

Influence of Temperature upon Electrotonic Currents. 383 



material, like clouds of water on the earth, but in view of the high 

 solar temperature it seems improbable that any body, except, perhaps, 

 carbon, could exist in any condition other than the gaseous state in 

 the solar atmosphere ; so that it seems more probable that sun-spots 

 are due, at least partly, to reflection by convection streams of gas, 

 rather than by clouds of transparent solid or liquid particles. 



" Influence of Alterations of Temperature upon the Electro- 

 tonic Currents of Medullated Nerve."* By AUGUSTUS D. 

 WALLER, M.D., F.R.S. Received December 14, Read 

 December 17, 1896. 



(Abstract.) 



The effects of a rise of temperature upon electrotonic currents 

 may be briefly stated as follows : 



1. The ordinary electrotonic currents, A and K, are temporarily 

 diminished or abolished at about 40. 



2. At about 30 of a rising temperature the K current is increased 

 without notable alteration or with actual diminution of the A current. 



3. On returning from 40 towards the normal (15 + 2) tempera- 

 ture, the A and K currents reappear. K is increased and A is 

 diminished, so that the previous normal inequality A > K is 

 diminished, or actually reversed to A < K. In all cases the quotient 

 A/K is diminished ; in some cases it actually falls below unity. 



[The negative variation is temporarily abolished at about 40 ; a 

 positive gives place to a negative variation in consequence of a 

 raised temperature to 40.] 



The above three statements are illustrated by Experiments 2366, 

 2322, and, from the examination of their records, it will be clear 

 that there is here no question of the effects being due to alterations 

 of resistance. A and K are tested for alternately, and the deflection 

 by O'OOl volt is taken at intervals of about ten minutes. [Other 

 examples of a similar character are given in the * Proceedings of 

 the Physiological Society' for November, 1896, and a record of 

 temporary diminution of the negative variation is given in fig. 12 

 (Experiment 777), * Phil. Trans.,' 1897.] 



* In all the experiments referred to in this communication, the polarising cur- 

 rent is by one Leclanche cell (the resistance in its circuit being about 100,000 

 ohms). The nerve lies upon four unpolarisable electrodes fixed at intervals of 

 12 mm., serving as leading-in electrodes to the polarising current and leading-out 

 electrodes to the electrotonic current. On the galvanometer records, the anelectro- 

 tonic deflection A reads upwards, the katelectrotonic deflection K reads downwards ; 

 aiter-anelectrotonic and after-katelectrotonic deflections A' and K' read respectively 

 downwards and upwards (there being under the conditions of experiment no 

 marked homodromous after-katelectrotonic deflection). 



