SQUIERELS 65 



that the shamming death of certain species of the 

 Articulata, when threatened by danger, was due to 

 cataplexy. The condition was attended in certain 

 animals by stupor, violent tremblings of the (x- 

 tremities, and other pronounced disturbances of function 

 and psychic state. This writer then explained the con- 

 dition, called by some " shamming death," by a sudden, 

 powerful, unexpected, and unusual stimulus acting on 

 the centripetal nerves, producing an emotion of fear 

 which acts on the will, inhibiting it and producing 

 stupor; "deathly terror," in a word, is the condition, 

 and not feigning, according to Preyer. 



The well-known physiologist, Heidenhain, performed 

 many experiments, chiefly on the human subject, with 

 a view of arriving at a physiological solution of these 

 remarkable phenomena. He has framed the theory, 

 that hypnotism is due to the inhibition of the cortical 

 cells of the cerebrum, caused by the gentle prolonged 

 stimulation of the nerves of the face, eyes, or ears. 



Dr Clarke, in the Popular Science Monthly (vol. ix.), 

 discusses the results of Czermak and others, and con- 

 cludes that "they depend wholly and only on fear," 

 for he maintains that the experiments succeed best in 

 the wilder individuals of the species. But Dr Clarke 

 is scarcely consistent, for he points out in the same 

 paper that animals cease to struggle because they find 

 it useless, and this he ascribes to intelligence. 



Dr D. W. Prentiss, in the American Naturalist (vol. 

 xvi.), examines the matter from the physician's point 

 of view. After referring to the " dancing," " convulsive," 

 and " laughing " manias, and to certain phenomena in 

 animals like those already described, he concludes that 

 the factors entering into the phenomena of Czermak 

 and others are fear, dissembling, curiosity, training, 

 changes in the condition of the blood (deficiency of 

 oxygen from restrained chest movements), and imitation. 



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