. The biology of the frog . ays little attention to may often be caught by dangling small bits of redyarn before them on a hook. When the yarn is seized, theanimal may be jerked out of the water. According toKnauer, frogs and toads have the power of ejecting indigest-ible bodies from the stomach by way of the mouth. Bits ofgrass or moss accidentally swallowed with the food are gottenrid of in this way. Protrusion of the Tongue. — The frog is able to throwout its tongue with remarkable rapidity, but the method by which this feat is ac-complished was, untilrecently, but inade-quately un
. The biology of the frog . ays little attention to may often be caught by dangling small bits of redyarn before them on a hook. When the yarn is seized, theanimal may be jerked out of the water. According toKnauer, frogs and toads have the power of ejecting indigest-ible bodies from the stomach by way of the mouth. Bits ofgrass or moss accidentally swallowed with the food are gottenrid of in this way. Protrusion of the Tongue. — The frog is able to throwout its tongue with remarkable rapidity, but the method by which this feat is ac-complished was, untilrecently, but inade-quately ! and Gaupp 2have found that theprotrusion is broughtabout by the pressureof the lymph in thelarge sublingual lymphsac. This may bereadily shown if we cutoff the upper jaw of the frog and inject air or liquid throughthe mylohyoid muscle, which extends beneath the lymph spaces become filled, and this causes the tongue • ! Hartog, Ann. Nat. Hist., May, (7), 7, 1901. 2 Gaupp, Anat. Am., 19, 1 - FlG. 6.— Figure showing the ton^ifrog in three different positionsWiedersheim.) of the(After ii HABITS AND NATURAL HISTORY OF THE FROG 27 to be raised up and thrown forward. If, says Hartog, we inject with melted cocoa butter colored with car-mine or alkanet, and keep up the pressure until the masssets, we find that it fills an enormous lymph sac between themuscle and the body of the hyoid, extending through themedian intermuscular fissure into the tongue itself, sendingbranches between the fan-shaped ramification of the intrin-sic muscles at the edges of the tongue and into its terminaldilatations. According to Hartog, the contraction of themylohyoid muscle expels the lymph from the subhyoid spaceinto the tongue and thus effects the protrusion of this organ. Locomotion. —The locomotion of the frog is effected byleaping and swimming, and in both of these operations thelong hind legs play the chief part. In the ordinary restingposition the body is in
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