INSTITUTO OSWALDO CRUZ 
CAIXA POSTAL 926 
BRASIL — RIO DE JANEIRO 
Rio de Janeiro, April 1935* 
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i4 ad a m e-^t^pe-&a: ^ -& Ht ry---t>tejabeg&--0#--tlt^ -T^Ofaefi’-'S- ■ Giiibr^“ant±"<^^ :- 
I±‘ someone were to ask you tills question offliandj- 
**V/hat is one of the most characteristic sounds of Brasilj one which 
vifould probably attract the notice of a foreigner visiting the tropics 
for the first time?'*what would you say ? Perhaps you would hasten 
to mention the ringing of the church bells all over Brazil of a 
Sunday morning. Or perhaps the jingling of the donkey- harness , or 
the clatter of wooden shoes on hard cobblestones might seem more 
expressive of the busy activities of urban existence. But if you 
go away from these things out into the countryj whethei* to the. 
mount8.inous uplands or to the costal regions borderir^ the Ocean, you 
v/ill hear the true voice of Brazil - the chorus of singing frogs. - 
Your train nay pass for a little distance on an 
elevated trestle near a marsh, and even above the roar of the 
driving wheels 2 ^ou caui distinguish a volume of sound that seems 
to come from all parts of the marsh at once, - a rather rhythraic 
harmony that corresx^onds almost to measures in r.iUsic interspersed 
here and there by a shriller or a deeper note, as if the 
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.ngers 
had reached a climax of enthusiasm in their eternal chant. You may 
never have seen a frog singii:ig, and you ask me how he does it. iiie 
whole performance is most amusirg even to the usual spectator and 
becomes of absoi*bing interest to the scientific investigator, for 
the, ^ voices' of different species of frogs are characteristic, and 
it is often by hearing a strange voice among the chorus that a 
collector of frogs is able to secure a ”new'’species - that is, 
a kind not previously/ knovm to science, - ’which is one of the fond 
dreaus of every/ collector's heart. Ihe frog singer may be. sitting 
on a little tussock of grass at the boi’der of ttie marsh, or he may 
be clinging to the stem of a waterpbnt some distance from tj,ie 
ground. At any^ rate, let us suppose that we have got one in view. 
You will notice that when the call is made 
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apxDears momentarily on the 'throat, and that when the call ceases, 
the bubble contracts into a little knot of wrinkled skin, .hen a 
frog calls, 'the mouth and nostrils are ker^t tightly closed and the 
air is di’iven back and forth between lungs and mouth. Usually one 
or tvifo slits are yoresent on the floor of the mouth, and the air 
escay^ing through them is caught in a pocket of the subhyoid or 
adjacent muscles which it dile.tes, into one or more balloon, like 
resonating organs, nhe sacs are continuations of the lining of the 
mouth- cavity covered by more or less thinned sheets of muscles & 
skin. Now as to the actual sounds made by frogs end toads, opinions 
may/ differ as to 'their musical quality. Some are certainly/ not 
music, but noise in its truest sense. Some frogs utter e x.’laintive 
whiningery which is most irrita.ting and nerve -v/rac king to a huiaan 
listener after endurir-g it for a short time. Other species pii')e, 
whistle, or chirrup'' as one does to encourage a horse. One species 
gives a cry which sounds exactly like that of a small baby, and 
it is this sound heai*d at night in out - of-the“.,'ay x)laces which 
has given rise locs.lly/ in many yo laces to a suycerstition thafo the 
ghost of an unba.pt i zed ba. by/ haunts 'the spot in ¥/hich it was buried. 
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Typ. do Instituto Oswaldo Crii2 
