160 



EXPERIMENTAL PHYSIOLOGY. 



sciatic nerve, there is no contraction, but on stimulating 

 the muscle itself contraction takes place. 



3. RosenthaTs Modification. 



(a.) Prepare a frog as in the previous experiment, ligature 

 the left leg all except the sciatic nerve and inject curare 

 as before. After complete paralyses occurs, dissect out both 

 legs with the nerves attached, but retain the legs, as in Fig. 

 58. Attach straw flags (N P and P) of different colours to 

 the toes of both legs by pins, and fix both femora in muscle- 

 forceps (F) with the gas- 

 trocnemii uppermost. 

 Place the nerves (N) on 

 the platinum points of 

 du Bois-Reymond's elec- 

 trodes (Fig. 47). 



(b.) Arrange the induc- 

 tion apparatus as in Fig. 

 58. The primary coil is 

 as before, but the ter- 

 minals of the secondary 

 coil are connected by two 

 wires with the piers of a 

 Pohl's commutator (Fig. 

 58) without cross-bars 

 (H). Two other wires 

 pass from two other bind- 

 ing screws of the commu- 

 tator to the electrodes 

 (N), while two thin wires 

 pass from the other two 

 binding screws (C) and 

 their other ends are 

 pushed through the gas- 

 trocnemii muscles. 

 Place the commutator on 

 a meat plate and fill its 



holes with mercury. The commutator enables the tetanising 

 currents to be passed either through both nerves or 

 both muscles. It is more convenient if the secondary 

 circuit have a key, so that it may be short-circuited when 

 desired. 



Fig. 58. Scheme of the Curare Experi- 

 ment. B, Battery ; I., primary, II. , 

 secondary spiral; N, nerves; F, 

 clamp ; N P, non-poisoned leg ; P, 

 poisoned leg; C, commutator; K, 

 key. 



