26 



PASTORAL AND AGRICULTURAL BOTANY 



FIG. 5. The terrapin's heart, ventral view, showing how to cut an apex strip for 

 experimental purposes and how to split this apex into smaller pieces. (Greene.) 



.1 Digitalis 0.06% 



^ 



FIG. 6. Experiment showing the action of digitalis on the rhythm and tone of a 

 strip of terrapin's ventricle. The strip was contracting in physiological saline. Be- 

 tween the words "on" and "off" it was subjected to 0.06 per cent, of digitalis in saline. 

 (Greene.) 



