78 BREWSTER’S WARBLER. 
other is unknown, the experiments may be complicated and obscured through 
the chances of impurity of the parent stock. The long twelve-month intervals 
between successive generations, too, would place further obstacles in the path 
of him who tried to solve this problem by breeding the birds in confinement. 
Mr. Brewster, arguing in 1881 in favor of the hybrid theory of H. leuco- 
bronchialis, closed his brief with the following words: ‘‘The bars are down; 
the gate stands open; ‘he who runs may read.’”” Yes, the gate stands open, 
but what I read is a sombre inscription over the portal: 
LASCIATE OGNI SPERANZA, VOI CH’ ENTRATE! 
