Form and Color in Nature. 243 



the surface and thus affecting and exciting the nerves, re- 

 sulted by wholesome stimulation in increasing their sensi- 

 tiveness. So gradually arose a condition which enabled 

 the individual to perceive an object before it, perhaps, as 

 one biologist says, about as we perceive our hand when it is 

 passed between our closed eyes and the light. Such an 

 amount of vision, although seemingly of slight importance, 

 was, we may infer, sufficient foundation for the structural 

 changes which have followed, resulting in the formation of 

 the eye and connecting visual organs, as we know them in 

 the higher animals. 



Please note that it is not the eye it is the brain which 

 sees. The eye, with its connections, its lens and coats and 

 nerves, its rods and cones (which I am sure you would not 

 thank me to attempt to analyze and describe), is a highly 

 developed mechanism, although, says Helmholtz, very im- 

 perfect, whose function is to convey the motions of the 

 ether to the brain, which must interpret them. 



I apprehend that anybody who has not wholly forgotten 

 his skating days can remember times when he has seen a 

 great light " which never was on sea or land," and which 

 was not at all dependent upon the ordinary action of his 

 visual organs. This light was clearly traceable to motion, 

 but to motion anything but ethereal in its character. I 

 will say nothing of many spectacles which we have all of us 

 seen with our eyes closed, both while awake and in " the 

 visions of the night when deep sleep falleth upon men," 

 since these involve other questions. 



How far the senses of smell and hearing may have 

 been developed before organic life passed from the water 

 into the air I am not aware that any one has attempted to 

 investigate, or even to state in the form of speculation. 

 They are foreign to the field allotted to me, and I will only 

 note incidentally one or two points. Sound is a mental 

 impression resulting from wave motion in the air, as light 

 and color are mental impressions resulting from wave mo- 

 tions in the ether. An odor is a mental impression which 

 appears to result from motion produced by fine material 

 particles which impinge upon the proper organ, as taste is a 

 mental impression which appears to result from motion pro- 

 duced by a material substance applied to the palate. 



But sound may be perceived without the intervention 

 of the ear, through which it is ordinarily conveyed, as 

 taste and smell may be perceived without the direct exci- 



