282 Journal of Comparative Neurology and Psychology. 



That it exists, and that in good development, is certain. The existence of the 

 drum and columella, and the fact that frogs have a voice are unmistakable proofs 

 of hearing. The participation of the Papilla basilaris in acoustic functions is 

 rendered certain by comparative anatomical studies : the Papilla basilaris is the 

 nerve end-organ from vi^hich, in the mammalia, the undoubtedly acoustic organ 

 of CoRTi arises. From analogy of structure we may also infer an acoustic func- 

 tion in the Macula neglecta : on this as on the Papilla basilaris, there is a simple 

 tectorial membrane, and further the Pars neglecta, like the Pars basilaris, has a 

 strong thick wall which only in a limited region, namely, where it approaches a 

 part of the perilymphatic space, is markedly thinner. (For fish Breuer (1891) has 

 already stated that if they really hear — which is not proved — the Macula neglecta^ 

 alone can come into consideration in connection with the function for there is no 

 Papilla basilaris in fishes and the six other nerve end-organs apparently serve the 

 non-acoustic function.) 



. "In what way the sound waves come to the Macula neglecta has already been 

 discussed : it is most probable that the movements of the perilymph, which are 

 produced in the Spatium sacculare cave perilymphatici are transmitted to the 

 endolymph of the Succulus and that the waves of the endolymph continue from 

 the last directly to the Pars basilaris and Pars neglecta. The thin walled portions 

 of these two regions would have value as elastic vibratory structures, but they 

 could not serve, as might appear, for the transmission of waves from the peri- 

 lymph to the endolymph. 



"The fact that the vibration of the drum must be transmitted by the plectrum 

 and the Spatium sacculare cave perilymphatici first to the Sacculus deserves con- 

 sideration from the point of view of the assumption of a non-acoustic function of 

 the Sacculus. It must remain a question whether the movements produced in 

 the endolymph of the Sacculus are without effect upon the Macula sacculi, perhaps 

 by reason of the very large otoliths, or whether they do not come to perception 

 also at this place [Macula sacculi) . This same question arises also for the Lagena, 

 in which the wave of the endolymph of the Sacculus must be continued, as in the 

 Pars neglecta and the Pars basilaris. It is less probable that the movements may 

 be continued as far as the Macula recessus utriculi and the three Crista/ ampul- 

 larum. The question of Hensen is certainly justified in the case of frogs (1893) 

 "Hier (bei den Froschen) ist aber schon der acustiche Zuleitungsapparat nicht 

 erheblich viel schlecter als bei den Vogeln entwickelt ; sollte das nur zu Gunsten 

 des kaum im Warden begriffen Schnelkenanhangs geschehen sein?'" 



2. The ear of the frog. The anatomical references in 

 Gaupp's discussion may be made more intelligible by a brief 

 description of the ear. It consists of a large external mem- 

 brane, the tympanum, usually not more than a centimeter in 

 diameter in the green frog (see Fig. 3), the columella which con- 

 nects the tympanum with the labyrinth (see Fig. 2), and the 



'Anatomic des Frosches. VI. Lehre von Integument und von den 

 Sinnessorganen. S. 751-52. 1904. 



