Affective Tendencies 371 



namely the artificial maintenance of the greatest possi- 

 ble constancy in the environment, which is the necessary 

 and sufficient condition for preserving physiological 

 invariability. 



II. 



Closely connected with this inherent fundamental 

 tendency of every organism to strive to preserve its nor- 

 mal physiological condition or to restore it as soon as it 

 is disturbed, is still another attribute which in its turn 

 becomes the source of new affectivities. 



For as soon as the previous stationary condition can- 

 not be restored by any means, that is by any movements 

 or change of location, the organism disposes itself in a 

 new stationary condition consistent with its new external 

 and internal environment. In this way there originate 

 a large number of new phenomena called "adaptations." 



Thus, for instance, Dallinger's classical experiments 

 on the acclimatization of lower organisms suggested by 

 the observation that many organisms usually living in 

 water of an ordinary temperature, also live and flourish 

 in the hottest spring, have proved that Infusoria may 

 gradually become accustomed to a constantly higher tem- 

 perature so that finally after years of continuous slow 

 increase in the degree of heat, they can stand a tempera- 

 ture so high that any other individual not acclimated 

 would certainly die if subjected to it. It is likewise 

 known that the same species of Protozoa are found in 

 both fresh and salt water, and that it is possible to ac- 

 custom fresh-water Amoebae and Infusoria to a salt 

 habitat which would have killed them at the start, 

 and there are more instances of the same kind. 10 



10 See C. B. Davenport and W. E. Castle, "On the Acclimatisa- 



