66 ANIMAL INTELLIGENCE 
To my own mind all these explanations are partial 
and inadequate. That terror, surprise, etc. are in 
no sense essential for the induction of hypnotism is 
sufficiently evident from Czermak’s experiments on 
pigeons, which could not be put into this condition by 
mere restraint, but only after uniting with this steady 
gazing at a near object. Again, it is well known that 
the human subject can be hypnotised by the latter 
means alone, as Heidenhain first attempted to show. 
The latter’s explanation, though perhaps as good as 
can be given in the existing state of physiological 
knowledge, does not apply evidently in its present form 
to animals in which the cerebrum is not developed, 
as in insects and other invertebrates. The view of 
Dr Prentiss has the merit of breadth, but manifestly 
some of his factors, as training, imitation, etc., cannot 
apply to the hypnotic condition when first experienced, 
at least in the lower animals. 
Notwithstanding the inconsistency in Dr Clarke’s 
article, he is probably quite correct in explaining the 
quiet of animals, when restrained, in many cases by an 
intelligent perception that struggle is useless. I have, 
myself, frequently noticed, when controlling rabbits in 
the laboratory for the purposes of observation, that so 
long as there was no part of the fastenings loose, they 
remained quiet without any attempt at freeing them- 
selves; but, if only a single limb became the least free, 
then a general struggle began. But such an explanation 
will not suffice when a greater or less degree of un- 
consciousness supervenes. 
It may, I think, be said that the phenomena included 
under such terms as hypnotism, cataplexy, etc. are due 
to influences reaching the nervous centres, unusual 
either in quality or intensity, or with an altered relation 
as to frequency of repetition when compared with those 
associated with the ordinary experiences of the animal. 
