108 ELECTRO-PHYSIOLOGY CHAT-. 



ordinary prolongation of the contraction period (contracture) 

 exclusively arrests attention. If a frog is poisoned with suit- 

 cutaneous injections of 12 drops of, say, a 0'2 ' solution of 

 veratrin, after a short time a marked disturbance of the normal 

 movements usually makes its appearance characterised above all 

 by rapid and vigorous contractions, while the relaxation and 

 elongation of the muscle, on the contrary, are very sluggish. 

 This is still more plainly seen in experiments with isolated nerve- 

 muscle preparations, especially when the changes of form are 

 graphically recorded. While the ascending limb and summit 

 of the curve betray no great alteration, the stage of falling 

 energy is much protracted, and relaxation may be prolonged over 

 many seconds. Since v. Bezold determined these remarkable 

 effects of veratrin, it has been admitted that they are entirely 

 due to an altered state of the muscle -substance proper, and 

 depend, as Fick affirms, in all probability upon an " augmenta- 

 tion of the excitatory process beyond normal limits." In order 

 to produce maximal extension of contraction, it is advisable 

 to give larger doses of the poison ; we have found it convenient 

 to introduce 6 7 drops of a 1 % solution of veratrin acet. 

 into the posterior lymph sac, killing the frog (H. tempor.} after 

 ten minutes at the latest. Seven minutes usually suffice to 

 develop the symptoms characteristic of the poison. In the first 

 place may be mentioned the more or less pronounced convulsions 

 of the posterior extremities, which occur at short intervals, and, 

 are preceded by a general disturbance and spasmodic gaping. 

 One unmistakable symptom is that the muscles of the belly go 

 into protracted tetanus when mechanically excited, <-.</. on pinching 

 with forceps, as also occurs in a preparation of the sartorius 

 when the nerve is divided. The rapid twitch at the moment of 

 division is often succeeded, after a short pause, by a further, slowly 

 increasing contraction, which remains constant for some time, 

 and only gradually yields to relaxation. 



If the changes of form in such a veratrinised sartorius are 

 recorded, by fixing it between the stumps of bone left on either 

 side to Hering's double myograph (which will be described below), 

 one of the two movable non-polarisable electrodes having pre- 

 viously been fixed permanently, the same curves are usually 

 obtained, whether the excitation is produced by an induction 

 shock sent into any part of the muscle, or by minimal closure of a 



