SQUIRRELS 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 ex- 
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. 
Xvl.), 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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