THE PERCEPTION OF SPACE. 169 



judged multiple, — e.g., compass-points ou skin or stars on 

 retina, — the ordinary explanation is no doubt just, and we 

 judge the outward causes to be multifile because we have 

 discerned the local feelings of their sensations to be dif- 

 ferent. 



Capacity for partial stimulation is thus the second condi- 

 tion favoring discrimination. A sensitive surface which has to 

 be excited in all its parts at once can yield nothing but a 

 sense of undivided largeness. This appears to be the case 

 with the olfactory, and to all intents and purposes with the 

 gustatory, surfaces. Of many tastes and flavors, even sim- 

 ultaneously presented, each affects the totality of its re- 

 spective organ, each appears with the whole vastness given 

 by that organ, and appears interpenetrated by the rest.* 



* It may, however, be said that eveu in the tongue there is a determina- 

 tion of bitter flavors to the back and of acids to the front edge of the organ. 

 Spices likewise affect its sides and front, and a taste like that of alum 

 localizes itself, by its styptic effect on the portion of mucous membrane, 

 which it immediately touches, more sharply than roast pork, for 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 spatiallj' extended than heavy, 

 suffocating odors, 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, and thus excite an objectively larger surface. The asci* p- 

 tion of height and depth to certain notes seems due, not to any localization 

 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, ac- 

 cording to modern theories, the cochlea may have its separate nerve-termini 

 exclusively excited bj^ sounds of differing pitch, and yet the sounds seem 

 all to till 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 Januarj', 1879, 1 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 every luminous point 

 if there were no dioptric apparatus aflixed." And I added : " Notwith- 

 standing the brilliant conjectures of the last few years which assign differ- 

 ent 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 con- 

 fidently reject a theory of hearing which violated the principles advanced in 



