and Plants to the Elect rical Phenomena associated with it. 59 



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

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

 to " veratrinise " 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 muscular contraction being regarded, as I have 

 said, as discontinuous, the relation between it and the continuous con- 

 traction of veratrinised muscle has not been sufficiently considered. 

 AVhen therefore we set to work to measure the m aximum contractile 

 effect of a " veratrine spasm," I was both surprised and gratified to 

 discover that the tension of a veratrinised muscle* when excited by a 

 single instantaneous stimulus, was as great as that of a similar but 

 un veratrinised muscle when subjected to a succession of stimuli, i.e., 

 when artificially tetanised. 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 (Photo. 11) and found it to 

 be identical with that of an artificial tetanus produced by a succession 

 of stimuli of sufficient frequency. Its true character can be best 

 judged of by comparing it with Photo. 1'2, which was obtained by 



introducing into the unchanged circuit a constant difference of potential 

 in the way before explained (p. 54). 



The fact that the veratrine spasm has the mechanical and electrical 

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



* Electrical response of curarised and veratrinised Sartorius to an instantaneous 

 stimulation. Leading off contacts at middle and tibial end, exciting electrodes 

 near pelvic end. The initial rise of the curve is steeper than that of the comparison 

 curve (Photo. 12). 



