12 18 BULLETIN OF THE BUREAU OF FISHERIES. 



they reassumed their equihbrium. This was persistently retained up to about 

 the time of death, except when their eyes were temporarily covered. With the 

 blinders on, they invariably swam irregularly. All 9 fishes after the operation 

 were noticeably weaker in their responses than before it. Most of these fishes 

 lived only a few days and only one lived for as long as five days after the opera- 

 tion. 



These observations show that the utriculus and the semicircular canals of the 

 squeteague are not essential for the responses of these animals to sounds. They 

 show also that though these organs are concerned with equilibrium, they share 

 this function with the eye, for it is only after both sets of sense organs have 

 been rendered ineffective that permanent disturbances in equilibrium occur. 



There is, however, no reason to assume that in this relation the utriculus and 

 its canals stand second to the eye. They are certainly of prime importance as 

 sense organs in which impulses originate for the reflexes of equilibrium. In this 

 respect my results fully confirm those of Loeb (1891a, 1891b), Ewald (1891, 

 1907), Kreidl (1892), Lee (1892, 1893, 1894, 1S98), Bethe (1894, 1899), Gaglio 

 (1902), Quix (1903), and Frohlich (1904b) on various fishes. They also agree 

 with those of Tomaszewicz (1877), Kiesselbach (1882), Sewell (1884), and 

 Steiner (1886, 1888) in that they make evident that the destruction of the 

 utriculus and the semicircular canals is not necessarily followed by permanent 

 disturbances in equilibrium. Had these investigators, however, taken steps 

 to eliminate the influence of the eyes of the fishes on which they worked, it is 

 probable that they would have found these animals incapable of retaining their 

 equilibrium. I therefore can not agree with their conclusion, briefly put by 

 Ayers (1892), that the ear has nothing to do with equilibrium. The utriculus 

 and the semicircular canals of the squeteague are one or both certainly concerned 

 with this function, and this conclusion probably holds good for other fishes, but 

 whether the sense organs involved are the crista; acusticse of the semcircular 

 canals or the macula acustica recessus utriculi with its otolith, or both, I can not 

 say. These parts are also concerned with muscular tonus, as is seen by the 

 weakness of the fish after their destruction, a condition already observed by Ewald 

 (1891, p. 5; 1907, p. 191) for Anguilla and by Bethe (1894, p. 575) ior Perca 

 and Sardinius. 



SACCULAR ORGAN. 



The sacculus and lagena each contain sensory patches, i. e., on the 

 median face of the sacculus is the very large macula acustica sacculi, and on 

 the corresponding side of the lagena the much smaller papilla acustica lagenae. 

 The sacculus, as already mentioned, contains a very large otolith, the sagitta, 

 which rests on the macula acustica sacculi, and the lagena contains a much 

 smaller one, the asteriscus, which covers the papilla acustica lagenae. For 



