152 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



position of the eyes and fins can be produced by de- 

 struction of an ear or the acoustic nerve (i). If we 

 destroy in a shark the left auditory nerve or the left 

 side of the medulla, where the auditory nerve enters, 

 the left eye of the animal looks down, the right up. 

 This change of position of both eyes suggests that 

 the relative tension between the muscles that raise 

 the eyes has changed. In the left eye the tension of 

 the lowering muscles predominates over that of their 

 antagonists ; in the right eye the reverse is the case. 

 The fins, likewise, show associated changes of posi- 

 tion. The left fin is raised dorsally, the right is bent 

 ventrally. While it can be said that both eyes are 

 rolled about the longitudinal axis of the animal toward 

 the left, the fins are rolled about the same axis to the 

 right. Although the pectoral fins show the associated 

 changes of position most clearly, these changes also 

 exist in all the remaining fins, only with the difference 

 that the amount of the change of position decreases 

 the farther the segment is removed from the point of 

 operation. The influence of the operation must de- 

 crease as the distance of a ganglion increases. The 

 resistance to the transmission of the change increases 

 with the distance. 



These observations enable us to draw a conclusion 

 concerning the connection of the muscles with the 



o 



right and left halves of the corresponding ganglia. 

 We may assume that a permanent decrease, but not a 

 permanent increase in the tension of the muscles can 

 result from the destruction of one part of the brain. 



