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EXPERIMENTAL PHYSIOLOGY 



stimulation varies with the strength of stimulus employed. As it 

 is an afferent nerve, stimulation of its central end tends to produce 

 a pressor effect. This is the result if the stimulus be weak, and it 

 is accompanied by an increased rate of breathing, which also pro- 



Fig. 142. — Stimulation of the Central End of the Left Vagus in a Babbit. 



duces an effect upon the curve. Fig. 142 shows such a result, where 

 the effect is seen to persist for some time after stimulation ceased. 

 If the strength of stimulation be increased convulsive movements are 

 produced which send up the blood pressure; but at the same time 



