HABIT FORMATION IN THE DOG 15 



weeks were spent in training to the same tone without success; 

 following which twenty-three days were spent in the endeavor 

 to teach the animal to react to the words '' Mach schon,'' with 

 the same outcome. From Rothmann's brief account one gathers 

 that the animal reacted when noises or tones were made but 

 did not discriminate among them. Post mortem showed total 

 destruction of the posterior coipora quadrigemina in all the 

 animals. 



Extirpation of both temporal lobes in five dogs produced 

 deafness to both tone and noise when the entire area described 

 by Munk was removed; if the removal was not complete, some 

 traces of the reactions remained. A sixth dog, however, not 

 previously trained, having been deprived of both temporal lobes 

 and of one convolution of the gyrus sylviacus, was "success- 

 fully trained" in three weeks to react only to c-256 d.v. Seven 

 days sufficed to perfect reaction to the words "Nimm Fleisch.'' 



In two dogs not previously trained, both internal geniculate 

 bodies were destroyed. Neither could be trained to respond to 

 either tone or noise. From these results Rothmann concludes 

 that the dog's auditory center lies in the temporal region, but 

 that it extends over a wider area than that defined by ]\Iunk. 

 According to him the pathwa}^ from the end-organ passes through 

 the posterior coipora quadrigemina and the internal geniculate 

 bodies. 



The anatomical findings thus announced are certainly less 

 revolutionary and less spectacular than are those of Kalischer, 

 and conform fairly to the generally accepted view. It should 

 be remembered, nevertheless, that Rothmann's experimental pro- 

 cedure is as unreliable as Kalischer 's, if indeed not more so. 



Kalischer published in 1909 a report-' of continued work 

 done on reactions of dogs to musical tones. His conclusions 

 from his former work had left the end-organ for tone indeter- 

 minate, and he wished to test the theory of Helmholtz regarding 

 the function of the cochlea and the vestibular apparatus. In 

 this same report he gives account of its extension to olfactory 

 and color-vision tests on the dog. Apropos of the last men- 

 tioned part of his work it might be remarked that Kalischer 's 



-* Kalischer, Otto. Weitere Mitteilung ueber die Ergebnisse der Dressur als 

 physiologischer Untersuchungsmethode auf den Gebieten des Gehor — ,Gerucit5- 

 und Farbensinns. Arch. f. Physiol., 1909. 



