PRACTICAL CARP CULTURE. 79 



to lowness of station. Rank in the organic world can in most cases be es- 

 timated by structure. 



Applying this principle to the case in question let us examine the or- 

 gans of the fish and see what light they throw upon the problem. 



It will, however, be well before doing so, to pause and give a short ac- 

 count of the structure of the human ear, in order that what is to follow 

 may be more easily understood. 



The ear in its highest development consists of three parts the outer, 

 middle and inner ear. These rise in importance from the first to the last. 

 The outer ear consists of the "ear" so-called, or "concha," of the anato- 

 mist, (seen on the outside of the head), and of the blind tube leading in- 

 ward from it. These serve to catch the waves of sound in the surrounding 

 medium and conduct them to the machinery situated within. Their use 

 and importance, it may be therefore said, are strictly subsidiary and their 

 absence but slightly affects the action of the organ and in no way abol- 

 ishes the sense. 



It may be well to mention that by the sense of hearing will here be 

 meant that communication between the conscious centre and the outer 

 world which is effected by waves produced in or conducted through a sur- 

 rounding medium, solid, liquid or gaseous. These waves by striking vari- 

 ous parts of the organ awaken nervous movement, is translated by the 

 conscious centre into the sensation which we call sound. 



It will consequently make no difference whether the wave or vibration 

 be transmitted through the air as in ordinary hearing, or through water as 

 when a sound is heard by a diver, as through a solid pipe or rod as along 

 the metals of a railway. All these waves alike reach the sensory organ 

 somewhere and the resulting motion is converted into a nervous impulse. * 



The second "part of the hearing apparatus in man is the middle ear or 

 drum. This contains a membrane stretched tight across the tube above 

 mentioned and closing it altogether. This membrane the drumhead 

 forms the bottom of the tube and receives all the waves that pass down it 

 from the external year. In response to these it vibrates. Attached to the 

 drumhead is a chain of .three small bones through which the vibrations are 

 transmitted onward to their destination. The drum being closed against the 

 entrance of air through the external ear some other communication is ne- 

 cessary to keep the pressure equal on both sides of the drumhead. Pain 

 and injury would otherwise result. This is accomplished by a tube lead- 

 ing from the drum to the mouth. The Eustachian tube which can be heard 



* It is needless to discuss the question whether or not the wave is heard or felt by the 

 fish, because the same quibble might be raised in regard to our own hearing. The ear is 

 only a marvelously delicate and sensitive organ of touch, and whether t^he wave of con- 

 densation reaches it through the air, the water, or thebonesof the head is a matter of little 

 or no importance to our present subject. A blow violent enough to shake theob.iects around 

 us would doubtless be felt by our ordinary sense of touch and perhaps.in addition by our 

 muscular sense, and the same would be true of fish. But no such violent commotion is 

 now iii question, and the slight tremors that we call sound beside differing somewhat in 

 their nature from those that produce shocks an- Car too slight to be appreciated by any or- 

 iian save the refined mechanism of. the inner ear. 



