CHANGE OF TRADITION IN THE CASE OF CHIMNEY SWIFT. 59 
their offspring and by the experienced leaders to the multitude, and 
responded to by the instinct for imitation possessed by the young and 
inexperienced, will establish and perpetuate a more or less constant 
social, or habitudinal, type. And it should be especially noted that 
the habits thus transmitted from generation to generation determine 
the relations of the group to the environment, and, therefore, the form 
of selection that continues with cumulative results in successive gene- 
rations. The influence of habitudinal generalization is illustrated by 
the following case: 
4. Change of Tradition in the Case of the Chimney Swift. 
The chimney swift of eastern North America, often called the chim- 
ney swallow, has made an important change in its habits since the 
settling in this region of Kuropeans who build houses with chimneys. 
We know that before the coming of the European the traditions of this 
bird determined that hollow trees should be occupied as the appro- 
priate places for their nest-building. How the present tradition, giv- 
ing the preference to chimneys, was started, we are not informed; but 
we may believe that a pair of birds of an investigating spirit, finding 
that the hollow trees in which they and their ancestors had been in the 
habit of building had been cut down, ventured to make the new experi- 
ment. Being rewarded with success, election is on their side, and 
their descendants survive to perpetuate the habit. Other birds of 
the same species see their success and follow their example; and as 
_chimneys are multiplied, while hollow trees are diminished in number, 
the followers of the new habit in time outnumber the adherents to 
the old tradition, and from that time on the old conservative habits 
crumble rapidly away. The vast majority of the species have now 
abandoned the old tradition, and the newer tradition now prevails 
everywhere, except in the Dismal Swamp (a region about 30 miles in 
length and ro miles in width, in the States of Virginia and North Caro- 
ina), where their unconscious helper has failed to erect his chimneys. 
5. The Two Methods of Adjustment. 
Aptitudes are inherited forms of adaptation resulting from tentative 
variations accumulated by the survival of the fittest. Habitudes are 
traditional accommodations (that is, traditional forms of adjustment), 
resulting from tentative innovations accumulated by repetition and 
imitation of successful experiments. 
Adaptation in plants and in the lower types of animals is gained 
chiefly by varzation in the degrees of innate qualities and in the inten- 
sity of innate activities, molded in successive generations by the sur- 
vival of individuals having the fittest endowments in each isolated 
