The laws and mechanics of circulation, with the principle involved in animal movement . the drying of the external ligaments, and theshortening this produces in them causes the valves to revertupon the beveled edges, so that when fully dried the valvesare nearly at right angles. But nothing of the kind ever takesplace when the ligaments are kept moist, as in the livinganimal. So, then, there can be no doubt whatever of theexistence of a dual force in the adductor, or the power to ex-pand and contract under the volition of the animal. And DUALISM DEMONSTRATED. 469 turning from this, again, to t
The laws and mechanics of circulation, with the principle involved in animal movement . the drying of the external ligaments, and theshortening this produces in them causes the valves to revertupon the beveled edges, so that when fully dried the valvesare nearly at right angles. But nothing of the kind ever takesplace when the ligaments are kept moist, as in the livinganimal. So, then, there can be no doubt whatever of theexistence of a dual force in the adductor, or the power to ex-pand and contract under the volition of the animal. And DUALISM DEMONSTRATED. 469 turning from this, again, to the more complex movements inthe higher stages in development—notably, the action in thejaws—and the same circumstance is readily proven on thesemuscles also, the stage in development, for obvious reasons,making no difference in this respect. The Principle in Musculation Applied to the Action in theJaws.—Briefly, the muscles for opening and closing the mouthare the masseter (Fig. 195, 1) and temporalis (Figs. 196, 2,195, 3), and internal pterygoid (Fig. 197), one for each side,. Fig. 194.—Common Scallop (Pecten Jacobcea).—Jones, a, h, Lobes of the mantle ; b, g,branchial laniellse ; I, mouth ; k, lips ; c, adductor muscle ; i, foot ; d, e,f, visceralmass, principally filled with ova ; n, o, convolutions of intestine, seen through thetransparent tegumentary membrane ; m, anal orifice. which expand and contract for the purpose, the principlebeing the same as in the so-called adductor in bivalves;and there are no muscles for opening the mouth by con-tracting for the purpose, barring the small floating musclesin the infra-maxillary region connected with the hyoid boneand tongue for operating these organs in connection withdeglutition, sucking, speech, etc., in deglutition serving toapproximate the base of the tongue against the epiglottis,so as to close the glottis and prevent intrusion in the air-passages, which is the principal function of the genio-hyo-glossus, genio-hy
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