68 FUNCTIONAL INERTIA 



case of age-long type preservation. Again Huxley * 

 may be quoted as follows : " The tendency to 

 reproduce the original stock has, as it were, its 

 limits, and side by side with it there is a tendency 

 to vary in certain directions, as if there were two 

 opposing forces working upon the organic being, one 

 tending to take it in a straight line, and the other 

 tending to make it diverge from that straight line, 

 first to the one side and then to the other." Now 

 could we have the notion of functional inertia 

 better expressed short of using the term itself ? 

 It is by its inertia of mass in movement that a body 

 tends to travel with uniform motion in a straight 

 line, and similarly it is in virtue of the functional 

 inertia, as a property of living matter, that the 

 organism tends in Huxley's phrase to " go in a 

 straight line." 



The two tendencies thus rule the protoplasm 

 the tendency to maintain the status quo and the 

 tendency to vary, to respond to, i.e., to correspond 

 with environment the centripetal and centrifugal 

 impulses of Haeckel are functional inertia and 

 affectability. Not that necessarily every so-called 

 :t variation " is the result of environment act- 

 ing on affectability; under certain conditions the 

 atavistic tendency may bring to light some feature 

 which, with imperfect knowledge of the organism's 

 phylogeny, we might think to be a variation in the 

 sense of something new, whereas what has become 

 noticeable for the first time to the observer may 



* T. H. Huxley, " Darwiniana : Collected Essays," vol. ii. 1902, p. 398. 



