, rROCxNE. 339 



tlirectly to the proper spot, but first tried several holes as on the 

 first day of departure. At length, after many trips, the proper 

 method of approach suddenly dawned upon their consciousness, 

 and thereafter they made it with unerring skill. At that time 

 there was, under the house, a second nest with three slightly 

 incubated eggs, which I thought might be put to some use. By 

 watching the other birds I realized that many actions were the 

 result of newly acquired habits, and therefore might be influenced 

 by outside agencies. How far, though, did these habits control 

 instinct? Up to the present, evidence showed that young biids 

 with undeveloped intellect, ignorant of the life straggle before 

 them, even though homing instinct was predominant, were aide, 

 only by repeated trials, to recognise their home among sev<_'ral 

 others of similar ap])earance. Similarly tlieir parents, upon first 

 taking possession, had canied straw to each of the four holes 

 until they discovered that four nests were building instead of one ; 

 even then they would often carry to the next hole before dis- 

 covering their mistake. At length, after many trips, they became 

 so used to the proper location that no further errors were made. 

 Thus, even they vvere dependent upon a habit to point out their 

 permanent home ; a habit credited by repeated trials through 

 which sense of exact location became, at length, indelibly fixed 

 upon their brains. 



"The nest containing the three eggs in question, though placed 

 out of any direction rays of the sun, was exposed to the light of 

 day, so that the eggs were in plain view of the parent bird when 

 ap[)roaching tho nest. One day, I carefully marked the eggs 

 with blotches of" red ink, leaving uncoloured the large ends with 

 their air chambers, and placed them back in the nest as nearly as 

 possible in the same old position. At first the Martins were much 

 excited and looked at the eggs askance, ])eering this way and that, 

 as if they might Hud the lost originals hidden away in some 

 darkened corner. In a few minutes, however, deciding that, 

 tiiough they did lo(d\ different, they were still the same eggs, one 

 of the birds hesitatingly crouched upon them and tho incubation 

 proceeded as if nothing had occurrc^d. 



"The following day 1 removed both nests and eggs, putting 

 them in a prominent spot, only u few feet away from their 

 original resting place. 'Jhc |)arent bird, disturbed Ity my efi'orts, 

 flew excitedly about, and, tiie instant I left the ladder, flew to 



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