100 Messrs. T. L. Brunton and J. Fayrer on the [Jan. 22, 



Distance 9'5, very faint contraction in both tibial and gastrocnemic 

 muscles. Apparently equal in both legs. Heart quite still and con- 

 tracted. 



On testing the irritability of several of the frogs used in these experi- 

 ments on the ensuing day, the ligatured leg was found to contract on 

 irritation of the sciatic nerve, or of the muscles directly. The muscles 

 of the poisoned leg did not contract, either when irritated directly or 

 through the nerves. 



Experiment XLII. 



May 20th, 1873. In order to test the action of cobra-poison on the 

 ends of the motor nerves, without disturbing the experiment by ligaturing 

 one leg, two frogs were taken of as nearly as possible the same size. 

 Both were very small ; but No. 1 was somewhat larger and stronger than 

 No. 2. The sciatic nerve was exposed in one thigh of each frog and 

 placed on the hook electrodes used by Marey for his myograph. By 

 means of a Pohl's commutator, with the cross pieces taken out, an inter- 

 rupted current could be sent at will through either nerve. The distance 

 of the secondary from the primary coil at which the first faint contrac- 

 tion took place in the muscles of either nerve was noted. 



Instance of primary from secondary coil. 

 Time, Frog 1. Frog 2. 



About 1.25 17-7 22 



1.40 26'3 12*3 



1.46 26 18 Injected a solution of dried 



cobra -poison in water into 

 dorsal lymph -sac of frog 

 No. 1. 



2.7 31-2 24 



2.27 31 18-5 



2.50 24 17'8 



3.10 17'5 19 '2 Frog 1 moved the fore legs 



when the coil was at such a 

 distance (19 ?) that no move- 

 ment occurred in leg when 

 nerve was irritated. 



3.30 12 17'5 



3.40 10*5 15*5 



4 10 33 



4.17 9 37 



4.30 11 18 At 37 voluntary movements oc- 



occurred in legs of frog 2. 



4.50 8 37 



4.55 . . . . The brains of both frogs de- 



stroyed. 



4.58 7'5 16-5 



