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7 . That other muscles, by their contraction, can alter the 
shape of the organ, and thus modify the quality of the sounds 
emitted. 
What part the internal partition, or “ diaphragm ” (see figs. 3, 
8 , d\ takes in modification of sounds does not seem to be 
clearly established, except that, in the maigres, at any rate, where 
it is fairly developed, it does no more than play a very secondary 
part — “un effet bien accessoire, bien peu important dans 
remission de ces phenomenes acoustiques.” Space unfortunately 
will not permit us to consider the interesting modifications of the 
air-bladder, and the concomitant variations in vocal phenomena 
deducible therefrom, which are met with in the maigre, umbrina, 
the dorees and the dactylopterus; but mention must not be en- 
tirely omitted of the fact that in one of the sea-horses ( Hippo- 
campus brevirostris) the mechanism of the production of sounds 
is reduced to its simplest expression, being merely the vibration 
of voluntary muscles reinforced by an air-bladder having 
neither duct nor diaphragm, nor “ intrinsic ” muscles, both sets 
of organs being no better developed than in fishes which do not 
produce any sound whatever. 
As space further fails us for a proper review of the gamut of 
the piscine orchestra, we must content ourselves with one 
example. We will take the maigres, a description of whose 
musical performance has been already quoted at the beginning 
of this article. The sounds emitted by these fishes are notable 
principally for their length, having a mean of 25 seconds, and 
for their uniformity, 46 qui va jusqu’ a la monotonie la plus fati- 
gante.” The timbre varies very much, the most common 
being that of a common reed-organ or the reed of a flageolet. 
Another pretty fequent timbre resembles that of the largest 
string of a violoncello, sometimes passing to that of the bourdon of 
a contre-basse. Some sounds are, however, less sweet, and may 
have some likeness to the tone of a hurdy-gurdy or rattle, while 
others are clear and pure, resembling in their timbre those pro- 
duced by a hautboy, harmonica, or aceordeon. M. Dufosse would 
limit the range of sounds produced by the maigres, from the most 
acute to the deepest, to three or four tones. They have gene- 
rally a great tendency 64 to degenerate into a humming sound,” 
either from an excess or from a want of intensity. 
It would have been interesting, had the limits of this article 
permitted it, to have considered more fully the phenomena of 
sound just described, from a musical and physical point of 
view ; but as the subject has in these pages been regarded 
rather from a biological stand-point, I would fain leave the 
more mechanical part of it — one fraught with great interest, and 
most fully and ably discussed by M. Dufosse — to the consideration 
