THE PASSENGER PIGEON IN PENNSYLVANIA 27 



portions, viz : On the east slope of Appalachian moun- 

 tains, in New York and Pennsylvania ; in Indiana and 

 Ohio and two cities in Kentucky, one of which is de- 

 scribed by the great Audubon and the other by the 

 equally scientific naturalist, Alexander Wilson. That 

 is the data for approximating these birds at one hun- 

 dred millions in 1810, which was recorded in each lo- 

 cality, independently, by men who were unknown to 

 each other. Each man of them, evidently, believed 

 that he was telling a big story about all the Passenger 

 Pigeons in existence being gathered together in the lo- 

 cality of his own observations. 



In his great book, ''Origin of Species," Charles 

 Darwin has given us comfort, in the following para- 

 graph of Section 574, viz : ''We need not marvel at ex- 

 tinction ; if we must marvel, let it be at our own pre- 

 sumption in imagining for a moment that we under- 

 stand the many complex contingencies on which the 

 existence of each species depends. If we forget for 

 an instant, that each species does increase inordinately, 

 and that some check is always in action, yet seldom 

 perceived by us, the whole economy of nature will be 

 utterly obscured. Whenever we can precisely say why 

 this species is more abundant in individuals than that ; 

 why this species and not another can be naturalized in 

 a given country; then, and not until then, we may 

 justly feel surprise why we cannot account for the ex- 

 tinction of any particular species or group of species." 

 (In these chapters we are endeavoring to make plain 

 the cause for development of the passenger pigeons in 



