FUNCTIONAL INERTIA AS LATENT PERIODS, &c. 27 



rise to the necessity for the concept as embodied in 

 these terms. 



One more example of the use of the term inertia in 

 connection with the nervous system I should like to 

 quote, viz., that by Dr. A. D. Waller in his article, 

 " On the functional attributes of the cerebral 

 cortex." * He writes, ' The impulse influences 

 cellular energy ... it tends to overcome or actually 

 overcomes inertia, and in the latter case it effects 

 friction." ... ''I imagine the greater instability 

 oi the cell to be molecular, so that the disturbance 

 by a second impulse can propagate itself with less 

 diffusion, overcoming less chemical inertia, and pro- 

 ducing less friction than the disturbance produced 

 by a first impulse." 



Later on in the same paper, resistance in nerve- 

 cells is defined as " chemical inertia." I quote these 

 passages to show how thinkers-out of physiological 

 problems are constrained sooner or later in their 

 analyses, to come to the notion of inertia of the 

 living molecules. Whatever else Dr. Waller desires 

 to convey in the very searching analysis to which he 

 here subjects neural processes, he desires to convey 

 this, that there is a property of inertia possessed 

 molecularly by nerve-cells and expressed in chemical 

 phenomena : this is functional inertia. 



Dr. Mercier t in writing of the cells of the nervous 

 system explicitly says, " the molecules . . . oppose 

 increased inertia to the efforts of errant currents." 



* A. D. Waller, Brain, parts iii. and iv., 1892, p. 329. 

 f Mercier, " Sanity and Insanity/' p. 305. 



