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- 



