The physiology of the circulation in plants : in the lower animals, and in man : being a course of lectures delivered at surgeons' hall to the president, fellows, etc of the Royal college of surgeons of Edinburgh, in the summer of 1872 . ssentially vital in their nature, and independent of each a muscle or fibre or their component particles are endowedwith universality of motion, is apparent from the fact that whena muscle or a muscular fibre shortens, it is thrown into rugse orswellings ; the long axes of the particles of the swelled portionsbeing arranged at right angles to the lo
The physiology of the circulation in plants : in the lower animals, and in man : being a course of lectures delivered at surgeons' hall to the president, fellows, etc of the Royal college of surgeons of Edinburgh, in the summer of 1872 . ssentially vital in their nature, and independent of each a muscle or fibre or their component particles are endowedwith universality of motion, is apparent from the fact that whena muscle or a muscular fibre shortens, it is thrown into rugse orswellings ; the long axes of the particles of the swelled portionsbeing arranged at right angles to the long axes of the particlesrepresenting the constrictions or narrow parts. But those parts ofthe muscle or fibre which form the constrictions the one instantbecome the swellings the next, the direction of the long axes ofthe particles or sarcous elements of the muscle or fibre being inthis case reversed. Muscular movements are therefore the resultof a rhythmic motion in their ultimate particles, in all respectsanalogous to the rhythmic movements of the heart. The move-ments of muscles are characterized by two forces acting at rightangles to each other; the one force flying a fixed point, whilethe other seeks it (Fig. 115). Fig. Fig. 115 shows an element iry fibre of the skate in the uncontracted and contracted state. A.—Fibre in the condition of rest, r, Transverse markings or cleavage. s, Longitudinalmarkings or cleavage. B.—a, a, a, One side of fibre contracting or shortening. C—b, b, b. Both sides of fibre contracting or shortening. All parts of the fibre becomeinvolved in succession. Thus, the constrictions between b, b, b of C become the swellingsc, c of D.—Ajter Bowman. 178 DR J. BELL PETTIGREW ON THE In reality, the ultimate particles or sarcous elements of a muscleare correlated and definitely co-ordinated, neighbouring particles orgroups of particles exercising a centrifugal and centripetal powerwhich causes one set of particles to advance in one direction,
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