LS8 



BIOLOGICAL LECTURES. 



from the skin of the head, but it soon leaves off such attempts, 

 and settles down on the bottom of the aquarium, coiling up in 

 the normal fashion, or else it will continue to swim about the 

 tank for a time. In case only one ear is taken out, the animal 

 may (it does not always do so) swim with the injured side 

 lower than the other, or may even roll as it swims — especially 

 if it is excited to sioi)/i rapidly ; but like others, it will settle 

 to the bottom, and rest normally in its coil, coiling either away 

 from or toward the injured side. I thought I could notice in 

 some cases a tendency to coil away from the injured side ; i.e., 

 the normal side did the work of coiling ; but the case is by no 

 means clear that this coil is done oftener than the other. 



mu.. 



Fig. 14. — The right internal ear of the Hagfish 

 (.Mvx/>:e gliitinosa), seen from the inside or cerebral 

 face. Figure after G. Retzius. The figure represents 

 the ear somewhat enlarged, and does not show the 

 "r shape or e.xact positions of the contained sense- 

 organs. 



ah 



a Anterior ampulla. 



a/' Posterior ampulla. 



c Anterior and posterior canals. 



^'^ ! .\nipullar ends of the same. 

 cp S ^ 



d Ductus endolymphaticus. 



iini Macula utriculi et sacculi. 



;/ Xerve branchlets. 



// Utriculo-sacculus. 



s Sacculus endolymphaticus. 



Now, on the hypothesis that the ear is llie specific organ of 

 the cquilibrative sense, it might be argued that the removal 

 of one ear does not necessarily so jiowerfully affect the equi- 

 librium of the body as to destroy even the control of the 

 injured side ; for the imiii)iu"e(l side is able to take upon itself 

 the functions of the injured oi-gan in part at least. If that 

 were the case, when both ears were removed we should cer- 

 tainly expect to see the animal lose contiol ot its body ; but, 

 as I have alreadv said, the animal is even better off ivith both 

 ears reinored tliaii with one ear removed, Jor all traces of eqiii- 

 librativc disturbance disappear at once on the removal of the 

 second ear. 



How can the semi-circular canal with its two ampullae be 

 the special organ of dynamical equilibrium and the utriculo- 

 sacculus with its sense organs the special organ of statical 



