TEANSACTIONS OF SECTION A. 637 



aud since 



^v ^ 1 '^^^^ '■ " ^' ^'^ " ^''■^' ^® "°* '^'^'^®" 



If tlie objection be valid, it is not evident whetber we should use F or F,. 



8. But Poisson's equation requires only that, however small be the radius 'a' 

 of a sphere described about x y z, 



p4n-;--v=Ff/;- = - 47r {"inr'^ud)' 



and that is satisfied by both F and F,. For the purpose of Poisson's equation we 

 may use y-F and V'F, as interchangeable. 



9. Since — has different values for different waves, Fj should be the sum of 



dt 

 a number of terms of the form C6), each corresponding to a wave-lenpth. 



10. £t seq. — A calculation is made of the effect of using F( instead of F in 

 case of a disturbance spreading in spherical waves from a source. 



SATURDAY, SEPTEMBER 8, 

 The following Reports and Papers were read :— 



1, Report on Determinincf the Magnetic Force on Board Ship, 

 See Reports, p. 45, 



2. Final Report on the Sizes of Pages of Scientific Periodicals. 

 See Reports, p. 45. 



3. On the Similarity of Effect of Electrical Stimidus on Inorganic and 

 Living Substances. By Jagadis Chundee Bose, M.A., D.Sc, Pro- 

 fessor of Physical Science, Presidency College, Calcutta. 



If we take a piece of living tissue, say a piece of muscle, and subject it to an 

 electric stimulus, there will be produced a contraction; the stimulus causes a 

 rearrangement of the particles of the living substance by which the form of muscle 

 is changed. On the cessation of stimulus the muscle, recovering from the mole- 

 cular strain, gradually attains its original shape. The effect of stimulus on nerves 

 is, however, not apparent ; there is no change of form. The molecular disturbance 

 due to stimulus can, however, be detected in an indirect manner from certain 

 electromotive variations that are produced. If now a mass of metallic filings be 

 taken and subjected to electric shocks, there is no visible change. The substance 

 appears to be irresponsive or dead to stimulus. Are inorganic substances then 

 really irresponsive ? Could this apparent want of response not be due after all to 

 our inability to detect the profound molecular changes that may have nevertheless 

 taken place in the substance under the action of stimulus ? In nen'es it is seen 

 that the molecular changes can only be detected indirectly by an electric method. 



The author describes an electric method based on the variation of conductivity, 

 by which the molecular change due to an electi'ic stimulus in an inorganic 

 substance is detected and measured, CurvBS are in this manner obtained with the 

 conductivity v.ariation (proportional to molecular effect) as ordinates, and the time 

 of exposure to the stimulus or the time of recovery from the effect of stimulus as 

 abscisare. ' 



It is next shown that the effect on matter of electric stimulus, of widely varying 



