NOTES 



know. The physical perfection that permits such journeys as birds 

 take is cause for admiration. In this connection much of interest 

 will be found in 



The Bird (Beebe), chapter vii, ''The Breath of a Bird," from 

 which we make a brief quotation. ''Birds require, compara- 

 tively, a vastly greater strength and 'wind' in traversing such a 

 thin, unsupporting medium as air than animals need for terrestrial 

 locomotion. Even more wonderful than mere flight is the per- 

 formance of a bird when it springs from the ground, and goes cir- 

 cling upward higher and higher on rapidly beating wings, all the 

 while pouring forth a continuous series of musical notes. . . . 

 A human singer is compelled to put forth all his energy in his vocal 

 efforts; and if, -while singing, he should start on a run even on level 

 ground, he would become exhausted at once. . . . The average 

 person uses only about one seventh of his lung capacitj^ in ordinary 

 breathing, the rest of the air remaining at the bottom of the lung, 

 being termed 'residual.' As this is vitiated by its stay in the 

 lung, it does harm rather than good by its presence. . . . As we 

 have seen, the lungs of a bird are small and non-elastic, but this is 

 more than compensated by the continuous passage of fresh air, 

 passing not only into but entirety through the lungs into the air- 

 sacs, giving, therefore, the very best chance for oxygenation to take 

 place in every portion of the lungs. When we compare the esti- 

 mated number of breaths which birds and men take in a minute, 

 — thirteen to sixteen in the latter, twenty to sixty in birds, — we 

 realize better how birds can perform such wonderful feats of song 

 and flight." 



