MOTION IN ANIMALS AND PLANTS. 847 



comitants that it here concerns us. Without prejudice to the ques- 

 tion whether, as Fick and Gad maintain, the relaxation of a nuiscle 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 ])e made. 



THE CONTINUOUS RESPONSE OF A VERATRINIZED 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 

 physiological salt solution in which a nuiscle has been kept for several 

 hours is sufficient to give it this property, or, as it may be expressed, 

 to " veratrinize'' it thoroughly. The alteration of the properties of a 

 muscle by veratrine in such a way that it must continue an effort 

 once begun has been long known. It is an example of perfectly 

 continuous contraction. Normal uuiscular contraction being regarded, 

 as I have said, as discontinuous, the relation between it and the con- 

 tinuous contraction of veratrinized muscle has not been sufficiently 

 considered. When, therefore, we set to work to measure the maximum 

 contractile effect of a "'veratrine spasm," I was both surprised and 

 gratified to discover that the tension of a veratrinized muscle when 

 excited by a single instantaneous stimulus was as great as that of a 

 similar but unveratrinized muscle when subjected to a succession of 

 stimuli, i. e. , when artificially tetanized. It can also lift as great a 

 load and hold it up for several (10-20) seconds at as great a height. 

 (Tracings shown.) 



We then proceeded to investigate the electrical concomitant of the 

 veratrine ''tetanus," if I may so call it (photograph 11, PI. IV). and 

 found it to be identical with that of an artificial tetanus produced Ijy 

 a succession of stimuli of sufficient frequency. Its true character can 

 be best judged of b}^ comparing it with photograph 12 (PI. V), Avhich 

 was obtained by introducing into the unchanged circuit a constant 

 difference of potential in the way before explained. 



The fact that the veratrine spasm has the mechanical and electrical 

 character of a continuous contraction is of value, not from its bearing 

 on the mode of action of a particular chemical substance, but from the 

 evidence it affords that discontinuity is not essential to energic dis- 

 play of contractile force. In this respect it would be wholly irrele- 

 vant to object that the data derived from experiments on a poisoned 



^The veratrine used was kindly prepared by my friend Professor Dunstan, F. R. S. 



