418 NATURAL SCIENCE [December 
assume all manner of different appearances by appropriate previ- 
ous manipulation, so that the attitude can be of a most bizarre 
kind. During the continuance of the immobile state the organs 
of sensation, peripheral and central, show no evidence of any alter- 
ation, and the animal thus appears to be conscious of the various 
sensations produced by external impressions, but if these are suffi- 
ciently intense to evoke an efferent discharge from the cerebral 
hemispheres, the state at once ends and recovery takes place. This 
recovery is shown to be ushered in by augmented contractions of those 
muscular groups which are in the state of more pronounced contrac- 
ture; at first these are ineffectual to alter the position of the whole 
body, but with their repetition the contracture subsides and the alter- 
ation is effected. The author has not been able to confirm Danil- 
ewsky’s observation that during the state reflex excitability is lowered ; 
he regards the previous evidence of such lowering as due to the 
peculiar condition of the muscles, which owing to contracture are 
incapable of adequate response to central nervous discharge. Lowered 
reflex excitability only occurs when an animal has been manipulated 
many times in rapid succession, in which case central fatigue mani- 
fests itself and the contracture is correspondingly diminished. It will 
be seen from the foregoing description that the characteristic condition 
of the muscles, 7.e. tonicity, disproves the existence of any inhibition 
of lower neuro-muscular mechanisms during the state; on the con- 
trary, the lower centres—cerebellum, medulla, &c., being released from 
cerebral control, now discharge a continuous stream of nervous im- 
pulses such as occurs in the decerebrate mammal, and this produces 
the marked decerebrate rigidity described by Sherrington, Horsley, 
and others. 
With regard to the second factor in the production of the state, it 
is shown that the cessation of the discharge of impulses from the 
cerebral cortex is a complete one. Such complete cessation must 
exist when the cerebral hemispheres have been previously removed ; 
in such animals the immobile state can be produced with great ease, 
and is always of a most prolonged type, whilst the stimulating agencies 
necessary to produce recovery, have to be of an intense character. In 
the intact animal the author considers that the sudden cessation of 
cerebral discharge cannot be explained as due to the lack of stimu- 
lation of the motor areas existing in the cerebral cortex since the 
physiological avenues for sensation are unaffected. He believes that 
the paralysis of these centres is brought about by a sudden inhibition 
due to the activity of special parts of the nervous system or to special 
conditions of the centres themselves. His conception of such condi- 
tions is set forth at some length in the concluding chapters of the 
work, and is framed upon the lines of Hering’s well-known views of 
the physiological states of activity and repose. 
The whole work affords most striking instances of the opposite 
roles to be assigned to cerebral and to lower centres respectively, 
hence, its perusal may be confidently recommended to all those whose 
special interests lie in physiology or neurology. But apart from the 
obvious scientific value of the book, the earlier chapters contain a de- 
scription of phenomena which will enable those interested in hypnotism 
to realise what the so-called hypnotic state of an animal is like, and 
