4 FUNCTIONAL INERTIA 



extent, that I have undertaken in the following 

 pages. 



Life consists as much in the organism corresponding 

 with its environment as in its not being at the 

 mercy of every stimulus it may encounter : life 

 consists in the organism not being the facile play- 

 thing of every environmental change, but in the 

 organism being insusceptible to certain changes, 

 inaccessible to certain stimuli, unaffected by certain 

 conditions, so that neither unrestrained activity 

 nor complete inaction is the result, but action 

 alternating with inaction, activity with rest, fresh- 

 ness with fatigue. These things cannot be so 

 unless protoplasm possesses, in addition to affect- 

 ability, a property equally fundamental with it, and 

 hitherto unrecognised as such, functional inertia. 

 It seems to me logically impossible to subsume all 

 the varied manifestations of vitality exhibited 

 throughout the animal and vegetable kingdoms 

 under the category of a single primary property 

 of living matter excitability. But this is what 

 is virtually done in those text-books where any 

 classification of properties is attempted. 



When it is said *t that the vital properties of 

 protoplasm are : power of assimilation, irritability, 

 movement, secretion, automatic molecular changes, 

 reproduction, have we not the enumeration of 



* M c Kendrick, " Text-book of Physiology," vol. i. p. 33. (Macle- 

 hose, 1888.) 



t Foster, "Text-book of Physiology," pp. 1-15. (Macmillan, 



1877.) 



