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



Before leaving the subject of the strychnine reflex, I must refer very . 

 briefly to such previous observations as bear on our present inquiry. 

 The phenomenon is of interest as being one which could not have been 

 discovered had we not possessed the capillary electrometer. Its dis- 

 covery was, indeed, the outcome of the first attempt made by Professor 

 C. Loven to use that instrument for the investigation of the electrical 

 properties of muscle just twenty years ago. He was good enough to 

 make for me the electrometer which was used in some of my own 

 earliest experiments. Shortly afterwards, Mr. Page devised the 

 method of obtaining photographic records of our own results and, 

 amongst others, of those of Loven relating to the strychnine spasm. 

 Loven's observation has served ever since as a support for the doctrine 

 of discontinuity. No one would be tnore willing than he would, if he 

 were with us this afternoon, to recognise its true meaning. 



The conclusion to which all the facts we have had before us up to 

 this moment lead, is that normal muscular action is the manifestation 

 of what happens in the motor nervous system. If this motor impulse 

 is so short that we are obliged to call it instantaneous, the response is 

 correspondingly brief ; if it lasts longer, we call it continuous, recognis- 

 ing that the difference between the two is merely one of duration. 

 In either case it is of the essence of the response that it is terminable. 

 There is no difficulty in understanding on teleological grounds why a 

 muscle must relax ; but of the mechanism by which it is brought about 

 we know little, excepting that it is localised in the muscular structure. 

 Each element — each tagma — returns to its status quo in the same way 

 in a curarised muscle as in a normal one ; but whether this power of 

 recovery is a process by itself, as some physiologists hold, is a question 

 which is at this moment much debated, but by no means settled. It is , 

 only in so far as it relates to the electrical concomitants that it here 

 concerns us. Without prejudice to the question whether, as Fick and 

 Gad maintain, the relaxation of a muscle is dependent on a special 

 chemical process or not, it falls within our present scope to inquire 

 whether by comparing with a normal muscle, one which not only does 

 not relax but has been deprived of the faculty of relaxing, we can 

 arrive at any electrical indication of such a process. Fortunately we 

 have within reach a means by which this experiment can be made. 



The Continuous Response of a Veratrinised Muscle. 



The alkaloid veratrine* is an agent by which a muscle excited by an 

 instantaneous stimulus is deprived of its power of recovering itself . 

 The quantity of the alkaloid required to produce the effect is extremely 

 small. The addition of one part in a million of veratrine to the 



* The reratrine used was kindly prepared by my friend Professor Dunstan, 

 F.R.S. 



