522 



SCIENCE, 



[Vol. VIII., No. 200 



subject would then locate the spot where pain was 

 felt in himself, and was correct even to a very 

 narrow and definite limit. It seemed a wild guess 

 to suppose that he formed his judgments from the 

 small portions of the movements of the arms only 

 of the third person, which were visible to him ; 

 and yet further experiment showed, that, if a 

 screen were placed so that he could not see any of 

 the movements of this third person, his ability to 

 locate entirely disappeared. Experiments some- 

 what similar showed that the patient could tell 

 what word the operator was writing, simply by 

 the general movements of the arms of the latter. 



Burgson himself calls attention to these experi- 

 ments more as evidences of what he terms uncon- 

 scious deception on the part of the hypnotized 

 subject, than for other reasons. He calls atten- 

 tion, however, to the necessity of repeating those 

 experiments of the English members of the Society 

 of psychical research which seemed to point to 

 mind-reading pure and simple. The average 

 literary man who handles these latter facts does 

 not seem to be aware of the great objection which 

 holds against them scientifically. Absolutely the 

 only way hitherto known of mental communica- 

 tion is the expression of an idea through physical 

 media, and the retranslation of this back into a 

 mental state. Mind-reading pure and simple does 

 away with the intervening physical medium of 

 expression. It is a fact of a different order from 

 any now known. If it can be shown that what 

 really takes place in these cases is cornea- reading, 

 or some similar occurrence, the facts are re- 

 duced to those of the same order as ordinary mind- 

 reading or muscle-reading, and they admit of a 

 scientific explanation. 



But these experiments also afford, as it seems 

 to me, the most conclusive evidence yet offered of 

 the law laid down by Helmholtz, that the exist- 

 ence of a sensation is always neglected in behalf 

 of the meaning conveyed by it. Here the minute 

 image on the cornea is perceived, not as what it is, 

 but as a series of two or three figures which are defi- 

 nitely and correctly located in their proper spatial 

 position. There is in these experiments no ques- 

 tion of conscious deceit. The subject does not 

 secretly and consciously perceive the image on the 

 cornea, and then pass off the knowledge thus 

 gained as if he had actually seen the figures. He 

 himself is a victim of the deception. He thinks 

 he sees them on the book. His sensations, in 

 short, are mere signs or s\mbols, to which in 

 themselves he pays no attention. He observes 

 only the objective bearing, the information con- 

 veyed. The proof of the theory did not require 

 such a crucial experiment as this, perhaps, and 

 yet it is as striking an evidence as could be desired. 



But it also shows that the interpretation of the 

 sensation is governed by the conceptions already 

 in consciousness, and this affords a valuable con- 

 tribution to the growing theory of apperception. 

 There is an increasing tendency among psycholo- 

 gists to regard all perceptions as judgments passed 

 upon sensations by means of the conceptions pres- 

 ent in the mind at the time of their occurrence. 

 The sensation is interpreted into harmony with 

 these dominant conceptions ; so that we see not 

 merely what is really there to see, but what the 

 mind is adjusted to see, what it can read in out of 

 itself. All hypnotism is one page of evidence to 

 the influence of dominant conceptions, but the | j 

 present instance is typical of the extent to which ■ ' 

 it may be carried. It is to be hoped that some one 

 will carry the experiments further, and particularly 

 see how far unsuspected cornea and muscle read- 

 ing has entered into the as yet unexplained cases 

 of mind-reading, so called. J. D. 



VOLUNTARY AMPUTATION AMONG CRAY- 

 FISH. 



In referring to limb-shedding as a voluntary 

 act among certain crustaceans, Professor Huxley 

 tells us in his 'Crayfish' that "this voluntary 

 amputation is always effected at the same place ; 

 namely, where the limb is slenderest, just beyond 

 the articulation which unites the basal joint with 

 the next. The other limbs also readily part at the 

 joints ; and it is very common to meet with cray- 

 fish which have undergone such mutilation." 

 Quite recently (Sept. 4) M. H. de Varigny, in a 

 very instructive paper which he has published in 

 the lievue scientifique, entitled " L'amputation 

 reflexe des pattes chez les crustaces," presents' us 

 with the results of a long series of experiments of 

 his, undertaken with the view of throwing ad- 

 ditional light upon this subject. M. Varigny 

 studied the phenomenon in quite a variety of 

 species and in several hundred individuals. He 

 claims that in every instance the amputation is 

 voluntary, and is truly an amputation, and not a 

 disarticulation due to the feebleness of the inter- 

 articular membrane of the joint. Much less is 

 the throwing-off of the limb ever due to a 

 fracture. 



Then referring to the previous researches of 

 M. Fredericq, M. Varigny further claims that this 

 act on the part of the crustacean will not only 

 follow a direct blow, but may often be induced 

 through either scratching or bruising the claw, or 

 simply rubbing it, or through the action of the 

 electric current. Moreover, it is found that the 

 amputation is reflex, and depends upon the action 

 of the central nervous system, for when the latter 



