174 BONE AS A SYMBOL OF THE BODY. Nothing, however, has so much elevated the physiological dignity of bone as the recent revelations of Neumann and Bizzozero, to the effect that a vast number of the blood corpuscles, the most essential element of this most essential fluid, are developed in the marrow of bone. These observers have discovered in the marrow all the transition forms between the white lymph corpuscles and the red blood corpuscles, so that bone comes to rank with the liver and the spleen as one of the cradles in the rearing of the blood. Bone is often used as a symbol of the whole body. "Flesh of flesh and bone of bone" is the phrase used to express the intimacy of the conjugal union. Was not from a rib in the same symbolic sense developed the whole female body? Schiller says jestingly : "Behandelt die Frauen mit Nachsicht! Aus krummer Rippe war sie erschaffen, (Handle a woman with care! She was made from a crooked rib, God could not make her perfectly straight, If you bend her, she will break.) а But it was reserved for M. Frederic de Rougemont, a distinguished theologian, to solemnly announce satisfactory reason why "God in his infinite wisdom selected the rib in preference to any other bone of Adam's body." He says: "He took no piece of the head-woman would then have had too much intelligence; He took no piece of the legs-woman would then have been too much on the move; He took a piece near the heart, that woman should be all love!" Gretchen sings in her utter desolation: Wer fühlet Wie wühlet Der Schmerz mir im Gebein. (Who feels, how rages, the pain in my bones.) MUSCLE AND ITS PROPERTIES. Agamemnon (Troilus and Cressida) is addressed :- "Thou great commander, nerve and bone of Greece." 175 and when Achilles, later in the same play, wished to express in the death of Hector, the total overthrow of Troy, he exclaims: "Now Troy sink down, Here lies thy heart, thy sinew and thy bone." LECTURE IX. MUSCLE AND ITS PROPERTIES. CONTENTS. Etymology of Muscle-Muscular Motion-Striped and Smooth Muscle -The Color of Muscle-The Anatomy of Voluntary Muscle-The Sarcolemma-The Muscle Fibre-Muscle Protoplasm-General Properties of Muscles-Names of Muscles-Form and Shape of MusclesSmooth Muscle-Disposition of Smooth Muscle-The Chemistry of Muscle-The Reaction of Muscle-Specific Properties of MuscleThe Elasticity of Muscle-The Tonicity of Voluntary MuscleTonicity, a Reflex Phenomenon-Tonicity of Involuntary MuscleThe Sensibility of Muscle-Sensibility and Sensation-The Sensation of Fatigue-The Exercise of the Muscular Sense. Etymology of Muscle. The muscles are the active organs of motion. The word bone (Saxon, ban; Swedish, ben; Danish, been; German, bein), means something set or fixed. The word muscle (Latin, musculus) originates, according to some etymologists, from μvs, a mouse or rat, because the ancients compared the muscles to flayed rats or mice, but is more probably derived from μve to move, motion being the most striking and distinguishing property of this tissue. Brawn, an old English synomim of muscle, expressed the fact that the bulk and 176 MUSCULAR MOTION. strength of the body was expressed or made manifest in its flesh or muscle. Muscular Motion. Though the mere existence of motion can not, as once taught, be accepted as a point of differentiation between animals and plants, because it is a protoplasmic endowment common to both, nevertheless a high degree of it and a ready exhibition of it does distinguish animals high in the scale of development. All visible motion is produced solely by the action of muscles. The complicated movements of the higher forms of animal life require a great number of muscles, properly disposed and adjusted in their arrangement, quickly responsive in their action, and nicely poised, coördinated, and antagonised, in their effect. In man there are, subject to the control of his will, over one thousand muscles, whose mass constitutes half the bulk or volume of the body. Besides these so-called voluntary muscles, this tissue in the form of fibres or layers enters into the composition of nearly all the organs of the body connected with the vegetative life. The digestive, respiratory, circulatory, genitourinary, etc., systems are in part constructed of muscular tissue whose insensible action is involuntary, that is, beyond the control of the will. Striped and Smooth Muscle. The voluntary are readily distinguished from the involuntary muscles under the microscope by the fact that the voluntary muscle fibres are striped while the involuntary are smooth. Yet there are some exceptions to this rule. The muscle-substance of the heart, for instance, is striped, though its action is entirely beyond the control of the will, as is also that of the pharynx, of the rectum and urethra. THE COLOR OF MUSCLE. 177 Wherever promptitude of response and power of contraction is needed the muscular tissue is always striped, whether voluntary or not. In man and the higher vertebrates these two varieties of muscular tissue are distinctly separated, but in the lower vertebrates, and still more markedly in invertebrates, transition forms occur. In the echinodermata (star-fish, seaurchins, etc.), all the fibres are smooth, as also, in the rule, in the molluscs. In the helminths the muscular fibres are almost always smooth, the only instance of striped muscle existing, strange to say, not in the apparatus of locomotion, but in the uterus of the echinorhynbhus nodulosus (Leydig). It should be stated also in this connection that some fibres which were formerly regarded as smooth are now known to be striped. Thus Margo discovered that the closing muscle of the bivalves, hitherto described as unstriped, under high magnification and fine definition, distinctly exhibits very fine striæ or stripes. And that the marked degree of difference formerly attached to the histological division of muscular tissue no longer holds good is evidenced by the fact, reported by Vierordt, that the same organ in different animals has sometimes striped and sometimes smooth fibres to accomplish the same purpose. In the body of man, the heart, whose action is involuntary, is composed of striped muscle, while the accommodation of vision for objects at different distances, a voluntary act, is effected by the unstriped, involuntary, choroid muscle. The Color of Muscle. The deep red color of striped muscle, is partly due to the blood which circulates throughout its substance, in a rectangular network of capillaries, whose distribution is among the finest in the body. The cruel custom prevailed among butchers, formerly more extensively than now, of subjecting young animals, calves, etc., to frequent bleedings before final slaughter in order to render the flesh more tender. The butchers were said to "bleed the animal white" as the muscle thus became much paler in hue, but no abstraction of blood will make muscle absolutely colorless. Even though a muscle be washed free of blood outside of the body, or water be injected into its vessels until it escapes colorless, the muscle substance will still preserve a distinct amber hue, which may be regarded as the intrinsic color of muscle protoplasm. Kölliker observes that the color of muscle is due to the presence of a coloring matter analogous to, but independent of that of the blood, and Fremy has given to this peculiar yellow coloring matter, in the case of the salmon and other fish, the name, salmonic acid. Kühne and Ranvier washed out red muscles with "artificial serum" (a half per cent. solution of common salt) and established the fact that the color of muscle is not due to the presence of blood, but to hæmoglobin. The Anatomy of Voluntary Muscle. Striated muscles, of the size and shape adapted for the special purpose, consist of bundles, fasciculi, aggregated in mass, and enveloped in firm but elastic sheets of connective tissue, which also sends in partitions to surround the smaller bundles within. These smaller bundles, with intervening blood vessels, connective tissue, and fat masses, are distinctly visible on cross section of a muscular mass. In longitudinal separation of the bundles, we finally arrive at the ultimate muscular fibre, with its investing sheet of connective and elastic tissue, the sarcolemma. The Sarcolemma forms both the dura and pia mater of the muscular fibre in that by its density it contains the diffluent muscle |