ACTIOX OF CAFFE1XK 



245 



EXPERIMENT XLVII. 

 Caffeine. (Frog: Muscular Work.) 



1. Pith a frog and ligate the right thigh tightly so as 

 to shut off the circulation. Fasten the animal down on a 



Very fine copper 

 wires, attached to 

 tack and to tendo 

 jchillis 



Fig. 224. Arrangement of a frog and apparatus for recording "fatigue tracings" 

 from the gastrocnemius muscle. The drum should have a slow speed. (For descrip- 

 tion see text.) 



board as shown in Fig. 224. Isolate the tendo Achillis 

 of the right leg and arrange as illustrated for stimulating 

 with single shocks. The primary current is best inter- 

 rupted by a metronome as illustrated, but if this is not 



