24 HOMING AND RELATED ACTIVITIES OF BIRDS. 



Sinn von der Strommesrichtung abhangig ist. Es ist das der sogenannte galvanische 

 Schwindel, auf den hier einzugehen nicht der Ort ist. Bei der Taube verrath er sich durch 

 Neigungen des Kopfes, Augenbewegungen u. s. w. Ich suchte also wahrend der Hinfahrt 

 das Thier durch diese Drehempfindungen iiber die thatsachlichen Wendungen und Drehun- 

 gen zu tauschen. Wenn der Vestibularapparat das Thier wahrend der Hinreise orientirte, 

 so miisste durch das Hinzutreten des galvanischen Schwindels diese Orientirung vernichtet 

 werden, oder doch zu einer Orient irungstauschung fiihren. 



The birds were continuously stimulated all through the forward journey. 

 Upon reaching their destination they were freed from the apparatus and 

 released. The first release was made 54 km. from Vienna. They were all 

 released on April 16, with the following results: (1) the adult control bird 

 (armed with the same apparatus during the forward journey, but not elec- 

 trically stimulated) was released at ll h ll m , reaching Vienna in the early 

 morning of April 18; (2) the young control bird, released at ll h 16 m , did not 

 return; (3) adult bird electrically stimulated, released ll h 18 ra , reached 

 Vienna on the same day at l h 50 m ; (4) young bird electrically stimulated, 

 released at ll h 32 m , did not return. 



Many other experiments of this type were made, with essentially the same 

 results. As many birds electrically stimulated returned as normals. Exner 

 next completely anaesthetized with ether several adult and young birds and 

 kept them so during the whole of the forward journey. On reaching their 

 destination the birds were restored and allowed a certain length of time for 

 recovery, and were, then released. In the first experiment they were released 

 43 km. from Vienna. The results were: (1) normal animal, released at 6 h 

 a. m., did not return; (2) anaesthetized animal, released at 6 h 20 m , did not 

 return; (3) anaesthetized animal, released at 6 h 49 m , returned at ll h ; (4) 

 normal animal, released 10 h 21 m , returned at 12 h ; (5) young normal animal, 

 released at 10 h 26 m , did not return; (6) old anaesthetized animal, released at 

 10 h 30 m , returned at 12 h ; (7) young anaesthetized animal, released at 10 h 

 35 m , did not return. 



From these experiments of Exner, it is evident that he worked with very 

 poor material, that is, with birds which were poor flyers. Nevertheless, it 

 seems clear from his experiments that electrical stimulation, ansesthetization, 

 etc., during the forward journey have a negative result upon the return of 

 the birds. 



