FEATHERED GIANTS 153 
but in this instance man is guiltless, for they 
lived and died long before he made his ap- 
pearance, and the ever-convenient hypothesis 
“change of climate” may be responsible for 
their disappearance. 
Something, perhaps, remains to be said con- 
cerning the causes which seem to have led to 
the development of these giant birds, as well 
as the reasons for their flightless condition and 
peculiar distribution, for it will be noticed 
that, with the exception of the African and 
South American ostriches the great flightless 
_ birds as a rule are, and were, confined to unin- 
habited or sparsely populated islands, and this 
is equally true of the many small, but equally 
flightless birds. It is a seemingly harsh law 
of nature that all living beings shall live ina 
more or less active struggle with each other 
and with their surroundings, and that those 
creatures which possess some slight advantage 
over their fellows in the matter of speed, or 
_ strength, or ability to adapt themselves to sur- 
_ rounding conditions, shall prosper at the ex- 
_ pense of the others. In the power of flight, 
_ birds have a great safeguard against changes of 
