BDELLOSTOMA DOMBEYI, LAC. 1 59 



equilibrium when the animal maintains its perfect equipoise 

 without them? If in hii;her forms each canal appreciates 

 movements in its own plane and by definite functional combi- 

 nations of two or more canals is able to mediate all possible 

 rotational movements, what function has the single canal in 

 Myxime, or the two canals in Petromyzon ? Both of these 

 creatures are subject to the same mechanical conditions in their 

 progress through the water that the higher vertebrates are. 

 The fact that thev do not have the canals proves that vertebrates 

 can swim as admirably without this apparatus as with it, and 

 such being the case, what was the physiological incentive 

 which lead to the production of the other canals ? I have 

 elsewhere given a sufficient mechanical explanation of the 

 genesis of the canals, but I have yet to learn of a sufficient 

 physiological one. Who will add to our knowledge in this 

 particular .'' 



It is said that the semi-circular canals in man, for example, 

 are delicate organs whose special function is to take cognizance 

 of all the motions of the body in their respective planes, and 

 that they thus control either singly or by various combinations 

 with the other canals of the opposite side of the body, all 

 possible movements of the body. 



One mav readil}' disprove this assumption by a very simple 

 experiment. Have some person with normal ears and normally 

 developed muscles swim for a distance on his back with closed 

 eyes — first with his hands and arms alone, keeping his legs 

 straight, and second with his feet alone, folding his arms on his 

 breast. The average man is stronger on the right side of his 

 body than on the left, and consequently when he pulls himself 

 through the water with his arms alone — eyes closed — he 

 unconsciously pulls himself to the right and swims in a circle 

 — {Rcitbaliu bcivcgiingcii of Gcnnan physiologists !) When he 

 swims with his feet alone he pushes himself through the water 

 and consequently ])ushes himself over to the left side and 

 swims in a circle in an opposite direction to what he did before 

 {circus i/ioi'ciiiait to the left!) and he is, so long as his eyes 

 remain closed, unconscious of the fact that he is moving to 

 one side i.e., diverging from a straight line — but he becomes 



