€0 Prof. J. Burdon-Sauderson. Relation of Motion in Animals 



Photograph 12.* 



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

 evidence it affords that discontinuity is not essential to energetic 

 display of contractile force. In this respect it would be wholly 

 irrelevant to object that the data derived from experiments on a 

 poisoned muscle cannot be applied to a normal one. All that it is 

 required to prove is that it is possible for a spasm which is not dis- 

 continuous to be as effectual for the doing of external work as a normal 

 contraction. It can hardly be disputed that the contraction of a vera- 

 trinised muscle is continuous. It is, therefore, no longer possible to 

 assert that discontinuity is essential to functional capacity. 



That our results differ from those of other observers is to be 

 attributed to the mode of using the alkaloid, and to the homoeopathic 

 minuteness of the dose. We estimate the quantity of veratrine which 

 actually enters the muscle not to exceed 1/10,000 milligram. 



The Heart 



We now turn from the skeletal muscles to the organ by the 

 rhythmical contractions of which the circulation is maintained. The 

 mechanical response of cardiac, like that of skeletal, muscle can be 

 evoked either directly or indirectly, but the heart has this peculiarity 

 that each part of it has attributes which we are accustomed to regard 

 as nervous rather than muscular. It has above all the property which 

 belongs, as we have seen from our experiments with strychnine, to the 

 motor cells of the spinal cord — that of discharging itself rhythmically 

 when in a state of continuous excitation. It is characteristic of heart- 

 muscle that it exhibits alternating periods of rest and activity, and we 

 have now the clearest evidence that it is not in virtue of its possessing 



* Comparison curre obtained by leading off from the compensator a current of 

 E.M.F. equal to that of the " action current " ; leaving the unexcited muscle in 

 circuit. 



