FUNCTIONAL INERTIA AS LATENT PERIODS, &c. 37 



centre is the emission of discharges intermittently 

 and not as " constant activity." Supposing that 

 the blood is a " constant stimulus/' the centre 

 could through its inertia behave with regard to this 

 in the same way that the neuro-muscular mechanism 

 behaves with regard to constant stimuli, viz., by 

 rhythmic discharges. But it does not need an 

 environment at all neither blood nor other stimuli 



FIG. 7. Record of tremor of dying diaphragm of the rabbit ; both 

 phrenics cut average periodicity, 5 per second : time in half 

 seconds. 



to enable it to discharge intermittently, since Marck- 

 wald * has shown that in an eviscerated marmot 

 respiratory spasms were still observed. Of course 

 this state of matters cannot be kept up, death 

 ensues owing to lack of nourishment, but rhythmic 

 discharges, in the absence of all stimuli, are an 

 evidence of the inertial factor in the behaviour of 

 this centre. Doubtless double vagotomy and tran- 

 section through the Pons Varolii cut off the avenues 

 of arrival of nerve-stimuli intermittent in character, 



* Marckwald, " The Movements of Respiration/' translated, 

 (Condon : ^Haig, 1888.) 



