HEARING AND ALLIED SENSES IN FISHES. 
63 
These few notes serve to show that different species respond very differently 
to the same forms of stimuli and emphasize the importance of refraining from 
generalizations on the functions of the lateral-line organs and the ears in fishes 
before a considerable number of species have been fully examined. 
SUMMARY. 
1. Normal Fundulus heteroclitus reacts to the sound waves from a tuning-fork 
of 128 vibrations per second by movements of the pectoral fins and by an increase 
in the respiratory rate. It probably also responds to sound waves by caudal-fin 
movements and by general locomotor movements. 
2. Individuals in which the eighth (auditory) nerves have been cut do not respond 
to sound waves from the tuning-fork. 
3. The absence of responses to sound waves in individuals with severed eighth 
nerves is not due to the shock of the operation or to other secondary causes, but to 
the loss of the ear as a sense organ. 
4. Fundulus heteroclitus therefore possesses the sense of hearing. 
5. The ears in this species are also organs of prime importance in equilibration. 
6. Normal Fundulus heteroclitus swims downward from the top of the water 
and remains near the bottom when the aquarium in which it is contained is given a 
slight noiseless motion. 
7. Individuals in which the nerves to the lateral-line organs have been cut will 
swim upward or remain at the top while the aquarium is being gently and noiselessly 
moved. 
8. The lateral-line organs in this species are probably stimulated by a slight 
mass movement of the water against them. They are not stimulated by sound waves 
such as stimulate the ears. 
9. Individuals in which the nerves to the lateral-line organs have been cut swim 
downward and thus escape from regions of surface wave action. They also orient 
perfectly in swimming against a current. Since surface waves and current action 
stimulate fishes in which the nerves to the lateral-line organs and to the ears have 
been cut, these motions must stimulate the general cutaneous nerves (touch). 
10. The vibrations from a bass-viol string when transmitted to water stimulate 
the ears and the lateral- line organs of Fundulus. They also stimulate mackerel and 
menhaden, but not the smooth dog-fish, which responds only when in contact with 
solid portions of an aquarium subjected to vibrations. 
The work recorded on the preceding pages was done at the biological laboratory 
of the United States Fish Commission at Woods Hole, Mass., and I take this oppor- 
tunity of expressing my indebtedness to the Director, Dr. Hugh M. Smith, and 
to his assistants for much help rendered me. I am also under obligations to Prof. 
W. C. Sabine, of Harvard University, for advice and assistance in connection with 
the sound-producing apparatus, and to Prof. F. S. Lee, of Columbia University, for 
friendly criticism and many suggestions. 
