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SOME NEW BOOKS 
THE HYPNOTISING OF ANIMALS 
BEITRAGE ZUR PHYSIOLOGIE DES CENTRALNERVENSYSTEMS I. DIE SOGENANNTE Hyp- 
NOSE DER THIEREN. By Max Verworn. 8vo, pp. iv+92, with 18 text-figures. 
Jena: G. Fischer, 1898. Price M. 2.50. 
PROFESSOR VERWORN is to be congratulated upon the production of 
the above work. The subject-matter is one of very great interest; 
it is set forth im such lucid and agreeable style as to make the book 
excellent reading, whilst the method of treatment adopted by the 
author gives the treatise a high value, and renders it an experimental 
contribution to the physiology of the nervous system based upon 
original lines. This will be made clear by a short sketch of the scope 
and aim of the work. 
The so-called ‘hypnosis’ of animals is a well-known state of 
immobility resembling on superficial examination the condition of 
hypnotic trance which can be produced in man. A dissimilarity 
between the ‘state’ in lower animals and that in the hypnotised 
human subject is however present at the very outset, the means 
of production being different in the two cases. In man those mental 
states which are implied by the term ‘suggestion’ play an important 
part as precursors of the condition ; but in lower animals the essential 
agency is the maintenance of the body by external force in an 
abnormal position. Examples are given in the book of the state 
of immobility into which animals of very different types may fall 
under these conditions. The original part of the work is the demon- 
stration by Professor Verworn that the immobile state in these 
animals has two prominent characteristics which are significant of 
the physiological factors concerned in its production. These are, first 
a special form of activity in the muscles, and, secondly, a peculiar 
condition of inactivity of the cerebral hemispheres. 
With regard to the muscles the author shows that persistent 
reflex tonus is present, and is most marked in such groups of 
muscles as the animal would utilise for regaining its normal posi- 
tion of bodily equilibrium. If, for example, the state has been 
caused in the guinea-pig by keeping it upon its back, then the 
muscles concerned are those the animal employs for turning into 
the customary attitude. When held by force in the abnormal 
position the animal vainly contracts these muscles for this pur- 
pose, and the immobile state commences with the sudden cessation 
of the nervous outflow from the higher centres producing these 
vain efforts; this is immediately succeeded by a set tonus of the mus- 
cular groups especially those involved in the previous efforts. If the 
restraint has been such as to affect one group more than others, 
then the subsequent tonicity or ‘contracture’ is particularly pro- 
minent in this group. The state thus differs from sleep in the 
disposition of the limbs, trunk, head, eyes, &e., which may be made to 
