THE GENESIS OF FUNCTIONAL INERTIA 125 



up to it : we eat to work the fed and unexercised 

 horse will become " too fresh/' as it is called, will 

 become "spontaneously" active, and unless driven 

 or ridden will kick his stall dow r n. 



In this sense anabolism is the " internal stimulus " 

 for katabolism, only in this sense the high state of 

 nutrition is a stimulus. On analysis, however, there is 

 no new idea here : by the too great building up of 

 biogens their instability is brought about, and the 

 unstable molecules " topple over " on the advent of 

 a stimulus so excessively minute as to be practically 

 negligible, certainly extremely difficult of detection. 

 Much spontaneity is of this order metabolically. 



We have seen that one of the expressions of 

 functional inertia is the setting of limits : this point 

 is worthy of attention here. There is nothing to 

 prevent a crystal growing indefinitely large if con- 

 tinually supplied with sufficient soluble material 

 for its accretion, but there is a very definite limit 

 set to the growth in bulk of the organism. Trees 

 do not, like the Tower of Babel, grow up until their 

 tops reach heaven ; protoplasmic inertia precludes 

 such infinite affectability ; as Maudsley says of the 

 organised being, " it cannot overstep the laws of its 

 form. The plan is the law, and the law is not some- 

 thing outside, but inherent in it." * This " inherent " 

 something, this " law " that is opposed to the en- 

 vironment, is protoplasmic inertia once again setting 

 limits. 



* H. Maudsley, Body and Mind, p. 166. 



