286 The Inter-Relations of the Senses. [May, 
carrion, — warns us, in faCt, by no means to eat it. But the 
tongue, if once we venture on the experiment, pronounces it 
delicious. On the contrary, the nose detects a faint but 
attractive fruit aroma in the infusion of even chamomile, or 
even sometimes in that of gentian, liquids which the tongue 
rejects with abhorrence.* 
The two remaining senses seem at first glance essentially 
distinct and having no relations. True, both take cognizance 
of vibrations, the one relatively slow as the other very rapid. 
But, as a rule, they neither supplement each other, nor does 
an impression made upon the organ of the one call forth 
any reaction in the other. Exceptional cases, however, 
occur, and to these we wish to direCt attention. Certain 
persons, namely, on hearing a given sound, or class of 
sounds, assert that they perceive at the same time or are 
conscious of certain colour-sensations corresponding to and 
varying with the sound heard. 
Two observations must here be made. The only evidence 
we have of the phenomenon in question is the assertion of 
the person under observation. If he merely fancies that he 
experiences colour-sensations in connection with sounds, — 
if the phenomenon is due to some early association, or if 
he is simply amusing himself at our expense, we have no 
means for his detection. 
The second preliminary point is that we have no instance 
on record of a converse association. No one, as far as we 
have been able to trace, on seeing a colour has heard, or 
fancied he heard or experienced any corresponding sound- 
sensation. Sound, it would seem, to some persons at least, 
suggests colour, but colour does not suggest sound. 
The first notice of this subject appeared as far back as 
1873, when Dr. Ntissbaumer contributed to a Vienna 
medical paper an essay on “ The Subjective Sensations 
of Colours Produced by the Objective Impression of the 
Hearing.” The subject has since been studied by Bleuler 
and Lehmann in Germany, by Pedrono and De Roches in 
France, and by Velardi, Berti, Bareggi, Quaglimo, Lussana, 
Grazzi, and Ughetti in Italy. The evidence collected by 
these observers, however, can scarcely be said to agree 
beyond the fundamental point that sounds heard suggest 
or call up the impression of colour. 
M. Pedrono’s subject perceives a different coloured sen- 
sation for each musical note ; but he is unable to define the 
* The toleration of and even liking for bitters is a symptom of decaying 
vigour, individual or racial. 
