ON ELKCTRICAL CHANGES IN MAMMALIAN NERVE. 457 



(6) Experiments have also been performed with reference to the 

 question of the dependence of the E.M.F. of demarcation source upon tlie 

 sectional area of the nerve and number of individual tibres contained in it. 

 It has been found that the laying of two nerves side by side with their 

 cross-sections upon the same electrode does not increase the available 

 E.M.F., whilst adding to the current by a diminution of resistance ; but 

 that if one of the nerves is drawn along the other and away from this 

 electrode, so that the cross-section of one remains upon the electrode, but 

 that of the other is removed from it, but lies in contact with the longi- 

 tudinal surface of the first nerve, then there is an increase of the available 

 E.M.F. This summation of the E.M.F.'s, due to either singly, increases 

 with the distance between the two cross-sections up to a certain limiting 

 distance when the maximum summation is reached, It is believed that 

 from the details of such experiments interesting evidence can be obtained 

 of the position and limits of the demarcation source and current within 

 the nerve. 



The experiments also provide a considerable amount of evidence as to 

 the dependence of the available E.M.F. between cross-section and longi- 

 tudinal surface upon the distance of point on longitudinal surface from 

 the cross-section. It is believed that the E.M.F, increases up to a certain 

 point when a maximum is i-eached, and that this maximal value is obtained 

 until the second cross-section at other end of nerve is approached. 



It is also believed that a similar law is true for longitudinal currents, 

 as also for electrotonic currents, namely, that with the proximal electrode 

 upon a fixed point the removal of the distal electrode further and further 

 from this point produces the same kind of variation. 



In addition it is reported that in reference to the further error to which 

 it was conceived the variations -of blood-pressure in the blood-vessels of a 

 mammalian nerve might give rise — namely, to electromotive phenomena 

 similar to those recorded in case of the carotid and femoral arteries — a 

 number of experiments have been conducted to decide the causation of 

 this phenomenon. It was considered for purposes of further experiment 

 that its causation might be due to (1) changes in the muscular walls of 

 arteries ; (2) variations in a conceivable current due to frictional How 

 through the peripheral vessels. 



Experiments carried out upon these two lines have produced some 

 evidence in support of (1), but none in support of (2). In case of the 

 latter supposition the perfusion of saline solution through excised organs 

 under varying pressure was not found to be productive of any current 

 changes other than such as might be explained by changes of resistance 

 &c., which were also measured. 



The Physiological Effects of Peptone and its Precursors tuhen introduced 

 into the Circulation. Report of a Committee., consisting of Professor 

 E. A. ScHAFER, F.U.S. {Chairman), Professor C. S. Sherring- 

 ton, F.E.S., Professor R. Boyce, and Professor W. H. Thompson 

 (Secretary). (Drawn up hy the Secretary.) 



During the year, control work arising out of the research was in the 

 first place brought to a completion and will shortly be published. This 

 deals with the influence which the solvent employed in the peptope 



