18 HOMING AND RELATED ACTIVITIES OF BIRDS. 



bird remained immovable. She only flew when tossed up in the air. In spite 

 of the open door, she made no effort to return to her nest. Even in the vesti- 

 bule she made no attempt. She did not return to the nest if placed just in 

 front of it, but remained on the spot. This test shows only that the ordinary 

 olfactory sense is not acute in the pigeon. 



On the basis of an experiment to be described, he advanced the view that 

 the direction and temperature of the wind act upon the olfactory mucous membrane. 

 As we understand him, his theory is based, on its sensory side, upon the func- 

 tioning of the tactile nerves (largely V th ) in the nasal cavity. 



Cyon's experimental data in support of this theory are exceedingly limited. 

 He selected 3 young homing pigeons of equal age and ability, which had 

 been trained to return from distances of 4 to 500 km. (direction not stated). 

 Pigeon A was used as a norm. Pigeon B had the anterior nares closed with a 

 cocaine-saturated plug, the whole coated with collodion. In the same man- 

 ner the auditory meatus of pigeon C was closed. The 3 birds were carried 

 at 7 h 30 m a. m. from Spa in a railway carriage to the station at Huy, which by 

 rail was 60 to 70 km., and in an air-line, 50 to 55 km. from Spa. Huy was 

 chosen because it lay in a valley and was separated from Spa by a mountain. 

 The weather was clear and fine. Pigeon C did not stand the trip very well and 

 ate apathetically the day before release. They were released in the following 

 order: A, at 10 h 13 m a. m.; B, at 10 h 19 m a. m.; C, at 10 h 26 m a. m. There 

 was some difference in the orienting flight. The norm, A, arose perpendicu- 

 larly and began to make the characteristic circular flights. It then took sud- 

 denly the direction of northwest, following the line of the railway. B ascended 

 fully as rapidly, but not perpendicularly, veering towards the east. Finally 

 it took the direction south. C was released 7 minutes later and arose with 

 slower speed; its circles were smaller; oftentimes, in place of going higher, 

 it descended. It took the direction east. Pigeon C (auditory meatus closed) 

 was the first to reach home, at ll h 35 m . It required, therefore, 1 hour and 9 

 minutes for the trip. The normal pigeon appeared at 12, requiring 1 hour and 

 47 minutes. It probably chose the railway back, going through Liittich and 

 Peppinster, while C probably chose the air-line. Pigeon B (nasal passages 

 closed) appeared 4 days later, September 6, between 4 and 6 p. m. This bird 

 required 78 to 80 hours for the trip. It was found that the nasal passage 

 was completely clear, both of the cotton and collodion. 



Cyon does not believe that this belated return was accidental, nor that the 

 pigeon was held in durance, because a large price was offered for a report of it. 

 He feels that the bird wandered more or less aimlessly until it could free its 

 nose of the plugs, after which it sought its way home. Cyon's position may be 

 summarized as follows: (1) Orientation, in the last analysis, depends not upon 

 purely instinctive and reflex processes, but upon intelligent adjustment (habits 

 based largely on cutaneous sense) . (2) Orientation is attained with the help 

 of two senses: " ... des Gesichtsinnes und eines speciellen Spiirsinnes, 

 der in der Schleimhaut der Nase (und vielleicht der Stirnhole) seinen Sitz 

 hat. Letzteren Sinn kann vom Geruchsinn unabhangig sein. Er wird vor- 

 zugsweise durch die Qualitaten der Winde (Richtung, Intensitat, Temperatur, 

 . . . ) in Thatigkeit versetzt." (3) The vestibular portion of the ear func- 

 tions only as an equilibratory mechanism. 



