THEIB NATURE AND EFFECTS. 23 



repeated, with, however, some modification ia the 

 details. 



The electric arrangements were as follows : — A coi;i- 

 stant difference of potentials was maintained by means 



%f a galvanic battery between the terminals of the 

 primary series of coils of a Thomson's Slide Resistance. 

 Two flexible insulated wires, the free ends of which 

 terminated in platinum needles, and were used as the 



• electrodes, were connected, the one to the zero end of 

 the primary series of coils, and the other to the sliding 

 contact of the secondary coils. By suitably moving 

 the sliding contacts, any desired difference of potentials 

 could thus be established between the electrodes. 



Experiment VII. 



A frog (Rana tigrina) was killed mechanically at 

 12. 18 P.M., but reflex action continued for some time 

 afterwards. 



1.6 P.M. Muscle was found to be infinitely sensitive. 

 Nerve, stimulated with 06 volt, produced distinct 

 contraction ; both sides give the same result. 



This experiment shows how sensitive muscle and 

 nerve remain for some time after death from purely 

 mechanical causes. 



Experiment VIII. 

 Tifie right thigh of a frog (Rana tiqrina) was ligatured 

 so as to completely prevent the blood circulating in the 

 part below the ligature. The sciatic nerve was not 



