186 w. JAMES :

I should have been willing some years ago to name with- out hesitation a third condition of discrimination saying it would be most developed in that organ which is susceptible of the most various qualities of feeling. The retina is un- questionably such an organ. The colours and shades it perceives are infinitely more numerous than the diversities of skin-sensation. And it can feel at once white and black, whilst the ear can in nowise so feel sound and silence. But the late researches of Donaldson and Hall, 1 Blix and Gold- scheider, on specific points for heat, cold, pressure and pain in the skin ; the older ones of Czermak (repeated later in "Wundt's laboratory), showing that a hot and a cold compass- point are no more easily discriminated as two than two of equal temperature ; and some unpublished experiments of my own all disincline me to make much of this condition example, which stimulates all parts alike. The pork, therefore, tastes more spacious than the alum or the pepper. In the nose, too, certain smells, of which vinegar may be taken as the type, seem less spatially extended than heavy, suffocating odours, like musk. The reason of this appears to be that the former inhibit inspiration by their sharpness, whilst the latter are drawn into the lungs, arid thus excite an objectively larger surface. The ascription of height and depth to certain notes seems due, not to any localisation of the sounds, but to the fact that a feeling of vibration in the chest and tension in the gullet accompanies the singing of a bass note, whilst, when we sing high, the palatine mucous membrane is drawn upon by the muscles which move the larynx, and awakens a feeling in the roof of the mouth. The only real objection to the law of partial stimulation laid down in the text is one that might be drawn from the organ of hearing ; for, according to modern theories, the cochlea may have its separate nerve- termini exclusively excited by sounds of differing pitch, and yet the sounds seem all to fill a common space, and not necessarily to be arranged alongside of each other. At most the high note is felt as a thinner, brighter streak against a darker background. In an article on Space, published in the Journal of Speculative Philosophy for January, 1879, I ventured to suggest that possibly the auditory nerve- termini might be " excited all at once by sounds of any pitch, as the whole retina would be by eyery luminous point if there were no dioptric apparatus affixed". And I added : " Notwithstanding the brilliant conjectures of the last few years which assign different acoustic end-organs to different rates of air- wave, we are still greatly in the dark about the subject ; and I, for my part, would much more confidently reject a theory of hearing which violated the principles advanced in this article than give up those prin- ciples for the sake of any hypothesis hitherto published about either organs of Corti or basilar membrane". Professor Rutherford's theory of hearing, advanced at the last meeting of the British Association, already furnishes an alternative view which would make hearing present no exception to the space-theory I defend, and which, whether destined to be proved true or false, ought, at any rate, to make us feel that the Helmholtzian theory is probably not the last word in the physiology of hearing. 1 See MIND x. 399 and 5V7.