mann] A SCHOOLROOM STUD Y OF A ROBIiV'S .VEST 269 



quill and vane, in form and material. The development of the 

 feather is a difficult subject and it was presented by the teacher 

 and illustrated by means of blackboard sketches and simply 

 constructed paper models. 



We next studied the wing itself, noticing the mother as she 

 came and went folding and spreading her wings and rising or 

 alighting. Primaries, secondaries, and coverts were now easily 

 distinguishable on the wings of the young birds. Wings of 

 pigeons- (or chickens), prepared and spread upon cardboard 

 mounts were studied concerning the arrangement of the feathers. 

 Here again we sought the adaptations. 



But the wing alone does not tell the story of the bird's power 

 of flight. The whole body is built so as to secure the greatest 

 strength with the least weight. Pigeons were used for demon- 

 strating the air sacs and the relation of these to the lungs and to 

 respiration. The trachea and syrinx were noted and also the 

 large pectoral muscles by means of which the wings are moved 

 We also found and worked the automatic device of bone and ten- 

 don that makes the act of perching and clasping a branch so 

 simple and so sure. We sketched the viscera in position and 

 learned the work of each part of the alimentary canal in preparing 

 the food which must furnish the energy for all the activities of 

 bird-life. 



The amount of food consumed increased as the birds grew 

 larger but the actual gain in weight steadily decreased. There 

 was an actual loss in weight on two days when feather formation 

 was very active and the question, Wny ? came up for discussion. 

 The difference in the kinds of food brought to the May brood and 

 to the June brood was interesting. The former received a con- 

 siderable variety; earthworms, ants, beetles, small moths, flies 

 and various insect larvae, among which were injurious cut-worms. 

 The June brood was fed almost entirely upon earthworms. Here 

 again we sought the reason. In this connection we took up 

 briefly the economic value of birds, especially at the nesting sea- 

 son, as destroyers of injurious insects. We referred to the work 

 of other observers of nestling birds and compared their work and 

 results with ours. 



By the tenth day the nest had become quite crow'ded and as 

 the birds were active, moving about and clambering over each 

 other continually, No. 3 had the misfortune to fall from the nest 



