal lines is less, often by a half, but liable to variety from the cause already spe- cified. In a paper, entitled " On Fibre," read before the Royal Society, on the 16th December and the eth January last,f Dr. Barry describes the fibrilla to be a flat filament rounded at the edges, and deeply grooved along the middle line on both its surfaces. He states that this flat filament consists of two spiral threads placed side by side, wit/i their coils interlacing : that it " is so situated in the fasciculus (ele- mentary fibre) of voluntary muscle, as to pre- sent its edge to the observer;" and that the curves of the spiral thread, then seen, seem to have been the appearance that " suggested the idea of longitudinal bead-like enlargements producing the ; In Dr. Barry's opinion " th
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