TALKS WITH YOUNG OBSERVERS 291 



her egg, the cowbird had probably been watching 

 near by, and had seized it the moment the nest was 

 vacated. Her plan was of course to deposit one of 

 her own in its place. 



I now made a more thorough search for the nest, 

 and soon found it, but it was beyond my reach on 

 an outer branch, and whether or not the cowbird 

 dropped one of her own eggs in place of the one she 

 had removed I do not know. Certain am I that 

 the vireos soon abandoned the nest, though they do 

 not always do this when hoodwinked in this way. 



I once met a gentleman on the train who told me 

 about a brood of quails that had hatched out under 

 his observation. He was convinced that the mother 

 quail had broken the shells for the young birds. He 

 sent me one of the shells to convince me that it had 

 been broken from the outside. At first glance it did 

 appear so. It had been cut around near the large 

 end, with the exception of a small space, as if by 

 regular thrusts or taps from a bird's beak, so that 

 I this end opened like the lid of a box on a hinge, and 

 let the imprisoned bird escape. What convinced the 

 gentleman that the force had been applied from the 

 outside was that the edges of the cut or break were 

 bent in. 



If we wish rightly to interpret nature, to get at 

 the exact truth of her ways and doings, we must cul- 

 tivate what is called the critical habit of mind ; that 

 is, the habit of mind that does not rest Avith mere 

 appearances. One must sift the evidence, must cross- 

 question the facts. This gentleman was a lawyer, 



