38 FUNCTIONAL INERTIA 



and we do then approximate to the state of matters 

 in which the centre is influenced by the " constant " 





'^ 



FIG. 8. First line: record (through diaphragm) of normal respiratory 

 rhythm of puppy (anaesthetise:! with ACE mixture). Second line : 

 time in half -seconds. Third line : record (through diaphragm) 

 of respiration of same animal after section of both vagi nerves. 

 (Reduced to natural size.) 



FIG. 9. First line ; time in half-seconds. Second line : record of move- 

 ments of diaphragm of puppy (under ACE mixture). Third line : j 

 at commencement of black mark central end of one vagus was 

 stimulated, " inspiratory tetanus" of diaphragm resulted. 



stimulus of venosity of blood alone : the rhythm of 

 discharge is now very slow (Fig. 8). 



The superior limit of discharge from the respiratory 

 centre can be reflexly brought out by " tetanic " 

 stimulation of the central end of one vagus, when 

 (with intact phrenics) the diaphragm is held down 



