No. I.] THE VERTEBRATE EAR. 243 



phenomena in the following manner. This author recognizing 

 the great similarity between the motor disturbances in Pigeons 

 whose heads are fixed in abnormal positions and those whose 

 semicircular canals have been cut, concluded that since when 

 the canals are injured the animal loses control of its head (and 

 body), and since when it is forced to lose control of its head 

 with canals intact it likewise loses control of its body, it was 

 evident that the semicircular canals form an apparatus subserv- 

 ing the equilibrious function, and the cristae acusticae were in 

 reality the equilibrious sense organs of the head and mediately 

 of the body entire. 



Goltz assumed that the sense organs in the ampullae were 

 capable of being stimulated by pressure or other mechanical 

 change similar to the nerves of the skin. The stimulation 

 necessary for perception of spatial relations was supplied by 

 the column of endolymph contained in the canal. Since this 

 fluid would press most strongly on the lower parts of the canals, 

 and since with variation in the position of the head one or other 

 of the three canals would serve as vertical canal or horizontal 

 canal, Goltz thought to have discovered the modus operandi of 

 the canal function. 



Each position of the head would be represented by a specific 

 nerve stimulation from which the animal would be able to judge 

 of its position in space. If, however, the canals were injured, 

 these nerve stimuli, on which the animal depends for regulating 

 its body, are due to injury, and consequently convey false infor- 

 mation ; the co-ordinating apparatus making use of these stimuli 

 induces false movements, or, as we say, co-ordination of move- 

 ment is destroyed, and equilibrium of the body is lost. In 

 1872, Cyon re-examined Goltz's hypothesis and formulated a 

 theory embodying the same ideas, and the same view was ac- 

 cepted on experimental evidence by Mach (1875, 188''), Breuer 

 (1875, 41), Crum Brown (1874, 43''), Spamer, and some few 

 others. About the only difference of views between these later 

 observers and Goltz is the assumption by the former that in the 

 movements of the head currents are set up in the canals whose 

 flow will depend upon the amount and rate of the motions of 

 the head. Thus they sought to establish the so-called dynami- 

 cal theory of the semicircular canals as expressing more of the 

 truth than Goltz's statical theory. This latter theory could only 



