82 THEORETICAL BIOLOGY 



of the surrounding-world, but which, on the other hand, 

 reproduces spatially the distribution of the circles of their 

 indications. In the eye are assembled all the nervous elements 

 that are directed on the colour-indications of the surrounding- 

 world. The same holds good for the ear, as regards the 

 indications of sound. In the mouth lie the receptors for taste, 

 and in the nose those for smell. 



As a rule people try to explain this remarkable anatomical 

 separation of the quality-circles within the body by pointing 

 to the uniformity of the method in which the related properties 

 act in the surrounding-world. The etheric vibrations require 

 specific transformers if they are to be converted into nervous 

 excitation ; so do the air-waves. The same may be said 

 of the substances soluble in water that yield the taste stimuli ; 

 and the stimuli of the sense of smell are conveyed by air- 

 currents. 



But this explanation will not hold for aquatic animals. 

 Here the stimuli of smell as well as of taste are delivered by 

 substances dissolved in water. And nevertheless, fishes, like 

 other vertebrates, have their olfactory and gustatory organs 

 quite distinct from one another. 



For the anatomical separation of the receptive organs 

 into quite distinct unities, the chemical or physical connec- 

 tion with the surrounding-world cannot be held responsible. 

 What are responsible are the attention-forms of the mark- 

 signs, of which they are the spatial images. And thus the 

 representations we draw in space of the quality-circles acquire 

 increased significance. When we study the sense-organs of 

 animals, we see Nature herself at work, and in the very act 

 of reproducing in extensive forms the laws of intensive 

 magnitudes. 



This makes our research very much easier, for, in inves- 

 tigating animals, we can never hope to attain to a know- 

 ledge of their sensations. All we can determine by experiment 



