. The biology of the frog. Frogs. 6o THE BIOLOGY OF THE FROG right position. According to Verworn/ the muscles invoh-ed in the righting movements are in a state of tonic contrac- tion as if these movements were suddenly inhibited. The breathing movements and the heart beats are at first accel- erated, but at a later stage their rate falls below the normal (Heubel), and there is a decreased responsiveness to ex- ternal stimuli. Dif- ferent frogs vary greatly as regards both the ease with which they may be hypnotized, and the duration of the hyp- notic state. In some cases if a frog is sim- ply
. The biology of the frog. Frogs. 6o THE BIOLOGY OF THE FROG right position. According to Verworn/ the muscles invoh-ed in the righting movements are in a state of tonic contrac- tion as if these movements were suddenly inhibited. The breathing movements and the heart beats are at first accel- erated, but at a later stage their rate falls below the normal (Heubel), and there is a decreased responsiveness to ex- ternal stimuli. Dif- ferent frogs vary greatly as regards both the ease with which they may be hypnotized, and the duration of the hyp- notic state. In some cases if a frog is sim- ply placed on its back without being held, it may become hyp- notized after it has righted itself a few times, and lie for a long time in some phase of the pro- cess of turning over. Specimens of Rana esculenta, according to Verworn, when laid on their backs, sometimes quickly draw the hind legs close to the body, close their eyes, and He with their muscles in a state of tonic contraction,— a condition which suggests the death feigning of certain insects. Tonic contractions of different parts of the body may 1 Verworn, " Die sogenannte Hypnose der Thiere," Fig. 7. — Rana temporaria in the so-called hypnotic state. The upper figure shows the position assumed when the back is rubbed with the finger. The same attitude is maintained when the frog is placed on its back, as is shown in the lower figure. (Modified from Verworn.). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Holmes, Samuel J. (Samuel Jackson), 1868-1964. New York Macmillan
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfrogs, bookyear1916
