120 ELEMENTAET PHYSIOLOGY. [XI. 



15. Repeat any of the above observations (§ 2 — 13). 

 No reflex actions wUl now be produced. 



B. Automatic Action. 



I. The Lymph-Hearts. 



1. Placing the animal on its belly watch the move- 

 ments of the posterior lymph-hearts. They may 

 be seen beating on either side of the extremity 

 of the urostyle, in a depression between that bone 

 and the hip-joint. The contractions are generallj' 

 visible through the skin, but become more evident 

 if the skin be removed, care being taken not to 

 injure the lymph-hearts themselves. 



2. Observe that after destruction of the posterior 

 part of the spinal cord the lymph-hearts cease 

 to beat 



II. The Heart. 



1. Lay the frog on its back, make a median incision 

 through the skin, and from the middle ■ of this 

 make transverse incisions. Raising up the end 

 of the sternum with a pair of forceps, cut it 

 through a little above the end so as to avoid 

 cutting the epigastric vein. Then again lifting 

 up the sternum cut it through longitudinally 

 with a strong pair of scissors; pin back each 

 part of the sternum, cutting through such 

 muscles as may be necessary; the heart will 



