58 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
electrical apparatus, lie found that on pressing lightly upon the vesicles a negative 
variation in the current from the nerve could he detected. As this negative varia- 
tion is evidence of the momentarily active condition of the nerve, it follows that 
pressure differences may he assumed to he a means of stimulating the vesicles of 
Savi. No such results were obtained from the nerves distributed to the ampullae 
of Lorenzini, hut the nerves from the unmodified lateral-line organs in Raja clavata 
and R. asterias showed negative variations when their terminal organs were sub- 
jected to pressure. Dilute acids and changes of temperature were not stimuli for 
any of the terminal organs tested, and Fuchs (1895, p. 474) concluded that pressure 
was the normal stimulus in the skate for the lateral-line organs, and in the torpedo 
for the vesicles of Savi, hut not for the ampulbe of Lorenzini. 
Apparently without knowledge of the work done by Fuchs, Richard ( 1 89G, p. 
131) performed some experiments on the gold-fish. These consisted in the removal 
of the scales from the lateral line and the destruction of the sense organs under 
these scales by cauterizing with heat, silver nitrate, or potassic hydrate. After this 
operation some of the fishes were unable to keep below the surface of the water, and 
though they soon died, Richard (1896, p. 133) believed that lie had evidence enough 
to show that the lateral-line organs were connected with the production of gas in 
the hydrostatic apparatus. 
Richard’s conclusions were called in question by Bonnier (1896, p. 917), who 
pointed out the severity of the operations employed by the former and intimated 
that the results were more probably dependent upon the excessive amount of tissue 
removed than upon the destruction of the lateral line. Bonnier (1896, p. 918) 
further recorded experiments of his own in which the lateral-line organs were 
destroyed by electro-cautery. Fishes thus operated upon showed two character- 
istics — they could easily be approached by the hand and even seized, and they 
failed to orient themselves in reference to disturbances caused by bodies thrown 
into the water. Bonnier concluded from his experiments that the lateral line, in 
addition to other functions, had to do with the orientation of fishes in reference to 
centers in the water from which shock-like vibrations might proceed. 
Lee (1898, p. 139), whose experimental methods were much the same as those 
used by Bonnier, obtained some significant results, particularly with the toad-fish, 
Batrachus tau. When the pectoral and pelvic fins of this fish were removed, so that 
the animal might be said to be without its usual mechanical support, and the lateral- 
line organs wei‘e destroyed by thermo-cautery, the animal would lie quietly for some 
time, either on its side or back, and acted as though it had lost its “sense of equili- 
bration.” That its condition was not due to excessive injury was seen from the fact 
that a Unless fish in which an equal amount of skin had been cauterized, but in 
which the lateral-line organs were intact, showed no lack of equilibration, and in its 
general behavior closely resembled a normal fish. Moreover, stimulation of the 
central end of the lateral-line nerve resulted in perfectly coordinated fin movements, 
and Lee (1898, p. 144) therefore concluded that the organs of the lateral line are 
equilibrating organs. How these are stimulated Lee does not attempt to decide, 
though he suggests (1898, p. 143) that pressure changes in the surrounding medium 
may be the means of stimulation. 
From this brief historical resume it must be evident that thei’e is still very little 
unity of opinion as to the functions of the lateral-line organs. 
