150 PSYCIIOLOOY. 



ness, following the degrees of complication and aggrega- 

 tion of the primordial mind-dust. To prove the separate 

 existence of these degrees of consciousness by indirect evi- 

 dence, since elirect intuition of them is not to be had, be- 

 comes therefore the first duty of psychological evolutionism. 



SOME ALLEGED PROOFS THAT MIND-DUST EXISTS. 



Some of this duty we find already performed by a num- 

 ber of philosophers who, though not interested at all in 

 evolution, have nevertheless on independent grounds con- 

 vinced themselves of the existence of a vast amount of 

 sub-conscious mental life. The criticism of this general 

 opinion and its grounds will have to be postponed for a 

 while. At present let us merely deal with the arguments 

 assumed to prove aggregation of bits of mind-stuff into 

 distinctly sensible feelings. They are clear and admit of a 

 clear reply. 



The German physiologist A. Fick, in 1862, was, so far 

 as I know, the first to use them. He made exj^eriments on 

 the discrimination of the feelings of Avarmth and of touch, 

 when only a \evj small portion of the skin was excited 

 through a hole in a card, the surrounding parts being pro- 

 tected by the card. He found that under these circum- 

 stances mistakes were frequently made by the patient,* 

 and concluded that this must be because the number of 



* His own words are: " Mistakes are made in the sense that he admits 

 having been touched, when in reality it was radiant heat that affected his 

 skin. In our own before-mentioned experiments there was never any de- 

 ception on the entire palmar side of the hand or on the face. On the back 

 of the hand in one case in a series of 60 stimulations 4 mistakes occurred, 

 in another case 2 mistakes in 45 stimulations. On the exton.sor side of the 

 upper arm 3 deceptions out of 48 stimulations were noticed, and in the case 

 of another individual, 1 out of 31. In one case over the spine 3 deceptions 

 in a series of 11 excitations were observed ; in another, 4 out of 19. On 

 the lumbar spine 6 deceptions came among 29 stimulations, and again 4 

 out of 7. There is certainly not yet enough material on which to rest a 

 calculation of probabilities, but any one can ea.sily convince himself that 

 on the back there is no question of even a moderately accurate discrimina- 

 tion between warmth and a light pressure so far as but small portions of 

 skin come into play. It has been as yet impossible to make corresponding 

 experiments with regard to sensibility to cold." (Lehrb. d. Anat u, 

 Physiol, d. Sinnesorgane (1862), p. 29.) 



