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SOME NEW BOOKS 



The Hypnotising of Animals 



Beitrage zur Physiologie des Centralnervensystems I. Die sogenannte Hyp- 

 NOSE her Thieben. 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 in 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, &c., which may be made to 



