Transmission-time of Reflexes in Spinal Cord of Frog 63 



conclusions that one kind of cell behaves in a diflferent way from another 

 to the same drug, the one having its excitability increased greatly, the 

 other remaining wholly unaflected. They rather suggest, so far as they 

 have gone at present, that strychnine can increase the charge made by both 

 the sets of cells ; but that in the one case and not in the other it has first 

 to bring them into array, and that the difference lies not so much in the 

 cells themselves as in the way in which collateral or other fibres are 

 distributed to the one or the other. With regard to these matters, it seems 

 to me that the electrical responses of muscle, when recorded photographi- 

 cally by such an instrument as the capillary electrometer, are capable of 

 giving information about the physiological stimuli which evoke them 

 which can never be obtained from records of the mechanical response 

 alone. 



It will give me pleasure to supply any physiologist with copies of 

 photographs relating to any particular experiment in which he may be 

 interested. A great deal of the value of some of the experiments lies 

 in the resemblances (or differences, as the case may be) between the 

 records of successive responses, and it is only samples of them, and those 

 only of comparatively few experiments, that could be reproduced within 

 the limits of this paper. 



All the experiments described in this communication were made with 

 apparatus which belonged to Sir John Burdon-Sanderson, and on which 

 he had spent a great deal of labour, time, and money in trying to make as 

 complete as possible. I had already been using it in its different stages for 

 some years, and any work that has yet been done or will be done with 

 it may in a sense be regarded as a continuation of his work. That 

 this should be continued, and that what was already done in his lifetime 

 should be made use of to the fullest extent possible for suggesting new 

 lines of research and for the acquirement of new knowledge, is, I feel sure, 

 the tribute to his memory which he himself would most desire. 



The recording part of the apparatus was made under the direction of 

 Mr H. S. Souttar, by whom it was to a considerable extent designed. 

 He has also supplied me with the very quick capillary electrometers with 

 which all the records have been obtained, and I am greatly indebted to him 

 for so doing. I have also to thank Professor Sherrington for valuable 

 criticism and for the interest he has taken in the work. 



The working expenses have been defrayed out of a grant from tlu' 

 Government Grant Committee of the Royal Society. 



