1885.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 103 



EXPLANATION OF PLATE I. 



Fig. 1 represents the tracings taken wliile the heart was working under the in- 

 tiiience of atropized blood. 



Fig. 2 shows tracings obtained while the heart was under the influence of normal 

 nutrient blood-mixture ; it is also intended to illustrate the promptness and couiiilete ■ 

 ness with which the heart passed out from under the influence of atropia, as can be 

 seen on the left-hand side of the figure where part of the tracing taken under atro- 

 pized blood is left on for the purpose of showing this, 



