102 



HOMING AND RELATED ACTIVITIES OF BIRDS. 



Under these conditions we find evidence that the light is exerting only a 

 slight stimulating effect. While the responses are only 63 per cent correct, 

 the fact that no pronounced position habit developed is the most significant 

 evidence that the light lies within the animal's range. 



January 24- I tried the pigeon on the same wave-length, but increased the intensity of 

 the spectrum by using the arc light as a source. The slit in the collimator was closed to 

 0.5 mm. The light was over my threshold (with light-adapted eye) the moment it was 

 exposed. Results: 



Light left, response right. 



Light right, response wrong. 



Light right, response wrong. 



In the above tests, since the light was so intense, I allowed only 10 seconds adaptation. 

 Since a left position habit was forming, I increased the adaptation period to 30 seconds. 

 70 per cent correct. 



Light right, response right. 

 Light left, response right. 

 Light right, response wrong. 

 Light right, response right. 

 Light right, response right. 

 Light right, response wrong. 



Light left, response right. 

 Light right, response right. 

 Light left, response right. 

 Light right, response wrong. 

 Light right, response wrong. 



Since there was a left-position tendency growing I decided to retrain on 

 X = 5800 (which was employed in the early training work). 



January 25. Nernst lamp is the source. Slit in collimator 0.75 mm. Object of test, to 

 see if position habit carried over to a situation where the stimulus was known to be effective. 

 X = 5800. Responses, 70 per cent correct. 



Light right, response right. 

 Light left, response right. 

 Light right, response wrong. 

 Light right, response right. 

 Light right, response wrong. 

 Light right, response right. 

 Light right, response wrong. 

 Light right, response right. 

 Light right, response wrong. 



Light left, response right. 

 Light right, response right. 

 Light right, response right. 

 Light left, response right. 

 Light right, response wrong. 

 Light right, response right. 

 Light right, response right. 

 Light right, response right. 

 Light right, response wrong. 



This was an extremely difficult series in view of the fact that all but three 

 trials were given on the right side. Even granting this, it is obvious that 

 animal needs further training to remove position habit. 



January 26. Conditions as above. 



Light right, response right. 

 Light left, response right. 

 Light right, response wrong. 



Light right, response right. 

 Light left, response wrong. 



The last trial shows that left position habit has given way and that the 

 large number of trials given on the right during the preceding day is tend- 

 ing to give a right position habit. From now on light alone should control 

 response. That such is the case appears from the results of the remainder 

 of the test, which gave 90 per cent correct. 



Light right, response right. 

 Light right, response right. 

 Light left, response right. 

 Light right, response wrong. 

 Light right, response right. 



Light left, response right. 

 Light right, response right. 

 Light right, response right. 

 Light left, response right. 

 Light left, response right. 



