CHAPTER II 



FUNCTIONAL INERTIA EXPRESSED AS LATENT 



PERIODS, LIMITS, INSUSCEPTIBILITIES AND 



RHYTHMS 



THE phenomenon known as " latent period " is, 

 under the time-category, an expression of the 

 possession by protoplasm of functional inertia : 

 " Physiological lost time " is perhaps a better 

 term. All cases of this in unicellular organisms I 

 take to be manifestations of protoplasmic inertia. 



With reference to light as a stimulus, certain 

 Protistae do not, for some measurable time, exhibit 

 the positive or negative phototropism of which they 

 are capable. 



In regard to ciliary activity a very primitive 

 function Verworn,* writing of a ciliated infusorian, 

 Pleuronema chrysalis, says, " the motion of the cilia 

 does not begin at the exact moment at which the 

 light strikes, but only after ' a latent period ' of 

 from one to two seconds. " Certain ciliated infusoria 

 exhibit no affectability towards light at all, with 

 reference to this stimulus their functional inertia is 

 infinite complete physiological insusceptibility. 



* Verworn, " General Physiology/' p, 401. (London : Macmillan, 



1899-) 



