and Plants to the Electrical Phenomena associated tvith it. 57 



although the reflex spasm resembles a short artificial tetanus as regards 

 the way in which the muscle contracts, the contractions are shown by 

 their electrical concomitants to be of a different nature. The strych- 

 nine spasm, as it is rightly called, is seen not to be a tetanus, i.e., not 

 to consist of a series of single twitches, but to be a succession of con- 

 tinuous contractions, the rhythm of which depends on the spinal cord, 

 not on the muscle. 



Photograph 10.* 



The grounds on which this conclusion is founded appear to me to be 

 unequivocal. The observation is a simple one. The automatic 

 mechanism, which carries the photographic plate, liberates as before, 

 at the beginning of the period of exposure, an induction current which 

 pricks the skin of the preparation. After an interval which may be 

 about a tenth of a second (during which a ^^^si-psychological process is 

 going on in the spinal cord) the muscle responds. A curve is drawn 

 simultaneously by the writing lever to which the end of the muscle is 

 attached, which indicates that it is in spasm ;f but it is the photo- 

 graphic curve which tells us the nature of that spasm. Each ascent of 

 the meniscus is seen to be the response, not to a single instantaneous, 

 but to a short continuous, stimulation, of which the duration can be 

 easily deduced by measuring the time interval between the beginning 

 and the culmination of an excursion. By subjecting the muscle arti- 

 ficially to series of excitations of similar duration with corresponding 

 intervals of inactivity, one can produce an imitation of the strychnine 

 spasm which, both in its mechanical and electrical characters, resembles 

 the natural one (see Photo. 7). 



* Freshly prepared Sartorius attached to pelvis and connected to spinal cord by 

 its nerve. Leading off electrodes on hilus and tibial end. Exciting electrodes 

 applied close together to skin of flank of decapitated preparation. 



f The curve is often toothed, the teeth corresponding in frequency with the 

 electrical undulations. 



