434 Dynamic Theory. 



tains the papillae. The frog has them for a short time only in the spring 

 in his swollen thumb. (See page 124.) In birds they are in the toes, 

 or the web if they be web-footed. In the cat, &c. , they are at the roots 

 of the whiskers. In the mole they are on the tip of the snout ; and in 

 the elephant and tapir, on the trunk. In monkeys they are in the 

 hands and sometimes the tail. They are by no means all over the human 

 body, and many papillae are destitute of nerves, as are even some of 

 those in the palm of the hand. 



CHAPTER XL VI. 



SIGHT, AND THE EYE, 



In tracing the comparative anatomy of the eye, we find that the first 

 visible sign of such an organ in the lowest of animal life is a pigment 

 spot, which is in direct contact with a nerve, and forms through it a 

 connection with other nerves which control the action of some muscle 

 or motor organ. 



An undifferentiated skin, if such a thing were possible, when subject 

 to the impact of various tones of energy, is brought into various de- 

 grees of harmony with them. The tones .of the impacts on all bodies 

 are in great variety, consisting of all the rates of vibration, from the 

 very first octave which gives the sensation of sound, up to the fort} r - 

 fourth, which gives the sensation of light. It is quite certain that the 

 constitution of protoplasm is such that some of the tones in every oc- 

 tave are competent to set its molecules or molecular spaces into vibrar 

 tion. If a body having a certain fundamental pitch be agitated by a 

 force tuned in" unison, it will be set to vibrating in tune; but if the agi- 

 tating force be not in unison, it will simply cause a jar or shock in the 

 receiving body, and not a rhythmical vibration. The first nine octaves 

 have found elements in organic protoplasm that can be vibrated in uni- 

 son with most of the tones in those octaves in the production of sound. 

 But it would seem that the tones of vibration from the 10th to the 43d, 

 inclusive, have not yet been able to set up rhythmic vibrations in an ani- 

 mal bod}'. They fall upon it in a promiscuous and helter skelter fash- 

 ion, interfering, no doubt, with each other, and producing in the ani- 

 mal an undifferentiated sensation of heat. If some certain predominant 

 or specially suited tone of one of these octaves, could have its way with 

 the animal body without interference from other tones, there is no rea- 

 son to doubt that the part of the body subject to the impact of such 

 tone would become differentiated to respond to it .rhythmically, and thus 

 a new sense be created. If one big dog trots across a light truss 

 bridge, he will throw it into a vibration in tune with the movement of 



