48 Prof. J. Burdon-Sanderson. Relation of Motion in Animals 



Photograph 2 * 



o-7see. 



The experiment may be further varied by altering the seat of excita- 

 tion from r to /. You thus obtain a photographic record which 

 represents what happened at d in the unligatured muscle. If the muscle 

 is in a normal state, this is an exact reversed counterpart of photo- 

 graph 2. 



If instead of placing the ligature half way between p and d, we 

 place it close to the distal electrode d, the proximal may then be 

 placed in a succession of experiments at different distances from the 

 seat of excitation without altering the form of the recorded variation ; 

 the time at which it begins depends in each case on the distance of 

 the proximal contact from the seat of excitation.! 



In all of these instances the ligature acts as a block. Without 

 interfering with the condition of any other parts it kills the part 

 which it grasps and makes it incapable of transmitting the excited 



* Photographs 1, 2, and 3. — Curarised Sartorius kept for about twenty-four 

 hours in 0'6 per cent, solution of chloride of sodiuni. Temperature during obser- 

 vation 9° C. Contacts, &c, as in Diagram 5, but p much nearer to d. 



t An experiment of this kind is by far the most exact method which we possess 



of measuring the conduction -rate in muscle. This rate is most correctly expressed 



, L . , . , Difference between the distances -, . , 



by the quotient = - as measured in two experiments 



Difference between the times 



in which the distances are different. 



