Yerkes, The Sense of Hearing in Frogs. 281 



fail to respond after the eighth nerves have been cut. The con- 

 clusions to which Parker was led by his vivisectional experi- 

 ments are clearly and briefly stated in his own words, thus : 



"The skin, lateral-line organs and ears represent, figuratively speaking, three 

 generations of sense organs. The oldest is the skin stimulated by varying press- 

 ures, such as are produced by irregular currents, and capable of initiating equi- 

 libration responses. From the skin have been derived the lateral-line organs 

 stimulated by water vibrations of low rate, and also significant for equilibration. 

 Finally, from the lateral-line organs have come the ears stimulated by water 

 vibrations of a high rate and important for equilibration. The ear, unlike the 

 skin and lateral-line organs, is differentiated for its two functions, the sacculus 

 for hearing, the utriculus for equilibration."^ 



In the literature on the senses and reactions of frogs I have 

 found nothing which contributes importantly to our knowledge 

 of the sense of hearing. Most of the investigations which deal 

 with the ear are concerned with the equilibrational and orienta- 

 tional fimctions of the labyrinth organs and have nothing what- 

 ever to say about hearing. In the natural histories the existence 

 of a well-developed sense of hearing is usually assumed, and 

 numerous instances of what are supposed to be reactions to 

 sound are cited. It is to be noted, however, that none of the 

 observations in these popular works furnishes satisfactory proof 

 of the exclusion of the influence of visual stimuli. Among the 

 few references to frog audition of which I have knowledge the 

 only one which seems worthy of special notice is that of Gaupp 

 in his "Anatomie des Frosches. " Since his few paragraphs 

 sum up the state of our knowledge on the subject, while at the 

 same time furnishing an illustration of the assumption of hear- 

 ing on the basis of analogy, I present the substance of them in 

 free and slightly abbreviated translation. 



"The labyrinth organ has an acoustic and a non-acoustic (static) function^ 

 For these two functions, according to the leading if not generally accepted view, 

 entirely different portions of the organ are in question, and since the non-acoustic 

 is attributed to the three Cristae acusticae ampidlai-iun and the three Alaculae 

 {M. recessiis utrictdi, M. sacculi, M. lagenae) there remain for the acoustic function 

 only the Papilla hasilaris and the Macula neglccta. It is not certain, however, 

 that the non-acoustic organs do not participate in the acoustic function. 



"With regard to the acoustic sense of the frog nothing exact is known.. 



'Abstract of paper read before Section F. of the Amer. Assoc, for the Ad- 

 vancement of Science in Philadelphia, 1904. Science, 21, 265, 1905. 



