678 THE AMERICAN NATURALIST [Vol. XLI 



frogs gave no motor reaction to various sounds, their response to 

 tactile stimuli accompanied by these sounds was greater than to 

 the tactile stimuli alone. He concludes that sounds varying in 

 pitch from those of 50 to 10,000 vibrations affect the frog. In 

 nature, " the sense of hearing apparently serves rather as a warning 

 sense which modifies reactions to other simultaneous or succeeding 

 stimuli than as a control for definite auditory motor reactions." 

 In the spring months he found that sounds had a marked influence 

 upon both males and females, but during the winter there was "a 

 much diminished sensltiv(Mioss to auditory stimuli in both sexes, 

 but especially in the inalc." 



The description of Dr. ^■(M•k(■.^' exi.crinicnfs uiveii l.y Trofessor 

 Kirkpatrick, at Cliicauo I nivci'sity, orcatiy intcrolcd ilic writer. 

 Having once kept a fro.u' d.ronuh ilie winter and often succeeded 

 in making him croak by iiniialini!; his call, it scorned {)rol)able that 

 motor responses followiMl ceriain soiuids. On July 1st 1 had an 

 opportunity of testing the re.pon.e of toads to the mating call. 



In the course of a ^^ail. ah.n- the ^hore of Lake Michigan, we 

 camctoashallou pool in ilu-sand just behind a l.reaku a(er. The 

 y)0()l was tluvv or foin- in<-hes deep, six or (muI,( feet wide, and 

 several hundred feet long. In one part of this w(- foun.l nine pairs 

 of toads, the IVniales lavin- eg-s in Ion- strings upon ih.^ bottom 

 of the pool. Theiv wei'e also two or three unpaired nial.^. d1ic 



'J^he fenndes uere of o,,,,! si/,., their sides bein- pulled out ^^ith 

 eggs. ()„ the s.n.l ilun uer" too hea^^ to hop, and m, ualked on 

 all fours like a dog. One female ha.l been sei/ed by two males. 

 AVe separated her from both, and plaee<I them about ten feet apart. 

 One of the tnales .non uttered a shrill, trilling note.— a penetrating 

 .sotmd that was uell .ustain<-d for WUvvu or twenty seconds. In 



i.sland in the iniddle of the pool' and the inah>s into tlu- water about 

 ten feet away. In four or live mimites they were all mated in 



